Chris, Regarding the decoding method.
As i stated earlier, i'm using a CMMR-60p, which seems to just be a small DSP. If i am remotely successful at my current version, my thoughts are that i would replace the CMMR with a similar DSP, and just FFT the crap out of the signal at 60khz... but i have no serious experience at this... so i could be just talking air here... -Lenny On Sat, Mar 26, 2011 at 6:54 PM, Chris Albertson <[email protected]>wrote: > Lenny, > > You are ahead of me by many months. I'm building a WWVB receiver > also. Actually I expect I will need to build several before I get > 24x7 coverage. My breadboard works only at night in the So. > California area. My plan is to place the entire receiver, antenna > and all on a mast far from the house and use an RS422 serial line to > send the data back to a computer indoors. > > Do you intend to publish your work? I'd be most interested in how > you decode the signal. I'm conflicted between two approaches (1) To > declare the signal "invalid" if there is any error at all or (2) to > try and extract as much signal out of the noise as I can. I may do > the latter and then have some kind of quality indicator. The WWV > audio decoder built into the NTP reference implementation can extract > time code from what sounds like white noise and static to the human > ear using sophisticated DSP. My first receiver will use #1. > > About measuring the PPS.If you had a nice HP Universal counter with a > computer interface that would be best. You put the PPS from a good > GPS on one channel and the PPS from WWVB on the other. Lacking that > and if you only need to get down to uS level you can use two serial > orts in a Linux box and use PPS line disciplin on each oert the kernal > will time stamp the PPS when they happen and software can read and log > the time stamps. Use the command "ldattach pps <device>" for each > serial port. Good to about 1 uSwhich for WWVB might be enough > > > > On Sat, Mar 26, 2011 at 1:26 PM, Lenny Story <[email protected]> wrote: > > Greetings All, > > > > This is my first post to this board. > > > > I've completed the first run of a WWVB receiver board and Antenna (custom > > wound quad). Its an 8051 microcontroller, with a serial port really, but > it > > can decode the signal accurately pretty much all day long. (I'm just > north > > of boston, MA). > > > > I'm wanting to evaluate its performance, my guess is i'll have to produce > a > > plot of its PPS. In reading the LeapSecond.com site (awesome btw), the > > "Allen Deviation" is used. As this is my first technical, experience in > > this area, is there a resource or method that is preferred by those who > know > > this technology ? > > > > The code reports the time delta between each detected second. If i log > the > > PPS deltas for an entire day (or week) of detected signal, is that enough > > data to start figuring out how to do the "Allen Deviation" calculations ? > > > > Any resources can you recommend to figuring out the graphs i need to > produce > > ? > > > > Thanks in advance for your help ! > > -Lenny Story > > _______________________________________________ > > 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. > > > > > > -- > ===== > Chris Albertson > Redondo Beach, California > _______________________________________________ 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.
