HFU HF Underground
Loggings => HF Beacons => Topic started by: ChrisSmolinski on December 19, 2012, 1300 UTC
-
Kilokat7 and I have been hearing these this morning, first noted around 1245z.
Dashes every 6 seconds Several different dash rates, about 3 and 6 seconds its seems, more observations are necessary. Noted on these frequencies so far:
6934
7038
7250
7469
7695
7928
8167
8413
-
I checked some remotes, signals are much stronger near the East coast.
-
By 1319z, they all appeared to be off the air.
They have moved (to higher?) frequencies, now noted on:
8669
8799
9198
9479
10200
10364
It seems as though there are two transmissions on each frequency, spaced about 3 seconds apart, repeating about every 6 seconds. The repetition rate does not seem to be very precise.
-
Interesting, the original list included some frequencies in the 40 meter ham band. Are those still active? Will give a listen this evening.
-
They went off the air, but are back again at 1646z, copying on these freqs:
4920
5380
6200
6420
7922
8040
8530
9050
9190
Update: these went QRT at 1705z.
-
I note the use of 9050 kHz again.
I saw this signal for a few minutes this morning before I went to work, I recorrded them but had no time to look closely at them. Definately looked like at least 2 sources but could possibly be a single source changing beam direction or power before sending the second pulse.
Might be interestinng to figure the time delay between source one and source two for two different receiving locations. If nothing else this will give a distance delta for those two locations. And, if the time between start of pulse one and start of pulse two are different for two different receive locations then that will say for sure more than one source. The exact start time of any one pulse does not need to be known, just the time delta between start of one and start of two.
T!
-
These dashers have been around at least since January of this year. I recognized the dashes as having the same characteristics as those I logged earlier this year:
Jan.11th, 2012:
0348 UTC: 2800, 3000, 3075 & 3450 KHz
0355 UTC: Frequencies shifted to: 2325, 2725, 2925, 3050, 3150 & 5475 KHz
I also noticed some of the dashes would seem to fall off in signal strength from one to the other while listening to a single frequency.
-
I note the use of 9050 kHz again.
I saw this signal for a few minutes this morning before I went to work, I recorrded them but had no time to look closely at them. Definately looked like at least 2 sources but could possibly be a single source changing beam direction or power before sending the second pulse.
Might be interestinng to figure the time delay between source one and source two for two different receiving locations. If nothing else this will give a distance delta for those two locations. And, if the time between start of pulse one and start of pulse two are different for two different receive locations then that will say for sure more than one source. The exact start time of any one pulse does not need to be known, just the time delta between start of one and start of two.
T!
I made some stereo recordings, with the second channel recording UTC time from the 1 PPS output of my GPS.
FWIW: The spacing of the dashes does not seem to be uniform at all.
-
Noted again at 1801z (they may have started earlier, that is when I first noticed them):
5220
5880
6240
6720
6820
7025
8160
8280
Off at 1715z, looks like the changed frequencies again...
-
1815z frequencies:
5140
5839
5970
6270
6920
7460
7570
8400
-
this must be what I have been seeing a lot lately ?
it stopped just as I started recording.
http://archive.org/download/Jc1974-ShortwavePiratesFreebandersUnidsMilOddities/6920-video-2012-12-19-13-46-55.mp4
-
FWIW: The spacing of the dashes does not seem to be uniform at all.
Chris, there is uniformity there. Lets keep in mind that I only had a few minutes before going to work to record some signals, but I did record on several frequencies in the 1330 to 1350 time period (Dec 19, 2012).
In every recording I made during that time period there is a set pattern.
Pick any single pulse as a starting point. The pulse should be 700 msec long. Now look 11.200 seconds after the start of that pulse, ignoring any other pulses you see prior to 11.200 sec after your selected pulse, there should be another pulse starting exactly 11.200 after your selected pulse. I found this to be the case for my recorded periods, plus and minus my ability to determine start time, about 1 msec. So the period from any pulse to the next pulse from what is probably the same source is 11.200 sec.
Now, divide 11.200 seconds by 700 msec, you get 16. If there are multiple sources and it is some kind of test you would not want to have one pulse stop and the other begin right away, so allow a dead space of 700 msec before the next begins, allowing for 8 sources. However, it looks to me like there is only 4 sources. This means there should be a pulse about each 2.800 seconds. Because of path length distances this will vary.
Call your first selected pulse pulse A0. Call the pulse 11.2 sec after that A1. Call the pulse at 22.4 seconds after the A0 pulse A2, etc, etc.
Roughly 2.8 seconds (this time will be affected by path length differences to you from A0 source and B0 source, in my case this turned out to be 2.672 sec) after pulse A0 you will find another pulse, call this B0. 11.200 seconds after pulse B0 you will find another pulse, call it B01, and so on each 11.200 sec.
Roughly 5.6 seconds after A0 you will find another pulse, again the exact time is dependant on path length (in my case this turned out to be 5.833 seconds), call this pulse C0. Every 11.200 seconds after C0 you will find another “C” pulse.
Roughly 8.4 seconds after A0 you will find another pulse, again the exact time is dependant on path length (in my case this turned out to be 8.055 seconds), call this pulse D0. Every 11.200 seconds after D0 you will find another “D” pulse.
The next pulse after D0 will be A1, and it should be 11.200 seconds after A0.
The gross errors from the 2.8 second spacing, and the fact that one trip around the Earth is only 133.4 msec, would suggest that the system does NOT space the pulses at 2.8 seconds, but rather some value near that. I don’t know, but that was my starting point to look for sets of pulses and a pattern.
All four sources / pulse schedules where seen in my 2 minute recording of 8799 kHz at about 1332 UTC.
T!
-
Hi Token,
Thanks for the detailed analysis. I think my error was in assuming that there were two stations with a roughly 6 second repetition rate, vs the actual 11.2 second rate.
Now, let's see if they return today.
-
Not hearing much of these down in my neck of the woods, but did come across these two:
@ 21:04z on 8413 USB Underneath a ute there was an alarm or siren type tx - not a dasher, but interesting.
Audio: http://archive.org/download/ShortwaveOddsSodsTransmissions/8413Usb2104z12-19-12.mp3
@ 00:17z-00:18z on 7038 USB Could hear a faint dasher next to a het, but this one probably fits the bill.
Audio: http://archive.org/download/ShortwaveOddsSodsTransmissions/7038Usb0017z-0018z12-20-12.mp3