"Compensating" Pulse in PI, what it does?

[eclipse]

Consider the following schematic.
What the compensating pulse part does (the parts with in the gray rectangle)?
It is 100us wide, 100us before the TX pulse (or could be 100us wide just before the TX, with no pause between).

[Ferric Toes]

I have used a similar arrangement in an industrial PI. It is an auto-zero arrangement for the preamp which saves having to use an offset trimmer.

Eric.

[eclipse]

Thanks Eric.
In this case probably is best to have the compensating pulse right before the TX pulse starts, without pause between.

[Geo]

I have used a similar arrangement in an industrial PI. It is an auto-zero arrangement for the preamp which saves having to use an offset trimmer.

Eric.

Eric, do you mean XR7p???

[kt315]

Thanks Eric.
In this case probably is best to have the compensating pulse right before the TX pulse starts, without pause between.

yes, released in Delta Pulse. compensating pulse 80us length just before the TX pulse starts.

[eclipse]

I've seen it in Skif PI Autotune, Clone PI & Delta Pulse, but wasn't sure what exactly it does.
It maybe a good addition to other projects, requires just one additional pulse and few extra parts.

[kt315]

good only for full-static-nonmotion pi device. for minimalistic design like surf bara clone etc is not optimal.
Eric is right refering 'industrial'.

[Ferric Toes]

The other reason for using such an arrangement in an 'industrial' setting is that you can tailor the TC's in the feedback amplifier U1.4 so that there is a roll-off in gain of U.1/U.2 at low frequencies so as to lessen the effect of 50/60Hz line noise.

As you say, the sample is best just before the TX pulse. I used the same pulse width as the other samples. U1.4 was configured as a 2nd order filter. If I can find the schematic I will post it.

Eric.