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Thread: Rant... FT8...

  1. #1
    Administrator KD8TUT's Avatar
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    Rant... FT8...

    Ok... so I've been on an FT8 bender lately. Been enjoying the setup and computer integration side of it as well. Have made about 500 contacts in three weeks.

    But....

    When oh lord will hams learn that over modulating a digital mode is a no no? Can we grow up now? Please?

    2018-03-27 17_35_13-WSJT-X - Wide Graph.jpg
    --
    So there I was, totally naked. With only a rubber hose and a stuffed animal...

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    Forum Addict WZ7U's Avatar
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    Michael, these are the same types that believe in all knobs right at the 11 position is the best output possible. The ones on ssb with their mike gain so high you can hear their wives farts three rooms away with the rugrats screaming in the backgroound and the TV blaring over it all on Inside Edition or TMZ. Send them a macro how their signal is overdriven and they suck for it. I would.

    Besides, I see a couple you didn't point out. I bet after three it gets kinda pointless, huh?

    Pointless pointing. I made a funny.
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    Administrator KD8TUT's Avatar
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    Quote Originally Posted by WZ7U View Post
    Michael, these are the same types that believe in all knobs right at the 11 position is the best output possible. The ones on ssb with their mike gain so high you can hear their wives farts three rooms away with the rugrats screaming in the backgroound and the TV blaring over it all on Inside Edition or TMZ. Send them a macro how their signal is overdriven and they suck for it. I would.

    Besides, I see a couple you didn't point out. I bet after three it gets kinda pointless, huh?

    Pointless pointing. I made a funny.
    You did...
    --
    So there I was, totally naked. With only a rubber hose and a stuffed animal...

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    "Island Bartender" KG4CGC's Avatar
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    Sorry. That was me. I looking for a quick and easy method to get on the air so I just held up the microphone to the computer speaker.
    RIP Albi
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  5. #5
    Master Navigator kom's Avatar
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    Let me disabuse the CB'er in you.

    Quote Originally Posted by KD8TUT View Post
    Ok... so I've been on an FT8 bender lately. Been enjoying the setup and computer integration side of it as well. Have made about 500 contacts in three weeks.

    But....

    When oh lord will hams learn that over modulating a digital mode is a no no? Can we grow up now? Please?

    2018-03-27 17_35_13-WSJT-X - Wide Graph.jpg
    A better question would be, "When Oh Lawd, when will Licensed Amateur Radio operators stop looking at waterfalls displays and cease to act like Chicken-Banders crying over "Bleed-over" on the channel?

    Correct me if I am wrong but, a waterfall display isn't calibrated and is not a "Spectrum Analyzer"; is totally dependent upon the workings of your antenna system, the front end of your radio and the sound card / computer doing the decoding. Nor does not take into consideration that an operator may have a set of stacked Yagis 100 feet in the air, pointed directly down your "Throat".

    Maybe "Mother-Nature" has raised her "skirt tails for you" or, "The Skip-Gods are shining down" on somebodies' station.

    If his "Over-Modulation" is affecting my radio reception and enjoyment of the hobby, I would (figuratively) "spin the dial" or change bands.

    Now, if I had a rant about FT-8, it would be with the "Free-for-all" nature of the FT-8 timing versus JT-65 or JT-9; there was enough time between transmit and receive to allow special people like me to look up the other half of the contact on QRZ and then, personalize my 73 message to him.

    Can't do that on FT-8.

    What's next, FT-16 where the Transmit-Receive cycle is every 15 seconds?

    .

  6. #6
    Administrator KD8TUT's Avatar
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    Quote Originally Posted by kom View Post
    A better question would be, "When Oh Lawd, when will Licensed Amateur Radio operators stop looking at waterfalls displays and cease to act like Chicken-Banders crying over "Bleed-over" on the channel?

    Correct me if I am wrong but, a waterfall display isn't calibrated and is not a "Spectrum Analyzer"; is totally dependent upon the workings of your antenna system, the front end of your radio and the sound card / computer doing the decoding. Nor does not take into consideration that an operator may have a set of stacked Yagis 100 feet in the air, pointed directly down your "Throat".

    .
    According to the FT8 Operating Tips guide available at www.physics.princeton.edu:

    "If you get your transmit levels badly wrong (such as the FT8 station labelled 0 in pink below), you mayunknowingly be generating ‘ghostly barcodes’ (1-5): despite looking like some obscure new
    digimode, these are audio harmonics caused by generating too much audio output from the PC
    sound card which overloads the audio input circuits in the radio"

    The operating guide is here: https://www.physics.princeton.edu/pu...ating_Tips.pdf

    Secondarily, something that is not mentioned in the OTG:

    The Windows Audio Subsystem, along with software like VAC/Voicemeeter/USB audio codecs, do resampling when an audio signal has too much gain. This is to reduce digital clipping. However, while the digital clipping is mitigated by the resampling, the effect is a compression of the audio which can create artifacts as shown in my waterfall picture (and is also observable on a spectrogram). In effect a widening and distortion of the signal.

    This can also be seen in single sideband operation when mic inputs are over driven and ALC compression is applied- regardless of power output.

    So the issue isn't the accuracy of the waterfall relative to gain but the evidence of the widening of the signal- especially in consideration of the low power levels used for weak signal modes.

    This is often true on the JT modes as well as WSPR. The solution is to back the gain off at the *beginning* of the audio chain and running a DB or two below maximum gain so that your input is -1db into the radio. On more complex audio chains, PC audio might make transit through a few virtual devices before entering the radio so it is important to avoid over driving anything in the chain.

    Back to the "Chicken Band"! :)
    --
    So there I was, totally naked. With only a rubber hose and a stuffed animal...

  7. #7
    Master Navigator kom's Avatar
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    Quote Originally Posted by KD8TUT View Post
    According to the FT8 Operating Tips guide available at www.physics.princeton.edu:

    "If you get your transmit levels badly wrong (such as the FT8 station labelled 0 in pink below), you mayunknowingly be generating ghostly barcodes (1-5): despite looking like some obscure new
    digimode, these are audio harmonics caused by generating too much audio output from the PC
    sound card which overloads the audio input circuits in the radio"

    The operating guide is here: https://www.physics.princeton.edu/pu...ating_Tips.pdf

    Secondarily, something that is not mentioned in the OTG:

    The Windows Audio Subsystem, along with software like VAC/Voicemeeter/USB audio codecs, do resampling when an audio signal has too much gain. This is to reduce digital clipping. However, while the digital clipping is mitigated by the resampling, the effect is a compression of the audio which can create artifacts as shown in my waterfall picture (and is also observable on a spectrogram). In effect a widening and distortion of the signal.

    This can also be seen in single sideband operation when mic inputs are over driven and ALC compression is applied- regardless of power output.

    So the issue isn't the accuracy of the waterfall relative to gain but the evidence of the widening of the signal- especially in consideration of the low power levels used for weak signal modes.

    This is often true on the JT modes as well as WSPR. The solution is to back the gain off at the *beginning* of the audio chain and running a DB or two below maximum gain so that your input is -1db into the radio. On more complex audio chains, PC audio might make transit through a few virtual devices before entering the radio so it is important to avoid over driving anything in the chain.

    Back to the "Chicken Band"! :)
    Thank you for the edification.

    Carry on station.

    .

  8. #8
    Volcano Tamer suddenseer's Avatar
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    You guys are so official on the publicly viewed pages. You ought to see the secret rooms!

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  9. #9
    Administrator KD8TUT's Avatar
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    Quote Originally Posted by suddenseer View Post
    You guys are so official on the publicly viewed pages. You ought to see the secret rooms!
    What? I'm still not wearing pants.
    --
    So there I was, totally naked. With only a rubber hose and a stuffed animal...

  10. #10
    Forum Addict WZ7U's Avatar
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    Quote Originally Posted by suddenseer View Post
    You guys are so official on the publicly viewed pages. You ought to see the secret rooms!
    Funny, I don't feel official. I must've missed the memo.

    According to some over yonder I'm the devil for hanging out here. So be it. I'm not going to detail what they are. Deep down they already know.
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