Thinking of getting an sdr dongle - is there much interesting stuff going on around t

euser1984

For somebody with a curious mind, but not a particular interest in hobby radio; is it worthwhile getting a DVB-T dongle to satisfy my curiosity?
If so, can someone recommend one on ebay? I'm interested in developing and buying antennas, so there wouldn't be a problem there if the desktop omni antenna isn't good enough.
Thanks.

jmcc

Yes. However the sensitivity of many of these SDR dongles is not going to be as good of that of a scanner or dedicated radio. But they are very interesting devices. The other aspect is that the antennas you are using matter. The stock antennas that come with most of them are not really any use. A good antenna for the band in which you are interested makes a lot of difference but some transmissions are strong enough to be picked up easily even on the stock antennas. Even the stock antennas can pick up broadcast FM, some aircraft voice traffic, aircraft transponder (squawk) data, some amateur radio transmissions.

It would be best to get an SDR from a reputable manufacturer like Nooelec ( www.nooelec.com )rather than a no-name brand one from eBay. I've two here from Nooelec. (You can actually order them via Amazon.co.uk). They are slightly more expensive than the others but they do seem to be more sensitive and the better Nooelec ones have a temperature compensated crystal oscillator (TCXO) instead of an ordinary quartz crystal oscillator. (The SDR dongles can get warm when operating so without a TCXO, there can be a bit of drift in frequencies.

The connector on the SDR dongles can be an unexpected issue. The better ones use SMA connectors but a few also use MCX (an even smaller microwave connector) but these generally have an adapter (typically MCX to SMA) supplied. If you are going to develop antennas, then it might be best to get an adapter for the SDR to the connector type that you use generally. A lot of ham radio stuff uses BNC connectors for the VHF/UHF bands and sometimes N connectors for UHF and low microwave frequencies. Cable types like RG58, RG213 are also readily available but it is best to use a pigtail (a piece of coaxial cable with the relevant connectors on both ends rather than connecting the antenna cable directly to the dongle.) The SMA connectors are generally good to about 10GHz but they are literally gold plated and can cost about six Euro or so each. By using a common connector format, you can use cheaper connectors and may already have the cabling, connectors and crimp tool to hand.

The SDRs nominally have a 75 Ohm impedance but a lot of Ham gear, and other transmission gear has a 50 Ohm impedance. It is possible to use 75 Ohm cable such as RG59 and RG6 along with F-connectors for experimentation and the mismatch should be small. RG59 and RG6 cable, along with F-connectors should be a lot easier to find than SMA connectors and RG174 cable and crimping tools. Alternatively, there are suppliers like Radionics or Farnell but the crimping tool for SMA connectors can cost over €40 so it may be a better strategy to change to a cheaper connector type for experimentation unless you do the kind of RF development work that requires SMA connectors. A lot of the add-ons like low noise amplifiers, up-converters and filters also use SMA connectors.

The software available for these SDR dongles is amazing. It effectively gives you your own spectrum analyser in addition to the various data decoders. If you want to build filters, it is possible to use an RF noise source (there are plans available on the web to build cheap and nasty versions) and the SDR and software to tweak filters. While this is not going to be on the same level as professional gear, it is thousands of Euro cheaper than a professional spectrum analyser and noise source.

There are some good sources on the web for information and Reddit has a section specifically for SDRs. The RTL-SDR blog is a good place to start as it does have a lot of interesting data in addition to having published a hobbyist's guide to SDRs. ( http://www.rtl-sdr.com/ ). There's also a blog by a chap in Cork ( http://www.radioforeveryone.com/ ) that might be interesting.

If you are thinking about using the SDR for shortwave/HF work, it might be better to get an upconverter or an SDR like SDRplay which can handle HF rather than a modified SDR. There is a few types of upconverter on the market and they each have their own merits. However HF does seem to be hammered by other devices in the radio spectrum such as switch mode power supplies and other computer/TV interference. You may want to get a USB extender cable so that you can place the SDR dongle and antennal as far away from your computer as possible.

Regards...jmcc

euser1984

Fair play for this concise effort: I'll have to go back over it again and read more carefully.....what type of antenna would you recommend - parabolic? omni? and what Dbi?
Will I need a few antennas to scan from 100 hz right up? I'm only starting in the antenna stuff and I know that in  my experience each antenna has a limited amount of frequency range.....such as 2.4Ghz; also have some dual band ones....I'm assuming that those desktop omnis they come with cover a very wide range?

jmcc

euser1984 wrote: »

Fair play for this concise effort: I'll have to go back over it again and read more carefully.....what type of antenna would you recommend - parabolic? omni? and what Dbi?

It depends on what you want to receive. The SDRs have a limited range typically from around 27 MHz to 1.7GHz depending on the tuner but the reception quality and sensitivity can vary over that range.

Will I need a few antennas to scan from 100 hz right up?

Very low frequencies (think below Medium Wave/Long Wave (time signals and other stuff) tend to require different antenna types due to the wavelength but they can use what are effectively coils wound on a ferrite former much like the ones in MW/LW/SW radios. For shortwave/HF, you are going to need a longwire (essentially a long piece of copper wire) or an active antenna and an upconverter along with the SDR. Most SDRs do not cover very low frequencies or HF frequencies.

It is possible to use a wideband antenna like a discone which would give some coverage from about 120 MHz to about 1.2GHz depending on the design but with higher frequencies/shorter wavelengths, you might be better off going for band specific or directional (parabolic, Yagi etc) designs. Noise and amplification are also an important aspect to examine as some SDRs have poor sensitivity and a low noise amplifier can solve some of those problems. There are wideband LNAs available (I think that the LNA4ALL one is about €20 plus postage.)

I'm only starting in the antenna stuff and I know that in  my experience each antenna has a limited amount of frequency range.....such as 2.4Ghz; also have some dual band ones....I'm assuming that those desktop omnis they come with cover a very wide range?

The desktop antennas are very much like pieces of string in terms of reception. They will work well for broadcast FM and will pick up nearby Ham radio stuff and some other stuff. But you can't expect the performance of a scanner and good antenna from an SDR dongle and a stock antenna.

If you want to learn about antennas and see immediate results, you could experiment with receiving aircraft transponders (A-DSB) which transmits at 1090 MHz. The wavelength is short enough to make it easy to play with antenna designs and test which provides the best results. There's mapping software that will take the decoded data bursts and plot them on a map. A better design will result in more data packets received and the increased range can be seen on the screen. This is a lot better for experimentation than relying on Ham radio where there can be little or no traffic. Because the aircraft are relatively high, you can receive data from aircraft up to 150 miles away or so. (The desktop magnetic antennas supplied will do that.) When you've got used to playing with antenna designs, you can the scale designs them for other frequency bands to see how they operate.

There are also weather satellites that can be received. They might be interesting exercises for larger antennas like helicals. Parabolic antennas tend to be better at higher frequencies but some weather satellites operate around 137 MHz and other designs, like the helical antennas, would be better due to the gain of a parabolic antenna being linked directly to the wavelength of the frequency.

With antennas, you've got to think in engineering terms rather than software terms. Look at what you want to receive, the frequencies involved and the power levels involved. Sometimes it is better and cheaper to have a dedicated antenna than a wideband antenna for particular bands. It is even possible to make decent antennas from properly cut pieces of coaxial cable (Coax collinear) or even pieces of wire (J-pole, quarter wave ground plane antenna etc). This site has a caculator for a few different designs (mainly for 1090 MHz experimentation from the photos) but the calculators allow you to enter different frequencies. ( http://jeroen.steeman.org/Antenna/Antenna-Design-Calculators )

Regards...jmcc

euser1984

After reading above and to iterate your thoughts, a desktop antenna will be good enough for the aircraft ADS-B correspondence. I suppose that could be an interesting start....I thought that traffic needed one of these antennas - https://www.flightradar24.com/files/free-ads-b-equipment-67_400.jpg

Is that a yagi mounted vertically? (attached link to picture) Or just an omni - the antenna linked above seem to be quite expensive....

jmcc

euser1984 wrote: »

After reading above and to iterate your thoughts, a desktop antenna will be good enough for the aircraft ADS-B correspondence. I suppose that could be an interesting start....I thought that traffic needed one of these antennas - https://www.flightradar24.com/files/free-ads-b-equipment-67_400.jpg

Well I've a stock desktop antenna (one of the magnetic telescopic ones that came with the dongle) picking up ADS-B data here and it sitting on top of an upturned biscuit tin as the ground plane as an experiment. It is working. The good thing about the ADS-B transmissions is that they are quite narrow bandwidth and the transmitters are very high so you can get far more range on them than you would for a terrestrially based receiver and transmitter over the same distance.

Is that a yagi mounted vertically? (attached link to picture) Or just an omni - the antenna linked above seem to be quite expensive....

It is an omni (a Yagi is typically a number of elements (reflector, driven element and director(s)) and is directional). The good thing about the frequency is that the antennas are physically small and easy to build.
( http://jeroen.steeman.org/ADSB/Antenna-Comparison-Tests ).
That image might be an end fed J pole or a Slim Jim or a Collinear. ( http://jeroen.steeman.org/Antenna/Antenna-Design-Calculators )

You can also see immediate results from any antenna experiments because you will receive more data packets with better placed and designed antennas.

Ireland has a busy airspace. There's the usual transatlantic traffic and there's also a lot of traffic between Irish airports and the UK.

Regards...jmcc

Indeed a very addictive hobby, I have an SDRPlay, MK I. But have no proper antenna yet because I'm moving soon and did not want to go to the hassle of setting up another antenna.

Shortwave, 100 Khz - 30 Mhz is pretty mysterious, all sorts of signals. It will require a sizeable antenna and may not be suitable for town and city gardens and can suffer form radio interference from all sorts of modern gadgets such as mobile chargers, LCD TV power supplies, laptop power supplies, LED Lights , all made in China with very poor filtering of radio interference.

You can also receive weather satellites.

A dedicated SDR receiver like the SDR Play will work out of the box with nothing else to do apart from install a proper antenna for the bands you want to use.

The cheap dongles require a converter to work on the lower frequencies such as shortwave and are less complicated to set up. The best thing about the likes of the SDRPlay is that it performs as good as a receiver costing hundreds of euro's more.

You can also receive DRM digital radio or Digital Radio Mondiale, it's amazing to receive signals from countries thousands of miles away crystal clear on shortwave radio.

If you live in an urban environment then a magnetic loop antenna will work best and will be easier to install, externally is best.

Here's a link to the SDRplay.

http://www.sdrplay.com/

briany

I'd also be interested in getting one of these dongles. I have questions about signals I can pick up, though, if anyone would indulge me...

1. I've been doing a little bit of reading on the subject of suitable antennae for picking up a signal, and it's my understanding that it comes down to the length of your antenna (oo-er). So, if I want to pick up shortwave stations in the HF band (99-10 metre wavelength), I should be looking at an antenna that is, at minimum, a 1/4 of the wavelength I'm trying to pick up, e.g. a 2.5 metre antenna for 10 metre WL (30 MHz). But, that's minimum, and really the longer the better.

But, if I go on to Amazon, and type in 'shortwave radio', I come across something like this , the Tecsun PL-880. It's listed as a Shortwave/Longwave radio, and there are even customer reviews stating it picks up shortwave clearly without the need for a longwire antenna plugged in.

Now, I'm thinking how can this be, because, looking at the included aerial, I can't think it's that long. Certainly not the apparent 25 metres it would need to be in order to cover the whole HF spectrum. So, what's going on there? Is there also a significant factor of distance from the transmitter? Do you think they're simply paid shills? Do radios like this include an amplifier that will boost SW and LW signals? If so, what's the difference in, say, signal noise vs just a really long antenna?

Hmm, this question turned out longer than I expected...

Try spend extra and avoid dongles, they're not really designed for radio applications and you will most likely be disappointing by the noise.

Spend a bit extra and get the SDR Play RSP1A and it will make a big difference. available here at Radionics in Dublin , it's U.K stocked so you'd have to order it first, they'll deliver or you can pick up in their store. I highly recommend the RSP1A over any dongle. + wioth a dongle you'll most likely have to purchase a up converter because the dongle isn't designed to work on shortwave,LW or MW.

https://ie.rs-online.com/web/p/radio-frequency-development-kits/1503954/

The dongles can be plagued with noise.

Better again is the Airspy HF+, it's a very low noise very sensitive SDR and miles better than any of those dongles but it needs a very good low noise antenna. The Airspy receives frequent updates but as I said it needs a very good antenna and proper quality Coax better would be HF 155 it's the best for noisy environments. I'll explain more about noise in a bit. The HF+ can be got further down the road when you're more into the hobby.

The Tecsun PL-880 is a very good radio and gets good reviews , it is sensitive, the radios are designed to work with their built in telescopic antennas and are tuned to be much more sensitive with their telescopic but it's obviously limited by size and if using indoors.

Noise, Noise is atmospheric ( Thunderstorms) and created by man made electronics such as switch more power supplies and older LCD tv's with fluorescent back light. Plsama tv's but not too many of those now.

Mobile phone chargers can be really bad also laptop power supplies and bad quality led light bulbs.

You can and will even pick up lots of crap from your neighbours if you live in an apartment or housing estate.

What I did was turn off the house electricity at the consumer to hear the difference it made and it was big so I went around with a small portable radio on medium wave to eliminate sources of noise or known as RFI or QRM which means man made noise.

There's nothing like having a physical radio in your hands which SDRs can't replace , the tecsuns are good on SW but not so good on LW/MW. But the real stuff is on SW.

You can attach 20-30 feet of cable out your window and attach to a tree and tie it to the telescopic antenna and see the difference it makes then you can experiment with different antennas but you can over load the radio with strong signals too.

With your SDR you'll need a proper antenna, try something like this https://hamradioshop.net/en/Antennas/MegaLoop-FX-Active-Loop.html

Get the 10 meter version. It's fantastic for receiving and low noise if you live in an area with lots of noice loops can really help , wire antennas such as dipoles are good for transmitting but are noisy. The Bonito loop is expensive but a radio is only as good as it's antenna.....

You could also try this loop https://hamradioshop.net/en/Antennas/H-Field-active-Loop-Antenna/Paloran-200-passive-Loop-Antenna.html

It's passive meaning no built in pre-amplifier and has the potential to be even quieter , amplifiers amplify everything including noise. The passive loop is larger too to compensate for having no preamp and if you have the space, it's 15 meters, I'd actually install that. In my opinion it will be far better than any wire antenna you will use.

Speaking of power supplies, I had to replace some of them with linear supplies from China, I replaced the Satellite receiver and broadband modem power supplies and also my Kiwi SDR.

If you want to hear my Web SDR with the amplified Bonito FX 10 meter Loop you can have a play with it here. http://emeraldsdr.ddns.net:8073/ If you can stay up late you can hear interesting radio stations past Midnight. on 5040 Khz in the 60 Meter band you will hear a station called Radio Havana Cuba and it can be quiet interesting. Signal varies and conditions are not the best lately but this is the way it goes, one day a station will belt in loud and clear and another day you'll hardly hear it.

At 2am Radio Havana Cuba will transmit on 6000 Khz in the 49 meter band and also 6165 Khz, 6 Am on 6060 Khz and 6100 Khz.

Check out this site and it will give you the times of stations and their schedules and frequencies. http://www.short-wave.info/index.php

Radio New Zealand International can also be picked up on 9700 and 9765 from 8am.

You can also hear interesting stations from the U.S after midnight and as the night goes on. When I work nights I get to hear a lot of interesting stuff on my web SDR.

If I were you I would get the Tecsun and get the feel for having a radio in your hands, get one of these https://www.amazon.co.uk/Tecsun-External-Antenna-Improve-Performance-AN03/dp/B01BRG3CPA/ref=sr_1_2?ie=UTF8&qid=1519161956&sr=8-2&keywords=shortwave+antenna and connect it to the telescopic antenna.

If you pick up lots of static and noise then get in the car , bring the radio and long antenna reel with you drive to somewhere quiet and see the difference it makes.

I hope I didn't overload you with too information, before you get the Tecsun PL-880 have a play with my SDR here http://emeraldsdr.ddns.net:8073/ then you can compare this to signals you pick up or if you hear signals on mine and don't on yours you can figure out why, is it the antenna, is it noise from my house, neighbours etc oh and you can easily connect the passive 15 meter Bonito Loop to the Tecsun too if you want using a BNC to 3.5mm adaptor. https://hamradioshop.net/en/Coax-cables/Adapter-cable-BNC-to-3-5mm-jack-plug-oxid.html

And this https://hamradioshop.net/en/Antennas/Antenna-Accessories/Flat-Coaxial-Door-Window-Jumper-Cable-with-BNC-or-PL-connectors.html is dead handy for bring cables through windows rather than drilling holes !!!

You'll love this hobby, you obviously have the interest, any questions feel free to ask !

briany

Well, that's certainly a post and a half above ^^^^

That looks like some very good gear in the links, although between the time of my last post and this one, I already did put in an order on that RTL-SDR Blog V3 dongle and antenna bundle, just to dip a toe in, for now. But even if that's a disappointment, 23 Euro for the brief lesson isn't the end of the world. But as the dongles go, that dongle and, actually, that dongle bundle, seems well-received, so I'll give it a try and see how that goes, learn the software and just get used to it all.

In a sense I'm already aware of the noise issue that can plague a residential home nowadays, because I've spent time messing around with recording equipment and am constantly battling electrical noise and things like that. Under no illusion about it being any different with radio (and worse, even, because you're dealing with a whole other cacophony that recording equipment cannot necessarily pick up)

I have seen recommendations about the SDRPlay, and thought I would get that instead. That is until I saw the price, which I thought was just a bit beyond my range I was willing to spend. On the one hand, it's always good to buy good gear right out of the gate (anyone here ever regrettably bought 20 euro binoculars from Tesco?), but there is also that thing of buying something you fear you'll end up not using. But I see the RSP1A has a supposed frequency range of 1KHz up to 2GHz. Beyond whatever upconverter or other special technology it has going on inside to enable that kind of range, the antenna needed to fulfill that potential would surely need to be something special, being either very, very, very, very long, or one of those fancy active ones which cost a packet.

And it's nice to know the Tecsun is a solid SW radio, although, again just a bit pricey at this early stage. Is there a hardware radio below, say, 100 Euro that can capably pick up air and marine chatter and even some SW signals with a similar quality to the PL880? Because although I don't mind messing with software at all, I know a couple of people who would like to listen to that kind of radio traffic and would much prefer a hardware solution.

Best of luck with the SDR , at the price you can't go too far wrong.

The SDR Play RSP1 indeed does go all the way to 2 Ghz. I don't really have much interest beyond 17 Mhz.

Check out Shanwick at around 5649 Khz on USB mode too.

What antenna do you intend to use ? this will be the most challenging part of this hobby. Antenna and noise and believe me you will have your work cut out here to eliminate noise. But hopefully it won't be too bad for you. You can also get the likes of the Bionito passive loop somewhere down the line.

Try use the SDR with the laptop only running on battery.

There are a couple of radio options too you can get such as the below Tecsun R-9700 DX, I like this radio, it's not perfect but offers decent performance and has a backlight display, I just love analogue tuning radios for casual listening. It also has decent sound and makes scanning bands quick to see what bands are active or not. It does suffer from some imaging, but common on cheaper radios, for instance you could find a station on a frequency that it's actually not transmitting on which can happen at night when Shortwave is most active.

https://www.amazon.co.uk/R-9700DX-Sensitivity-Receiver-Speaker-Conversation/dp/B077HCYLC1/ref=sr_1_1?ie=UTF8&qid=1519166787&sr=8-1&keywords=R-9700DX

This radio if you prefer digital tuning, it would be more sensitive but poorer on Lw/Mw https://www.amazon.co.uk/Tecsun-PL310ET-stereo-Radio-Receiver-Black/dp/B00F8441WG/ref=sr_1_2?ie=UTF8&qid=1519167013&sr=8-2&keywords=tecsun+pl-310et Maplin also stock them, or used to.

Or just scan around on ebay, there are plenty of old radios both analogue and digital and I just love playing around with old radios.

briany

As it stands, I won't have any antennas to use besides the set that comes with the dongle. The set that comes with the dongle is, looking at an unboxing, 2 antennae that extend to a little over 1 metre each, and 2 that extend to slightly under half a foot, along with a base with a suction cup, and tripod legs you can screw in. And I think you're supposed to use two of these antennae at a time as the mount has seems to have two screw in connectors, giving the 'rabbit ears' (dipole?) type of antenna.

I'm not under any illusion that these will give me any kind of amazing reception, but I will still tool around with it because why not. But on the subject of this type of antenna, I know that they're supposed to be quite directional (the memories of struggling with those little old indoor terrestrial TV antennae are suddenly coming back), so the challenge of pointing them in the right direction to maximise the reception could be interesting.

What are the differences (besides the obvious) between a dipole and monopole antenna?

Also, per the recommendation on the reel antenna extender, can you just clip this onto the end of the existing antenna? Would any length of existing insulated wire do?

The reel antenna is really only good for clipping on to the already sensitive telescopic antenna of the likes of the Tecsun radios. Due to it's high impedance it wouldn't work on an SDR designed for an impedance of 50 Ohms not without an antenna tuner, this will match the impedance of the to the SDR and also try to match the antenna to a particular band your listening to but it's not the right tool for the job in reality, tuners are mostly required for transmitting on the likes of long wire antennas.

This site maybe of use http://www.antenna-theory.com/antennas/monopole.php

The antenna supplied with your SDR won't be much good for anything other than FM if it's the ones normally supplied.

If possible when funds permit definitely go for one of the Bonito Loops , preferably the larger passive one as the antenna is the single most important part of any radio. It will go to 200 Mhz only though so if you're interested in anything above this you're looking at another antenna.

Don't be discouraged if at first all you hear is lots of noise and buzzing with the supplied antenna on all but FM radio.

With the right antenna you can also pick up weather satellites.

Do you live in an estate, apartment, country etc ?

And try out my SDR to get an idea of what you can listen to on LW/MW and SW http://emeraldsdr.ddns.net:8073/

briany

Deleted User wrote: »

The reel antenna is really only good for clipping on to the already sensitive telescopic antenna of the likes of the Tecsun radios. Due to it's high impedance it wouldn't work on an SDR designed for an impedance of 50 Ohms not without an antenna tuner, this will match the impedance of the to the SDR and also try to match the antenna to a particular band your listening to but it's not the right tool for the job in reality, tuners are mostly required for transmitting on the likes of long wire antennas.

This site maybe of use http://www.antenna-theory.com/antennas/monopole.php

The antenna supplied with your SDR won't be much good for anything other than FM if it's the ones normally supplied.

If possible when funds permit definitely go for one of the Bonito Loops , preferably the larger passive one as the antenna is the single most important part of any radio. It will go to 200 Mhz only though so if you're interested in anything above this you're looking at another antenna.

Don't be discouraged if at first all you hear is lots of noise and buzzing with the supplied antenna on all but FM radio.

With the right antenna you can also pick up weather satellites.

Do you live in an estate, apartment, country etc ?

And try out my SDR to get an idea of what you can listen to on LW/MW and SW http://emeraldsdr.ddns.net:8073/

What about an active wideband antenna like the GIGACTIV GA3005, for example? That looks compact, well-built, and can cover almost the entire radio spectrum, or at least the bit that contains interesting listening, although I don't necessarily expect it to be as simple as that in trying to receive all those frequencies.

I live in an estate that is bordering on the countryside/coast.

briany

briany wrote: »

What about an active wideband antenna like the GIGACTIV GA3005, for example? That looks compact, well-built, and can cover almost the entire radio spectrum, or at least the bit that contains interesting listening, although I don't necessarily expect it to be as simple as that in trying to receive all those frequencies.

I live in an estate that is bordering on the countryside/coast.

I have no data on the GA3005 , I would assume that if you are interested in frequencies up to 3 GHZ then it's a good choice, but it's more susceptible to man made noise in the LW/MW/SW bands due to it being an E-Field antenna.

I have the MegActiv MA305 and it's a good antenna, amazing actually for it's size, I use it with the optional 40 Cm Whip also an E-Field Antenna. I live in a very quiet listening environment in the country, I used to live in a mid terrance an my neighbours older LCD TV wiped out all bands and unfortunately it was on most of the day until sometimes well after midnight. This is how bad some tv's can be. So now I'm in radio heaven !

You'll need to use Good screened coax such as HF155 with either of the Antennas and not the cheaper RG58.

Also on any radio, SDR you should use one of these https://hamradioshop.net/en/Antennas/Antenna-Accessories/Galvanic-Antenna-Isolator-GI300.html these are proven to help reduce noise but unfortunately they're out of stock at the moment.

You might find that on SW the Loops will provide better noise reduction and will work best on these bands.

With the Ma305 and GA3005 and the FX Active Loop antennas the optional power supply while very quiet in general will produce some noise in the LW/Mw bands so linears are your friend, I got some 5 volt for powering the Kiwi SDR and 12V for powering the broadband modem and satellite receiver the difference was amazing.

You can power all the Bonito antennas with one of those mobile phone booster batteries for mobile use also or for general listening, I just needed the linear because my Loop and Kiwi SDR are powered on 24x7x365 for the Web SDR.

Discover what bands you want to work , that would be a good start. Then get an Antenna to match. And eliminate noise sources from your house and mount any antenna as far away from any house you can will greatly help also.

The Loops and Ma305 are very portable too if you want to head off in the car some evening bring one of the USB booster batteries and you're all set.

briany

Deleted User wrote: »

I have no data on the GA3005 , I would assume that if you are interested in frequencies up to 3 GHZ then it's a good choice, but it's more susceptible to man made noise in the LW/MW/SW bands due to it being an E-Field antenna.

I have the MegActiv MA305 and it's a good antenna, amazing actually for it's size, I use it with the optional 40 Cm Whip also an E-Field Antenna. I live in a very quiet listening environment in the country, I used to live in a mid terrance an my neighbours older LCD TV wiped out all bands and unfortunately it was on most of the day until sometimes well after midnight. This is how bad some tv's can be. So now I'm in radio heaven !

You'll need to use Good screened coax such as HF155 with either of the Antennas and not the cheaper RG58.

Also on any radio, SDR you should use one of these https://hamradioshop.net/en/Antennas/Antenna-Accessories/Galvanic-Antenna-Isolator-GI300.html these are proven to help reduce noise but unfortunately they're out of stock at the moment.

You might find that on SW the Loops will provide better noise reduction and will work best on these bands.

With the Ma305 and GA3005 and the FX Active Loop antennas the optional power supply while very quiet in general will produce some noise in the LW/Mw bands so linears are your friend, I got some 5 volt for powering the Kiwi SDR and 12V for powering the broadband modem and satellite receiver the difference was amazing.

You can power all the Bonito antennas with one of those mobile phone booster batteries for mobile use also or for general listening, I just needed the linear because my Loop and Kiwi SDR are powered on 24x7x365 for the Web SDR.

Discover what bands you want to work , that would be a good start. Then get an Antenna to match. And eliminate noise sources from your house and mount any antenna as far away from any house you can will greatly help also.

The Loops and Ma305 are very portable too if you want to head off in the car some evening bring one of the USB booster batteries and you're all set.

Eliminating much noise may be difficult but I'll see how I get on.

What you can actually hear on SW/MW/LW - I've been listening to a number of web-based radios, including yours, over the last few days and it's been interesting to listen to things like the famous 'Buzzer' signal, for example. I don't think that listening to commercial channels on SW or below is that interesting simply because in the Internet age, any channel worth hearing is probably going to have a livestream online. But I can appreciate the satisfaction some could get from being able to pick up signals over large distances. And, of course, it's good to have shortwave as a redundancy strategy to pick up these channels in something like a power failure.

Other things I hear on SW/MW/LW - Steady tones, noises like a synth filter self-oscillating, Morse code (- - -.), and an old modem on the go. Sounds to occupy a frequency, or transmit data?

Do a lot of strange signals come and go if you monitor certain bands intently? Or strange channels, or strange people?

One reason I like scanning SW commercial stations is because you can really hear interesting conversations you wouldn't on streaming stations because you would most likely not bother to click on that station, Keep listening , you never know what you'll hear.

You can hear air traffic, look up shanwick frequencies.

Numbers stations, these are mysterious as hell, Spies in the field, real James Bond stuff.

Open my SDR and click Navtex then select the frequency and see what messages you can decode.

You can also use it to decide weather fax used by ships. Click on fax and in the box that comes up select various frequencies until you see a signal.

There's lots others but don't have time to get into it right now. All interesting stuff. But don't rule out listening to commercial SW, a lot of interesting stations become available after dark especially late at night.

Oh and you can decode digital DRM SW commercial stations too. Using a virtual audio cable and software called DREAM.

Chat later.

jocko4

I was only made aware of SDR recently by one of my customers who is into audio & SDR. I'm in Ireland & manufacture ultra low noise USB audio devices that run directly on internal LiFePo4 batteries & have high speed USB isolation. This customer is currently using a 4 port isolated USB hub (ISO-HUB) on his audio system & has just received an Airspy HF+ which he will be testing with/without the ISO-HUB. If anyone is interested I will post his impressions & link to my website?

Sure , post away.

jocko4

The customer won't have done his testing until this weekend so I'll report his impressions then.

But there are two devices that are obviously applicable to the SDR area for reducing noise:
- the first is a battery power supply (ISO-PS) which has some particular unique features - it uses Lithium nano ferrous phosphate (LiFePO4) - a very stable & safe battery technology which doesn't catch fire from over-charging or short circuiting, like other Lithium batteries are prone to do. It has none of the usual battery charge concerns as it's designed so that it can be used while also being charged without noise issues. Huge current output capacity (120Amps instant, 50Amps constant)

- the second, probably more interesting product, is a USB hub with 4 high speed isolated USB ports (ISO-HUB)

Both of these products would, I suspect, bring significant noise reduction advantages to SDR & if this proves to be the case, I may look towards incorporating this noise reduction technology together with an SDR device within a single aluminium case.Two advantages of this - the further noise reduction available by powering circuitry directly from the LiFePo4 batteries rather than through a voltage regulator which adds self-noise to the power - the elimination of the USB cable connecting USB isolation & SDR device.

In reading through stuff on SDR, I noted that a lot of the techniques being mentioned/used in SDR are the same ones that some audio designers involved in computer audio, are becoming aware of - ground loop noise issues; SMPS leakage currents; USB shield induced noise; USB common mode noise. A lot of people have discovered that battery power reduces a lot of this noise through elimination of some types of leakage currents. BTW, if people find excessive noise from SMPS, try grounding the negative output of the SMPS - usually the outside of the DC barrel plug.

I have been using these particular LifePO4 batteries for many years to power my audio devices but it is only recently that I investigated the benefits of USB isolation - this does not mean clean 5V power instead of 5V from USB - I always understood that sensitive' low noise circuitry should never use USB power if optimal results were the goal. USB isolation means eliminating the common mode noise which is on the USB signal line D+ & D-. The benefits of eliminating this noise is evident in digital audio & I'm pretty sure translate to SDR.

I have been told that "SDR measured 3 to 6 dB reduction in the noise floor using the Intona USB 2.0 Hi-Speed Isolator" - this USB isolator still uses USB power. I have also been told that running an SDR from battery can result in equal, if not more reduction in noise floor. Combining both of these positive effects in one box would seem to be worthwhile?

Any thoughts welcome.

I had typed a lengthy response and this ridiculous cloudfare DDOS protection boards.ie have implemented is the most irritating thing on this planet, now I have to make a conscious effort to copy all my posts before posting because it sometimes wipes them out.

Sort it out boards.ie !

Sorry about that Jocko4, I couldn't face typing again , wasn't feeling the best yesterday anyway.

In order to eliminate noise from the MAC usb and boy was it noisy I used 14 turns of the USB wire around a FT240-31 Ferrite ring and it eliminated all my USB generated noise. The mac touchpad caused horrific noise on the MW band and the ferrite ring also eliminated this.

Then the other noise sources are switch mode power supplies as you already know where in pretty much all modern electronic equipment due to regulation however, they do not test to see if they comply to radio regulations, a lot of the SM PSUs do not have important filtering components and can send a lot of QRM through the house electrical wiring and it can act like a gigantic antenna.

I replaced the Power supply powering my Kiwi SDR with a linear supply and that alone made a huge difference. Next I replaced an external satellite receiver PSU with Linear and again, big difference. Then the broadband modem PSU also replaced with linear.

Next I binned some Iphone chargers, Ipad chargers are much better.

All of this made a massive, massive difference to the level of noise the receiver picked up.

Next to do on the list is replace the RG58 Coax with better shielded H155 and grounding the MA305 Antenna, the Loop doesn't really need grounding.

I've also got a Airspy HF+ so tell your customer there are frequent firmware updates but if he's buying such a device he probably already knows and about the above sources of QRM.

The Airspy HF + is a very sensitive receiver and will pick up lots of noise so you have to eliminate as much noise sources as possible.

I have two different antennas, the Bonito FX 10 meter loop and Bonito MA305, the MA305 is an E-Field antenna and is more susceptible to noise but the Loop is a H-Field antenna and responds more to the magnetic part of the signal. The loop is a very quiet antenna.

So , so much to do to eliminate noise or QRM.

Anyway, I'd be interested to see your project in action , I would say test it on a macbook as it's very very noisy but also check it on different computers.

One thing I would say though is that if a simple Ferrite ring can eliminate noise you might find it harder to sell to SDR enthusiasts however I could see it sell to Audiophiles who want clean sounding Audio. But you might be able to sell to less experienced SDR users and those new to radio in general.

In the meantime check out my Kiwi SDR here http://emeraldsdr.ddns.net:8073/

Best of luck.

jocko4

Thanks Mad_Lad - much appreciate your reply

Yes, I too find the Macs to be one of the noisiest computers around, particularly the Mac Mini which is attractive to audiophiles - mostly because of their internal SMPS.
In audio use ferrite rings on USB cables do not do the job so I guess there are some other noise frequencies that need reducing in these cases. Full galvanic isolation is different to ferrite rings or common mode chokes which is what they essentially are. Ferrite rings (CM chokes) present a high impedance for certain range of frequencies. CM chokes operational frequencies depends on the material they are constructed from, number of turns, etc. Magnetics is a specialist area of knowledge which I wouldn't claim but transformers leak certain frequencies across their primary & secondary Full galvanic isolation does a much better job of blocking noise as it blocks & recreates the USB signal across the isolation barrier (in the ones I use - a patented capacitive coupling) thus eliminating noise.

But SDR seems very similar to audio in that I've seen comments from SDR users about their fatigue in listening to certain setups because the audio produced is tiring. This is exactly the same complaint that audiophes often have about digital audio. My isolation devices completely eliminate this unease with digital audio (not because it cuts out high frequencies but because it eliminates noise which causes distortions causing unease after long listening sessions)

How much of your noise is air borne & how much is coming through electrical connections such as USB or mains? My devices deal with the noise coming through electrical connections but being in full aluminium cases they are also blocking a lot of RFI. I've read your posts on this thread & the lengths you have gone to try to eliminate noise - I wondered how much of this was actually coming through your mains?

If you are interested in comparing how much more effective my battery powered USB isolated device (ISO-HUB) might be, I would be happy to come to some arrangement (which would cost you nothing) to send one to you.

I don't know what antennae he is using but I know that he is currently using a Winradio & when he powers it from a 12V SLA battery he measures about 20dB drop in the noise floor - I guess this is compared to SMPS but not sure?

I have a number of audio users currently using many different types of computers including Macs & they all register big improvements in sound quality but you are correct, in SDR we are dealing with a whole different range of frequencies which needs checking.

I have checked into your Kiwi SDR - excellent work & congrats on this initiative

BTW, a review of my devices has just been published on a review site here

Well congrats, that's a very complimentary review, well done !

It's obviously working superbly for audio applications so yes I'd be delighted to try one out ! Thanks. I'd be very interested to see if it further improves my noise floor.

Speaking of Galvanic isolation, I have a Bonito GI300 ordered an due to the bad weather will most likely be a week or more delayed. I've seen youtube videos of this working so can't wait to try this out.

You can read about it here, https://www.bonito.net/newsroom/the-galvanic-isolator-gi300/?lang=en

I've no idea how much noise comes through the mains wiring and perhaps one of those mains filters Audiophiles use might help in that department.

I've gone around the house with my portable radio on MW , running on battery and I could not find the source of QRM that was there sometimes so it was wrecking my head so I decided one day to go on the hunt, I got the the bedroom and the noise was strongest in the outside wall and I simply could not figure this out so went back into the bedroom and eventually found that it was coming from an Iphone charger, this is no longer used, we use Ipad chargers or an old Sony Tablet charger but it turned out that the Iphone charger was sending RFI through the mains wiring which is what I was experiencing in outside in the wall which has the mains wire, the charger was in the opposite end of the room.

Next is the electric car charge point made by ABl Sursum which I intend to replace soon enough but one day I went on the hunt and followed the noise and it got louder as I got towards the hot press so I opened the door and put the radio against the timers and was left scratching my head as to how in the hell the timers could be causing this but it turned out that it was the EV charge point sending this horrid noise back through the mains cabling in the house and funny that it only happens when the car is plugged in and it doesn't have to be charging just plugged in.

But how much other noise is coming through the mains I do not know, if you know of a mains filter that might help please let me know.

At least my Airspy setup is battery powered, I use a mobile phone battery booster and it works a treat. But It's a very sensitive receiver so I will try better coax and the Galvanic Isolator on the RF input and see if that helps.

There are other sources of noise that is atmospheric and related to ESB poles with dodgy or loose arcing connections or dodgy transformers which they'll usually oblige to fix , well if you're a licensed ham they will anyway because I suppose the way they look at it it could become a more major fault in the future.

I've also binned some LED light bulbs which can emit horrid noise and replaced with Philips and Osram, the Philips were by far the best.

LCD TV's with old skool fluorescent backlights cause some of the worst source of QRM I've heard yet no doubt due to the inverter for the tubes. In my Mothers I've heard this noise travel some 30 meters away !

I believe electronics companies should do more to ensure their equipment complies to regulations which a lot of them do not and no one checks or cares.

I've seen videos of some Chinese made SMPs without adequate filtering and in some cases these components were not installed as indicated on the PSU, they were printed on the board but not installed at the mains end.

My SDR is down at the moment will investigate shortly.

jocko4

Deleted User wrote: »

Well congrats, that's a very complimentary review, well done !

Thanks, there's another one coming shortly on Enjoythemusic.com

It's obviously working superbly for audio applications so yes I'd be delighted to try one out ! Thanks. I'd be very interested to see if it further improves my noise floor.

Great, I would love to have someone with expertise in SDR checking this out after my customer gives me feedback on the ISO-HUB. I'm also thinking of an SDR specific device which incorporates battery power & USB isolation which I would be interested in discussing with you. Perhaps if this forum is not the appropriate place to do this & you are interested, we could communicate via email?

Speaking of Galvanic isolation, I have a Bonito GI300 ordered an due to the bad weather will most likely be a week or more delayed. I've seen youtube videos of this working so can't wait to try this out.
ly
You can read about it here, https://www.bonito.net/newsroom/the-galvanic-isolator-gi300/?lang=en

Thanks, I had a quick look & this noise strikes me as arising from current leakage issues from the SMPS laptop brick getting into the Perseus & causing noise issues because of a ground loop. As I'm sure you know, the size of the loop is one of the critical factors in ground noise loops - plugging everything into the same mains outlet often greatly reduces these issues.

The Bonito looks good but the first approach I would take, apart from the above, is to ground the DC negative coming out of the SMPS - I reckon this will totally eliminate this noise. Run a wire to mains ground from this DC negative input - probably easiest to do within the Perseus? You could probably try this yourself? The power surge, lightning protection functions? of the device seems very worthwhile but are these not implemented anyway on ariels connected to devices?

BTW, in the Bonito plots when the laptop is being powered by the brick, not only does the noise floor increase by some 30dB but it also introduces two new frequency spikes/spurs which I presume are related to the SMPS oscillator frequency & its harmonics. These spurs are still there even with the Bonito in circuit - presumably these would interfere with any stations broadcasting at these frequencies?

I've no idea how much noise comes through the mains wiring and perhaps one of those mains filters Audiophiles use might help in that department.

No need for mains filters - using battery powered devices kills most of these ground loop issues.

I've gone around the house with my portable radio on MW , running on battery and I could not find the source of QRM that was there sometimes so it was wrecking my head so I decided one day to go on the hunt, I got the the bedroom and the noise was strongest in the outside wall and I simply could not figure this out so went back into the bedroom and eventually found that it was coming from an Iphone charger, this is no longer used, we use Ipad chargers or an old Sony Tablet charger but it turned out that the Iphone charger was sending RFI through the mains wiring which is what I was experiencing in outside in the wall which has the mains wire, the charger was in the opposite end of the room.

Next is the electric car charge point made by ABl Sursum which I intend to replace soon enough but one day I went on the hunt and followed the noise and it got louder as I got towards the hot press so I opened the door and put the radio against the timers and was left scratching my head as to how in the hell the timers could be causing this but it turned out that it was the EV charge point sending this horrid noise back through the mains cabling in the house and funny that it only happens when the car is plugged in and it doesn't have to be charging just plugged in.

But how much other noise is coming through the mains I do not know, if you know of a mains filter that might help please let me know.

As I said above, you don't need a mains filter if you protect your sensitive receiver circuitry from ground conducted noise - ground noise just won't get through to this sensitive area.

I'll check out external mains filters but they are probably not as effective as inbuilt chokes on some Schurter mains sockets which more effectively block this
one of these earth line chokes between the IEC ground and chassis:

https://www.mouser.com/ds/2/358/typ_DEN-1275812.pdf

https://www.mouser.com/ProductDetail/Schurter/DEN-25-0001?qs=sGAEpiMZZMsg%252by3WlYCkU%2fBUuRpviN4BP2fy9AwEMEc%3d

You can read here how a similar earth line choke integrated into an IEC inlet can help with ground noise:

https://www.schurter.com/content/download/677076/13557172/file/SCHURTER_AN_Ground_Choke_1508_en_LR.pdf

At least my Airspy setup is battery powered, I use a mobile phone battery booster and it works a treat. But It's a very sensitive receiver so I will try better coax and the Galvanic Isolator on the RF input and see if that helps.

Yea, these are worthwhile although probably not optimal as they use voltage regulators on their output & if the consist of multiple batteries, will have battery balancing circuitry also - both of which create their own noise. Whether this is noticeable in SDR, I don't know - I know it is in audio - it's often the case that these issues aren't obvious/noticed until they are removed. I power all my devices directly from battery without intervening voltage regulators or balancing circuits. This is what I would be looking to do for an SDR device i.e I was thinking of using something like a Thumbnet N3 which already addresses noise issues & incorporating it internally in an ISO-HUB device, bypassing the onboard voltage regulators & feeding 3.3V directly from battery while also using the USB isolation function of the ISO-HUB.This would be a proof of concept device

There are other sources of noise that is atmospheric and related to ESB poles with dodgy or loose arcing connections or dodgy transformers which they'll usually oblige to fix , well if you're a licensed ham they will anyway because I suppose the way they look at it it could become a more major fault in the future.

I've also binned some LED light bulbs which can emit horrid noise and replaced with Philips and Osram, the Philips were by far the best.

LCD TV's with old skool fluorescent backlights cause some of the worst source of QRM I've heard yet no doubt due to the inverter for the tubes. In my Mothers I've heard this noise travel some 30 meters away !

I believe electronics companies should do more to ensure their equipment complies to regulations which a lot of them do not and no one checks or cares.

Yes, the regulations should diminish this noise if they are adhered to but in some instances the regulations are not enough. For instance, current leakage allowed from power supplies is much lower in the medical field then is allowed in general consumer devices.

I've seen videos of some Chinese made SMPs without adequate filtering and in some cases these components were not installed as indicated on the PSU, they were printed on the board but not installed at the mains end.

Funnily enough, it's often the filtering in an SMPS needed to meet emissions regulations that are the cause of increased current leakage . Not saying the Chinese devices are designed like this by design.

My SDR is down at the moment will investigate shortly.

Would love to hear if connecting together the grounds from all devices to one point & connecting this to mains earth, in your setup reduces your noise!

dxhound2005

Deleted User wrote: »

There are other sources of noise that is atmospheric and related to ESB poles with dodgy or loose arcing connections or dodgy transformers which they'll usually oblige to fix , well if you're a licensed ham they will anyway because I suppose the way they look at it it could become a more major fault in the future.

I doubt if many in the ESB would know about radio interference. Have you ever contacted them?

I have a pole with a transformer very near my house. I suspect it has been causing noise for years, but I never got round to doing anything about it. Late last year the noise became extremely severe, even extending into the FM broadcast band. I was going to contact them in the New Year, but when I came back from being away around Christmas, the trip switches had triggered and there was no power. Next door told me there had been a small explosion and fire on the pole Christmas Eve and the ESB came out shortly after to do repairs. Someone had thrown a piece of metal up on top of the wires, and it must have been there for a few weeks.

The noise went back to the previous level, which is still severe, more especially in the HF bands above 10 MHz. After this weather has cleared I will see about contacting someone to maybe inspect the pole again. But from what I read the arcing could be from another pole at some distance, and being transmitted along the wires.

Anyone with a medium wave radio in the car, drive round some town, with a weak signal channel, and hear the horrendous noise at some places where there are poles. So I think it is a common problem, and maybe not one which will get much action from the ESB. But I will report any developments.

A friend of mine is a licensed HAM and he called the ESB a few days ago and they said they'd be out the next day. But I haven't been talking to him since , I must send him a text.

I think they'd rather fix a potential issue before it becomes a problem which may lead to a costly repair or outage.

jocko4

jocko4 wrote: »

Thanks, there's another one coming shortly on Enjoythemusic.com

Great, I would love to have someone with expertise in SDR checking this out after my customer gives me feedback on the ISO-HUB. I'm also thinking of an SDR specific device which incorporates battery power & USB isolation which I would be interested in discussing with you. Perhaps if this forum is not the appropriate place to do this & you are interested, we could communicate via email?

Thanks, I had a quick look & this noise strikes me as arising from current leakage issues from the SMPS laptop brick getting into the Perseus & causing noise issues because of a ground loop. As I'm sure you know, the size of the loop is one of the critical factors in ground noise loops - plugging everything into the same mains outlet often greatly reduces these issues.

The Bonito looks good but the first approach I would take, apart from the above, is to ground the DC negative coming out of the SMPS - I reckon this will totally eliminate this noise. Run a wire to mains ground from this DC negative input - probably easiest to do within the Perseus? You could probably try this yourself? The power surge, lightning protection functions? of the device seems very worthwhile but are these not implemented anyway on ariels connected to devices?

BTW, in the Bonito plots when the laptop is being powered by the brick, not only does the noise floor increase by some 30dB but it also introduces two new frequency spikes/spurs which I presume are related to the SMPS oscillator frequency & its harmonics. These spurs are still there even with the Bonito in circuit - presumably these would interfere with any stations broadcasting at these frequencies?

No need for mains filters - using battery powered devices kills most of these ground loop issues.

As I said above, you don't need a mains filter if you protect your sensitive receiver circuitry from ground conducted noise - ground noise just won't get through to this sensitive area.

I'll check out external mains filters but they are probably not as effective as inbuilt chokes on some Schurter mains sockets which more effectively block this
one of these earth line chokes between the IEC ground and chassis:

https://www.mouser.com/ds/2/358/typ_DEN-1275812.pdf

https://www.mouser.com/ProductDetail/Schurter/DEN-25-0001?qs=sGAEpiMZZMsg%252by3WlYCkU%2fBUuRpviN4BP2fy9AwEMEc%3d

You can read here how a similar earth line choke integrated into an IEC inlet can help with ground noise:

https://www.schurter.com/content/download/677076/13557172/file/SCHURTER_AN_Ground_Choke_1508_en_LR.pdf

Yea, these are worthwhile although probably not optimal as they use voltage regulators on their output & if the consist of multiple batteries, will have battery balancing circuitry also - both of which create their own noise. Whether this is noticeable in SDR, I don't know - I know it is in audio - it's often the case that these issues aren't obvious/noticed until they are removed. I power all my devices directly from battery without intervening voltage regulators or balancing circuits. This is what I would be looking to do for an SDR device i.e I was thinking of using something like a Thumbnet N3 which already addresses noise issues & incorporating it internally in an ISO-HUB device, bypassing the onboard voltage regulators & feeding 3.3V directly from battery while also using the USB isolation function of the ISO-HUB.This would be a proof of concept device

Yes, the regulations should diminish this noise if they are adhered to but in some instances the regulations are not enough. For instance, current leakage allowed from power supplies is much lower in the medical field then is allowed in general consumer devices.

Funnily enough, it's often the filtering in an SMPS needed to meet emissions regulations that are the cause of increased current leakage . Not saying the Chinese devices are designed like this by design.


Would love to hear if connecting together the grounds from all devices to one point & connecting this to mains earth, in your setup reduces your noise!

I'll reply to your post in more detail soon, haven't got the chance today.

jocko4

jocko4 wrote: »

Sorry for the delay in replying.

Great, I would love to have someone with expertise in SDR checking this out after my customer gives me feedback on the ISO-HUB. I'm also thinking of an SDR specific device which incorporates battery power & USB isolation which I would be interested in discussing with you. Perhaps if this forum is not the appropriate place to do this & you are interested, we could communicate via email?

Sure no problem, PM me and we can discuss more via email, remember , I'm no expert.

jocko4 wrote: »

Thanks, I had a quick look & this noise strikes me as arising from current leakage issues from the SMPS laptop brick getting into the Perseus & causing noise issues because of a ground loop. As I'm sure you know, the size of the loop is one of the critical factors in ground noise loops - plugging everything into the same mains outlet often greatly reduces these issues.

Here's some lengthy reading for you.

http://audiosystemsgroup.com/RFI-Ham.pdf

And on SMPs

http://www.samlexamerica.com/support/faqs/faq18.aspx

jocko4 wrote: »

The Bonito looks good but the first approach I would take, apart from the above, is to ground the DC negative coming out of the SMPS - I reckon this will totally eliminate this noise. Run a wire to mains ground from this DC negative input - probably easiest to do within the Perseus? You could probably try this yourself? The power surge, lightning protection functions? of the device seems very worthwhile but are these not implemented anyway on ariels connected to devices?

I only receive this noise when the laptop is plugged in, the other noise caused by the USB is eliminated by 14 turns of the usb cable around the ferrite. I mostly use the laptop on battery.

The noise floor is still high but the Airspy HF+ is supposed to be wicked sensitive which is good in some ways but makes you realise that you didn't have as quiet a listening environment as you thought, I do really but the AirSpy is teaching me ways to improve it such as Grounding the antenna which I have yet to do, using better coax, which I have yet to do, I have the Coax but haven't got the chance to install it and ground it.

I have not tried it yet on the Loop antenna which is naturally quieter and doesn't need grounding as it responds mainly to the magnetic part of the signal but I also intend to replace the coax to the Loop.

The Noise floor is not an issue on the SDRPlay RSP1A but that's probably because it's not as sensitive, it's not hearing it as with most radios, the HF+ SDR is supposed to be one of the most sensitive available.

jocko4 wrote: »

BTW, in the Bonito plots when the laptop is being powered by the brick, not only does the noise floor increase by some 30dB but it also introduces two new frequency spikes/spurs which I presume are related to the SMPS oscillator frequency & its harmonics. These spurs are still there even with the Bonito in circuit - presumably these would interfere with any stations broadcasting at these frequencies?

Yes basically the SDR will show the switching frequency of the SMP which could be every 60 Khz in some parts of the spectrum.

The spurs you were seeing, I'd have to watch the video again but are you sure these weren't actual radio frequencies ?

jocko4 wrote: »

No need for mains filters - using battery powered devices kills most of these ground loop issues.

As I said above, you don't need a mains filter if you protect your sensitive receiver circuitry from ground conducted noise - ground noise just won't get through to this sensitive area.

Exactly, that's why I poser the Bonito Via battery and also use the SDR when the Laptop is on battery.

But this noise is transmitted by the SMP itself and effects battery radios also, some of them actually wipe out the entire shortwave spectrum.

My Neighbour in my old house had an old skool LED backlit TV and it wiped out everything, LW/MW and SW and he was amazed at how bad the noise was which could be picked up 40 meters away on my battery radio, it's only in the last month when I finally got the courage to ask him to let me try figure out what was causing it, form 8am to about Midnight or 2am I could not listen to anything and it was extremely frustrating.

My Samsung LED TV does not emit any noise and I can assume the noise was caused by the Fluorescent inverters, the same noise though not as bad comes from my Mothers TV which has Fluorescent backlighting and not LED.

I believe that the noise is transmitted back along the mains wiring creating a gigantic antenna.

If I had stayed in the house I would have offered to buy him a LED TV on condition I took his old TV and destroyed it.

But the problem doesn't end there, some LED lights with SMPs are probably eliminating essential filtering components to allow them fit in small packaging, I had to bin some which were horrific.

LED lighting is the greatest headache for a lot of HAM operators today.

jocko4 wrote: »

I'll check out external mains filters but they are probably not as effective as inbuilt chokes on some Schurter mains sockets which more effectively block this
one of these earth line chokes between the IEC ground and chassis:

https://www.mouser.com/ds/2/358/typ_DEN-1275812.pdf

https://www.mouser.com/ProductDetail/Schurter/DEN-25-0001?qs=sGAEpiMZZMsg%252by3WlYCkU%2fBUuRpviN4BP2fy9AwEMEc%3d

You can read here how a similar earth line choke integrated into an IEC inlet can help with ground noise:

https://www.schurter.com/content/download/677076/13557172/file/SCHURTER_AN_Ground_Choke_1508_en_LR.pdf

You'll know a lot more about that than I would but I expect it wouldn't help a lot if the noise is transmitted via mains wiring it might help to a degree. But interesting if you find out.

jocko4 wrote: »

Yea, these are worthwhile although probably not optimal as they use voltage regulators on their output & if the consist of multiple batteries, will have battery balancing circuitry also - both of which create their own noise. Whether this is noticeable in SDR, I don't know - I know it is in audio - it's often the case that these issues aren't obvious/noticed until they are removed. I power all my devices directly from battery without intervening voltage regulators or balancing circuits. This is what I would be looking to do for an SDR device i.e I was thinking of using something like a Thumbnet N3 which already addresses noise issues & incorporating it internally in an ISO-HUB device, bypassing the onboard voltage regulators & feeding 3.3V directly from battery while also using the USB isolation function of the ISO-HUB.This would be a proof of concept device

Basically , anything that has no SMP will work, that's why I eliminated as many SMPs as I could such as the Boroadband Modem PSU, Satellite receiver and the one powering my KIWI SDR, linear supplies all the way.

I don't detect any noise from the USB battery but you're correct , the only way to know is to eliminate and try again so I might power it via 12V sealed Lead Acid battery, back to basics lol but it it works.....

jocko4 wrote: »

Yes, the regulations should diminish this noise if they are adhered to but in some instances the regulations are not enough. For instance, current leakage allowed from power supplies is much lower in the medical field then is allowed in general consumer devices.

Not going to happen, people care less and less about radio and shortwave, though there's a surge in those receiving ham licences in the last few years and those purchasing SDRs most people have no interest and only care about internet and streaming and SKY TV and radio is something some people might listen to only in the car because they have no streaming devices in their cars just yet.

It's actually sad because you will have a whole generation who stream night and day and do not listen to the news, hear a voice from a DJ, hear the banter etc, it's another way of removing people from human contact and this is both dangerous long term and quiet sad. People will become less and less informed about world affairs and won't care at all and perhaps this part of a more elaborate plan by the powers that be ? lol.

jocko4 wrote: »

Funnily enough, it's often the filtering in an SMPS needed to meet emissions regulations that are the cause of increased current leakage . Not saying the Chinese devices are designed like this by design.

The issue lies in reduced cost and also the size of devices are getting smaller, people don't want to carry around a huge brick of a power supply like they would if they had to carry around linear supplies , a mobile phone charger is a fraction of the size it otherwise would be without SMP, ok perhaps the higher current supplies like the Ipad and the modern USB C chargers.

jocko4 wrote: »

Would love to hear if connecting together the grounds from all devices to one point & connecting this to mains earth, in your setup reduces your noise!

Usually Hams have a separate earth away from mains. But I suspect this wouldn't reduce much if the noise is transmitted rather than flowing through the mains to the receiver , as I said battery radio reception on LW/MW/SW can be completely wiped out by a single SMP.

Try it yourself, get a portable MW on battery and go around the house, or better yet, tune to where there is a particular buzzing noise then switch off the mains at the consumer unit and see if the noise is eliminated, reduced or still there , if you'r ein an estate, apartment etc it could be coming from the neighbours.

For all those interested, my friend who is a licensed ham operator got his RFI sorted, the ESB came out and discovered a faulty newly installed Transformer so they replaced it and he no longer has any RFI from this.

Happy days, so the ESB do take this seriously as it can reflect an issue later on and can prevent a more serious related incident or unplanned outage.

Indeed my friend was very Grateful.

briany

Here's a pertinent question,

I still don't have any SDR hardware of my own, but I've been listening to a number of Spy servers through SDR#. I know you can record stuff in .wav format to listen back to later, but this is limited to what you're actually listening to at the time of recording.

What I would like to be able to do is to be able to record the entire segment of bandwidth I'm on (e.g. 2.4 mhz or 660 khz or whatever), as a data file or whatever, and then be able to peruse that later for interesting signals. In my limited research on this so far, I've been directed to some SDR# plugins like IF Recorder and baseband recorder, but they're just giving me the same result - a .wav file limited to what the marker was on at the time of recording. I realise such a data file might grow large quite quickly, but space is not so much of a concern. I have plenty of that.

Anything for SDR# that can do this? Any SDR software that can do this at all?

I've never recorded any spectrum of SDR's but it's something I would like to do in the future whenever I can get my SDR set up in such a way as I don't have to dismantle it, I have 2 yr 3 month old and 3 yr 10 month old boys and they literally wreck the house. I've had to put all the chairs in the dining area and lock them in the conservatory to stop them climbing on work tops and pulling stuff out of presses, a nightmare !

All my radios are locked away, have to hide the laptop etc and at this moment in time I don't have a room that I can set up stuff and lock the door , unfortunately. I have the Kiwi SDR locked in the shed though which I can access remotely, it's not an environment I would keep a laptop though.

Anyway, try this link and see if it provides you with any useful information, it seems a bit tricky to set up. https://swling.com/blog/2016/11/portable-shortwave-spectrum-capture-for-the-urban-city-dweller/

There's a lot of interesting stuff late at night on SW and it would be great to be able to record entire bands.

Most SDRs won't capture more than 2 Mhz at a time and at that you'll probably need a Core i5 CPU minimum, some like the Airspy HF+ only show about 750 khz of bandwidth at a time which is fine for me.

My Kiwi SDR is capable of seeing from about 10 Khz all the way to 30 Mhz and it would be nice to be able to capture this when I can't sit up all night. I must pop the question on the Kiwi forums.

briany

Deleted User wrote: »

I've never recorded any spectrum of SDR's but it's something I would like to do in the future whenever I can get my SDR set up in such a way as I don't have to dismantle it, I have 2 yr 3 month old and 3 yr 10 month old boys and they literally wreck the house. I've had to put all the chairs in the dining area and lock them in the conservatory to stop them climbing on work tops and pulling stuff out of presses, a nightmare !

All my radios are locked away, have to hide the laptop etc and at this moment in time I don't have a room that I can set up stuff and lock the door , unfortunately. I have the Kiwi SDR locked in the shed though which I can access remotely, it's not an environment I would keep a laptop though.

Anyway, try this link and see if it provides you with any useful information, it seems a bit tricky to set up. https://swling.com/blog/2016/11/portable-shortwave-spectrum-capture-for-the-urban-city-dweller/

There's a lot of interesting stuff late at night on SW and it would be great to be able to record entire bands.

Most SDRs won't capture more than 2 Mhz at a time and at that you'll probably need a Core i5 CPU minimum, some like the Airspy HF+ only show about 750 khz of bandwidth at a time which is fine for me.

My Kiwi SDR is capable of seeing from about 10 Khz all the way to 30 Mhz and it would be nice to be able to capture this when I can't sit up all night. I must pop the question on the Kiwi forums.

Firstly, I'm surprised that this practice isn't asked about more. Looking at other discussion forums on the topic of SDR, it's not one that comes up ever so often.

I don't know about ye, but the idea of monitoring a radio spectrum in real time doesn't really interest me because I worry that amounts to hearing a whole lot of dead air. Computer hardware and automated software could monitor and record radio far more efficiently than I could manually.

In the link you posted, the guy seems to be using an Airspy. However, my problem would be that I don't have one at my disposal, and the configuration options are different for different hardware in SDR#. I've made a couple of attempts at recording bandwidth with 3 different recording plugins available, but they all give the same .wav output and only play back an extremely narrow spectrum of about .010 MHZ. That's pretty much just what I had the dial set to at the time of recording.

briany

briany wrote: »

I don't know about ye, but the idea of monitoring a radio spectrum in real time doesn't really interest me because I worry that amounts to hearing a whole lot of dead air. Computer hardware and automated software could monitor and record radio far more efficiently than I could manually.

I don't get what you're trying to achieve reading this ?

I get you want to record but what exactly ?

briany

Deleted User wrote: »

I don't get what you're trying to achieve reading this ?

I get you want to record but what exactly ?

Shipping traffic, aircraft, 2m Ham, ISS downlink. That kind of thing. But this type of traffic can be intermittent, I suppose, hence the preference to record these bands (not at the same time, obviously) and pick through them later.

Yes it would be convenient. Head off to bed and listen the next day.

WHL

You can do this with SDR Console. I have a SDRplay 2 and have used the scheduled recorder to capture the entire MW band during nighttime to see if I can pick up transatlantic stations. It works well.
SDRplay has a bandwidth of up to 8 MHz so you could presumably record that amount of spectrum at one time

I use SDR console sometimes and I never noticed this, but I must check it out , thanks, I kinda like scanning the SW bands live lol.

WHL

There is a Rec/Playback tab along the top of the SDR Console screen. I usually listen live on HF also but I do record overnight sometimes from 5 to the hour until 5 past to get the top of the hour ident

briany

WHL wrote: »

There is a Rec/Playback tab along the top of the SDR Console screen. I usually listen live on HF also but I do record overnight sometimes from 5 to the hour until 5 past to get the top of the hour ident

That's such a useful feature. Combining a data recorder with some way of triggering that recording using certain signal characteristics (strength/pattern parameters) would be a powerful automated setup.

Ok so after some playing around, SDR Console , SDRUno and Airspy's SDRSharp all record Spectrum, I actually came across an old recording I did a while back with the SDR Play which I recorded in SDRUno and must have forgot about.

They're called IQ files or recordings.

Here's a link to about 5-6 mins of a recording of the 49 Meter Shortwave band I recorded last night. It's about 1GB recorded as a WAV file which is uncompressed.

I think I noticed SDRSharp can compress it to MP3 or WMA.

https://www.dropbox.com/s/xp39drtl6euyoh2/SDRSharp_20180320_005114Z_6280000Hz_IQ.wav?dl=0

Remember to open it in SDRConsole only as it might not work properly with SDRconsole, SDRConsole has great filtering to try out too.

You can download SDRSharp here It's called Windows SDR Software Package top one on the page.

https://airspy.com/download/

Then extract the zip to a folder called SDRSharp and then run the SDRSharp.exe , there's no installation.

On the very top of the program it says Source, click on that and select from the list IQ file WAV then select the WAV file I linked to and then select play at the top of the window beside the "cog"

I think SDRConsole is the best software to use because it's the only one really compatabile with the Airspy HF+ at this time, it will work with a plug in with SDRConsole and SDRUno but a lot of the functions are not available and it won't work properly.

So now you'll be listening to the 49 Meter SW band just as you had the HF+ and the Bonito MA305 Antenna connected and it will give people an idea of what SDR's are all about.

Remember it's only about 5 mins and will keep looping back to the start automatically, enjoy