QRN and AGC

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  • Updated 4 years ago
I run a 75 meter SSB traffic net at 5pm local.  The last two afternoons in New England have been plagued with heavy QRN from far off lightning strikes.

In these cases I have to abandon my 6500 for my K3.  I would prefer to stay with the Flex, but the QRN is much worse on the Flex, sharp and loud.  The K3 smoothes it out.

There may be some setting I am missing.  I have tried setting the AGC to Fast, Med, Slow, and Off.  I have varied the AGC-T from high to low.  I have tried some NR and even NB.  Nothing seems to help.

I am guessing that the K3 does better since it allows me to set AGC slope, AGC threshold, AGC hold, and has AGC pulse suppression.  Since these don't appear to be parameters users can set on the Flex, I am stuck with some parameters in the firmware that don't work well in all situations.

What am I missing?

73 de K1ESE
John
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K1ESE

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  • puzzled

Posted 4 years ago

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Bill Reid

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Did you try reducing the RF gain control ?  

73
Bill
VA3QB
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Lou, i4AWX - AB1FJ

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I have been a Flex user since the very beginning with the SDR1000 then upgraded to the Flex 3000 and 6500 now. I love Flex radios but quite frankly these features (noise reduction & NB) are still behind competition and must be improved in future software releases to be brought up to competing standards.
Lou AB1FJ
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Bill -VA3WTB

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Did you not know they are working on this for v1.5?
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Walt - KZ1F

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Perhaps they will be there in 1.5
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Walt

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I think the Flex 6000 series will get there - With the K3 around 8 yrs. old and at version 5 of the software, it has a few years of development ahead of the Flex.  I am confident that the 6000 series will be a mean machine in 5 more years and version 5 of SSDR.  And if I am wrong, then I will move on to the next vendor,

It would be interesting to hear from anyone who had a K3 during its version 1.4 of software to see what the comparisons are - if they can be compared at all, since we are talking different platforms.
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Ned K1NJ

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   Those storms brushed by my area; close enough that I disconnected equipment.
I don't know about the K3, but the Flex 5000 does better with static crashes.
However, I guess that is a different platform, although it is also an SDR.
   5 years is forever in today's world. If Moore's law still applies, devices might be 2^3 smaller and/or faster. Radio hardware will change to support more powerful software and the SDR niche will no longer be a niche.  Programmers will use SW packages like MATLAB to produce code. This will be translatable by SW produced by companies like Xilinx, directly into FPGA (or the device of the era) code that will run the newer generation of SDR.  You will have a lot more than just an effective
noise blanker.

Hope to see you there,
Ned,  K1NJ
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Walt - KZ1F

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@Walt - if you look at sherweng.com over the years the K3(S) has steadily moved up on Rob's list to be, numerically, second.
@Ned - no, I think Moores is pretty much capped due to manufacturing constraints.  Wirth's has been eating away at what Moore's has been credited with.
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Stan - VA7NF

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To help make it better, perhaps you/someone can record the impact of the QRN under several radio settings and submit it to Flex. 

To Flex:  Perhaps you can release some API and GUI code that will record and playback into the flex some captured data for "reprocessing" under different conditions.  This fat pipe would likely need limits such as the range of a slice (including diversity = from 2 SCUs) and not be real-time (buffered)

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John n0snx

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I have been a Flex user for over 6 yrs now and here in the midwest lighting /static crashes are the norm in the spring/summer... I have never not been able to tame the crashes on 80 and 160 mtrs with the AGC-T unless they are 20 to 30 db.... use the NR and adjust it to desired setting ....AGC on SSB should always be set to slow..... move the AGC slider left until you get the desired effect you can live with.... Now sometimes the crashes are 20 to 30 db strong.. thats when you just turn your radio off and chase the YL around the bedroom... But be careful... you might catch her and get the hell knocked out of you...RESULTS MAY VARY.
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Ken - NM9P

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Hi john, I have found that SLOW AGC is a bit TOO slow, especially with summer static crashes...it takes too long to recover each time. MED has been a better match for me. But that is Personal preference. When in a lot of static crashes, I agree with Jim, that FAST might be better, in conjunction with carefully adjusting AGC-T and using some NR. Each band and set of conditions will require a different setting to get maximum performance.

Static from AC power lines or other impulse noise is a different story. While I noticed some incidental improvements in the last two releases, NB improvements are still awaiting the release of 1.5.
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Jim, KJ3P

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John, I feel your pain, but I had quite a different result last evening running an EPA traffic net with the same strong line of t-storms "next door" in NJ (I saw that it extended up into your area).  AGC set to fast, AGC-T set just below the noise threshold (about 35-40 at this location), and the NR slider set to 70 or so.  Made a huge improvement to the static crashes.  Using v1.4.11.
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K1ESE

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Jim -

I tried most of that, but didn't push the NR that high.  I will note those settings for the next (inevitable) static serenade.

73 de K1ESE
John
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Marv

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In conjunction with the SLOW/MED/Fast settings have you adjusted the slider that controls the sensitivity of those settings?  I have an 6500 and find Med inconjuction with the slider to be very effective in reducing noise.