CW Autotune will not work for weak CW signals

David43

The signal threshold for the CW Autotune for both One Shot and Intermittent is set much too high to be any value for weak CW signals. In my opinion it should bet set to just above the average noise in and around the selected CW bandwidth.

David, K1MT

Russ Ravella

Hi David,

Yeah, agree. Hope this and the "Tune to Closest" (not "strongest") option are being worked on.

73 Russ KR6W

Al_NN4ZZ

https://community.flexradio.com/discussion/8032487/4-0-ssdr-new-cw-auto-tune-feature-and-one-more-option-to-consider

David43

I believe I have a solution to fix the issue with the Autotune not being effective for weak CW signals in both the One Shot and Intermittent settings. Here's the algorithm I would suggest:

1.) Within the selected CW BW, e.g. 500 Hz, determine the pdf for each FFT bin using just the noise samples, after eliminating the signal samples based on the nature of their characteristics.

2.) From the noise pdf, select the +noise component level at the 0.99% point in the distribution.

3.) Add 10% from step "2" and use this as the threshold point to lock on to the nearest signal to the selected frequency within the CW BW.

4.) Once locked on to this signal disable the Autotune function both for the One Shot and Intermittent alternatives. I would also change the Autotune names to Manual Zerobeat and Auto Zerobeat.

5.) This algorithm should be designed so that the CW Zerobeat is done within 50ms.

If the Autotune tunes to a close by undesired signal the operator should tune the dial.

David, K1MT