Hi Brad: To get the best s/n radio you need to have good narrow filters. The NRD-545 uses DSP for the IF filters and so can be adjusted to a 10 Hz bandwidth. This is the lowest IF bandwidth I know of in any HF receiver including the high end and military models. The only things with narrower bandwidths are the HP/Agilent 4395A in spectrum analyzer mode where there is a 1 Hz bandwidth or the PC sound card spectrum analyzers where you can get sub Hertz bandwidths. http://www.prc68.com/I/NRD545.shtml http://www.prc68.com/I/4395A.shtml#SA
The 114BR Time Comparator was used with WWV and WWVH in conjunction with a receiver and scope. http://www.prc68.com/I/TF_rack.html You could duplicate the function of the HP 114 using a variable time delay for phase comparison. The antenna is about as important as the receiver for HF and LF signals. For HF I really like the B&W Terminated Folded dipoles. Chirp receiver testing showed them to be far superior to every thing else. http://www.prc68.com/I/RCS-5A.shtml#Ant The trick to getting a PIC to decode the subcarrier data would be best done by audio filtering prior to amplitude detection. I haven't worked with the DSPics but that would allow doing better filtering in the PIC. http://www.prc68.com/I/TF_rack.html For WWVB the amplitude changes but the carrier is always there. Starting Jan 1 2006 the modulation depth was changed from 10 to 17 dB, see: http://tf.nist.gov/timefreq/general/pdf/2139.pdf It's very important that you filter out close by RF signals. Here is a 0 to 200 kHz spectrum plot: http://www.prc68.com/I/Spec_0002.shtml you can see that there are plenty of signals there. Have Fun, Brooke Clarke http://www.prc68.com Brad Stockdale wrote: > Hello all, > > Thank you to everyone that has helped (and some that continue to > help) me with my GPSDO equipment post... I've got a few leads out > there and hopefully I'll be able to get ahold of some of these units > soon... I really am looking forward to getting to work with some other > GPSDO's. > > Anyway, on to the reason for this post... I'd like to get some > receivers so I can HEAR and USE the WWVB, WWV, and WWVH signals... I > know that HEARING them may not be a 'normal' request, but I just > would like to monitor the audio as well as being able to decode the signals... > > I guess the first thing to take care of is receiving the signals. > Can anyone recommend decent receivers for these stations? I guess the > list of frequencies would be: > > o WWVB = 60 KHz > o WWV = 2.5 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz > o WWVH = 2.5 MHz, 5 MHz, 10 MHz, or 15 MHz > > Hmm, I just noticed that WWV and WWVH overlap... How in the heck > do you differentiate between the two stations if they broadcast on > all the same channels? > > Anyway, I wouldn't mind a kit type of project that would let me > receive these signals... Maybe I'll check out Ramsey Electronics, > Rainbow Kits, Velleman, et al. Surely one of them has kits for these > broadcast ranges. > > Can anyone suggest a kit, or project listed online with > schematics and parts lists, or I guess even reasonably priced commercial > units? > > If I can't get radios that have built in decoders for these > stations, I'd be happy just receiving their audio and then trying to > build my own decoder using a PIC or something... > > Thanks for any advice. > > Brad > > > > _______________________________________________ > 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.
