On Sun, 26 Feb 2017, g3zjo wrote:
Many cheap GPS modules have an awful lot of jitter, not being designed for
accurate 1PPS timing applications. I tried several with SpecLab and was not
happy with the jitter performance. I have not tried one of the jittery ones
for EbNaut.
i use a very cheap uBlox NEO-6M gps module. the 1pps pulse has been
shortened to 1ms, and i haven't disabled SBAS (which should further help
with jitter, but i forgot to do it).
it works very well with vlfrx-tools (haven't looked at the code, but
probably Paul included some magic code to average out jitter). i haven't
measured it, but the vlf spectra have one sharp single peak on the tx
frequency, even when i analyse a lot of data in very narrow bandwidth
(such as 6h of data with 47uHz bins).
these modules are about 11 euro on a local auction site, probably cheaper
when ordered directly from china. i don't think you can get much cheaper
than this
VY 73
Jacek / SQ5BPF
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