[hpsdr] Meaning of ADC-L and ADC-R metering in PowerSDR

[John Marvin]

Perhaps PowerSDR could use the wideband data (which cuSDR and KISS 
console use for displaying the wide bandscope) to produce a full 
broad-band ADC reading.

John
AC0ZG

On 2/22/2014 1:01 PM, Warren C. Pratt wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
>
> Hi Brian,
>
> These values return the total signal into the "slice" BEFORE the 
> bandpass filter.  So, they do not vary based upon the bandpass filter; 
> however, of course, they do vary depending upon what is within the 
> total bandwidth of the slice.
>
> As far as I recall, there is no return of total ADC reading from 
> hardware to software.  The closest thing is just the ADC Overload bit.
>
> In brief, no they don't allow you to see the total ADC input.
>
> 73,
> Warren  NR0V
>
> On 2/22/2014 11:05 AM, Brian Lloyd wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>>
>>
>> Today I was using my ANAN-10 to get an idea of the total power coming 
>> in from my Pixelsat loop. This is a broad-band untuned loop with a 
>> preamp, good pretty much from DC to 30MHz. (Really it is useful from 
>> about 50kHz to 20MHz but it does have significant output above and 
>> below that range.) My assumption was ADC-L and ADC-R represented the 
>> actual ADC values relative to full-scale, based on the fact that 
>> PowerSDR labels the value in dBFS (decibels relative to full-scale).
>>
>> You can imagine my surprise when I discovered that this value changed 
>> as I "tuned" the radio. (Yes I did check the attenuator and made sure 
>> it was set to 0dB for these tests.) Now my supposition is that what 
>> ADC-L and ADC-R are reporting are the values of the samples in a 
>> given RX "slice" rather than the actual ADC values. If this is the 
>> case, perhaps a new label is in order in PowerSDR? May I suggest, 
>> "Not Very Useful - L" and "Not Very Useful - R". Or perhaps, "Slice - 
>> I" and "Slice - Q".
>>
>> But a reading of how close the input is to saturating the ADC(s) 
>> would be very useful.
>>
>> -- 
>> Brian Lloyd, WB6RQN/J79BPL
>> 706 Flightline Drive
>> Spring Branch, TX 78070
>> brian at lloyd.com <mailto:brian at lloyd.com>
>> +1.916.877.5067
>>
>>
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