Yes. I regret now that I rounded off the WA6ZTY frequency to the nearest 0.1 Hz. I might have been exactly in agreement if only I had rounded to the nearest 10 millihertz.
I used a Ten-Ted RX340 receiver, which has the advantage that it accepts an external 10 MHz frequency reference at its rear panel and phase-locks all its oscillators to the 10 MHz reference. That made the measurement comparatively easy. I would set the receiver for CW reception with its BFO offset 800 Hz from the center of the passband, and feed the output to SpectrumLab, running on my laptop with an external USB sound card. I calibrated the sound card against WWV audio before the test. I captured the Spectrum lab measurements to a text file, which I imported into Microsoft Excel to compute the mean and standard deviation of the peak frequency within a passband centered on 800 Hz. This worked well for the W1AW measurements: once having tuned the receiver, I left its dial alone for the duration of the test. As I recall, the one-sigma jitter on the received W1AW frequency was 1 or 2 Hz -- so I certainly did NOT consider my measurement more accurate than about 0.1 Hz. Unfortunately, when it came to the WA6ZTY part of the test, I kepttweaking the receiver frequency by a Hz or so (it tunes in one-hertz steps) and that made the spreadsheet file captured from SpectrumLab less useful. I didn't fell confident that I had made a good estimate of the standard deviation of the measured frequency. because of my mistake of tweaking the receiver frequency. So I rounded that measurement, too, to the nearest 100 millihertz. If I had only NOT disturbed the receiver tuning during the WA6ZTY frequency measurement, I could have made a better estimate of the one-sigma frequency jitter. Then I would have had a better estimate of the accuracy of the measurement, and might have rounded it to the nearest 10 millihertz rather than to the nearest 100 millihertz. -- James Maynard Salem, Oregon, USA Connie Marshall wrote: > Hi James, > > Looks like your W1AW 40m reading is inline with the rest of the readings. I > still think Joe (W1AW station manager) may have just made a typo mistake > when he copied the readings to the email he sent me. My W1AW 40m signal was > good, about 55 db out of the noise on Spectran. My WA6ZTY signal was fair to > good. My reading for WA6ZTY would be the same as yours if I rounded to the > nearest tenth. > > Would be nice to find someone capable of doing 2 or 3 runs per year. I'm > wondering if WA6ZTY would be interested in doing some unofficial FMT runs > several times a year. Sure would help get the math errors out, if we all got > more than one shot per year. I would be glad to do it but I wouldn't be > anymore accurate than W1AW on TX as I currently have no way of locking my TX > signal to a stable standard. But then again, maybe high accuracy is not as > important as just the experience of getting it all together to make a > measurement under the time pressure of 3 minutes. Were you active in the old > days when W1AW made 3 or 4 FMT's per year and reading to the nearest Hz was > considered good hi hi. > > Hope your having a good Holiday Season > > Connie > K5CM > > PS: by the way my Daughter's call is N5KK > > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Behalf Of James Maynard > Sent: Friday, December 29, 2006 4:22 AM > To: tim-nuts mailing list > Subject: Re: [time-nuts] FMT > > > My numbers were: > W1AW (40 m band): 7038806.3 Hz > (1.4 Hz higher than the official reading) > > WA6ZTY: 7028351.5 Hz > (0.03 Hz higher than the official reading) > > I only submitted readings to the nearest 100 mHz (that is, 0.1 Hz), > as I didn't think my measurements supported more digits of precision > than that. > > I could not copy W1AW by ear, although I did pick out the call sign > once during the test. I could not copy the announcements of when they > were measuring the 160 m, or the 80 m, or the 40 m signal. I only saw a > faint waterfall trace, and only on 40 m. > > -- > James Maynard, K7KK > Salem, Oregon, USA > > > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > . > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
