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I don't understand this sentence: > Instead, it elected to send a “mirror feed” of telemetry from the STARS servers at N90, traveling over 130 miles of commerc

I don't understand this sentence: > Instead, it elected to send a “mirror feed” of telemetry from the STARS servers at N90, traveling over 130 miles of commercial copper telecom lines, with fiber optics to follow by 2030. This does not make any sense. If they would really transmit data over a 130 miles copper line (which I doubt even still exist, especially not commercial ones), we would be talking rates in the low Mbit/s. I suspect the situation is that the "last mile" of the center is served by copper connections, not good either but by far not as bad as a 130 miles copper connection. EDIT: I should add if they really would have a link running on copper lines it would have repeaters, which would be sitting in datacenters. In New Jersey there would by 1000s of km of dark fiber floating around, so it would be trivial to convert at least the majority of the link to fiber.

quesera 1y ago
Telephone providers lease "dry loop" lines for point-to-point signalling. I've used them for telemetry systems with acoustic modems on both ends. Also for sending audio between broadcast studios. I recall that it was priced by bandwidth (in the literal, analog, sense), e.g.: 5kHz (~AM radio) was less expensive than 15kHz (~FM radio). For comparison: A normal phone call is 3kHz. So yes, copper and repeaters. But very inexpensive and quick to provision. :)
- cycomanic 1y ago
  Not sure I understand your point, using a 15 kHz carrier gives you nowhere near enough bandwidth to transmit even just 100 Mb/s.
  - quesera 1y ago
    I am guessing that the data feed requirements of ATC telemetry are fairly modest, well within the range that a pair of analog modems could handle. You don't have to send a raw radar feed to the airport, just put the intelligence (object detection, delta computation, etc) at the endpoints and transmit the results. I'm also guessing that they do this every day at hundreds of other airports, and it works just fine. Moving to fiber gives you greater bandwidth, reliability, multipath redundancy, etc. But I bet the real motivation is access to newer and more general communications equipment. Maintaining the old, perfectly adequate but increasingly unusual hardware/software is more of a pain than replacing with new stuff that exceeds requirements but is maintained just like all the other modern stuff everywhere. All guesses. I do not work in ATC, but I've seen the pattern in other industries with similarish requirements.

quesera 1y ago

Telephone providers lease "dry loop" lines for point-to-point signalling. I've used them for telemetry systems with acoustic modems on both ends. Also for sending audio between broadcast studios. I recall that it was priced by bandwidth (in the literal, analog, sense), e.g.: 5kHz (~AM radio) was less expensive than 15kHz (~FM radio). For comparison: A normal phone call is 3kHz. So yes, copper and repeaters. But very inexpensive and quick to provision. :)

cycomanic 1y ago
Not sure I understand your point, using a 15 kHz carrier gives you nowhere near enough bandwidth to transmit even just 100 Mb/s.
- quesera 1y ago
  I am guessing that the data feed requirements of ATC telemetry are fairly modest, well within the range that a pair of analog modems could handle. You don't have to send a raw radar feed to the airport, just put the intelligence (object detection, delta computation, etc) at the endpoints and transmit the results. I'm also guessing that they do this every day at hundreds of other airports, and it works just fine. Moving to fiber gives you greater bandwidth, reliability, multipath redundancy, etc. But I bet the real motivation is access to newer and more general communications equipment. Maintaining the old, perfectly adequate but increasingly unusual hardware/software is more of a pain than replacing with new stuff that exceeds requirements but is maintained just like all the other modern stuff everywhere. All guesses. I do not work in ATC, but I've seen the pattern in other industries with similarish requirements.