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Since at least as far back as January of 2018 a 1 pulse per second odd signal has periodically been seen up and down the HF bands. This is a signal that sounds very much like a time station, ticking one time per second, changing frequency sometimes swiftly, sometimes slowly. Naturally, it has been reported on several forums. Some of the places it has been discussed:
https://forums.qrz.com/index.php?threads/time-signal-intruder.614510/
https://www.hfunderground.com/board/index.php/topic,41025.0.html
https://forums.radioreference.com/u...s-ham-40-meter-band-01-jan-2018-2238-utc.html
Various plotting methods have been applied to the signals, most results seem to point to the area around Chicago, Illinois.
Most of the reports seem to be in the ham bands, however that might just be a factor of how many people watch the ham bands at any given moment. To the best of my knowledge, the frequency ranges that have been observed and reported have been:
6320 to 6510 kHz
7095 to 7300 kHz
8100 to 8400 kHz
10100 to 10150 kHz
12200 to 12450 kHz
14060 to 14350 kHz
18065 to 18160 kHz
21200 to 21300 kHz
You can see it has at least 3 full bands that are well outside the ham bands, and a few frequencies just outside ham bands. There absolutely may be more ranges outside ham bands that are simply not being reported because no one has noticed. The reports of operation inside ham bands vastly outnumber the reports of operations outside ham bands, however I am not sure if this is an actual trend, or if it is just a result of the source of data (mostly hams). I know watching the signal today it seemed to spend as much time outside the ham bands as inside.
Various sources have tried, or tentatively, connected these transmissions with High Frequency Trading (HFT) experiments. Some specific HFT experimental licenses have been suggested as related to these transmissions, the following license are sometimes quoted:
WI2XNX
WJ2XGD
WH2XWU
WH2XVO
However, none of these license cover all of the frequencies observed. In fact, all of the authorized frequencies for all of those licenses combined still do not cover all of the frequencies observed.
Further, the HFT application of radio links is in a quest to gain advantages of milliseconds, if not microseconds, on trading transactions. So even if the pulses observed did contain data (and they don't appear to) they would update that data only once per second. It seems, to me, an unlikely fit.
It has been suggested that these pulses have nothing to do with the data of HFT itself, but are just tools to measure or model propagation delays for future HFT ventures. While certainly possible (the signal does look like a propagation / scatter experiment to me) the frequency ranges observed are pretty narrow, and such measurements generally do not require stepping across such narrow frequency ranges. Is moving 10 kHz every 2 or 3 minutes really going to tell you much about the real time propagation variations between the frequencies?
So, what is this 1 PPS oddity? I really don't know. But the more I look at it the less convinced I am that it has anything to do with HFT experiments, or any of the license so far identified. Can anyone convince me differently?
T!
https://forums.qrz.com/index.php?threads/time-signal-intruder.614510/
https://www.hfunderground.com/board/index.php/topic,41025.0.html
https://forums.radioreference.com/u...s-ham-40-meter-band-01-jan-2018-2238-utc.html
Various plotting methods have been applied to the signals, most results seem to point to the area around Chicago, Illinois.
Most of the reports seem to be in the ham bands, however that might just be a factor of how many people watch the ham bands at any given moment. To the best of my knowledge, the frequency ranges that have been observed and reported have been:
6320 to 6510 kHz
7095 to 7300 kHz
8100 to 8400 kHz
10100 to 10150 kHz
12200 to 12450 kHz
14060 to 14350 kHz
18065 to 18160 kHz
21200 to 21300 kHz
You can see it has at least 3 full bands that are well outside the ham bands, and a few frequencies just outside ham bands. There absolutely may be more ranges outside ham bands that are simply not being reported because no one has noticed. The reports of operation inside ham bands vastly outnumber the reports of operations outside ham bands, however I am not sure if this is an actual trend, or if it is just a result of the source of data (mostly hams). I know watching the signal today it seemed to spend as much time outside the ham bands as inside.
Various sources have tried, or tentatively, connected these transmissions with High Frequency Trading (HFT) experiments. Some specific HFT experimental licenses have been suggested as related to these transmissions, the following license are sometimes quoted:
WI2XNX
WJ2XGD
WH2XWU
WH2XVO
However, none of these license cover all of the frequencies observed. In fact, all of the authorized frequencies for all of those licenses combined still do not cover all of the frequencies observed.
Further, the HFT application of radio links is in a quest to gain advantages of milliseconds, if not microseconds, on trading transactions. So even if the pulses observed did contain data (and they don't appear to) they would update that data only once per second. It seems, to me, an unlikely fit.
It has been suggested that these pulses have nothing to do with the data of HFT itself, but are just tools to measure or model propagation delays for future HFT ventures. While certainly possible (the signal does look like a propagation / scatter experiment to me) the frequency ranges observed are pretty narrow, and such measurements generally do not require stepping across such narrow frequency ranges. Is moving 10 kHz every 2 or 3 minutes really going to tell you much about the real time propagation variations between the frequencies?
So, what is this 1 PPS oddity? I really don't know. But the more I look at it the less convinced I am that it has anything to do with HFT experiments, or any of the license so far identified. Can anyone convince me differently?
T!