Topband: SDR Mythbusters - ADC Overload myths debunked...

[James Rodenkirch]

His "explanation," if I read it correctly, seems to be a tad "at odds" with what Sherwood Engineering's measurements show....or am I missing it????
 
> From: w8ji at w8ji.com
> To: rodenkirch_llc at msn.com; topband at contesting.com
> Date: Tue, 6 Oct 2015 18:29:09 -0400
> Subject: Re: Topband: SDR Mythbusters - ADC Overload myths debunked...
> 
> 
> From Stu, K6TU
> 
> As with any technological change, there are many myths, past truths or part 
> truths that get repeated endlessly and out of context by those frightened or 
> challenged by the change.
> 
>  Software defined radios are no exception to this in the world of Ham Radio.
> 
>  Steve Hicks, N5AC and the VP of Engineering at FlexRadio has posted an 
> excellent explanation and bust of the ADC overload myth on the FlexRadio 
> community.  You don’t need to be registered on the community to read this 
> excellent write up:>>>>>>
> 
> Regardless of the fact they cannot possibly overload, they overload here.
> 
> I don't understand his explanation at all.
> 
> We had ONE transmitter on while trying to receive. The ADC could not handle 
> the level of one transmitter.  Because there was no in-band front end 
> selectivity, the spacing did not matter.  We could not get the strong local 
> signal outside a roofing filter.
> 
> With two transmitters on different non-synchronized frequencies, there will 
> be periods of time when the voltages add. There will be periods when the 
> voltages subtract. Anything following the summing point has to handle the 
> random peaks, even an ADC.
> 
> The Flex we tried here, using it to listen while ONE transmitter was 
> running, just went nuts. It was equally bad no matter what the spacing. At 
> least with a radio with roofing filter, we could move the radio up or down 
> band and use it.
> 
> 73 Tom 
> 
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