Since Dec. 30th, I have been hearing an unusual pulsing signal intermittently on 14.320 MHz. The signal consists of 50 regularly spaced, long pulses per minute. The pulses are audio modulated in two frequencies of about 500 and 1000 Hz. The pattern is always the same: 37 pulses at one frequency, then 37 more at the other, then repeating. The signal is usually heard within the hours of 16:00 to 23:30 Universal Time. It is highly variable in strength, and sometimes as strong as S. 9 (4 bars). The signal has been heard at points at least as far afield as California, New England, and the Bahamas. Can anyone on this forum hear these transmissions and/or suggest what sort of signal this is; what sort of technology is behind it, or where the transmitter might be located? Amateur radio operators, in whose 20 meter band allocation this signal falls, have so far been unable to explain it.

Radio Ham experiments?

Propagation monitoring/sounding?

Low power over-the-horizon radar?

???


If the radio hams are on to this, it won't take very long for it to be located and found out!

Intriguing...


Keep searchin',
Martin

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As one of those hams, I thank you for your confidence in our ability to find out about the signal. I've been aware of it for just over a month. The signal may not have been there much longer than that. Some things have been learned about it, but not, as far as I know, it location, or its mode of operation. I doubt that ham experiments are involved, because the signal never gives a call sign identification. Hams are required to do this at frequent intervals. I've listened to many ionosondes, propagation beacons, and OTH radars over the years. This signal has the characteristics of none of these. Ionosondes sweep a continuous signal rapidly over a range of frequencies, which makes pulses as it crosses a single frequency being monitored. The signal on 14.320 MHz always remains on that one frequency. Propagation beacons automatically transmit a call sign identification frequently in Morse code. As noted above, this signal gives no i.d.s. OTH radars tend to ignore the proprieties of frequency allocations, and they *do* pulse rapidly. In order to build up a radio picture of what they're looking at, they pulse at rates of several to many times per second. The signal on 14.320Mhz pulses at less than 1Hz. In addition, OTH radar signals tend to be very broad-banded, and to jump from one range of frequencies to another. The signal I and others have heard is confined to one. relatively narrow channel. Michael

There is obviously intelligence behind the signal. Now you just have to determine it's origin. The 20 meter band is loaded with applications and it could be any one of these or somebody just goofing off with a powerful linear amp.

I've listened to recordings and on-air examples of a great many modulation schemes and signal types. None of these is like the signal heard on 14.320 MHz. No one to whom I've described the signal, or who has heard it on their own, can identify the technology employed. Its exact repetition and persistence over time seem to point away from a casual unauthorized user and to something more deliberate, exacting, and unusual. Michael

When you say that the modulation is unusual what do you mean. Is it frequency modulated between those two frequencies. Amplitude Modulation, single side band ?. Full cycle or class C ?.

Is there any other intelligence indicated other than the periodicity ? and the 37 count.

When you say that the modulation is unusual what do you mean. Is it frequency modulated between those two frequencies. Amplitude Modulation, single side band ?. Full cycle or class C ?.

Is there any other intelligence indicated other than the periodicity ? and the 37 count.

The pulses appear to be caused by turning a transmitter on and off, which is reminiscent of radio telegraphy. The pulses themselves have what sounds like a rough audio modulation at two fixed tones, approximately 500 and 1000 Hz. This modulation could be digitized data streams within the pulses. I reviewed audio recordings of a great many digital modulation modes last evening. None of these resemble the signal heard on 14.320 MHz. The coincidence of an unknown or at least extremely obscure modulation mode, and its apparently unauthorized intrusion into the 20 meter Amateur Radio allocation strike me as a very unusual situation. Michael

could those be what they call burst transmissions from military sites?

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In a rich man's house there is no place to spit but his face.
Diogenes Of Sinope

could those be what they call burst transmissions from military sites?

Probably not. The military likes burst transmissions because they are relatively secure. They occur over very short periods of time at very high data rates, and so have a low probability of being detected. The way the 14.320 signal sometimes persists for long periods of time would tend to defeat the advantage of such transmissions. It seems to call attention to itself in this way, and also by consistently using one frequency in the 20 meter Amateur band. The military generally uses relatively obscure frequencies, in the Fixed, Maritime Mobile, and Aeronautical Mobile Service bands. Michael

Any word on this signal?

I was able to hear the signal as recently as Saturday, Feb. 11th, late afternoon, Pacific Time. A good deal of static interfered, but at one point it settled down, and I got a reasonably good oscilloscope trace. The pulses appear to be simple audio sine waves. This seems to rule out most ordinary signal modes, including digital ones. I hope to do some direction finding work on the signal when it appears again. Assuming the pulses *are* sine waves, the only information they contain is the fact that they exist. I am now considering the possible significance of the consistent repetition of 37 pulses, first in one tone, then in another. Perhaps I should add at this point that the first and last pulse of each group is shorter than the others. The significance of this isn't obvious, either. The following merely offered for whatever it might be worth-- If the two short pulses count as 1/2 pulse each, then the total is 36, instead of 37. The sum of all the whole numbers between 1 and 8 equals 36. 36 is a simple triangular number, with 8 units per side. Michael

I think someone is yanking your chain or you are yanking ours.

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Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

I think someone is yanking your chain or you are yanking ours.

I'm quite in ernest. Anyone with a reasonably good high frequency receiver and external antenna, and a good deal of patience, can hear this signal for themselves. If someone is fooling me by sending this odd signal, it's a rather elaborate, protracted, and illegal, hoax. It has been heard throughout North America, if not farther afield, for the past month and a half, at least. Would you care to expand on what you said? Michael

What it appears to me that you are implying is that these signals you have detected are from somewhere other than earth and may be generated by, for lack of a better term, ET. If that were so, I think that somewhere in the scientific community someone other than you would have also detected said signals and sounded the alarm. So, who is it that you think is generating the signal you have picked up and what do you think the content of the signal is?

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Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

I wonder if someone is using this as a testing platform for homing in on that signal from distant locations.

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In a rich man's house there is no place to spit but his face.
Diogenes Of Sinope

What it appears to me that you are implying is that these signals you have detected are from somewhere other than earth and may be generated by, for lack of a better term, ET. If that were so, I think that somewhere in the scientific community someone other than you would have also detected said signals and sounded the alarm. So, who is it that you think is generating the signal you have picked up and what do you think the content of the signal is?

Thanks for your interesting reply. I believe it would be premature to assign a source to the signal discussed, extraterrestrial or otherwise. If I wanted to assert such a thing, and had sufficient evidence to back it up, I could have set up this thread in the SETI Science section, instead of this, the Science (non-SETI) section. &&& As to detection of, or interest in, the signal by the scientific community: The signal lies in a very active band allocated to amateur radio. I doubt that this band receives much scientific scrutiny. &&& If one assumes normal propagation of 20 meter radio signals, and given the distribution of reports I have of it, certain areas of origin can probably be ruled out. These include the states of California, Oregon, Nevada, the Northeast part of the U.S., Most of Florida; the Bahamas, Cuba, and Jamaica. Also Minnesota, Iowa, Wisconsin, much of Illinois, Nebraska, The Dakotas, Missouri, and Michigan. Further reports from various areas would be useful in locating the signal, or at least in ruling out certain additional areas. The meaning or even the transmission mode of the signal remain unresolved. If anyone sees some sense in the signal, beyond what I've already observed, or recognizes the technology behind it, I'd appreciate hearing from them. Michael

I wonder if someone is using this as a testing platform for homing in on that signal from distant locations.

It's notoriously difficult to get an accurate bearing on a high frequency signal. Fading in and out of the signal, and propagation of the signal by varying routes complicate the picture. Much lower radio frequencies are preferable where the aim is to accurately determine the location of a transmitter. I was hoping to get a very rough idea of the direction of the signal on 14.320 MHz. This has not proved possible, so far, despite various attempts and the use of different methods. Michael

If it occurs on the other side of the world and is reflected by the atmosphere, then it would appear to come from all around you.

I found this during a Google search:

My chart shows it a mariners beacon and weather warning station for the N & W Indian Ocean.

There are a number of these stations around the world. The pulse is so ships know they are on 14.320MHz and have not drifted off. and they can use it with a direction finder

If it occurs on the other side of the world and is reflected by the atmosphere, then it would appear to come from all around you.

I found this during a Google search:

My chart shows it a mariners beacon and weather warning station for the N & W Indian Ocean.

There are a number of these stations around the world. The pulse is so ships know they are on 14.320MHz and have not drifted off. and they can use it with a direction finder

Thanks for your response. The station to which you refer is an amateur radio communications net, not a commercial maritime station. It is based in Perth, Australia. It gives weather bulletins and carries on communications with vessels in the Indian Ocean. It operates between 11:15 and 11:30 Universal time. This schedule does not match the times the unidentified signal on 14.320 MHz has been heard. &&& Commercial maritime stations send SITOR pulses (A kind of teletype signal) and Morse Code call letters at frequent intervals. The pulses I and others have heard on 14.320 Mhz are not SITOR but simple sine waves. I have checked this myself, by examining the pulses on an oscilloscope. No transmission of identifying call letters has ever been heard, despite many hours of listening. Michael

Interesting. It's been a very long time since my radio days in the army, so forgive any ignorance I show.

Have you checked for harmonics?

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