Hi,
why in TLC having negative TX values is valid? How can we transmit something if the transmission power is in the negative?
Why for at least in fiber optics the “no signal received” was established to be -40 dbm rather than 0?
In: 0
RSSI is just a scale, like Celsius or Fahrenheit. 32°F is the same temperature as 0°C. It’s easier to measure water in Celsius and there are benchmarks to that. 0°C is ice, 100°C is gas.
However, for signal strength, there’s only a maximum amount I can have, but with sensitive enough equipment, there’s not really a lower limit. That makes it hard to put a positive maximum value on it, but easier to measure how much less there is. If I’m directly at the source, I have all the signal, so we mark that as the maximum, 0dbm. If I move away a bit, I now have 40dbm less of a signal, so the value is -40dbm. If I move farther, I have 80dbm less of a signal, so -80dbm, -120dbm, etc.
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