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Re: [Discuss-gnuradio] a simple qustion about the attenuator for the SMA
From: |
Dan Halperin |
Subject: |
Re: [Discuss-gnuradio] a simple qustion about the attenuator for the SMA cable |
Date: |
Wed, 5 Nov 2008 10:08:41 -0800 |
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On Nov 4, 2008, at 2:31 PM, Bill Stevenson 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.
- -Dan
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