K5CM FMT May 16, 2012 (9 PM CDT)
K5CM 20 - 14056201.113 with a reference of 14056000.000
Two stations, W3JW and WB6BNQ, managed to repeat last weeks performance with "Dead On" readings. Adding to the Zero error list were K7HIL, and W6IHG. Several more stations, including AB4RS, VE3OAT, W5NZ, WA1ABI, K1GGI/M3, WA2DVU, N4AU, AA8K, N7EP, and K3SIV were .007 Hz or less. Even though Ed, K1GGI/M3 did not make the "ZERO LIST", he deserves top billing for making his .003 Hz reading from his car driving down the Interstate. That's just pretty COOL!!! Ed, did you calculate your Doppler based on car speed and direction (I'm kidding).
From a scientific point of view we have not had enough readings to say unequivocally that readings are enhanced by using a reference signal 200 Hz from the FMT signal, but it does seem to point in that direction.
I would like to move on to 2 KHz delta for the next series of test. At least two simple methods remain at this delta. One being the standard peak_f low - peak_f high method in SL, although resolution is starting to be poor at this delta, and the other being AM mode and then a simple peak_f average of the readings. The AM method should give the best results if the sound card is properly calibrated. This is about as high as we can go with out more elaborate methods. So be thinking about what you will do with 20 KHz and 100KHz delta.
Because of other things going on it is difficult to plan so many FMT's many days in advance. If you would like a text message sent to your phone I will try to accommodate a few. Just email your number to me.
K5CM 20 Meters (9:00 CDT)
|Call||Section||Grid||TX Frequency||Measured Freq||Error in Hz||Error in PPX|
|K7HIL||AZ||DM42ph||14056201.113||14056201.113||0.000||0.00E+00||Wow - the ref signal sure made all the difference. I made individual measurements for each direction and the delta from highest to lowest frequency was 0.00028 Hz. I made a best guess without the ref and the best I could do was about 0.038 Hz. ---- Setup was using an IC7800 ref to a Thunderbolt GPSDO. First calibrated the sound card, then calibrated the CW pitch frequency and tuned in the signals so that I could "see" both test and ref signal on Spectrum Labs. Lots of time post processing - this is the first time I have a high degree of confidence in my numbers (still acknowledge I may be off :) ). --- Never heard the 2 KHz offset - out of my bandpass and did not know about that part of the test in time to prepare for it.|
|W3JW||VA||FM17TN||14056201.113||14056201.113||0.000||0.00E+00||Used SL with screen approximately 250 Hz wide. Used the published reference frequency plus locally determined delta F.|
|WB6BNQ||SDG||DM12||14056201.113||14056201.113||0.000||0.00E+00||As with the last dual tone FMT, it still took a lot of spreadsheet processing time and careful analysis due to being in the "Grey-line" area.|
|W6IHG||VA||FM09tb||14056201.113||14056201.113||0.000||0.00E+00||Flex5000a, HP3336, both with Thunderbolt GPS. Spent lots of time analysing an intermod product, above the Unk signal instead of the real Ref Signal below. It fit what I thought I should see but did not match the announced freq. My I/Q recoding was a disas|
|AB4RS||VA||FM18hw||14056201.113||14056201.114||0.001||7.11E-11||Interesting doppler activity, the observed frequency increased through the first run, remained steady during the second, and decreased during the third. Relative offset between the two signals remained fairly consistent. Didn't check my email so I missed the second run with the 2 kHz offset.|
|VE3OAT||ON||FN25eg||14056201.113||14056201.114||0.001||7.11E-11||Didn't seem to be much Doppler as the results were pretty consistent. Did it my old calibrator comparison method and the new reference frequency method on three transmissions. Connie, thanks for the test.|
|W5NZ||AL||EM62vi||14056201.113||14056201.115||0.002||1.42E-10||Used TS-570D(G) and SpecLab to measure delta between frequencies. Only measured first (East) run. Monitored 15MHz WWV on separate receiver to ascertain Doppler effect -- varied almost 0.5Hz here in Alabama. Thanks for the new ideas on how to use SpecLab!|
|WA1ABI||RI||FN41jp||14056201.113||14056201.111||-0.002||1.42E-10||Measured audio beat note at 201.111 Hz using AM detection, then added that to the reference. East, North, and West 200 Hz spacing runs agreed within 3 mHz. Also recorded the 2 KHz beat note with AM detection - it measured 1999.979 on Spectum Lab. I don't do any soundcard correction in Spectrum Lab. Normally I use low freq beat notes (50 Hz or lower) to minimize the effect of soundcard clock error.|
|K1GGI/M3||PA||FN11||14056201.113||14056201.116||0.003||2.13E-10||Halfway to Dayton, in the middle of PA, so method was to capture the AM beat note on laptop. Had found hi pwr line qrm nr motel, so went driving on interstate during test. Recorded a cal tone before leaving home, but when played tonite, was suprised to find it pretty far off nominal. Hoping for a miracle.|
|WA2DVU||SNJ||FM29nc||14056201.113||14056201.110||-0.003||2.13E-10||Fed 7600 audio into SL - good sigs, listed fx is east - s9, north sig was s4, and west was s2. No qrm. Thanks again Connie. Peak fx readings ran 201.105 - 201.115.|
|N4AU||AL||EM62vp||14056201.113||14056201.110||-0.003||2.13E-10||Thanks Connie. Tried the AM method and Delta method. AM looked more stable so entered it. I had about 200 mHz difference in the calculations, maybe due to the accuracy of my cursor in SL. I used only the East run.|
|AA8K||MI||EN82sx||14056201.113||14056201.110||-0.003||2.13E-10||I used Open HPSDR, Flex-Radio's PowerSDR, Trimble Thunderbolt GPSDO, TAPR TADD-2, and Spectrum Lab. 5 Meter tall ground-mounted vertical antenna.|
|N7EP||WWA||CN87uk||14056201.113||14056201.107||-0.006||4.27E-10||Great fun Connie. The east signal was loaded with Doppler and I didnít use it. The North signal was S7 and the West was S9+ and both had significant Doppler. At the start I was bothered by a very strong CW signal close to K5CMís signal which made identification difficult. What I thought would be a simple FMT, just measure the difference of the two signals and add it to the reference signal, turned out much harder. No Doppler, receiver frequency error or drift to worry about. During this FMT sound card sample rate calibration became important and the standard tones I recorded at the start of the FMT, didnít agree with the playback frequencies? My biggest problem was that I couldnít get repeatable answers when trying to squeeze the last mHz out of a graphical solution. Thanks for teaching me a lot about Spectrum Lab.|
|K3SIW||IL||EN52ta||14056201.113||14056201.120||0.007||4.98E-10||Only had the West run to work with because my passband was narrow around 14055 kHz and couldn't copy anything that way. Finally opened up the passband and found the signal. The reference signal helps because my signal gen doesn't lock to GPS and my GPS-driven counter only displays to 0.1 Hz precision.|
|W8XN||MI||EN82dg||14056201.113||14056201.100||-0.013||9.25E-10||Signals were strong here in Michigan on a Clifton active vertical with a bit of dropoff in the west-beaming test. I recorded the NetSDRís IQ outputs, ran them through a 2-mega-point FFT, and averaged just the keydown products. Doppler was quite a bit different than a week ago: east test was -6 mHz, north was +218 mHz, and west was back to -9 mHz. All three beaming results were within +/- 5 mHz when corrected, so I averaged them to come up with a guess. Thanks for another interesting FMT, on to wider spacings!|
|K9KK||OK||EM15||14056201.113||14056201.099||-0.014||9.96E-10||Used the "DELTA" method. Recorded the Reference, Delta, and the FMT. Averaged 111 "DELTA" readings. Worst QRM I have encountered for an FMT.|
|KA1BQP||RI||FN41||14056201.113||14056201.098||-0.015||1.07E-09||Good signals, all three runs. I captured the beat note in AM mode and added the reference frequency to the measured tone. Tnx Connie.|
|KD2BD||NNJ||FN20XD||14056201.113||14056201.194||0.081||5.76E-09||A solid-state Hammarlund HQ-140-X receiver with AM detector was fed into a sound card and recorded along with a 1000 Hz tone from my homebrew WWVB frequency standard on individual audio channels (44100 Hz @ 16 bits). The audio channels were separated and bandpass filtered using SoX software, and their individual frequencies measured using Baudline software. The frequency measurement was added to the published RF reference carrier frequency after compensation for soundcard sampling error, determined through identical measurement of the 1000 Hz standard, was made. Results for the East transmission were submitted. North was 0.9 mHz lower, and West was 4.0 mHz lower than the shorter path to the East. Kp was 2. TNX Connie!|
|VE2IQ||ON||FN15nt||14056201.113||14056201.018||-0.095||6.76E-09||Poor SNR due to operator error. It was apparent many times the ref tone was weak while test tone was strong and vice versa, so I decided to difference the averages instead of averaging the differences. (NSWAG?)|
|NO5K||STX||EM10CM||14056201.113||14056200.972||-0.141||1.00E-08||Not so good this time, loads of QRM and fumbling. Did not find startine transmission until well into the Test. Unable to figure out where 2KHz up was, nothing heard around there. Got ten samples of the Reference tone at 14056000.340 If I look at the last few samples of the reported 14.0562x transmission they trend to 40 mHz lower than Reported Value.de NO5K|
|N2GL||AL||CN85ko||14056201.113||14056201.288||0.175||1.25E-08||Tried a variation. Developed an average error between WWV and GPSDO of ~.35Hz and added that to the audio beat freqency. Too big delta probably. SLM w SpacLab, scope to find 1850Hz IF.|
|K6BZZ||AZ||DM33xb||14056201.113||14056200.899||-0.214||1.52E-08||Going to Dayton. There was strong qrm right in the middle of the two signals. Thanks again for your efforts.|
|W3SA||NC||EM95qb||14056201.113||14056201.577||0.464||3.30E-08||First time using SL. setup to use the wspr at same time and recorded a wave file to use SL. WSPR was way of compared to what I was able to determine using SL and Excel work sheet.Looking forward to seeing how my swag comes out.All three runs were 5NN in NC. Thanks|
|W5EMC||STX||EM10cl||14056201.113||14056201.610||0.497||3.54E-08||Two frequencies are too much. I don't work S02R either.|
|aa7oo||AZ||DM43fe||14056201.113||14056201.905||0.792||5.63E-08||FMT reported it the west run, not an average.Copied all runs including the 2Khz run. All signals were clean and very distinct. My local reference tone was setup prior to the runs at what I thought was out of the way and non interfering. It actually was in|
|W3GXT||MDC||FM26||14056201.113||14056199.820||-1.293||9.20E-08||I am confused if you want all three runs.Run1. 14056199.82 Ref: 14055999.02Run2: 14056199.95 Ref: BadRun3: 14056199.76 Ref: 14055998.88Very strong signal here, sued IC7000 and log wire.Keep the tests coming and thanks.|
|KG0HY||NE||EN20||14056201.113||14056202.673||1.560||1.11E-07||Signals on first run were distorted, but the next two runs look good on Spectrum Lab. The measured difference was 202.6726 Hz, for the last two runs. The receiver is WinRadio G313, connected to a HF vertical. Spectrum Lab is on a Windows 98 computer. 73 KG0HY, Casey|
|N5DM||STX||EL29fs||14056201.113||14056201.600||0.487||3.46E-08||UPPER f = 14055201.600 / LOWER f = 14055000.400 / DIFFERENCE = 201.200 Hz / Signals: S2-/Doppler/QRM in STx. Worst copy ever.|
This from K7HIL
This pdf shows Michael's complete method (Great job Michael !!!)
FMT 5-16-2012 rev1.pdf
Transmitting equipment used by K5CM for this FMT:
A HP Z3801 GPS frequency source clocks a HP-3336B and a PTS-250. The outputs are combined and feed to a 10 db transistor amp which drives a 12BY7 / pair 6146. Then to the final amplifier, a Dentron 2500 running 300 watts out. There are no mixers or any device in the chain of amplifiers that might impact the accuracy of the GPS frequency source. As a reality check, I periodically log the frequency source against WWV and other GPS referenced sources. I monitor each transmission with a completely separate receive system to look for any instability or short term drift.
I typically see considerably less than 1 mHz difference at 10 Mhz when comparing two Z3801's or a Z3801 and a Thunderbolt, over a 10 to 10,000 second period.
160 - Vertical
80 - New Sloping dipole. Sloping down from 140'. (favors West, North, East)
40 - Standard Dipole hanging between two 80 foot towers. (favors East, West)
20 - 4el SteppIR at 70'
Current W6OQI FMT transmitting equipment for this FMT:
My Transmitting setup consists of a HP Z3801 clocking a HP 3336B which drives a Johnson Viking I transmitter, the output of which is attenuated by a 6 db attenuator, to then drive an Icom PW-1 amplifier to about 500 watts. The antenna is an inverted Vee which favors north and south from the Los Angeles area.
Note: Because I put the results up quickly, there will be mistakes, so don't hesitate to point them out quickly.
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