ARRL 2005 Frequency Measuring Test

Returning to the airwaves November 17 at 0245 UTC (Wednesday, November 16 in US time zones), the 2005 ARRL Frequency Measuring Test (FMT) once again will call on participants to measure the frequency of an audio tone modulating the carrier.

''Measuring the tone frequency, as opposed to that of the carrier, reinforces the understanding of the relationship between carrier frequency and the actual components of a transmitted signal,'' Engineer and ARRL Contributing Editor Ward Silver, N0AX, says in ''Tune In the 2005 Frequency Measuring Test,'' in November QST (p 54),
www.arrl.org/w1aw/fmt/2005/05fmtsilver.pdf.

''With the carrier largely suppressed for SSB signals, only the sideband components remain. A single modulating tone results in a single transmitted component.'' But, Silver notes, the frequency of the absent carrier is what the operator sees on the radio's display.

The FMT signals will emanate from Maxim Memorial Station W1AW this year on 160, 80 and 40 meters. The 20-meter transmission has been dropped for 2005 because of the generally poor conditions during evening hours on that band. The frequencies will be 1855, 3990 and 7290 kHz, and all transmissions will be on lower sideband (LSB). The FMT will replace the W1AW phone bulletin normally transmitted at
0245 UTC on November 17 (November 16 in US time zones).

Participants may utilize either direct or indirect techniques to
determine the tone frequency. ''Direct measurements assume a carrier frequency and measure the audio tone frequency directly,'' Silver explains. ''Indirect measurements obtain the transmitted frequency of the tone component at RF, then compute the difference between the published carrier frequency and measured frequency.''

Silver advises that since the W1AW exciters are independent units and not fed with a single local oscillator, participants can expect the measured tone frequency to differ slightly on each band.

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.

Submitted reports should include the time of reception and the tone frequency. Those using an indirect measurement method should show how they calculated the tone frequency. Participants also should include name, call sign and location in their reports, and they may submit separate reports for each band. A Certificate of Participation is available to all entrants.

Those entrants coming closest to the measured frequency as
determined by the ARRL Laboratory will be listed in the test report and will also receive special recognition on their certificate.

Entries must be received via e-mail or postmarked by December 16, 2005.

Send hard-copy entries to W1AW/FMT, 225 Main
St, Newington, CT 06111

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