I've got an Octo/RPi3 combination under test at the moment with vlfrx-tools version 0.8b. Running with 6 input channels at 96k frames/sec 24 bit samples. For testing the stability, I'm using vtnspec
So far I haven't been able to improve the PPS jitter of the Octo any better than 200nS. Significantly, when I give it a PPS from the PPS bus that supplies the three M-Audio cards used for VLF recepti
Hello Paul and all, Thanks for the detailed analysis (even though the reason for the sampling-point jitter is still unknown). Perhaps it's time to start developing our own A/D conversion hardware. Th
Is a simple design sampling to 10 bit resolution at 80kS/s or 62.5kS/s with embedded timestamp of any interest? I have one based on a 16F688 PIC and RS422 interface running at 2M baud. At the PC en
I'm getting about 2 degrees standard deviation of phase measurements of the 19531.25 Hz reference, taking one measurement per second. The 2 degrees equates to about 285 nS timing jitter. The PPS inte
Hi Paul I'm following your progress with interest as I have a couple of Octo/RaPi3. Did you get this request from Amazon: "As someone who owns Octo 8 channel sound card..., can you help this fellow c
I think that the sample clock triggers a conversion on all the channels at the same instant. Have a look at the data sheet for the CS42448 and see what you think. I put a copy here - http://abelian.o
Hello Paul I might need a bit of advice from Wolf or someone on how to use the rawtcp: mode of Spectrum Lab to pull signal from it. << It's the same compressed Ogg/Vorbis format with or without times
Thanks Wolf. I was wondering if it could also read the un-compressed streams. I seem to remember you putting something in which reads some header to determine if the stream was ogg/vorbis or uncompr
Yes I thought about auto-detecting uncompressed streams, 16 bit signed integer or 32 bit float, but dropped that since I had no use for it (when the WLAN connection between home and the site of VLF6
Well I'm wondering what the best way is to get the signal stream out of the Pi and into SL. rawtcp:// works already and receives the vorbis compressed stream. Eg, vlf6 can be read from the stream se
A further thought - does SL have the means to open a pipe and read raw samples from it? A popen() system call? If so, a more general interface is possible. SL could open a pipe to a script on the PC.
I'm not familiar with that. When I last tried "named pipes" on windows, they were not supported by the mainstream version (windows 98 or XP, not sure). And, as usual, Microsoft have invented yet anot
Not a named pipe, but an anonymous pipe to or from another process. popen() is a lot like fopen() except that it opens a handle to stdin or stdout of an asynchronous process. Eg FILE *f; f = popen( "
I had a bit of time to play again with the Octo, to investigate where the excess timing jitter comes from. The stereo audio injector is giving around 20nS jitter on the PPS from the neo-m8t. With the
...so it could be an EMC issue. One of the first things i've done is removing the ribbon cable and the audio jacks and use RG174 instead. To prevent a galvanic ground loop maybe it is worth to try to
Always good to hear about these adventures. 20 nS jitter is amazing. Meanwhile on this side of the pond, the aerial is iced and the current is quite low since last night but the transmissions on 8.27
Hello Joe, Can you give us a short overview in which days the day and/or night message was transmitted as announced? I would certainly give it a try. My tree has been on air for > 1 week now and i th
These glitches on the Octo input occur as the input signal passes through about +/- 1.4 volts. Regardless of the digital gain control setting. Still present if I bypass the input board and wire strai
...oh, then it may help to switch a impedance converter between the pulse forming RC network, like a non-inverting OP with gain 1. 73, Stefan Am 17.02.2018 22:09, schrieb Paul Nicholson: These glitch
