802.11b - Good signal, but with periodic dropouts?

blorg

I'm considering buying a 5dbi omni directional antenna, to replace the antenna built in to my Netgear DG824M access point/router. The issue I have is periodic dropouts - if pinging from another computer, there is a generally constant 2-3ms response, but every minute or two there is a 'request timed out'. Netstumbler shows a high constant signal but with occasional complete dropouts, which only last a second or so. This behaviour occurs when the computers are near the access point (e.g. next room) but not line of sight. It doesn't occur if the computer is in the same room as the access point and can see it.

Do you think replacing the antenna would help, or is the problem to do with the lack of LOS and likely won't be improved with a stronger antenna?

flywheel

are you using any other equipment that might be causing interference e.g. digital home phones or wireless video/tv relay

have you tried changing the channel used, or any anti-interference options if available (like intereference robustness on the airport equipment)?

hope that helps,
BrianG

blorg

No to any other 2.4Ghz equipment - I did try a videosender unit but it was unwatchable when the wireless LAN was on (thin lines of static going down the screen, with accompanying noise) so it went back. Microwave isn't used and is plugged out permanently. No cordless phone (don't know about neighbours). The dropout pattern is consistent, every minute or two, at any time of day or night.

I've tried a good selection of channels (1, 3, 6, 9, 11, and I think 13) and it doesn't make any difference.

There aren't any anti-interference options on the equipment that I can see.

quozl

try setting the ap to 5.5mbit, or 2mbit and see if the problem goes away. It may be because the AP is changing speeds between 5.5 and 11mbit due to the odd weak signal. That can cause ping spikes. I've never seen ones that last over a second, but some of the guys on the DublinWAN list were talking about them being possible,

Greg

blorg

Unfortunately I don't have that option on the access point. The only device which gives me that option is my PDA, I could possibly get the option on the desktop PC if I installed the utility that came with the network card, I don't know (I'm using XP's built in support). No chance of such an option on my laptop.

Duritz

Atmospheric conditions can effect them. Is the AP near a radiator or anything like that?

Eurorunner

know of someone who had similar problems with a d-link access point. A firmware/driver update sorted it.

hth

blorg

No, it's not near a radiator. We have the same router in the office, and a firmware update killed it stone dead, which is a bit bad really. Currently my router is on loan to the office, and I so am waiting until we get a replacement before trying another firmware update.

Peanut

Check the Netstumber separate signal and noise levels if you haven't already, and try to see if there are periodic sharp increases in the noise level.

If not, then either there is noise that is completely drowning out the signal periodically, or more likely I think there is a problem with your access point as was mentioned before. I had this problem on a d-link unit and had to play around with installing various firmware versions. I got the impression that it was due to the unit not handling the diversity antenna mechanism properly.

Have to say am not very impressed with the Netgear wireless bridge I got, a similar Linksys unit was considerably better in terms of actually working properly. Would suggest getting Buffalo, newer Linksys, SMC, 3com units etc..

blorg

I don't think its a physical problem with the AP, I've got a different one now (same model) and have exactly the same problem. I'm finally on the latest firmware (Netgear's firmware upgrade procedure is pretty bad, and doesn't actually work if you do it according to their instructions - had to find third party instructions on the net).

Is the noise the red part of the graph? I'm attaching a typical Netstumbler image - except that the dropout (black bar) would often drop into the red area also. Does this tell you anything?

Eurorunner

so you've got the latest firmware..but how about drivers?

Peanut

hmmm it's sortof hard to tell from the netstumbler graph...
I think your best bet would be to get a loan of a different model AP if possible and try that. If you have a look at the regional maps on irishwan.org there may be someone near you who could loan you something.

broadbandreports.com have some nice wireless hardware forums at http://www.dslreports.com/forums/18

According to them you need to be using firmware version 1.3 or higher for that particular unit.

blorg

If you mean drivers for the wireless network cards, I'm using XP's built-in drivers. I'm on v1.4.05 of the firmware, which is the latest. I'll try an ad-hoc network when I get the chance, to see if that makes a difference, otherwise I'll see if I can get a loan of a different AP. Thanks for all the suggestions!