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[SOLVED] How we can Decide for set BB gain, IF gain, RF gain???

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stackprogramer

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How we can Decide for set BB gain,IF gain,RF gain???

Hello my friend.I had a good Transceiver Hackrf one. i know some about transceiver . i know we can categorize Transceiver to three stage:
  1. BaseBand
  2. Intermediate Band
  3. Radio Band
Untitled.pngUntitled.png
for it we have define three gain.
BB gain
IF gain
RF gain


my question is how we can decide how much we set BB gain,IF gain,RF gain.................

whats relation between them?please guide
best regards stackprogramer
 

Romansh

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Re: How we can Decide for set BB gain,IF gain,RF gain???

Hi,
For the transmitter part:
1. You should set most of the gain on BB, since any noise that will be added in last stages, will not be amplified too much, increasing the Noise Floor.
2. For the receiver it is just the opposite, consider the noise figure and the linearity
3. Make sure your RF chain is not compressed in any stage (unless it the last stage in the power amplifier and you are using constant envelope modulation)
4. Keep certain power back-off from the output/input 1dB compression points to maintain EVM and IM3 requirements.
The above are very basic starting guidelines, there are more consideration that you should take into account.
You can build an excel spreadsheet or use Syscalc, Quick-sys or similar RF system analysis software.
 

Harry Zachrisson

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Re: How we can Decide for set BB gain,IF gain,RF gain???

The balance between amplification in the stages is quite tricky and depends on what dynamic range and noise figure you want.
More gain especially close to the antenna gives lower noise figure but also degrades dynamic range.
More gain=less dynamic range= intermodulation and false signals.
Less gain= less sensitivity but less false signals.
 

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