I'll add to the conversation. CHU is easier to deal with because its not a subcarrier as the 100 Hz WWV signal is. Its FSK and bell 103 modem style. Regards Paul WB8TSL
On Thu, Mar 29, 2018 at 10:08 AM, jimlux <[email protected]> wrote: > On 3/29/18 3:49 AM, Attila Kinali wrote: > >> On Thu, 29 Mar 2018 03:12:24 -0700 >> Hal Murray <[email protected]> wrote: >> >> What do I need in in order to get time from WWV or CHU? >>> >>> Do I need a fancy receiver as a front end? Do I have a chance with one >>> of >>> the low cost USB thumb drive size receivers? >>> >>> Is there an obvious software package to start with? (Linux) >>> >> >> I think the easiest is GnuRadio... A quick googling lead >> to https://github.com/jasonabele/gr-wwvb >> I don't know anything about it so use at own risk :) >> But at least it seems like something that can be done easily >> on a rainy evening. >> >> Normal RTL-SDR's do not work for WWVB as they have a lower cut of >> frequency in the range of 20-50MHz...unless you bypass the tuner >> chip and feed the signal directly to the ADC. As IIRC all RTL-SDR >> give you something like 2Msps, that should be more than plenty to >> decode WWVB and related signals. If you feed the RTL-SDR from an >> external frequency source, you should be able to related that >> frequency source to WWV. >> > > The RTL-SDR is an interesting device - I'm putting together a hobby HF > interferometer with GPS to provide time tags. > > Yes, most of the newer parts (RTL-SDR v3, for instance) provide a > programmable bypass of the front end downconverter (the part is actually > designed to tune TV signals and the L-band output of a consumer dish LNB) > The backend chip (RTL2832U) is a digital downconverter which mixes and > filters the nominal 3.5 MHz IF which is sampled at 28.8 MHz > > You can actually adjust the output sample rate - something around 2 > Msample/second is the default, but there's lots of other rates available. > For WWV you could crank it down, but.. > The ADC is 8 bits (7 ENOB) and the output is 8 bit I/8 bit Q. > > Folks have modified the RTL-SDR to accept an external frequency reference, > so you could take the output from your ensemble of Cesium references to > discipline a hydrogen maser (so your close in phase noise is better),then > use that to drive a 28.8 MHz discrete divide/multiply chain, and run that > into your $30 receiver to improve the frequency accuracy. (not for nothing > are we called time-nuts) > > > > > >> Attila Kinali >> >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
