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Frequency Measuring Test

Frequency Measuring Tests

      November 2017 Frequency Measuring Test (FMT) Format and Schedule

Frequency Measuring Test (FMT) manager Connie Marshall, K5CM, promised something “a little different” for this November’s FMT.

Instead of measuring a single frequency, this test will measure a pair of frequencies — a “two-tone” test. Although the two frequencies
will not jump back and forth at the rate of an actual FSK signal, you’ll be measuring both signals and the shift between them.

The test will be conducted on 80 and 40 meters. Here’s how the test will work:

Following the call up, the test signals will begin on the frequency announced below. This is the lower of the two test signal frequencies.

  • Approximately 1 minute later, the test signal will stop and resume on the second, somewhat higher frequency.
  • The shift between the frequencies will be approximately the same as a standard 170 Hz shift RTTY signal.


Your job is to measure:

  • The frequency of the initial, lower frequency RF signal
  • The audio frequency (AF) shift between the two test signals


To make the “Green Box” in the FMT results, an accuracy of <1 Hz is required for the RF signal and <0.1 Hz for the AF shift between them.

The FMT online data entry form provided by WA7BNM at www.b4h.net/fmt/fmtentry.php allows you to submit four different measurements, two on
each band.

For example, on 80 meters you might submit 3,562,410.4 Hz for the RF measurement and 168.75 Hz for the audio shift (all measurements are
entered in Hz). You can measure the frequencies of both RF signals and compute the shift or leave the receiver tuned to the initial lower frequency and
then measure the audio tone separately.

The FMT will begin 10:00 PM EDT on Thursday, November 2, 2017 (0200 UTC on Friday, November 3 for our DX participants). The test format, rules, and instructions can also be found on the FMT website at www.arrl.org/frequency-measuring-test. Changes or updates to the test schedule will be announced on that web page. K5CM notes that the call up may start a little earlier than published, but the initial test signal will start at the published time.

Submit your measurements using the data entry website. Results will be published on the same website immediately following the data entry deadline, which
is 9:00 PM EST on Sunday, November 5 (Monday, November 6 at 0200 UTC elsewhere in the world). If you’ve never entered the FMT before,
information on how to measure the frequency of a carrier is available at www.k5cm.com and several previous QST articles are listed on ARRL’s FMT page.

Change to Thursday Evening

In response to requests, K5CM and the FMT team have shifted the event to Thursday evening in North America. This is only for the November 2017
FMT. The day of the week for the test will be re-evaluated after the November FMT results are in.

Frequency Measuring Test Schedule, November 2017

  • Start: Thursday, November 2, 2017 at 10:00 PM EDT (0200 UTC, Nov. 3)
  • Results: Submit measurements online until Sunday, November 5, 2017 at 9:00 PM EST (0200 UTC, Nov. 6)

K5CM will make all transmissions

40 meters near 7,064 kHz
0200 UTC 3-minute call up
0203 UTC 2 minutes of test signals

80 Meters near 3,598 kHz
0220 UTC 3-minute call up
0223 UTC 2 minutes of test signals
0225 UTC end FMT

If there is interference on the published frequency, tune around to find the FMT transmissions.
 


 

 

More information on FMT measuring techniques can be found here on the K5CM website.

 


Other Frequency Measuring Tests links

 

 

FMT History & References

  • January, 1980 QST

    From the January, 1980 issue of  QST:

    ARRL Frequency Measuring Test, begins with a call-up at 0300 and 0600Z February 10 (10 P.M. EST February 9 and 1 A.M. EST February 10).

    W1AW transmitters will be on the air simultaneously (on 20, 40 and 80 meters for the duration of the test but in order to correlate your readings with those of the umpire measurements should be made during the specified periods. Approximate frequencies and measuring periods for the early run are 14,075 kHz between 0307 and 0312Z, 7030 kHz between 0315 and 0320Z, and 3565 kHz between 0323 and 0328Z. For the late run, 14,100 kHz between 0607 and 0612Z, 7090 kHz between 0615 and 0620Z, and 3525 kHz between 0623 and 0628Z. Submit your averages for each period to be compared with the umpire, a professional frequency measuring laboratory. Indicate how many readings you took to for in your average. Your report must be received by February 21. W1AW will transmit official results in an ARRL bulletin beginning February 23.

     

  • December, 1980 QST

    Frequency Measuring Test

    Frequency shifting occurred during the early 20-meter FMT on September 14, with stability attained near the end of the period. Late 20-meter signals suffered the fate of poor propagation and were not copied by the umpire. The umpire measured frequencies for the early run at 14,076.241, 7010.999 and 3550.415 kHz. The late run checked out at 7014.292 and 3560.422 kHz. A total of 80 entries were received, representing 825 individual measurements.

    Sixty-six of the 80 who submitted entries measured within 100 Hz, an annual requirement of 100 "precise frequency measurement." They are listed as follows, with average error preceding their call signs: (0 Hz) W1JH W1PLJ W2AXT WA4AXA W41BU W4NTO WA5NOM W5ZTN WA6IQL WB7CRU W8CUJ W8OK W9LCK K0KV W0USL, (1) W1BGW W3BFF W3WD W5FMO ex-7HM W8NWU, (2) K2RG K7AW, (3) WA3RXE W6RQ (4) K1VYQ WA4CAW W1FDH W6CBX K7CC, (5) K6MZN, (7) W3FYX, (8) W8LX W9HPG, (10) W2AIQ, (11) K9AUB, (12) W4DRF AJ5P, (13) K5FSA, (15) W2ND W0GW, (16) W4HU WB9VUO, (17) W0SS VE3FCU, (20) W4PKD, (22) N0ST, (24) W6DLL N8AU, (25) W3KEK W9TGN, (28) VE2JN, (29) W3KCM, (37) KE8X, (44) WA7DUY W7SC, (49) WA3CFC, (51) W6SSB, (63) N6PE, (72) VF4ZX, (75) WA2MID WA6NQF, (77) W7SK, (82) W4UCL, (88) W9KEZ and (97) W8ZRL. All entries measuring over 100 Hz have been notified individually.

    Excerpts

    The equipment used here for the tests consisted of a Heath SB-300 receiver using a 400-cycle band-pass filter. The VFO, i-f and het osc. frequencies were brought out of the receiver and went to a mixer unit, which in turn went to a homemade 8-digit counter. The counter was checked against WWV to four points (W2AXT). I enjoy the FMTs and am looking forward to the next one. Keep up the good work (WA4AXA). I enjoy getting set up for the FMT nearly as much as the actual FMT itself (W4IBU). I "cheated" and borrowed an HP-3586 wave analyzer from work. It's really an FMTer's dream in that it is fully synthesized to 0.1 Hz resolution. It has a 20-Hz i-f filter and a built-in counter to measure the exact frequency of any signal in its band-pass (K0KV). My plans to use all homemade equipment for this test did not get accomplished. Perhaps by the next test, I will have the receiver working well enough to use (W3WD). Any interest in an article on "How To" for frequency measuring? (W0USL). [Sure! - W1CKK] I use the NBS "transfer oscillator" method, using a Heath IB-1100 counter with modified time base (K1VYQ). I enjoy participating in the FMT and hope they continue for years to come (W2ND). Thanks for this event. Sometimes I even come close (W4UCL).

    Feedback

    W4NM measured 13 Hz average error for the May FMT instead of 72 Hz error as reported (sorry 'bout that).

    November 15 (UTC) is the date set for the next FMT. Be sure to check the "Contest Corral" column in November QST for full details. Good luck! Jeannie DeMaw, W1CKK

  • November, 1978 QST

  • August, 1970 QST

    From the August, 1970 issue of QST

    Open to All!

    THOSE Of you who have been following recent issues have realized that some basic changes in the quarterly FMTs were underway. For many years the procedures in the quarterly FMTs were essentially standard, to wit: Official Observers could participate in all four FMTs, while non-OOs were limited to participation in the two QST announced runs (held in February and September).

    In recent months, W1AW has been transmitting the official readings approximately ten days following each of the tests. The object of this is to get word back fast to those anxious to know how accurately they measured the test signals. (Well in advance of the necessary paper work by Hq.!)

    Considerable evidence exists that numerous listeners would like the opportunity to actively participate in the test, and have the accuracy of their measurements compared with others. Thus, effective with this FMT, we're attempting something different. Participants reporting their measurements prior to the W1AW transmission of results (about 10 days following the FMT), will be listed in QST. Results will be tabulated in order of average accuracy with a cutoff point at some still-to-be-determined percentage.

    FMT Procedure

    1. Do some listening an hour or so before the test, to get an idea of band conditions and consequently of which band or bands will be best for measurement purposes. 2. The FMT transmission will start with a general call (QST) at exactly 0130 GMT, September 12. 3.Transmissions for measurement, sent simultaneously on all frequencies, consist of 15-second key-down periods interspersed with W1AW identification. 4. The three periods for measurement will start at 0137 (80 meters), 0145 (40 meters) and 0153 (20 meters); for the "late" run, 0437, 0445 and 0453 respectively. Each period will last for five minutes, including a series of dits at the end of it and identification before the start of the next period. We suggest you make your measurements in that order to coincide as closely as possible with those of the umpire. The table herewith shows the approximate frequencies which will be used.

     

    Starts

    Starts

    Sept. 12, 1970

    0130 GMT

    0430 GMT

    First 5 min.

    3530 kHz.

    3535 kHz.

    Second 5 min.

    7064 kHz.

    7082 kHz.

    Third 5 min.

    14,063 kHz.

    14,078 kHz.

    5. Your percentage error is calculated on all the measurements you submit, so we suggest that you omit any readings in doubt. Watch out for careless mistakes in arithmetic, typing and other simple operator errors which can throw your percentage off. Submit more than one reading on each transmission and, if possible, measure more than one frequency so we can strike an average.

    No entry consisting of a single measurement will be eligible for QST listing of top results. Listing will be based on overall average accuracy, as compared with readings made by a professional lab. Never tried the FMT? An excellent introduction to the basic techniques can be found in the W2VMX article "Try the FMT", page 54 July 1968 QST.

  • September, 1969 QST

    Technical Correspondence

    Technical Editor, QST:

    For weeks before the recent Frequency Measuring Tests I had brayed to my friends on the air about how I would make a concerted effort to place high on the FMT results list. I had built a separate mixer, fed by my Drake twins' oscillators and followed by all outboard t.r.f. amplifier. The amplifier gives out a signal on whatever frequency is being tuned, directly into my newly acquired Hewlett-Packard 5216A frequency counter. With no interpolations involved, nothing could go wrong, I asserted.

    I was busy most of the day of the FMT preparing for the two runs that evening. The Tektronix 547/1A1 dual-trace scope was set up to afford envelope or sine presentations of the receiver's 50-kHz. i.f., as well as to monitor the counter's time base against WWV (from a second receiver), and to peak the signal going to the counter. It was disturbing to discover that receiver dial backlash and frequency drifting were a real problem at those last hours, when attempting to tune and maintain zero phase difference, so I haywired a multiturn vernier capacitor across the receiver p.t.o. With a large knob attached, I was able to "ride" a calibration marker quite well.

    That evening, at the start of the first FMT run, I was "loaded for bear," so I thought. All equipment was properly warmed up; I had attempted to stabilize the house temperature all day and had just closed all windows to prevent drafts. I was skeptical about receiving W1AW on 80 meters while it was still daylight here on the west coast, but there it was, right on schedule. However, the received signal on the scope was all fuzzed up with noise, and was bouncing from a nearby c.w. QSO. Tightening the bandwidth and using rejection tuning helped somewhat, but I still could not discern zero frequency clearly, much less ride zero phase as I had practiced earlier with a nice clean calibration signal.

    When key thumps informed me W1AW would now shift to 40 meters(1) I was horrified and thought aloud, "Wait! I'm not finished yet!" But I wheeled everything up to the next approximate frequency, and there was a beautiful, clean signal. But just as I was ready to take some readings, some clown came on with dashes in unison with W1AW, and nearly zero beat. The 20 meter run was received well, except that by then I was so spooked I may have booted that reading also.

    The second FMT run at 0430 GMT that evening was also chaotic here at W6FP. I never heard W1AW on 80 meters, not one peep. I had a good crack at a 40-meter reading, but the 20-meter transmission was hopelessly covered by heavy, continuous RTTY. By the end of the second FMT run, I was crushed by the enormity of my failure.

    I know I must improve my antennas in order to have more of a received signal to play with, especially on 80 meters.

    This will give me a cleaner scope readout. And I must groom my receiver regularly, not just wait until total outages force me to service it. Periodic tube checks, performance tests, and realignments "by the book" were let go here to my detriment, I subsequently observed.

    With a clean enough signal at the receiver i.f. output, perhaps I can phase-lock my b.f.o. I have tried mixing the received i.f. back to the signal frequency and counting this, with only marginal success. Perhaps with more work, this idea of measuring "regurgitated" received signals directly might be the answer - to use the receiver as a tunable window only. Thanks to the ARRL for the FMTs as a challenging program, and watch out for us next time! - Dick Carpenter, W6FP, 6634 Ampere Ave., North Hollywood, Calif. 91606.

    W1AW does not shift frequency during the FMT. The entire transmission is sent by all transmitters simultaneously. However, the "umpire" measures the frequencies in the order indicated in advance announcements. Actually, the frequency seldom drifts more than a few cycles during the entire transmission period, so any significant differences will be noted only when precision measuring equipment is in use. - Editor


  • July, 1968 QST

  • September, 1965 QST

  • September, 1931 QST