Re: [Discuss-gnuradio] Capturing maximum complex value

That's great! Thanks, Ron!

On 3/17/19 3:30 PM, Ron Economos wrote:
> I have a block that does what you need.
>
> https://github.com/drmpeg/gr-iqlevels
>
> Ron
>
> On 3/17/19 08:09, John Ackermann N8UR wrote:
>> I'm working on a flowgraph that generates an output waveform about 375
>> kHz wide with very high peak-to-average power -- at least 20 dB. This
>> is sent into a USRP1 with BasicTX board to generate an output at 29
>> MHz.  I'd like to show in the flowgraph GUI the peak instantaneous
>> output level, to help in setting the gain.
>>
>> It's painfully clear on a spectrum analyzer when the gain is too high.
>> The attached shows (a) single CW carrier at max output (orange); (b)
>> output without clipping (yellow); and (c) output with occasional
>> clipping (blue).  These are max-hold plots so the clipping is caught
>> even though it happens only very infrequently.
>>
>> Is there a probe or other function that can capture and hold the
>> maximum instantaneous value of a complex stream?  If not, is there a
>> way to create that capability out of other blocks?
>>
>> And, am I barking up the wrong tree -- is the distortion likely caused
>> by the complex output being driven into digital clipping when enough
>> vectors add up, or is this a function of the analog conversion in the
>> USRP?  i.e., is the problem likely to be on the input or output side
>> of the DAC?
>>
>> Thanks,
>> John
>>
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