TGC settings

[layanalhuneidi]

I'm trying to acquire raw RF data from the L20 HD3 scanner, and I was wondering what TGC settings I can and can't modify. I don't see a trend when playing around with the autogain function.
Also,
*The sampling rate of the digitized RF data is noted as 30 MHz or 60 MHz in the rf.yml files depending on the depth. Is this value fixed for a given depth, or is it an approximate estimate that needs to be calculated? Is there a way to change the sampling or transmit frequencies?
*Are there any preprocessing steps applied before digitization, such as filtering or gain adjustment?

[clariusk]

1. Suggested to turn autogain off, then you dont need to worry about changes to the analog TGC, any TGC slider change made on the interface is a digital gain and will only change the B mode, not the RF signal

2. For the sampling frequency, this is programmed based on how many samples the beamformer can handle at a given depth, so no equation neccessarily, this cannot be changed

3. For the RF signal, after the beamformer, there are no modifications (the analog gain gets applied prior to BF). For B mode, this goes through the typical filtering, demodulation, etc.

[layanalhuneidi]

Is the analog tgc a fixed tgc? or does it vary from one set of data to the other? I see a tgc curve of

• { 0.00mm, 15.00dB }
• { 39.70mm, 35.00dB }
  in the _rf.yml file.. I was wondering if this is accurate or just a rough estimate. I am trying to reverse this analog tgc to calibrate my attenuation estimation code on a phantom with knnown attenuation

[clariusk]

yes, fixed with auto gain off, this changes with auto gain enabled and you should look at the autogain tgc file