# Saleae Logic2 Analog filtering technical details?

**URL:** https://discuss.saleae.com/t/saleae-logic2-analog-filtering-technical-details/2427
**Category:** Support
**Created:** [September 13, 2023, 9:02pm UTC](https://discuss.saleae.com/t/saleae-logic2-analog-filtering-technical-details/2427 "2023-09-13T21:02:03Z")
**Posts on this page:** 1
**Showing post:** 17

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### Author: ![Sebastian](https://avatars.discourse-cdn.com/v4/letter/s/4da419/32.png) [@Sebastian](https://discuss.saleae.com/u/Sebastian)
#### Post date: [November 7, 2023, 9:07pm UTC](https://discuss.saleae.com/t/saleae-logic2-analog-filtering-technical-details/2427/17 "2023-11-07T21:07:43Z")

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@BitBob, I wrote a little python script to massage the JSON calibration file as by your suggestion, see here:  
[massagecal-anonymised.py](https://discuss.saleae.com/uploads/short-url/m47m5Wv4FzNdCnHZfRR7s58mGXj.py) (688 Bytes).

Indeed those filter settings seem to achieve the goal without obvious negative side effects.

Digging deeper into the settings, I see that the higher order filter coefficients (coef[2], coef[3] and coef[4]) all have b1 set to 2 and b2 set to 1. Isn’t that dubious in the first place?

Btw, I found that in my case a groupDelay of -1 would be more appropriate for the simplified filter channel at all sampling rates (although for 781250 and 1562500, groupDelay of 0 and -1 were a tie).

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