4 ms·
>10000x power alone Sorry to dig this up so late, there is a usual misconception when reasoning with power (which you might suffer from) : What matters is not
by GistNoesis 7y ago
>10000x power alone
Sorry to dig this up so late, there is a usual misconception when reasoning with power (which you might suffer from) :
What matters is not power, what matter is what we measure. We are measuring electric field in volts whose square is proportional to the power. Going 10x as far, mean measuring a voltage 100x smaller. Even with just the dynamic range if your analog digital converter is reading you 8-bits values (values going to 256) with a 100x voltage reduction you get a smaller blip going from 0 to 2.
- mlyle 7y agoWhat matters is signal to noise ratio. There is not really background noise in UHF and up; instead there is thermal noise in the receive amplifier. If you have SNR of 6dB over some integration interval which gave you acceptable results, and you have 40dB of additional path loss, you're now -34dB, and you need to make that up. There's no "taking half" because we're talking about only a 100x difference in receive voltage. Put another way, we already "took half"-- our SNR of 6dB (quadruple the power) was already only double the voltage. Our metrics for SNR already take what you're talking about into account. Dynamic range can be a factor, but you generally have some kind of automatic gain control that increases effective dynamic range (so that in absence of signal, you have noise much bigger than 1LSB showing up at the converter), and the conversion dynamic range "width" of the converter only matters when there are other in-band transmitters around you need to reject (because they limit how far you can turn up the initial gain before saturating the converter). Note also, not that it relates to what we said at all-- you can detect signals much smaller than 1LSB because of dither.