Number Station

[btlacer]

Hearing a number station on 5.895 AM with a good signal, Spanish language

 

[Token]

I assume you mean 5898, not 5895. This would have been Enigma ID V02a.

T!

 

[SKYNET156]

Isn't that listed in the cuban numbers station, I get the Cuban Numbers Station on 5895 Loud and Clear in Fort Worth, Tx Atleast Twice a Week around 0230hrs, I always wonder what it is and who's Rxing it?

 

[Token]

Isn't that listed in the cuban numbers station, I get the Cuban Numbers Station on 5895 Loud and Clear in Fort Worth, Tx Atleast Twice a Week around 0230hrs, I always wonder what it is and who's Rxing it?

First, listed where "in the cuban numbers station", what list? Second, is that time of 0230 hrs local time or is it UTC? The essentially universal convention is to report any radio intercepts in UTC (z,) because not everyone might know the time offset to your local time. However V02a has not been transmitting recently, that I am aware of, on 5898 (or anything close to that frequency) in the 0200z time slot. V02a (and its sister stations M08a and SK01) has been active on 5898 in the 0800z time slot several times a week, and that would be 0200 local time in Fort Worth TX. So my assumption is that you mean around 0230 local time, or 0830 UTC.

The Cuban numbers station carries the Enigma designator V02 and variants. Most commonly heard in recent times is V02a.

The 5898 kHz V02 transmission has been erroneously reported on 5895 kHz (and 5900 kHz) a few times in the past. Most often by listeners whose radio tunes in 5 kHz steps and who cannot tune to the real frequency of 5898 kHz. A few other reasons this station (and other numbers stations) are sometimes reported on incorrect frequencies: Some listeners have a habit (often there is not intention behind the habit) of always trying to find a station ending on 5 or 0. When you combine that with the fact that there is sometimes a BC station on 5900 it causes people to tune to the low side of the 5898 in an attempt to hear it more clearly and lo-and-behold it is indeed more clear near 5895, because the radio is tuned farther away from the interfering station. And lastly a radio with a fairly wide filter bandwidth can make it difficult to tell, in AM mode, what the exact center frequency is and this can be exacerbated when there are other nearby AM carriers. Just “tuning until it sounds the best” while in AM might not have you on center frequency and such should not be used to report actual frequency (particularly if it is not a BC station being received) unless there is no other method of frequency determination available.

So, how to confirm the frequency of an AM transmission when you care enough to know inside 1 kHz what it is on? If your receiver has LSB or USB simply select one or the other and “zero beat” the signal. This means find the carrier (it will sound like a steady tone) and tune the radio until the carrier tone is not heard any longer but the speech audio still sounds “normal”. With most radios this should get you well inside 1 kHz of accuracy, and possibly inside 0.1 kHz of accuracy, depending on the radio. If your radio does not have a separate LSB/USB switch, or if it has a BFO, this will not work for you unless you have determined where, exactly, on the BFO knob is zero freq, most commonly by tuning to a frequency standard like WWV and zero beating that for practice.

If you use an SDR you can see the carrier frequency on the display, and there is never any question of the actual frequency as long as your radio is in calibration.

I have tuned to this station and time slot a few dozen times over the last few months, and V02a (and SK01) has always been on 5898 kHz. M08a has been on both 5898 (both when MCW and CW) and 5897 (sometimes when CW). M08a is on 5897 when in CW because they use the transmitter in LSB mode and modulate the CW as a 1 kHz tone, putting the energy, or tone, on a center frequency of 5897 kHz (with the carrier on 5989 kHz and USB tone on 5899 kHz both suppressed as one would expect from an LSB transmission). M08a in MCW mode has sometimes incorrectly been reported as both 5899 and 5897 by users expecting CW and using their radios in CW mode, but the transmission actually being MCW (AM with modulated 1 kHz tones for CW). In this configuration and some radios you could tune to either 5899 or 5897 and still hear the CW, but you would not hear it if you were tuned to 5898 (remember, this is trying to receive the AM MCW signal with some specific receivers in CW mode).

As far as what it is and whose Rxing it, Google “numbers stations” to find out what it is. You also might research a CIA specific term “OWVL”, or One-Way Voice Link. As far as who might be receiving them, there have been several spy rings busted in the US that have been strongly tied via public court records to these specific stations, V02, M08, and SK01, although the specific stations are never mentioned. I believe terms like “the agents or network received communications via encrypted short wave transmissions from Cuba” has been used.

But wondering exactly what you are wondering is part of the allure, for some listeners, of Numbers Stations.

T!

 

[Token]

Last night I recorded this frequency and the spectrum +/- 25 kHz for the 0800 UTC time slot, basically from 0758 UTC to 0900 UTC. As expected the signal was seen on 5898 kHz. I have uploaded a video of about 100 seconds of this reception to YouTube, it can be found here: YouTube - Spanish Numbers station V02a, April 05, 2011, 0801 UTC, 5898 kHz AM

To help understand how someone might incorrectly interpret the frequency in AM mode, and to display how to “zero beat” an AM signal using an SSB mode, I made some tuning changes during the video. The times are listed below in the format XX:XX, so that “00:36” would be zero minutes and 36 seconds into the video.

I started with the receiver tuned to 5898 kHz and in AM mode with the spectrum display 50 kHz wide, to show the entire signal and other signals close-by including the BC station at 5890 kHz AM and the Link 11 digital signal around 5895 kHz USB. Note “pulsing” sound in audio, this is the Link 11 digital mode interference that is inside the lower sideband of the V02a signal. The carrier for the V02a signal can be clearly seen to be on 5898 kHz.

00:12 into the video, reduce visible bandwidth in steps to 10 kHz, so that only the upper sideband of the BC station, the Link 11, and the full V02a signal is seen.

00:22 select LSB mode of reception. Note that the audio for V02a is still clearly heard, as is the Link -11 signal, since the Link 11 is close enough to be inside the LSB of the AM V02a signal, even though the Link 11 is actually an USB signal at around 5895 kHz.

00:36 select USB mode of reception. Note that the audio for V02a is still clearly heard, but the Link 11 is no longer heard. All interference is still present on the waterfall display. This technique can be used to clean up an AM signal when an interfering signal is in either the upper or lower sideband only of a desire AM signal.

00:50 start to tune off (downwards in frequency) the AM signal while in the USB reception mode. Note the tone that is being heard, this is the carrier. At 00:57 I start to tune back up and the “tone” steps downwards. At 01:01 the tone is “zero beat” and the audio sounds normal. At this point the frequency readout is correct (well within 0.1 kHz) for the AM signal.

01:05 again select AM mode, note that the Link 11 interference pulses are again heard.

01:10 tune the receiver to 5900 kHz while still in AM mode. The Link 11 interference is no longer heard. As the V02a signal is “more clear” because of less interference it might be possible for a user that has no visible display and is relying solely on sound to peak an AM signal to incorrectly decide that the AM signal is on 5900 kHz. Note that the signal level meter is still showing 20 over S9 peaks, just as it does when the receiver is tuned to the correct frequency of 5898 kHz, also contributing to possible erroneous frequency reporting.

01:14 widen spectrum display to 20 kHz, to show that all close-by signals seen at the beginning of the video are still present.

01:33 tune the receiver back to 5898 kHz center frequency for the remainder of the video. While it might be noted that the audio sounds a little more “full” the inclusion of the Link 11 interference and the “same” signal level reading could cause a listener without video cues or without checking the signal in an SSB mode to conclude the 5900 kHz tuned frequency was “better”.


I hope this is helpfull.

T!

 

[majoco]

Might help if the OP told us what receiver he was using - may not even have SSB or tune in anything less than 5kHz steps to fit the HF BC bands.