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Re: [Discuss-gnuradio] RFX400 Antenna Connection

From: David Scaperoth
Subject: Re: [Discuss-gnuradio] RFX400 Antenna Connection
Date: Wed, 7 Mar 2007 21:57:23 -0500

On Mar 7, 2007, at 9:53 PM, Jeremy Chew wrote:

Thanks. Here is an update...

So far I have tried all the following together: - Increasing the cable attenuation value to 50dB - Cutting the receive gain setting to 0
- Using high-frequency cables

FWIW, I have had success with the Rx PGA gain set to max (65dB I believe) with 40dB of attenuation between the boards, and a TX multiplier of 2000 (I used the GMSK stuff for testing)...I think this was around 5dB CNR when I looked at it on the OScope.

There is no apparent change, so I may have to cut the transmit power.

----- Original Message ----- From: "Matt Ettus" <address@hidden>
To: "Jeremy Chew" <address@hidden>
Cc: <address@hidden>
Sent: Tuesday, March 06, 2007 1:40 AM
Subject: Re: [Discuss-gnuradio] RFX400 Antenna Connection

Jeremy Chew wrote:

I am trying to eliminate channel error by using a cable to connect two RFX400s together. The strange thing is that nothing useful seems to get through when the radios are connected by cable. I have tried attenuation in the range from 0 to 40dB and with several cables to no avail. Using antennas works much better.

Do you know what is wrong? And what should the cable attenuation be?
The cable attenuation needs to be at least 40 dB for safety. It probably needs to be more for signal integrity. Have you adjusted the receive gain downwards to compensate for the high signal levels?

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