Re: Has anyone built Ashhar's Specan?

Ashhar Farhan

you could just do rms of the audio. the main challenge would be that given 3 khz bandwidth, the 30 mhz scan would need a reading every 1.5 khz. that means, 20,000 readings for the full scan. it will take a long time. this ia why specans have variable bandwidths.
- f

On 26 Jul 2017 10:35 p.m., "Jerry Gaffke via Groups.Io" <> wrote:
If I were to create a pcb for the uBitx, it would have pads for an optional ad8307 (or ad8310) after the crystal filter, just before the demodulator.  Drives an ADC pin on whatever processor you happen to be using, 10 bits of ADC is plenty.  So in addition to having an all band HF xcvr, would have a low grade Spectrum Analyzer.  That ad8307 could also be used as an S meter.  Removing a jumper at the input to the ad8307 and plugging in something like a scope probe it could be used as an extremely wide dynamic range RF probe for trouble shooting.  

Or maybe instead sample the output of the demodulator using a 24 bit ADC, use DSP techniques on one of the cheap ArmCortex Arduino compatible processors to do an FFT for fine grained spectrum analysis.  This would be more difficult to do right.

Of course, you would have to build two if you want to check emissions on your new uBitx.

Jerry, KE7ER

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