Which frequency for a basic radio project?

riffmongous

Hi there everyone,

as part of a university project I am doing I want to be able to send a signal from a solar powered sensor station to a base station at a regular interval, just to check that the station is working. I don't really need to this (we could just buy some equipment to do it if I asked) but I thought it would be a good opportunity for me to learn some new skills and for the last year or so I've wanted to get involved in amateur radio so I want to give it a go.

Now, I would like to build it from a component level, I have put together a transistor receiver from components before and for me that is where my interest lies. For now I would like to have it as simple as possible, and then work upwards. My idea is just a simple circuit that turns on every hour or so, broadcasts a signal and have a receiver circuit listen for it and log that it received the signal (all done with micro-controllers).

First though I would like to get people's advice on what frequency region I should use? So the solar-station will be located at a maximum of 1 kilometre from the base, the area is slightly hilly farmland, but there is a town located about 2kms away.

It's in Austria but at the moment I am still trying to find out what the legal situation is here, it's tough since my German is not so good, so could we just assume Irish laws for now.

martinedwards

to be fully legal.......

I'm thinking PMR, which is ONLY legal if you have a type approved transmitter.

like the kids walkie talkies you get in Argos etc.

which would be easy to doctor.....

lock the PTT switch on, and set the power to come on every hour, transmit, then switch off again.

if you were a licenced ham, then any old frequency would do, so long as you transmitted your callsign with each transmission.

i think!!

riffmongous

martinedwards wrote: »

to be fully legal.......

I'm thinking PMR, which is ONLY legal if you have a type approved transmitter.

like the kids walkie talkies you get in Argos etc.

which would be easy to doctor.....

lock the PTT switch on, and set the power to come on every hour, transmit, then switch off again.

if you were a licenced ham, then any old frequency would do, so long as you transmitted your callsign with each transmission.

i think!!

Thanks for the info!

I guess a license is the way to go then

bandit7388

pmr446 is probably the best way to go being legal,you could also try 27mhz cb band also legal and would have better range than 446

riffmongous

bandit7388 wrote: »

pmr446 is probably the best way to go being legal,you could also try 27mhz cb band also legal and would have better range than 446

Cheers, is it allowed to ask questions regarding design and assembly in this forum before you have a license?

martinedwards

you can ask what ever you like!!

the licencing only kicks in when you want to transmit!!

bear in mi9nd also that (here in the UK) a foundation licence holder is NOT allowed to homebrew transmitters or even tinker inside. I assume that Eire is similar.

AND

if you get an foundation type licence in Eire, you will NOT be able to use it in Vienna.

a FULL licence will be easy, just go from EI**** to OE/EI****

FOUNDATION LICENCES are meant to be just for an intro using off the shelf equipment. for more experimental fun & games you need to move up the ladder, but if you are a tech savvy person, that won't be difficult.

ALSO, the radio exam carries UCAS points....... maybe useful for a masters?

martinsvi

in Eire there's no such thing as foundation license.. there's just one - general, that by UK standards is similar to advanced, or USA's - extra

martinedwards

ah right, youre laughing then.

get your ticket, and youre good for 90% of the world.

watty

Legal Methods:
433 MHz SRD CE certified modules or 864MHz SRD CE certified Modules or 2.4GHZ CE certified Modules (Zigbee, WiFi or Bluetooth). Or only in Ireland a cheap nearly instant Test Licence for the project duration, Location(s) and Organisation.

An Amateur licence isn't really appropriate, sadly. Part of reason for Ditching the name "Experimenter License" is Harmonisation and part is that there are CE modules and part is that any reputable company can apply for a Test Licence for ANY band, even co-existing with Broadcast, from Comreg.

Either go the Licence free CE marked "SRD" module route or apply for a test licence. The Amateur licence isn't appropriate and is only for one individual person and needs an exam. The Test Licence is for ANY frequency and power and range (as individually agreed with Comreg) and is for an entire Organisation, not an individual.

How do I know? The company I worked for had a test licence in the TV band for two way Point (20W) to Multipoint (1W) transmission with arbitrary gains of aerials. But for specific locations. It's quite cheap and no exam.

All the details of "licence free" SRD for data, Test Licence and Amateur Licence is on Comreg's site.

Using PMR446 and CB27 for such a project is illegal.
Using Amateur Radio licence can be done, but that is slow, inflexible and only for one Person.
The Test Licence is perfect match for this application.

You actually can't discuss what ever you like about transmitters here. See Charter.
http://www.boards.ie/vbulletin/showthread.php?t=2055083524

The "Test Licence" is a purely Irish thing. In Austria only the CE approved SRD Data modules permitted. As soon as you "doctor" a PMR446 or CB17 it's illegal ANYWHERE in EU, Austria and Ireland included.

Outdoors 1km to 2km clear path is possible with SRD 433 SRD 864 or 2.4GHz and off the shelf approved CE modules.

Even if you were an experienced RF designer for such a project off the shelf CE / ETSI approved gear would be used.

riffmongous

watty wrote: »

..

Hi, thanks for the advice! At the moment though I would really like to do it myself from a component level and so I will try to get an amateur license. For me it's really about getting as much experience as possible at all levels, particularly component and antenna design, purely out of interest.

The test license sounds interesting and I would probably go with that in the meantime if it existed here.

watty

Unless you are studying to be an RF Designer it will seriously impact your main project time and cost to do DIY RF at component level rather than buying modules, which doesn't preclude amateur route. But many countries do not allow such an autonomous application on an ordinary licence.

I've been designing RF gear since 1980s and I'd use off the shelf modules for this application.

Antenna

watty wrote: »

any reputable company can apply for a Test Licence for ANY band,

Including any amateur band??

I thought that the 2-metre ham band (144-146MHz) for instance was considered as being exclusively for amateur radio ?

watty

Talk to Comreg. I would hope they would normally refuse use in exclusive Amateur bands. A Test licence involves negotiation. But if you are a company designing a product for 2m band, then using a Test Licence (for the Organisation) IN the 2m band makes sense. An Amateur licence would only be for the holder and might not allow some of the on air tests (e. g. a repeater).

brownmini

bandit7388 wrote: »

pmr446 is probably the best way to go being legal,you could also try 27mhz cb band also legal and would have better range than 446

Sorry for 'nitpicking' here but 27MHZ is only licence free for the transmission of VOICE and only between 26.96x and 27.40x

Xantia

There's lots of stuff on youtube for short range 20m etc.
However if it was me and I was looking for something reliable over 1km then I would go for a LAN/Ethernet setup
probably licence free Mikrotik 5GHz point to point or standard WiFi point to point again from Mikrotik

martinedwards

what about a modulated laser?

I've used laser pointers and light sensor op amp circuits for burgalar alarm circuits for kids in school.....

you could rig a couple of raspberry PIs, one to send, turnng on & off the power to the laser pen to send morse, the other to decode using comething like CWget.......

at least you could show it as a possible solution in your design work.... gotta be worth a few marks!

brownmini

martinedwards wrote: »

the licencing only kicks in when you want to transmit!!

Are you sure about that?

brownmini

martinsvi wrote: »

in Eire there's no such thing as foundation license.. there's just one - general, that by UK standards is similar to advanced, or USA's - extra

For Info:
There is no such licence in the UK called the advanced.
The licence you are thinking is called the Full.

riffmongous

martinedwards wrote: »

what about a modulated laser?

I've used laser pointers and light sensor op amp circuits for burgalar alarm circuits for kids in school.....

you could rig a couple of raspberry PIs, one to send, turnng on & off the power to the laser pen to send morse, the other to decode using comething like CWget.......

at least you could show it as a possible solution in your design work.... gotta be worth a few marks!

We won't have line of sight at all times

Funnily enough we actually use a laser instrument for part of our work, except instead of sending morse signals though we measure the laser intensity to calculate the sensible heat flux

Xantia

http://www.radiometrix.com/content/ntx2

Radiometrix Transmitters - used also in a Raspberry PI flight
here
http://www.raspberrypi.org/

brownmini

Xantia wrote: »

http://www.radiometrix.com/content/ntx2

Radiometrix Transmitters - used also in a Raspberry PI flight
here
http://www.raspberrypi.org/

Also ... http://www.lprs.co.uk/

Have dealt with them in the past - no complaints (link is as customer only)