From: Dan H. [email protected]
To: Bill S. [email protected]
Cc: [email protected]
Sent: Wednesday, November 5, 2008 1:08:41 PM
Subject: Re: [Discuss-gnuradio] a simple qustion about the attenuator
for the SMA cable
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On Nov 4, 2008, at 2:31 PM, Bill S. wrote:
I have a rudimentary question about the attenuator. When I was searching some questions in the archive, I found that some guys mentioned when testing the transmitter and receiver for daughter board, the antenna should be connect by Tx/Rx SMA, the Tx and Rx can NOT be connected directly by cable and we need a attenuator about 40-50 dB!! What is the meaning of attenuator here? Is it a hardware? Thanks a lot for all!
An attenuator is a piece of hardware that weakens (“attenuate” means
weaken) the power of a signal transmitted along a wire. When you
directly wire a TX board to an RX board, the power transmitted is much
stronger than receiver expects (even a tiny bit of air gap induces a lot
of attenuation) and can fry the circuitry. So we simulate this air gap
with an attenuator.
Fixed RF attenuators can be had for fairly cheap ($10-20) I think.
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I got it!Thank you so much! But I think we could also attenuate the
transmitted power by
setting --tx-amplitude to a reasonable value. Do you think so? What’s