PhantomSDR Support Forum

General Category => PhantomSDR Hardware => Topic started by: Phil - NY4Q on Dec 16, 2024, 02:13 PM

Title: RX888MKII Samplerate
Post by: Phil - NY4Q on Dec 16, 2024, 02:13 PM
I was looking over the KA9Q software and came across this in the rx888.c file :

static int const Default_samprate = 64800000; // Synthesizes cleanly from 27 MHz reference

I am currently running my PhantomSDR+ instance at 60Mbps. Should I move that to the setting mentioned above for 'best case scenario' operation?

Phil
Title: Re: RX888MKII Samplerate
Post by: Bas ON5HB on Dec 16, 2024, 03:39 PM
Editted....as found the info.

Beware, if you set the sample-rate above 60MS (somewhere above it), it will disable the 30MHz Lowpass filter.
It has a 64MHz LPF:

https://www.rx-888.com/rx/ so you could try to set it higher.

I forgot the limit where it does that. But it will allow ALL frequencies to enter the ADC, could give 3m FM stations on HF or others.

The 27MHz reference means you have to use an external high-accuracy signal generator like a Bodnar.
If you use the internal this doesn't change anything.

The Bodnar uses GPS-PPS signal to make a very accurate 27MHz.

Look here:

https://websdr-maasbree.jouwweb.nl/websdr-maasbree-2-0/control-the-rx888-mkii-with-a-bodnar-reference-clock
Title: Re: RX888MKII Samplerate
Post by: Bas ON5HB on Dec 16, 2024, 05:55 PM
I just tested with 80M to 100MSPS...but it won't work, starts to stutter.

I adjusted buffers etc in the rx888 sources, but then all fails to work.

For my Intel test machine, with OpenCL it stopped arround 70MSPS.