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Tv stations do leak into adjacent bands. They contribute to the noise floor. It’s just that your real tv station broadcasts at 10,000W or whatever so it drowns

Tv stations do leak into adjacent bands. They contribute to the noise floor. It’s just that your real tv station broadcasts at 10,000W or whatever so it drowns out the other noise. When it comes to radar, they cannot increase the TX power and have to detect a lower RX power. Also since they are analog any interference manifests itself as a direct error. It’s like saying you should never be able to hear a whisper from your neighbours house. Obviously you can limit the amount of loud noises coming from your neighbours. You can’t silence them completely.

paulmd 5y ago
> When it comes to radar, they cannot increase the TX power and have to detect a lower RX power. other radar altimeters tolerate this just fine - it is a few specific models that have problems with rejecting signals that (according to design specifications) they should easily be able to reject. > It’s like saying you should never be able to hear a whisper from your neighbours house if local code says that a house should have noise insulation sufficient that a 100db noise source located at 30 meters away should produce no more than X noise level inside the house, and a 100db noise source at 60 meters away (twice the original specification) is still significantly greater than X - then yes, your house fails to meet code. It's defective. nobody is blind to the problem of radio interference. Design specs for what level of noise needed to be tolerated were standardized in the 70s. That spec hasn't been reduced, actually it has been relaxed to over twice the original guardband specification, and certain altimeters still fail. They're defective, end of story. Replace them with the models of radar altimeters which meet the original spec, done. They exist, it's not a universal problem, it's a few specific defective models of radar altimeters. Boeing just doesn't want to ground their fleet again, and the FAA is humoring them because of regulatory capture.
- tjohns 5y ago
  > rejecting signals that (according to design specifications) they should easily be able to reject Please link to this specification. Because I've read the specification (TSO-C87), and it actually says nothing about required levels of interference rejection. Should it? Probably. But neither the FCC nor the FAA wrote it in.

paulmd 5y ago

> When it comes to radar, they cannot increase the TX power and have to detect a lower RX power. other radar altimeters tolerate this just fine - it is a few specific models that have problems with rejecting signals that (according to design specifications) they should easily be able to reject. > It’s like saying you should never be able to hear a whisper from your neighbours house if local code says that a house should have noise insulation sufficient that a 100db noise source located at 30 meters away should produce no more than X noise level inside the house, and a 100db noise source at 60 meters away (twice the original specification) is still significantly greater than X - then yes, your house fails to meet code. It's defective. nobody is blind to the problem of radio interference. Design specs for what level of noise needed to be tolerated were standardized in the 70s. That spec hasn't been reduced, actually it has been relaxed to over twice the original guardband specification, and certain altimeters still fail. They're defective, end of story. Replace them with the models of radar altimeters which meet the original spec, done. They exist, it's not a universal problem, it's a few specific defective models of radar altimeters. Boeing just doesn't want to ground their fleet again, and the FAA is humoring them because of regulatory capture.

tjohns 5y ago
> rejecting signals that (according to design specifications) they should easily be able to reject Please link to this specification. Because I've read the specification (TSO-C87), and it actually says nothing about required levels of interference rejection. Should it? Probably. But neither the FCC nor the FAA wrote it in.