For at least 9+ years a type of transmission that I have called the Pips Network in my log has been periodically operation on multiple frequencies. There have been many loggings of this signal on the HFU forums, particularly in the Mystery, Utilities, and Other forums. Sometimes they are seen daily, sometimes it is months between being reported. I know there is more than one source involved, and I strongly suspect not all transmissions seen are related. There is one main network for sure, the one originally seen and for which the "Pips Network" name was coined, and possibly a couple other unrelated networks. However, they all have roughly similar habits, so they get logged under the same name in my log. What they are for is in question, I suspect that they (at least the original ones seen) may be some kind of ionospheric test or measurement signal, but that is a guess on my part.
The habits observed are typically that a dash or dot, sometimes long and sometimes short, is sent on multiple frequencies, from as few as 2 to up to 60+ frequencies. The pulses are not coincident in time, each pulse is sent on a frequency and the source then cycles to the next frequency on the list. Always to the next closest freq on the list. So the pulses/dashes cycle either up or down in frequency.
Often the pulse width and pulse interval are related, and sometimes that relationship defines how many frequencies can be used. For example a one second pulse might be sent with an interval of 15 seconds, or a 0.125 second pulse might be sent with an interval of 6 seconds. In the first case this would allow for up to 15 frequencies to be hit in sequence, in the second case it might allow for up to 48 frequencies to be used.
A slightly different version of this class of signals (in my logs, anyway) is one that uses few frequencies in relationship to the interval. In other words, it has time to do many frequencies but only does a few, but the other habits remain roughly the same. I am less convinced these are ionospheric tools, but it is still a good possibility.
One specific subset of this version includes a long pulse (over 2 seconds, 2.7 and 2.9 are common) and a very long interval (27 seconds seems to be common) on only a very few frequencies, and sometimes including a short burst of some kind of modulation at the beginning of each pulse. I have called these signals Long Dashes in my logs.
For the past few days I have been following and recording this later subset. I typically see four frequencies in use, there may be more but if so they are not making it to my location. The signals are heard here in California and at the same time on remotes in Europe. A video of the other days signals here, at the time of this video I was aware of only 3 frequencies in operation, I now know it is normally 4+:
https://www.youtube.com/watch?v=elESMkHAwAwThey may sit on one set of frequencies for hours at a time, or they may change sets every few minutes. The signal may be off air for hours at a time, or may run for hours on end. One frequency seems to be normally near 12500 kHz, one near 11950 kHz, one near 9980 kHz, and one near either 6500 or 6700 kHz. These freqs are loose, and I often find the signal +/- 100 kHz from those. I hear the signals best in the mornings, and this may indicate Asian or Pacific origins.
T!