Re: Will I have a problem if my IQ data coming in is not in sync with 48000, 96000, etc?
¿ªÔÆÌåÓý
Thanks Jim,
This sounds very encouraging.? I only need receive, and the sample rate will be as close to 48 kHz as I can get it with the clocking on the Pico.? I am using a PCM1808, but the timing signals are coming from the Pico, so that is where my error is coming from.?
This thing is very like a softrock sdr receiver using the Si5351a (one clock for I and one for Q and one for TX on digital mode.? I will be using only the mono audio for WSJT-X receive, and the
?ideas for digital mode transmission.? I? Then I want to try and make the rig only connected with the computer via WIFI.? That is when I need to use the PCM1808 and the data you have so kindly provided.? One of my
goals with this is moving to micropython for the MCU code.? The class I teach is not emphasizing the software, and I find students catch on to micropython a lot more quickly and easier than they do to C++.? I looked at all the existing protocols I could find
and after all that I decided the simple IQ and control data I'm sending is probably best just to use my own custom protocol.? We will see how it goes.
73,
Rob
KL7NA
From: [email protected] <[email protected]> on behalf of jimahlstrom via groups.io <jahlstr@...>
Sent: Saturday, November 25, 2023 1:27 PM To: [email protected] <[email protected]> Subject: Re: [n2adr-sdr] Will I have a problem if my IQ data coming in is not in sync with 48000, 96000, etc? ?
CAUTION: This email originated from outside the Walla Walla University email system.
Please take a look at function quisk_process_decimate() in quisk.c. Quisk can accept a variety of sample rates even if they are not multiples of 48 ksps. It decimates by an integer to a rate close to 48 ksps. The fractional rate correction happens after
demodulation when the audio is mono so there is no problem with images. This applies only to Rx.
I am not sure this helps. If you want I/Q data for a program like WSJT-X it won't work. But many digital programs can work with monophonic data. If you try to drift the frequency back and forth to average to 48.000 ksps, you will have frequency drifts in WSJT-X. I must point out that Pico is not a real audio codec. Jim N2ADR |
Rob Frohne (KL7NA)