Re: panadapter RTL-SDR IC-756pro2


You are used to the speed of the very coarse ProII built in panadaptor. It is very coarse so it takes very little time to accumulate enough data to show a completely fresh spectrum as the incoming signals change. SDRC generally runs with a longer term FFT, which requires a longer time to get the new data to show a new FFT. The dongle interface itself is also causing your problems. The rtlsdr interfaces generally run with large chunks of data for data transfer efficiency.

I bet you are mistakenly running the rtlsdr dongle at 250 kHz sample rate. The rtlsdr dongle requires a minimum buffer size of 16k samples. One buffer is a minimum of 64 ms of delay, long enough to notice and be annoyed with it. I don't remember how many buffers are cascaded into one transfer with the SDRC tool. I tried to refresh my couple years old memory on this - it looks like Simon's calls to "ReadSamples()" typically ask for 65536 samples. This would be about 4 times 64 ms or a whole quarter second.

Could this plus the FFT time contribute to your feeling that it's slow and lagging?


On 20200326 06:06:37, iz1fks wrote:
sorry I haven't read anything from you about delays, where is it? I think there is a misunderstanding here.
I don't understand in which way proII resolution is related, I'm receiving at the IF port, sampling rf with RTL-SDR.
I attach a video here where it can be seen that the issue is about the panadapter function with SDR=>Radio tracking activated.
With tracking function disactivated the spectrum is very good.
73 de Phil, iz1fks
* panadapter_video.mp4 <>

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