Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

agc pop

Lasse Moell
Lasse Moell Member ✭✭
edited April 2020 in SmartSDR for Windows
Listening on a strong CW signal I often hear a very noticable pop at the beginning of each character. If the space between chars are long enough for AGC to up the gain, I do have a pop at next character. This is specially noticable when the received signal have a hard keying and I am using narrow BW i.e. <2-300 Hz or less. This is related to AGC timing, and in slow setting it only occurs at the very first edge. The attached picture shows the severe pop just before the true character start.
Attached pic shows how it looks with wide BW (top 1000Hz) and narrow BW (BW 150 Hz) bottom. Notice how the audio blanks out before the character when using wide filter, and the popping sound replaces this when using narrow BW.
WNB/NB/NR are all off!

image

Any suggestion on how to fix this?
/Lasse SM5GLC

Comments

  • Bill W2PKY
    Bill W2PKY Member ✭✭
    edited March 2017
    I think you are hearing the filters set either on AUTO or slider all the way to the right, sharpest. Open the Radio Set up panel and look at the Filters tab. Try taking off the AUTO and slide the setting to a more wide setting to see if the the sound improves. Other settings that help CW sound better is setting the earphones slider [top right near REMOTE} all the way to the right and reducing the AGC slider while using about 50-60% of the speaker slider on the slice flag.
  • Lasse Moell
    Lasse Moell Member ✭✭
    edited March 2017
    I am using Maestro. Filters are chosen mostly to be narrow i.e. 150-300 Hz.  As I shown above wide filters: no pop narrow filters: loud pop.  AGC-T set to 45-65% depending on noise on the band. But varying this does not affect the popping sound unless signal is attenuated by the AGC-T setting.
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited February 2017
    Bill is referring to the filter sharpness / latency settings in the Settings->Radio Setup->Filters tab.
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited March 2017
    I have entered this behavior in our bug tracker as issue #4505 for further investigation. Thank you for the detailed report and screenshots.
  • Sergey R5AU
    Sergey R5AU Member ✭✭
    edited April 2017
    CW 100Hz filter , F6700
    image

    CW 400HZ filter F6700
    image

    the same station, real air, 40m band, filter sharp AUTO

    I wanna say ALC overregulated, sound so rigid + pop,  AGC-T fine tuned within band conditions on the border of the noise down

    SSDR 1.10.15
    signal recorded with Audacity on DAX
  • Lasse Moell
    Lasse Moell Member ✭✭
    edited April 2017
    I have tested the suggestion from Bill W2PKY, and yes I do notice a clear difference! Band condx not too good so had great difficulties to find a suitable strong signal, and finally found ON4UN calling on 40 meters :)

    image
    Lowest trace: Auto settings of filter
    Middle trace: Lowest latency
    Upper trace: One up from lowest latency.

    The pop is gone but at a price, less steep filters. Also interesting to see that the audio "mutes" instead of pop with less latency. I had a look with my other SDR receiver, and could not see a similar behavour on the envelope. This seems to be a "FRS first" :)
    Even if this is a work-around that seems to help, I still hope FRS can fine-tune the AGC charateristics so the annoying pop will be gone or reduced with higher latency/ sharper filters.

    Cheers
    Lasse SM5GLC
  • Sergey R5AU
    Sergey R5AU Member ✭✭
    edited February 2017
    Lasse I agree, AGC char. should be improved definitely
    IMHO - high gain in AGC process
  • Paul  KB3ML
    Paul KB3ML Member ✭✭
    edited February 2017
    My 6500 does this also.
    Thank you for opening a bug tracker !  


  • Sergey R5AU
    Sergey R5AU Member ✭✭
    edited February 2017
    Thank you Paul for feedback.
  • Lasse Moell
    Lasse Moell Member ✭✭
    edited August 2017
    Just want to push this into the light once more... the AGC "malfunction" is still there in v 2.0.17, now that the contest season is round the corner, I really need  steep filters. BTW just checked my other SDR-receiver filter and it has just as steep filters as the steepest setting in SSDR, and no pop what so ever. We really need  this problem #4505 to be adressed.

  • Mike_N1MD
    Mike_N1MD Member ✭✭
    edited April 2020
    I did not detect pops in any version 1.x of SSDR or Maestro. However, I have had noted a VERY serious popping problem in 2.0.17 exactly as Lasse describes above. It is worse by far in Maestro but annoying in SSDR as well. I originally thought I had "cured" the problem by re-installing SSDR and Maestro 2.0.17. The situation improved greatly at that point, but the pops are still a real problem, especially for DX chasing of strong signals and nearly crippling in CW contests.
    I am filing a help desk request today and will reference this string of posts and the bug tracker "4505.
  • Sergey R5AU
    Sergey R5AU Member ✭✭
    edited August 2017
    I am confirming , 2.0.17 yesterday evening got many times pops on 40m from strong stations. Really this is a point of frustration here,  AGC is one of the extremely important parts in RX in compare with some of "bells&whistles"
  • Unknown
    Unknown Inactive Employee
    edited August 2017
    Folks ,  

    I helped resolve the CW popping issue with Mike,  N1MD by performing a database reset on his radio..   Warning ,  please save your current profiles from the radio by using Export in the Profiles menu at the top of SmartSDR , to a remembered folder  (i just created a "Saved Profiles"   folder in my desktop)   then you can power down the radio..   Slightly different procedure for the 6300 verses the 6500/6700 from here..   

    On the next power up of the radio - 

    6300 -  Push and hold the power button in until the power LED turns white.   

    6500/6700 - Push and HOLD the "OK"  button on the front of the radio then momentarily push the power button to start the power up sequence.  Continue to HOLD the "OK" button until the count down in the OLED display reaches zero and the power led turns white,  then release the "OK"  button on the front. 

    In both cases the radio will come up with a single panadapter and slice at 14.100  CW as confirmation that the reset was complete..   

    If the radio operates OK in the cleared condition ,  then Import your saved profiles back in ,  it is recommended that you uncheck the Preference box when you import ,  this is previous screen settings ,  and could be part of the problem with an invalid setting in the persistence file .  

    This should help lots of little issues.  

    73,
    Dudley
  • Sergey R5AU
    Sergey R5AU Member ✭✭
    edited August 2017
    Dudley, this is not help much, pop still exist with signal strong fronts and high levels., and independently of SW version ( probably HW version?) but looks like AGC artifacts

Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.