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If any system could measure its own signal to noise accurately, it wouldn't have any noise in the first place.
by vasco 2y ago
If any system could measure its own signal to noise accurately, it wouldn't have any noise in the first place.
- sobellian 2y agoThis is a "truthy" statement that sounds right but is, in fact, false. Radio systems have an easily measurable SNR, but the noise cannot be eliminated.
- vasco 2y agoYou can measure is from outside the system itself if you know the original signal. Of course its possible to measure the noise externally if you know what was transmitted.
- sobellian 2y agoAFAIK this is incorrect. There exist modulation schemes where the received signal power is evident. For Wifi the signal is usually > 10-100x the noise floor and it is modulated with phase-shift keying. So there is no technical problem with seeing a noise floor, then receiving a much larger signal with constant envelope and calculating an SNR. ETA: Just to sharpen the point, this is clearest when considering digital noise and error correction. It is easier for error correction codes to indicate a corrupted message than it is to provide the correct message.
- Dylan16807 2y agoThat only works if you have an ultra-high-resolution record of isolated noise. An accurate measurement of signal-to-noise is just some power levels and basic knowledge of the shapes of the signals. It's easy to figure out and doesn't help you read back your data. It helps you configure appropriate transmission settings and doesn't do much else.