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Channel Selection on Airwave modules

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Hi !

Airwave modules have 4ch, but only 3 pin for selecting channel.

What combination of pin's corresponds of channel.

On TX module (630) I left not connected Channel Selection pins, and on RX module (634) too.

It works. What channel in this case is involved?

Thanks.

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All pins unconnected is CH-4. For the other channels, ground the corresponding channel pin.

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Hi !

Airwave modules have 4ch, but only 3 pin for selecting channel.

What combination of pin's corresponds of channel.

On TX module (630) I left not connected Channel Selection pins, and on RX module (634) too.

It works. What channel in this case is involved?

Thanks.

Lawmate tx channel selctor work like binary code, with three first switch, you can choose between 8 differents channels:

000= channel1

001=2

010=3

011=4

100=5

101=6

110=7

111=8

edit: oups sorry I misunderstand the question...

Edited by Vrflyer

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I got hold of an AirWave 10mW AV TX (Active Robot special offer about £5 http://www.active-robots.co.uk/media/pdf/608r609t.pdf ) which worked reasonably well on channel 3 with an NGH reciever (LawMate). I then found a reciever in the U.K. which used the AW frequencies (Pakatak about £20). All the channels were about usable when outputing the Rx to a TV although there was some flickering at the top of the screen. However, when I tried to get the video on my laptop via an ADS Video Express USB device the results were very dissapointing. The picture was very bad and colour was missing.

I'm assuming the problem is a poor Rx, although I have got another Rx, operating on the LawMate channels (obtained from e-bay for about £10) which works well with the laptop on channel 3.

Am I to give up on the new Rx or is there something I could try?

Incidentally does anyone else use the Video Express?

Many thanks.

Jon Davies

Edited by jonforstedavies

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There's often more than the frequency needed to match for everything to go well. I try to always use the matching receivers from the same manufacturer as the TX to avoid that kind of problems.

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There's often more than the frequency needed to match for everything to go well. I try to always use the matching receivers from the same manufacturer as the TX to avoid that kind of problems.

Thanks for the reply. I've sent the receiver back to see if it can be tuned more accurately. The video, when displayed on TV wasn't too bad, not perfect but probably acceptable for CCTV use. However, when displayed on a PC via the ADSTech device it was useless. I'll let you know what the retailer comes back with.

Thanks again

Jon Davies

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I've got an airwave AWM634 receiver and 631 transmitter. It appeared to work fairly well at room temperature (although there was always interference at home). Then I tried a range test outside (40 degree F day) and found that with the camera (CX161) and the transmitter sitting outside on a tree branch, the video began to loose sync. I started checking the range it when it started rolling and I thought I had lost signal, although there was no static. I was only a couple hundred feet away, so I went back to the transmitter and it was still rolling. Then for kicks I tried a different viewer - a portable DVD player with video in and it worked where the goggles wouldn't. My video recorder also doesn't like the signal and only grabs a few glimpses.

I didn't use a capacitor to couple the camera's video out and the AWM631 transmitter. Maybe that will help. I might have dig out a scope and do some poking. It's a pain in the butt to troubleshoot something that gets worse with temperature.

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I didn't use a capacitor to couple the camera's video out and the AWM631 transmitter.

The video coupling cap is very important (install it per the AWM631 data sheet). This may not solve your particular problem, but not following the data sheets is rarely a good thing. BTW, the AWM634 will also need a video coupling cap, so be sure to include it.

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The video coupling cap is very important (install it per the AWM631 data sheet). This may not solve your particular problem, but not following the data sheets is rarely a good thing. BTW, the AWM634 will also need a video coupling cap, so be sure to include it.

Where in the AWM631TX datasheet does it call out a coupling cap? I looked for it specifically before I started and found nothing, and that's why I intentionally didn't put one in. I did install the two bypass capacitors, one on the 5V supply input and one on the bypass pin per the datasheet, but nothing in series with the video signal like is called out for the receiver.

Did I miss something or am I just being stupid?

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Oh, it was me being stupid. The Airwave Tx's video input is internally AC coupled, so an external cap is not needed. So, you are good to go. I'm sorry for the unnecessary detour.

In regards to the video problem, is there any chance your camera voltage is not close enough to 5.0V? The CX161 has a narrow allowed operating voltage and can act funny if the voltage deviates too much from that.

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That's good to know the input is AC coupled. I won't bother trying to poke at that then. To be honest, I slapped a 7805 on the transmitter and wired the camera straight to it and didn't bother checking the voltage. It might be even be starting to fall out of regulation with a COLD 2S battery on it - I think it was around 7V but still 75% full. I'll check into it some more. Thanks for the help!

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The typical dropout voltage spec on LM78xx's VRegs is Vout+2V, so you may start to see voltage problems with a pack that is below 7V. For 2S LiPO apps, an LM2940T-5.0 LDO is better choice since the dropout spec is much lower.

For sure, check the camera voltage next time things start to get goofy. For the CX161 camera, you'll want to see 4.85VDC to 5.25VDC at its input (be sure to include the voltage drop on the camera's cable).

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