Quote Originally Posted by koØm 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".

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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"! :)