The messages are always 120 groups long and with the same preamble, such as this example: QRA DE P7X IIPII 072230Z GR 120 BT. The date/time group is always correct, except on the message repeats which will have the same time as the original transmission. This station will usually be on the air for several hours, and numerous messages will be sent. The messages themselves consist of random 5L groups, with the last group always the same as the first.
Between each CW transmission can be heard high-speed data transmissions. These signals are of a very high bit rate with a wide shift. The purpose of these signals is not known, but I have a theory. More on this later.
P7X has been heard quite often the past several years on 3278, 4416, 5125, 5397, 5431.5, 5879.5, and 8039.5. This station has been recently using two frequencies in parallel. When I first started logging this station I didn't ever hear any parallel freqs, so I don't know if this is a new characteristic of this station or not. I have also noticed this station using the callsigns E9I and K3C. P7X is the most commonly used callsign, and I haven't noticed any other callsign used for quite some time. I'm not sure if this is significant or not, but each callsign is a letter-number-letter callsign.
P7X tends to stay on one frequency for several weeks before disappearing for a while, only to appear on another frequency.
The big question is who is operating this station and for what purpose? It would appear that this station is being used for training purposes of some sort. Each message is always followed by the high- speed data signal. The question in my mind is why anyone would use slow CW (each message is sent at about 10 WPM) when they have the means to send high-speed data? It's obvious that CW would not be the main means of communication in this case. I believe that the data signal could be the correct text of the CW message sent to the receiving site for grading or comparison purposes. The CW instructor could then judge the student's copy with the correct message text. This is of course just speculation on my part. Another reason I suspect this is training activity is the fact that this station will transmit on one frequency for a few weeks, then disappear for a month or longer. This would not provide reliable communications for anyone. Normally stations will transmit daily, providing a constant link to their agents.
So who is operating P7X? I have heard it rumored that it is operated by the U.S. military, and others have said it is run by French intelligence. P7X usually has a good signal in North America, and judging from the frequencies used, is located somewhere on the continent. Without any good DF equipment, it is very difficult if not impossible to find out exactly where this station is located. The U.S. military theory wouldn't be out of the question.
Regardless of who is behind this station, it is a very professional operation. Mistakes are rare but they do still happen. On March 19, 21, & 26 1997 I copied P7X on 4416. Each transmission stopped short of completing the message, usually sending only 75-95 of the 120 groups.
Just a quick note now to inform everyone that a few of us in the midwestern states are planning on a get-together similar to the Kulpsville winter SWL fest to be held here in the midwest this summer. The cities that have been proposed are Wichita, KS; Kansas City, Tulsa, OK; St. Louis, MO; Lincoln, NE; or Omaha, NE. The general forum for the get-together will be general shortwave listening and pirate radio. If you are interested, contact me or e-mail Carl Dewhitt at [email protected].