Vietnamese numbers station activities, 10255 kHz USB

[Token]

I regularly report on the Vietnamese numbers station (10255 kHz, USB, OM, Vietnamese, 5f) on a couple of other forums, I thought I might include this one. It has been a while since I looked at this station because while I have been recording it on a daily basis I have not looked at the recordings in over a month, I simply have not had the time. And when I did look at them yesterday I saw some odd activity.

My last report to other forums included up to August 31, 2010, so I will pick up on September 1, 2010 for this report.

From September 1, 2010, until September 14, 2010 the station did just what it has done for months. It sent the same 42 group message it had been sending since April 22, 2010, this message is 3 minutes and 29 seconds long. It sent three messages a day with the same timing trends it had been using for months.

September 14, 2010, was the last numbers transmission I heard from this station.

From September 15 to September 25, 2010, no transmissions were heard at my location. This 11 day gap is by far the longest I have seen since I started watching this station, the previous longest period of no reception was 3 days.

Starting on September 26, 2010, and right on scheduled time for the numbers to start, a tone was heard. This tone was a steady 970 Hz with no information on it at all, just a steady tone. The tone lasted 6 seconds longer than the 42 group message would have. At approximately the time the second 42 group message of the day would have started the tone again started, and it ran 6 seconds longer than the 42 group message would have been. At about the time the third and final 42 group message of the day would have started the tone again started, and it lasted 8 seconds longer than the 42 group message would have.

From then through October 5, 2010, if any transmission was seen it was the tone, and the tone closely mimicked the habits of the 42 group messages. The 42 group messages are either 3 minutes and 29 seconds, or 3 minutes and 30 seconds long, depending on when the second hand of the clock falls. The tones were between 3 minutes and 35 seconds and 3 minutes and 38 seconds long. As if the transmitter would have been turned on a couple of seconds before, and turned off a couple of seconds after, the 42 group message audio would have been sent.

On October 6, 2010, the tone durations reduced to between 2 minutes and 29 seconds to 2 minutes and 31 seconds in length. All other habits remained the same. Still about the same spacing and still three transmissions a day. This lasted for 3 days worth of transmissions.

Today, October 11, 2010, the tone duration increased, going to about 3 minutes and 45 seconds in length. As I only have one days worth of samples, today’s three transmissions, I do not know if this is going to be the average or not. All other actions remained the same, three transmissions, and about the same gaps between transmissions.

Tones of 950, 970, and 985 Hz have been observed on different days, but the tone is steady through a given day. This might be a transmitter settling on a slightly different freq from day to day.

It is my opinion that the tones are being sent instead of the numbers transmission. As the tone is steady and contains no information I believe this might be a failure or operator error.

Further, the change in timing on October 6 and again on October 11 might indicate that a different message is being sent, or at least would be being sent if the audio were present.

T!
Mohave Desert, California, USA

My logs, September 1, 2010, to October 11, 2010. (complete trends can be seen on my VTN web page, http://token_radio.home.mchsi.com/VTN.htm )

September, 2010

- 09/01/2010 1557:30 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1602:07, 3rd msg start 1606:44
- 09/02/2010 No transmission heard</p>
- 09/03/2010 1557:29 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1602:07, 3rd msg start 1606:43
- 09/04/2010 1557:31 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1602:08, 3rd msg start 1606:46
- 09/05/2010 1557:30 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1603:07, 3rd msg start 1608:44
- 09/06/2010 1557:28 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1603:05, 3rd msg start 1608:41
- 09/07/2010 1557:27 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1603:04, 3rd msg start 1608:41
- 09/08/2010 No transmission heard
- 09/09/2010 No transmission heard
- 09/10/2010 No transmission heard
- 09/11/2010 1557:22 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1602:59, 3rd msg start 1608:36
- 09/12/2010 1557:21 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1602:57, 3rd msg start 1608:34
- 09/13/2010 1557:19 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1602:56, 3rd msg start 1608:33
- 09/14/2010 1557:18 UTC first msg, 42 grps, VT, OM, 5f, 2nd msg start 1602:55, 3rd msg start 1608:34
- 09/15/2010 No transmission heard
- 09/16/2010 No transmission heard
- 09/17/2010 No transmission heard
- 09/18/2010 No transmission heard
- 09/19/2010 No transmission heard
- 09/20/2010 No transmission heard
- 09/21/2010 No transmission heard
- 09/22/2010 No transmission heard
- 09/23/2010 No transmission heard
- 09/24/2010 No transmission heard
- 09/25/2010 No transmission heard
- 09/26/2010 No numbers heard, Tone, 970 Hz, 1557:05 – 1600:40 UTC, 1601:40 – 1605:17 UTC, 1606:17 – 1609:54 UTC
- 09/27/2010 No numbers heard, Tone, 970 Hz, 1557:06 – 1600:41 UTC, 1602:13 – 1605:49 UTC, 1607:20 – 1610:56 UTC
- 09/28/2010 No numbers heard, Tone, 970 Hz, 1557:04 – 1600:39 UTC, 1602:11 – 1605:47 UTC, 1607:18 – 1610:52 UTC
- 09/29/2010 No numbers heard, Tone, 970 Hz, 1557:04 – 1600:39 UTC, 1602:12 – 1605:46 UTC, 1607:18 – 1610:54 UTC
- 09/30/2010 No transmission heard

October, 2010

- 10/01/2010 No numbers heard, Tone, 985 Hz, 1557:02 – 1600:37 UTC, 1602:09 – 1605:44 UTC, 1607:15 – 1610:51 UTC
- 10/02/2010 No transmission heard
- 10/03/2010 No transmission heard
- 10/04/2010 No transmission heard
- 10/05/2010 No numbers heard, Tone, 950 Hz, 1557:02 – 1600:37 UTC, 1602:37 – 1606:14 UTC, 1608:14 – 1611:52 UTC
- 10/06/2010 No numbers heard, Tone, 950 Hz, 1556:58 – 1559:28 UTC, 1600:29 – 1602:59 UTC, 1604:01 – 1606:30 UTC
- 10/07/2010 No numbers heard, Tone, 950 Hz, 1556:58 – 1559:28 UTC, 1600:29 – 1602:59 UTC, 1604:00 – 1606:29 UTC
- 10/08/2010 No numbers heard, Tone, 970 Hz, 1556:56 – 1559:25 UTC, 1600:27 – 1602:56 UTC, 1603:57 – 1606:26 UTC
- 10/09/2010 No transmission heard
- 10/10/2010 No numbers heard, Tone, 970 Hz, 1556:52 – 1559:24 UTC, 1601:24 – 1603:55 UTC, 1605:56 – 1608:26 UTC
- 10/11/2010 No numbers heard, Tone, 970 Hz, 1556:51 – 1600:39 UTC, 1602:38 – 1606:23 UTC, 1608:25 – 1612:10 UTC

 

[bryan_herbert]

Check out 6185 KHz around 0749 UTC, ive been hearing similar activity. Strictly tone, length varies from 3-9 minutes.

 

[scanchs]

Here's an idea...

...
It is my opinion that the tones are being sent instead of the numbers transmission. As the tone is steady and contains no information I believe this might be a failure or operator error.

T!
Mohave Desert, California, USA
...

Token,

The first thing that came to my mind was that these tones might be a jammer, designed to prevent the intended recipient from receiving the numbers transmissions. If I worked for a government agency, and I thought a potential threat was being beamed into my area, I would try to block the signal somehow. After all, if you have figured out the timing of the transmissions, a government analyst could have done the same thing. It's a possibility...

Or, perhaps I just watched too many spy shows on TV when I was younger...

ScanCHS

 

[Token]

Token,

The first thing that came to my mind was that these tones might be a jammer, designed to prevent the intended recipient from receiving the numbers transmissions. If I worked for a government agency, and I thought a potential threat was being beamed into my area, I would try to block the signal somehow.

I think it is very unlikely this would be a jammer. And if it were it would be a poorly designed and implemented one. Also, the voice numbers transmissions are simply not there at all, it is not that they are being covered, they are just not present.

As the tone is a simple one frequency transmission with no other mdulation it would not "cover" the USB transmissions well at all. It would be concentrated in too small a range of the USB transmitted energy to be an effective jammer. As a continuous "unmodulated" transmission it is possibly 100 Hz wide at best, the USB audio is over 2600 Hz wide. I put unmodulated in quotes because in all likelyhood this is not unmodulated, but rather a simple 1 kHz tone driving a USB transmitter on 10255 kHz, but the results on the receive end are the same as a simple unmodulated AM carrier on 10256 kHz.

Even with no attempt to control it on the receivers end it would, at best, be an annoying tone that did not prevent the recipient from copying the message. And a simple automatic notch filter or a manual notch filter can completely remove it from the audio, allowing trouble free reception of the intended signal.

T!

 

[Token]

Check out 6185 KHz around 0749 UTC, ive been hearing similar activity. Strictly tone, length varies from 3-9 minutes.

You are sure about freq and time? At that time there are 4 or 5 SW broadcast stations on that frequency.

T!

 

[bryan_herbert]

Affirm. It was there again last night but Im sure now its a jammer. They moved from 6185 to 5950 and jammed the end of WYFR on accident and jammed the entire broadcast of whatever Spanish language station came up at 0900 UTC.

 

[Token]

Affirm. It was there again last night but Im sure now its a jammer. They moved from 6185 to 5950 and jammed the end of WYFR on accident and jammed the entire broadcast of whatever Spanish language station came up at 0900 UTC.

So, let me get this straight. Last night the sounds you heard were not on 6185 at about 0750, but instead they moved to 5950?

The Cubans regularly jam several Spanish and English language broadcast, particularly things like Radio Marti but sometimes others as well. It is very possible what you are talking about is such activity. But that is unrelated to the transmission on 10255 kHz USB.

Once you have heard one of the Cuban jammers (they have several different types) it becomes clear what they are any time you tune across one. On a good evening you can find 10 or more stations being jammed by the Cubans.

Again, as I said, not what I am hearing on 10255. On 10255 USB it is simply the numbers station operator making a mistake and transmitting a 1 kHz tone instead of the audio, I am just surprised it has gone on this long. I suppose I could put up a youtube of the SDR recording, but there is so little to see it would be boring...lol

T!