[Elecraft] Analog vs. Digital Front Ends

[Walter Underwood]

This might be an orthogonal opinion, but I think it is awesome that high-end direct sampling receivers are competitive with mid-range superhets.

We’ve been refining superhets since 1918, but when I worked on DSP in the 80’s, no one even considered direct sampling. It is still early for direct sampling technology, but it is good enough for people to think about the tradeoffs. Wow.

wunder
K6WRU
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Sep 15, 2015, at 5:35 PM, Lynn W. Taylor, WB6UUT <KX3 at ColdRocksHotBrooms.com> wrote:
> 
> On 9/15/2015 1:36 PM, Joe Subich, W4TV wrote:
>> 
>> 
>> 
>> On 9/15/2015 3:39 PM, Lynn W. Taylor, WB6UUT wrote:
>>> Maybe I'm wrong, but if the thing we're testing is supposed to be a
>>> radio, and we want to compare how radios work under conditions we'd
>>> encounter in actual use, it just seems intuitively obvious to the most
>>> casual observer that the tests should be the same.
>>> 
>>> 73 -- Lynn
>> 
>> 
>> Therein lies the rub ... direct digital conversion SDR devices have
>> their best performance (best sensitivity) at (composite) signal levels
>> just below the clip (overflow) point of the ADC in use.
> 
> I agree with you.  What I'm saying isn't about why an SDR or an Analog receiver might have problems.
> 
> If we're testing receivers, we should treat them as a black box and not look into the ciruitry to see how they behave.
> 
> After the test, then we could look inside and say "oh, the ADC is the limiting factor."
> 
> 73 -- Lynn
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