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Author Topic: VC01 Chinese Military Numbers Station on 7878-USB kHz, 1229 UTC, Feb 23, 2016  (Read 1717 times)

Offline Ron - Calif.

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CHINA. 7878-USB, VC01 Chinese military numbers
station at 1229 UTC and still here at 1302, on Feb 23.
So another day, like yesterday, that they did not switch
to 3519-USB, as they often do around 1130; erratic
schedule; fair reception.

My audio at  https://goo.gl/KoCKJu

Ron, listening in San Francisco, at Ocean Beach, California

Offline Ron - Calif.

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Please note that Hiroyuki Komatsubara (Japan) did
in fact hear VC01 at 1328 today on 3519-USB, so
they were very late making the switch in frequencies.
As I say - erratic schedule.

Ron

Offline Token

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This station has up to 6 frequencies active in a 24 hour period, apparently cycling frequency as conditions require.  They typically use a given frequency for about a month, changing frequencies around the start of the second week of each month.

And yes, as you noted, the time to change frequency daily is not very consistent. 

In addition to the recent frequencies noted on that forum there is one other that has been in use, 6916 kHz LSB.  That makes 3519 kHz USB, 6916 kHz LSB, and 7878 kHz USB one current set of frequencies.  There may be another set of three in use also. I have seen two sets active in the past.

This station is something of an enigma.  Obviously machine generated numbers, sent so fast that no human could keep track, implying machine reception of the numbers.  If machine on both ends, why do it in voice?  One possible answer is to look at the genesis of the signal in years gone by. 

One theory, and it is just a theory, admittedly weak in some areas.  The signal started many years ago as normal human read and copied air track data in the air defense network.  20+ years ago I did hear such Chinese networks on the air, but I cannot prove what I heard was related to what we have today, however the information sent was in a similar format.  Eventually the human read numbers was replaced by machine generated voice at normal human speeds, so that humans could still copy to plot boards.  Again, many years ago I heard such a network on the air, but cannot prove any connection, other than the same general format of data.  Weaker conjecture starts here.  What if a machine copied generation was introduced?  A voice to data capability?  What if these machine received nodes were slowly introduced and there was a mixture of machine and human copied nodes in use for a while until all units could be equipped with the machine copied ability?  After all units were equipped with the machine copy capability the rate of the transmitted data could be increased to faster than human rates, giving better track resolution and higher throughput rates.

Just a thought, attempting to come up with some possible reason we have obviously machine sent voice messages at rates faster than a human could dependably copy or use.

T!
T!
Mojave Desert, California USA

Offline Ron - Calif.

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Thanks "T" for the addition info.

Back in August 2011, Keith Perron (Taiwan) provided
the following info after seeing a log I posted back then,
questioning just what it was that I had heard -

"This is not the Taiwan number station . . . This station
comes from China . . . The station is operated by the
Chinese Navy and is very active during military exercises.
It's in no way a spy station . . . The reason it sounds the
way it does is because of the old technology being used
to generate the numbers. Back in the 70s Taiwan's number
station sounded the same until there was an equipment
upgrade in the late 70s or early 80s . . ."  (thanks again
to Keith for this info!).

Ron

Offline Token

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"This is not the Taiwan number station . . . This station
comes from China . . . The station is operated by the
Chinese Navy and is very active during military exercises.
It's in no way a spy station . . . The reason it sounds the
way it does is because of the old technology being used
to generate the numbers. Back in the 70s Taiwan's number
station sounded the same until there was an equipment
upgrade in the late 70s or early 80s . . ."  (thanks again
to Keith for this info!).

Ron

Ron,

I don't think anyone has tried to tie VC01 to spy numbers operations, it is pretty definitely not that.

Is it possible Keith is talking about another station?

Most sources today seem to think it is air defense related, not Navy (and it has a Morse code cousin also).  The station today does not seem to become any more active during exercises than it is all the time.

I pretty much have at least two frequencies in my log for any given dates (most often different times on those dates) I go looking for this station and sometimes I can find three freqs in use for a 24 hour period.  Like I said, sometimes I can detect what appears to be two sources, each with individual frequencies, but I am less sure about the validity of that.  What I know for sure is that I fairly often find at least 2 frequencies in use at the same time, but not in sync with each other.  Not all the time, but often enough that my log is pretty full of those occasions.  And the dates do not seem to correlate to published exercises.  For example a quick look at my logs (and recordings) shows that all of May, 2015, there were two frequencies in use very near each other, 5466 kHz USB and 5461 kHz LSB, often at the same time, and each with different traffic.

There appears to be at least two speeds for this station, I call them fast and slow in my logs (I see it first in my log a couple years ago), but they are all fast, occasionally, however, you can find one that is distinctly less fast than the others.  Often when I can find two freqs in operation at the same time one is noticably less fast than the other.

And then there are the transmissions that cycle power levels.  This one is not seen often, and it is pretty intriguing when I find it.  I see it at least several times a year.  These transmissions will be at one power level for a given period of time, step to another power level for a period, and then back to the original power level.  This goes on for hours at a time.  These steps are not the results of propagation changes, and are always synchronized to a very short pause in the data.  The last time I logged this (about 2 months ago) it spent 2 minutes 12 seconds at one power level (call it power 1) and 3 minutes 58 seconds at the other power level (call it power 2), repeating that cycle, 2:12 power 1, 3:58 power 2, repeat, for the hour that I watched it.

Further, using remotes I have looked at this cycling power.  Occasionally I have been able to detect inverted power levels on the remotes.  I mean, the cycle that was the higher power level for me was the cycle that was the lower power level for the remote.  And my low power cycle was the remotes high power cycle.  This may suggest that during the changed power signal the power does not change at all, but rather the antenna direction might change causing these cycles.  Of course, I have far to little data to draw a firm conclusion, but it is interesting to see.

T!
T!
Mojave Desert, California USA

Offline Ron - Calif.

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Feb 24

1134* UTC VC01 7878-USB

*1134 UTC VC01 3519-USB

Ron
San Francisco

Offline Token

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And right now, 1332z, Feb 24, 2016, VC01 is up on two frequencies, 3519 kHz USB and 6916 kHz LSB.

T!
T!
Mojave Desert, California USA