Possible HF Trading Link?

[delay877]

I first heard this communication link in eastern Connecticut on 1-5-26 at ~7pm till ~9pm. Centered on 9.067. mhz. Looking over at signalwiki, and a couple PDFs posted here about HF trading links didn't result in any matches. First time I caught it and last time as well..

Appears to be 1 way data transfer with an ending tone, could be path probing. Some packets sound different, in total I heard about 3 different types of continuous transfers. Have not heard it since. Please excuse the clipping in the audio samples, SDR++ CE has audio buffer issues on MacOS, the original SDR++ does not and I've switched to that. Hopefully next time I can get better recordings with an IQ stream.

Love the sound of the ending tone though. It sounds exactly like an MRI haha. Take all this with a grain of salt, I'm just someone with an SDR and a YouLoop who normally listens to Aero HF Radio.

This video shows quick data bursts.

1) First I Saw these spaced bursts.


1a) Zoomed in



2) Then comes maybe a path probe and a bunch of carriers. Maybe each tone is a separate data channel


4) after that, maybe muliple data transfer channels actually transferring information.


5) then short Bursts.

 

[Token]

I will start with, I do not know for sure what mode this is. The 16 data channels in the bursts, and the trailing tones should be a clue, but I can't think of any matches off the top of my head.

However, I tend to think not HFT related. Every data mode I have seen the HFT stations using has been wider banded, while this is pretty standard sub 3 kHz data. I am not saying it is impossible that this is HFT, but it is a bit uncharacteristic.

I suggest that when you are trying to get an ID of unknown HF signals, don't use AM mode for the recording. Most HF data modes are in USB. I suspect this signal is also in USB, but it could be LSB. For sure, it is an SSB mode. In AM it just sounds wrong, so not triggering any signal recognition here.

T!

 

[dlwtrunked]

I will start with, I do not know for sure what mode this is. The 16 data channels in the bursts, and the trailing tones should be a clue, but I can't think of any matches off the top of my head.

However, I tend to think not HFT related. Every data mode I have seen the HFT stations using has been wider banded, while this is pretty standard sub 3 kHz data. I am not saying it is impossible that this is HFT, but it is a bit uncharacteristic.

I suggest that when you are trying to get an ID of unknown HF signals, don't use AM mode for the recording. Most HF data modes are in USB. I suspect this signal is also in USB, but it could be LSB. For sure, it is an SSB mode. In AM it just sounds wrong, so not triggering any signal recognition here.

T!

Having monitored the many HFT from while right in front of them, I agree that it is unlikely an HFT but some do operated in the frequency area at times. Also, as Token aid, please do not use AM to record unknown audio--it is useless for helping identify. Even if too narrow, USB is much more useful. If the original poster has not seen not, find my UDXF item in the files

 

[kc2asb]

Very interesting. Granted, I don't know anything about HFT, but with all the bandwith available through the net, and considering propagation, interference, possible jammers, etc, I'm surprised that HF is a viable medium for them.

 

[nd5y]

Very interesting. Granted, I don't know anything about HFT, but with all the bandwith available through the net, and considering propagation, interference, possible jammers, etc, I'm surprised that HF is a viable medium for them.

The only reason they want HF is speed. RF (speed of light) in air is faster than fiber optic cable. It's faster than satellite because the path length is way shorter. It's also faster because there are fewer routers and switches involved.

 

[Token]

The only reason they want HF is speed. RF (speed of light) in air is faster than fiber optic cable. It's faster than satellite because the path length is way shorter. It's also faster because there are fewer routers and switches involved.

For those that have never looked at this, the propagation velocity in fiber is _much_ slower than in open air, typically 70% or less, without counting network overheads.

From my understanding, HFT leverages high density, very rapid responses, to small trends, be they up or down. The first one to pounce on a specific trend makes the most money on that trend, and milliseconds count. I have heard that microseconds count, but not being in the industry that is word of mouth.

So what is the improvement of open air over direct connect fiber?

The path from Chicago, IL to Amsterdam is roughly 4100 miles (~6600 km). Very simply (not counting things like open air multihop path or fiber network overhead), the fastest fiber can get the signal from one place to the other is roughly 0.031 seconds, while open air can get it there as quick as maybe 0.023 seconds, or 8 milliseconds faster. And I suspect the reality is that the time delta is much greater than that.

To use a geostationary satellite to relay these signals increases the path length by roughly ~44,500 miles (~71,600 km), requiring at least 0.239 seconds. Or more than 215 milliseconds later than open air RF on HF.

Literally, in this case, time is money. When talking big money even very small time of response improvements mean real money at the end of the day.

T!

 

[popnokick]

SigIDWiki has the waterfall display and some of the (many) frequencies used -
HF trading link '350 Hz idle tone' - Signal Identification Wiki

 

[Token]

SigIDWiki has the waterfall display and some of the (many) frequencies used -
HF trading link '350 Hz idle tone' - Signal Identification Wiki

Yeah, but that waveform shown on SigIDWiki is just one of dozens of possible types of HFT signals. The signals range from various forms of PSK, to apparent MFSK, to the tones shown there, to FMCW, and others.

T!

 

[dlwtrunked]

The only reason they want HF is speed. RF (speed of light) in air is faster than fiber optic cable. It's faster than satellite because the path length is way shorter. It's also faster because there are fewer routers and switches involved.

Though light in fiber is slightly slower, the primary problem with fiber optic cable is that is not a straight line with bends/curves due to *routing due to property lines*--this is the same reason that microwave links are not ideal. (For those who do not know, the goal is to lessen time latency to get your bid ahead of others.)

 

[dlwtrunked]

SigIDWiki has the waterfall display and some of the (many) frequencies used -
HF trading link '350 Hz idle tone' - Signal Identification Wiki

Note the allocations are in frequency bands rather that actual frequencies. The list in the wiki are just some actual ones that were picked in the past. This is similar to amateur radio where an amateur station can operate in a band but does not have a particular frequency assigned. I still think the below is a better reference (I need to update it with my latest write-up which adds more, newer, stations.)

https://www.udxf.nl/HF-Trading-Stations_03AUGL2023.pdf

 

[delay877]

Thanks for all the replies! Recoding in USB totally makes sense and I will do that from now on, thank you! There are no carriers so idk why I was in AM mode.

@Token 8ms faster seems like a great trade off for using HF for trading.

@dlwtrunked due to your reference, I automatically assumed it has HFT because of the frequency but had no proof otherwise. I hope I will catch it again in the future so I can actually record it correctly with an IQ file. I was too distracted to look on other WebSDRs to try and get an idea of its location. It faded in and out which made me believe it was not originating from the USA.

 

[Token]

Note the allocations are in frequency bands rather that actual frequencies. The list in the wiki are just some actual ones that were picked in the past. This is similar to amateur radio where an amateur station can operate in a band but does not have a particular frequency assigned. I still think the below is a better reference (I need to update it with my latest write-up which adds more, newer, stations.)

https://www.udxf.nl/HF-Trading-Stations_03AUGL2023.pdf

@dlwtrunked , does your newest information also list or indicate some of the stations that are now IDing via Morse code? The FCC revoked the "ID requirement exemption" for several (about a dozen?) licensees playing in the HFT world, and a lot more of them are now periodically IDing in Morse. I mean, Canadian stations have IDed for years now, but US ones are starting to now.

Since the IDing started (around the first of the year?) I have been able to correlate several waveforms that I have always assumed were HFT related to actual licensees. But three interesting waveforms that I have always strongly suspected are HFT I have not yet heard an ID for.

T!

 

[dlwtrunked]

@dlwtrunked , does your newest information also list or indicate some of the stations that are now IDing via Morse code? The FCC revoked the "ID requirement exemption" for several (about a dozen?) licensees playing in the HFT world, and a lot more of them are now periodically IDing in Morse. I mean, Canadian stations have IDed for years now, but US ones are starting to now.

Since the IDing started (around the first of the year?) I have been able to correlate several waveforms that I have always assumed were HFT related to actual licensees. But three interesting waveforms that I have always strongly suspected are HFT I have not yet heard an ID for.

T!

As I plan a visit to look at signals soon, you might want to let me know more about those three waveforms.