Distorted Receive Audio for about 1 second.

Michael Engstrom

I have noticed short-term (about 1 second) distortion on strong SSB signals with the NB ON. It seems like it takes the NB algorithm a little too much time to differentiate what is signal and what is noise, causing distorted audio for a second or so before normalizing, and it does normalize. I thought it may be associated with the Hardware ALC on/off. This distorted audio is particularly noticeable when a strong SSB station comes back to a very weak one. I have electric fence noise where I live and a low NB setting will reject it. Just upgraded from a Flex 3000. Has anyone else had this experience?

SteveM

Sorry, Mike, I might be the only one here right now. Elmer could answer much better than me. NB, NR, and ANF have been dissected and criticized for months. In fact, I have heard many state that they would rather have those features improved before any new features. Flex has heard the criticism and has promised those improvements delivered in SSDR ver1.4 (Jan 31, 2015).

KY6LA_Howard

NR,NB,ANF improvements are a "Science Project"to be part of SSDR ver 1.5. Not 1.4.

SteveM

Thanks, Howard. I thought they were mentioned in the last Insider, you have reminded me of the context. Sorry for the misinformation.

Bill -VA3WTB

And they are not just working on any noise blanker, they are working on things we have never seen before, it will be interesting.

Bill -VA3WTB

Gerald - K5SDR, Official Rep

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As I stated in the last Flex Insider, our goal is to up the game in noise and interference mitigation in v1.5.  There are many types and sources of noise so a single algorithm will not address all types of noise and operating modes.  We are not going for parity but to exceed what has been done before on any radio.  As I also said, this is a "science project."  We have a number of ideas that we want to try that have not been used in ham radio radio before.  We have a lot of options in the FPGA that are not available in legacy architectures. 

Jay Nation

Mike 
Hardware ALC is in the TX chain and is probably not responsible for the distortion your hearing. Do you get the distortion repeatedly on the same strong SSB signals, or does it improve after the NB learns the new environment? I don't use the NB at all so I can't offer any tips, except the thought that possibly running the AGC-T lower and turning on the AGC might make the signals distort less. I routinely run my AGC-T very low and ride the control constantly using the FlexControl knob.   Still strong SSB signals have to be adjusted for. They don't distort this way but do tend to give me a wake-up signal to adjust the AGC-T.

Michael Engstrom

Jay -

The audio normalized quickly (in abt a second). By normalize I meant to say that the distortion was gone and the received audio sounded excellent. I'll play with the AGC-T (now have it on FlexControl Aux1) and report any new data. Thanks for the clarification on the TX ALC,

Flex Model 6700.

Michael Engstrom

BB - "And they are not just working on any noise blanker, they are working on things we have never seen before, it will be interesting."

BB -
I've been up and running with my new 6700 for about a week now. Regarding the NB, I think Flex has covered those bases.