NEWINGTON, CT, Nov 2, 2004--There's a new twist to the ARRL Maxim Memorial Station W1AW Frequency Measuring Test (FMT). The 2004 FMT will take place November 18 starting at 0245 UTC (the evening of Wednesday, November 17, in US time zones), replacing the W1AW phone bulletin normally transmitted then. Rather than measuring the transmission's carrier frequency, participants in this year's FMT will be attempting to accurately determine the frequency of an audio tone. Engineer and ARRL Contributing Editor Ward Silver, N0AX, says measuring an audio tone will reinforce understanding of the relationship between carrier frequency and the components of a transmitted signal.
"The carrier is suppressed for SSB signals, leaving only the sideband components," Silver explains in "The FMT Strikes a New Tone," in November QST. "The frequency of components of the modulating audio signal is preserved as the difference between the carrier frequency and the transmitted component. A single modulating tone results in a single transmitted component."
W1AW will make the 2004 FMT transmissions on 80, 40 and 20 meters. The FMT will begin with a general W1AW "QST" starting at 0245 UTC sent simultaneously on the three W1AW transmission frequencies. The test itself will consist of three 60-second tone transmissions on each band, followed by a station identification. The whole test will run for about 15 minutes and will end with a station ID.
 All entrants will qualify for a Certificate of Participation, and those coming closest to the measured frequency--as determined by the ARRL Laboratory--will be listed in the test report and get special recognition on their certificates. |
The tone frequency will be the same on all three bands. Silver recommends that participants listen to W1AW's CW or digital transmissions prior to the FMT, so they can evaluate propagation and see which band works best for them.
The ARRL resurrected the FMT--an ARRL staple for nearly 50 years--in 2002. The first FMT, held in October 1931, employed three transmitting stations--W1XP at Massachusetts Institute of Technology, W9XAN at Elgin Observatory in Illinois and W6XK at Don Lee Broadcasting System in Los Angeles--and drew more than 200 measurement reports.
The increasing technical quality of amateur gear was one of the primary reasons that the FMT was suspended in 1980. Even so, the fact that operators continue to stray occasionally outside the amateur bands suggested a need to revive the FMT.
During the 2004 FMT, W1AW will indicate the band on which participants should measure. After the initial call-up, W1AW will begin the test by announcing, "Now 80 meters." Except for the tone transmission, all transmissions will be voice. Frequencies are 3990 kHz (LSB), 7290 kHz (LSB) and 14,290 kHz (USB), and all frequencies will be accurate to at least 0.1 ppm (eg, 3990 ±0.4 Hz).
Submitted report should include name, call sign, location, time of reception and, of course, the tone frequency. Those using an indirect measurement method also should include calculations showing how they arrived at the tone frequency. Silver says that in the indirect method, the frequency of the transmitted signal is measured as if it were an unmodulated carrier. The difference between the published frequency and the measured frequency is the tone frequency. "In the direct method, the measuring receiver is set to the published carrier frequency, and the audio tone frequency is measured with a frequency counter," he notes.
See Silver's article "The ARRL Frequency Measuring Tests," on the ARRL Web site (or in QST, Oct 2002, p 51) for additional details on indirect and direct measurement methods.
Send entries to W1AW/FMT, ARRL, 225 Main St, Newington, CT 06111. To be eligible, entries must be postmarked by Friday, December 17, 2004. Participants may submit a separate report for each band.
All entrants will qualify for a Certificate of Participation, and those coming closest to the
measured frequency--as determined by the ARRL Laboratory--will be listed in the
test report and get special recognition on their certificates.
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