Gain, Sensitivity and Range
时间：04-04
整理：3721RD
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Hi,
following statement is taken from a document of Keysight spectrum analyzer:
Finding a preamplifier that will give us better sensitivity without costing us measurement range dictates that we must meet the second of the above criteria; that is, the sum of its gain and noise figure must be at least 10dB less than the noise figure of the spectrum analyzer. In this case, the displayed noise floor will not change noticeably when we connect the preamplifier, so although we shift the whole measurement range down by the gain of the preamplifier, we end up with the same overall range we started with.
To choose the correct preamplifier, we must look at our measurement needs. If we want absolutely the best sensitivity and are not concerned about measurement range, we would choose a high-gain, low-noise-figure preamplifier so that our system would take on the noise figure of the preamplifier, less 2.5 dB. If we want better sensitivity but cannot afford to give up any measurement range, we must choose a lower-gain preamplifier.
It describes how to choose the preamplifier gain based on the sensitivity and the measurement range.
Question: Does this rule also apply for receivers?
Senmeis
following statement is taken from a document of Keysight spectrum analyzer:
Finding a preamplifier that will give us better sensitivity without costing us measurement range dictates that we must meet the second of the above criteria; that is, the sum of its gain and noise figure must be at least 10dB less than the noise figure of the spectrum analyzer. In this case, the displayed noise floor will not change noticeably when we connect the preamplifier, so although we shift the whole measurement range down by the gain of the preamplifier, we end up with the same overall range we started with.
To choose the correct preamplifier, we must look at our measurement needs. If we want absolutely the best sensitivity and are not concerned about measurement range, we would choose a high-gain, low-noise-figure preamplifier so that our system would take on the noise figure of the preamplifier, less 2.5 dB. If we want better sensitivity but cannot afford to give up any measurement range, we must choose a lower-gain preamplifier.
It describes how to choose the preamplifier gain based on the sensitivity and the measurement range.
Question: Does this rule also apply for receivers?
Senmeis
what does the rule you want to apply in your system ?
This document offer 2 methods for choosing pre-amp: prioritize sensitivity or dynamic range.
If your receiver near transmitters, ( including noise from other transmitter) the signal input too strong, it can make your receiver saturation and total gain would be decrease. You must chose pre-amp with low gain.
If you want the best sensitivity and aren't concerned noise from ambient, higher gain is a good choosing.
Usually, to increase sensitivity receiver, you have to improve the antenna system. Using pre-amps have many disadvantage and high cost
A Spectrum Analyzer IT IS a receiver. So, the same rule apply...