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Re: [Discuss-gnuradio] ham/amateur getting started

From: John B. Wood
Subject: Re: [Discuss-gnuradio] ham/amateur getting started
Date: Tue, 29 Dec 2015 06:43:34 -0500
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On 12/25/2015 01:02 PM, David McQuate wrote:
Broadcast radio & TV transmitters, police & fire repeaters, and others have potent 
signals.  If your system does not attenuate them, by using low-pass, high-pass, or band-pass 
filters, the peak voltage at your analog to digital converter may at times exceed "full 
scale".  The resulting non-linear response produces many spurious signals, that may mask the 
typically weak signals you are wanting to recieve.  An initial solution is to use broad-band 
attenuators to keep the total power reaching the ADC below full scale.  Then observe the spectral 
peaks and insert appropriate filters to knock them down.  The attenuation may then be reduced.  
Frequently AM broadcasters are the worst.  A high-pass with cutoff around 1.6 MHz may be all you 
Hello, and the Ettus USRP E310 has the front-end filters that may well accomplish the required receive preselection and transmit spurious filtering. Granted, the price of a E310 may put it out of consideration by many hams. Sincerely, and 73s from N4GGO,

                                            J. Wood

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