3 ms·

If the transmission consists of <CALLSIGN><ENCRYPTED PAYLOAD> then there is no way to determine if the payload is commercial in nature. One particular example i

If the transmission consists of <CALLSIGN><ENCRYPTED PAYLOAD> then there is no way to determine if the payload is commercial in nature. One particular example is business owners using amateur radio spectrum for business communications. Or some wise-guy using amateur spectrum for his high frequency trading to beat the speed of copper.

cwkoss 5y ago
can you actually beat copper?
- op00to 5y ago
  Yes. It is a simple Google search away.
- sparker72678 5y ago
  Surprisingly, yes! Signals in copper travel at about 0.7C, while radio in air travels at ~1.0C. (Light in fibre optic cable is also about 0.7C).
  - madengr 5y ago
    The signal travels in the dielectric between the copper conductors. If that dielectric is air, and it’s TEM propagation, it travels at 1.0C.
- themulticaster 5y ago
  Three thoughts: 1. HFT firms have definitely tried to perform HFT communication on HF bands before, see [1]. 2. IIRC there have been some undecipherable transmissions in ham HF bands that were suspected to be associated with HFT, but I can't find a source right now. 3. While you don't have any additional latency from routers and serialization delays in the path across the pond, you need to keep in mind that long-range HF communications rely on bouncing the signal on the F1/F2 layers of the ionosphere (an atmospheric layer with lots of charged particles/ions that act as a mirror to HF signals). If you're comparing HF transmission with a hypothetical straight-line fiber connection (assuming it the propagation speed in the fiber is comparable to the atmospheric propagation speed [2]), the fiber connection would win. Additionally, bandwidth is an extremely scarce resource in HF bands (compared to cellular networks or other common VHF/UHF systems). There's a reason people still use CW (morse code) or even PSK31 [3] instead of SSB (voice) [4] in HF bands: You need around 500 Hz for CW signals, around 3000 Hz for SSB signals. PSK31 only needs 31.25 Hz. My point is: While you might beat latency of fiber connections and routers along the path, the throughput is going to be quite low for HF transmission. [1] https://spectrum.ieee.org/wall-street-tries-shortwave-radio-to-make-highfrequency-trades-across-the-atlantic https://spectrum.ieee.org/wall-street-tries-shortwave-radio-... [2] Since you mentioned copper: Copper can be quite a bit slower than fiber depending on cable type, since the propagation speed of signals in copper cables depends on the velocity factor. Wikipedia gives a few examples: https://en.wikipedia.org/wiki/Velocity_factor https://en.wikipedia.org/wiki/Velocity_factor [3] PSK31 stands for Phase Shift Keying at 31 Bd. The short explanation is that PSK31 is a bandwidth-optimized text transmission mode. [4] SSB stands for Single Sideband. The short explanation is that SSB is a bandwidth-optimized AM voice mode.
  - blitzar 5y ago
    a bit more info on [1] for your there - its actually a 3 part piece. https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-trading-part-i-the-west-chicago-tower-mystery/ https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-tr... Bloomberg picked it up as well if you are into that side of things - https://web.archive.org/web/20180625133148/https://www.bloomberg.com/news/articles/2018-06-18/hft-traders-dust-off-19th-century-tool-in-search-of-market-edge https://web.archive.org/web/20180625133148/https://www.bloom...
- deleted 5y ago
  [deleted]

cwkoss 5y ago

can you actually beat copper?

op00to 5y ago
Yes. It is a simple Google search away.
sparker72678 5y ago
Surprisingly, yes! Signals in copper travel at about 0.7C, while radio in air travels at ~1.0C. (Light in fibre optic cable is also about 0.7C).
- madengr 5y ago
  The signal travels in the dielectric between the copper conductors. If that dielectric is air, and it’s TEM propagation, it travels at 1.0C.
themulticaster 5y ago
Three thoughts: 1. HFT firms have definitely tried to perform HFT communication on HF bands before, see [1]. 2. IIRC there have been some undecipherable transmissions in ham HF bands that were suspected to be associated with HFT, but I can't find a source right now. 3. While you don't have any additional latency from routers and serialization delays in the path across the pond, you need to keep in mind that long-range HF communications rely on bouncing the signal on the F1/F2 layers of the ionosphere (an atmospheric layer with lots of charged particles/ions that act as a mirror to HF signals). If you're comparing HF transmission with a hypothetical straight-line fiber connection (assuming it the propagation speed in the fiber is comparable to the atmospheric propagation speed [2]), the fiber connection would win. Additionally, bandwidth is an extremely scarce resource in HF bands (compared to cellular networks or other common VHF/UHF systems). There's a reason people still use CW (morse code) or even PSK31 [3] instead of SSB (voice) [4] in HF bands: You need around 500 Hz for CW signals, around 3000 Hz for SSB signals. PSK31 only needs 31.25 Hz. My point is: While you might beat latency of fiber connections and routers along the path, the throughput is going to be quite low for HF transmission. [1] https://spectrum.ieee.org/wall-street-tries-shortwave-radio-to-make-highfrequency-trades-across-the-atlantic https://spectrum.ieee.org/wall-street-tries-shortwave-radio-... [2] Since you mentioned copper: Copper can be quite a bit slower than fiber depending on cable type, since the propagation speed of signals in copper cables depends on the velocity factor. Wikipedia gives a few examples: https://en.wikipedia.org/wiki/Velocity_factor https://en.wikipedia.org/wiki/Velocity_factor [3] PSK31 stands for Phase Shift Keying at 31 Bd. The short explanation is that PSK31 is a bandwidth-optimized text transmission mode. [4] SSB stands for Single Sideband. The short explanation is that SSB is a bandwidth-optimized AM voice mode.
- blitzar 5y ago
  a bit more info on [1] for your there - its actually a 3 part piece. https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-trading-part-i-the-west-chicago-tower-mystery/ https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-tr... Bloomberg picked it up as well if you are into that side of things - https://web.archive.org/web/20180625133148/https://www.bloomberg.com/news/articles/2018-06-18/hft-traders-dust-off-19th-century-tool-in-search-of-market-edge https://web.archive.org/web/20180625133148/https://www.bloom...
deleted 5y ago
[deleted]