August 1, 2007 RESULTS
(9:30 PM CDT)
(10:00 PM CDT West coast run)
K5CM TX FREQUENCY :
80 Meters A - 3555425.1 Hz (Published Reference)
80 Meters B - 3555432.747 Hz
W6OQI TX FREQUENCY:
80 Meters - 3565567.313 Hz
Sort by best 80 meter "Corrected" reading (B - 3555432.747 Hz)
* Joe KM1P did not have time to calculate a corrected reading. He sent me his captured wave file and I used Spectrum Lab to calculated the difference frequency. Because of my potential bias, I did not make any subjective measurements of when I thought the best time to measure would be. I simply took Spectrum Lab's automatic calculated difference of 137 simultaneous A and B readings and calculated the average.
Sort by best 80 meter "Uncorrected" reading (B - 3555432.747 Hz)
Sort by best West Coast 80 meter reading ( 3565567.313 Hz )
|AA4RP||GA||Good copy on K5CM - weak copy on W6OQI. Used Spectran and direct reading on a Yaesu FT-847.|
|K5CM||OK||Good sig but the QRN was bad as might be expected in the summer. Thanks for doing the WC run.|
|K6APW||CA||Noise S5 OK S5 to S6 poorer quality reading of signal B. WC S9.|
|K6OQK||CA||I got some very interested traces showing both the A and B frequencies with some very well defined points to compare across the span. This was a very thought provoking FMT. Many thanks to you and Pam.|
|K6YAZ||CA||Connie very weak and spread out; unable to measure spread. Marv good stable signal. Used Spectrum Lab in delta cursor mode between off-air signal and local marker generated by my HP 3336B offset by about 4 Hz.|
|KC0VSJ||MO||Your Signal was fine tonight.. My process is improving; but I still am making mistakes in the “heat of the moment. Freq A was problematic - but vc I seem do have done better measuring Freq-B by its self. Lessons learned - run Laptop on battery and don't try to use a 250hz filter on the radio. Next time I'll try 500hz filter for some more 'working room'. Wait till next week!|
|KD2BD||NJ||Thanks to you and Marvin for another great FMT challenge. All carriers were measured individually using my usual carrier phase tracking method. K5CM was received with fair signals. W6OQI was noticeably weaker and not much above the noise level. Little fading on either signal. Results were frequency measurements over time and averaging readings during periods when the observed frequency was the least volatile. +0.375 Hz Doppler observed for carrier 'A' was applied to corrected" reading 'B'.|
|KM1P||MA||Pressed for time this week ... only got the uncorrected B measurement done.|
|N5PWG||TX||Good sig from both stations.|
|VE2AZX||QC||Your signal was 55.I have submitted the corrected B frequency from your published frequency A and my measured delta (7.843 Hz)The B frequency corrected from the error on freq. A (-0.15 Hz) is : 3555432.546 Hz. This value is probably not as reliable - since the freq. A and B measurements were not done simultaneously. Thanks for running these FMT's.|
|VE2IQ||ON||Another great test.This time the program counted 1832 beats covering 1964559 samples; so that's 1072.357532 samples per beat. This time we were sampling at 8200.397 samples per second; so the beat frequency is 7.6471 Hz.|
|W0PHD||MN||B tone average was varying .8 Hz A tone was even worse. At least no tornado in area like last week.|
|W1PW||AZ||80 meter signals were very weak (rst 3-3-9) from Oklahoma - probably due to the still 'pre-sunset' conditions. Static crashes from nearby T-storms were extreme too. WC signal seemed to have lots of Doppler but was S-9.|
|W3CSW||PA||The QRN level was at about S7 - but you maintained a solid S8-S9. I'm into yet another processing method here in hopes of getting a bit closer to ground truth.|
|W3JW||VA||Signal strength conditions were somewhat below average and QRN was less than most recent tests. Doppler effects (as observed on SL waterfall display) were significant but not as severe as recent tests. Most results were obtained with SpecLab. Was able to make relatively few valid counter measurements on the A and B keydown signals.|
|WB9FIP||WI||The Doppler spread lower in freq was quite apparent on analysis of K5CM run . West coast run was down in the noise - a very difficult challenge. Thanks for the fun!|
With the continued very close readings of several participants plus my own analyses of several captured wave files, I believe it is fair to say that a nearby signal (less than 10 Hz) can be used as an accurate indicator of Doppler. Close examination with FFT software and audio editing software indicated that selective fading does show up even at these close frequency spans (I will put some photos up soon). I think most expected this outcome at these extremely close spans, but it has given us a base to start from as well as developing our ability to measure to sub milliHz resolution.
Starting with the next FMT of this type, we will increase the Span to approximately 50 Hz. This can of course still be measured with most FFT software or audio editing software and a single receiver. Participants should be thinking about how they will measure two simultaneous signals, as the span is increased beyond 3Khz.
See Burt's capture of W6OQI July 25th. ....... (Burt is in ground wave range, about 8 miles from Marvin).
Listen to a short audio clip from VE2IQ audio/ABFAUG01-s.WAV
Listen to a short audio clip from KM1P audio/02AUG_K5CM_FMT_RX_KM1P_80M-s.wav
Listen to a short audio clip from K5CM of w6oqi audio/w6oqi-july11-s.wav
Bill, VE2IQ and Brad, WB9FIP turned in impressive "corrected" readings this week. Both "hitting the nail on the head"!!! This makes two weeks in a row for Bill.
Stations copying K5CM run to .1Hz or better uncorrected.
Stations copying K5CM run to .1Hz or better corrected.
VE2IQ, WB9FIP, K5CM/KM1P, W3JW, W6OQI, KC0VSJ, WB0LXZ, W3CSW
Stations copying W6OQI "West coast run" to .1Hz or better.
K6OQK, K5CM, N5PWG
Transmitting equipment used by K5CM for this FMT:
A HP-Z3801 GPS clocks a HP-3336B and a PTS-250. A small 10 db transistor amp follows and drives a 12BY7 / pair 6146. Then to the final amplifier, a Drake L4B at 300 watts output except on 30 meters where the power is 75 watts. There are no mixers or any device in the chain of amplifiers that might impact the accuracy of the HP-Z3801. As a reality check, I periodically log the HP-Z3801 against WWVB.
80 - Cage Dipole (favors East, West, and North)
40 - Dipole (favors East, West)
30 - Dipole (favors East, North, West)
20, 17 - 4 element SteppIR in Bi Direction Mode (East/West)
Current W6OQI FMT transmitting equipment:
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.
Thanks to all that participated.
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