Topband: SDR Mythbusters - ADC Overload myths debunked

[Tom W8JI]

> On Sat,10/10/2015 2:15 AM, Steve Ireland wrote:
>> Of course, I was talking about using a DUC/DDC in a single 
>> transmitter/receiver urban/semi-rural station setting on a quarter to 
>> half an acre block, which is the setting in which the vast majority of 
>> people who subscribe to this reflector would be using a transceiver.
>
> Your use is not nearly so much a majority as you might suspect. A fair 
> percentage of contesters operate SO2R. MANY hams live in proximity to high 
> power broadcast stations. Hams with good antennas in locations exposed to 
> many in-band and out-of-band signals are likely to encounter far higher 
> voltages at the input to the radio than you do.

I thought they were talking about overload from local transmitters.

If you look at Sherwood Engineering's tests, they show the problem we had. 
The wide spaced dynamic range of SDR's is only 96-99 dB.

The wide spaced dynamic range of the K3 is up around 105 dB. That 5 or 10 dB 
is helpful with local transmitters, but the real difference we noticed was 
the SDR just totally goes goofy when it overloads, losing everything, while 
the regular receivers just "noise up" or de-sense.

 Overload characteristics for strong signals have nothing to do with how a 
receiver works without strong signals to overload it.    :)

73 Tom