8600 CW High Pitch Hiss receive audio with APF activated

ad4vxtom · March 5

I also own an 6400 but now use the 8600. I am using SmartSDR v3.8.23 on a Windows 11 PC (native) connected to my 8600. I have the AGC-T set to 10 and my pitch set to 500Hz. When I activate APF, there is a high pitch hissing sound introduced to the signal that makes copy more difficult. The actual CW signal is louder, but the hiss is making decoding more difficult. I did not experience this problem with my 6400 with the same version of SmartSDR. This has been a constant problem since receiving my 8600 on Christmas Eve.

-Tom, W9TO

Trucker · March 5

Help Desk ticket time.

James

WD5GWY

Sergey KN7K · March 7

Tom,

Not sure what you hear but I do not think APF is working or working properly on 8600.

I barely used it on 6600 but when used it was working.

I opened a ticket a while ago and Tim promised to show my video to Engineers and get back to me, and now crickets …

Here is the video. My pitch also 500 (tried from 480 to 520 as well with the same results). For me APF is adding noise and not usable. Unless someone can point me to a direction to tune it differently.

https://drive.google.com/file/d/1Zuq4FdQfbfuui0fXMCzQFj6IbvdU4Xem/view?usp=sharing

Sergey, KN7K

K3CDY · March 7

That’s pretty much what my APF sounds like on my Mac SSDR. I think this is normal, and perhaps we can look forward to better all around DSP with the 8000 series.

My old SunSDR DSP beat the Flex hands down in this department.

Sergey KN7K · March 7

Bill, I do not know if it is normal, seems like pretty useless, like CW signal is not going through APF filter and APF filter enabling just adding noise.

Sergey, KN7K

ad4vxtom · March 7

KN7K/Sergey, Thanks for sharing the video and listening to it; that's what mine sounds like too. APF does not sound like that on my 6400 with the same version of SmartSDR. I'm very disappointed.

KD0RC · March 7

I find that on my 6400, if I am on a narrow setting, say 100 Hz or less, then it has minimal impact. On the other hand if I have it at 400 Hz or wider, it makes a dramatic difference (a good difference…). On 250 Hz, it helps a little. Since I rarely operate CW wider than 150 or 200 Hz, APF neither helps nor hurts much. I have it engaged at a level of 30 on all of my CW profiles, but I don't really pay much attention to it.

8600 CW High Pitch Hiss receive audio with APF activated

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