Might be a bit of a cost. The SDR runs $1495. Regards Paul On Wed, Sep 26, 2012 at 5:36 PM, Dennis Ferguson < [email protected]> wrote:
> > On 26 Sep, 2012, at 11:19 , Majdi S. Abbas wrote: > > > On Wed, Sep 26, 2012 at 10:13:22AM -0700, Tom Van Baak wrote: > >> My reading of the document(s) is that the new format will in fact allow > >> WWVB to be used as a frequency standard with even greater precision then > >> before, though not with unmodified legacy WWVB carrier receivers. My > hope > >> is that one of you will produce a clever reference design for such a T&F > >> receiver make it available to the group. It sounds like a very fun DSP > >> project; one that we can all learn from. Bonus points for making it an > >> open-source Arduino shield. Making it work with both DCF77 and WWVB > would > >> also be a plus. > > > > DSP would be good, although I also think an microcontroller > > implementation could be interesting. Atmel's ARM MCUs look like they'd > > be good candidates for this sort of thing. (Pretty fast, enough storage > > to do interesting things with it, and a fast enough ADC for 60 KHz.) > > This is fine, though to make it maximally useful for time and > frequency purposes I believe the hardware might need to provide a > way to synchronize the ADC clock to an external reference, and likely > some way to time-mark the incoming data (e.g. a quick-and-dirty version > might feed a PPS signal to the second channel of a stereo ADC, if no > more elegant solution is available). A control loop to discipline an > oscillator's output might use that oscillator to clock the ADC and adjust > the oscillator to zero the ADC's phase alignment with the input signal, > if that can be made to work. A system to measure WWVB propagation delays > and > signal levels might instead clock the ADC and the time marker with a > known-accurate frequency and PPS (e.g. a GPSDO). > > RFSpace makes commercial LF/MF/HF SDR equipment with almost the right > inputs > for this (an external frequency input and a timing trigger). What I'd like > is a tiny-budget version of this just for LF stations. > > > I've got a couple of these that I might use as a development > > platform: > > > > https://www.olimex.com/Products/ARM/Atmel/SAM7-P256/ > > > > Has anyone come up with a reasonable algorithm to implement in > > a microcontroller? (DSP development kits are a bit more spendy than I'd > > like to invest in a prototype. :) > > I guess the trouble with this is only that the availability of brute force > can sometimes make it unnecessary to deal with a lot of complexity. If > your > job is to do a convolution of a model of what you know was transmitted > against the incoming signal to measure the time alignment then using a > platform where you can store big blocks of data and do Fourier transforms > with wild abandon can provide really good results without having to spend > a lot of time thinking about it. Even quite modest modern PC hardware > comes > with a boatload of memory and is exceedingly speedy, and for some purposes > it can save a lot of time and effort just to make use of that compared to > trying to do without. > > I have a quick-hack DCF77 PM detector which runs on PC hardware and makes > use > of one of the above-mentioned RFSpace receivers for the data acquisition. > While > it is now in boxes being moved, when I get it back up I would love to lose > the > RFSpace receiver in favor of something much less costly, but would hate > trying > to make this work with something less capable than the PC. Using a > microcontroller > like that to do the A/D conversions and send the data collected out (say) > an > ethernet port to a PC which does the heavy computational lifting (that's > what the > RFSpace receiver does) would appeal to me, but trying to do without the PC > would > not. > > Dennis Ferguson > > > _______________________________________________ > 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. > _______________________________________________ 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.
