v1.577: NBFM and AM/SSB de-emphasis
From the CHANGE_LOG file:
v1.577 Feb 6, 2023
Audio response de-emphasis for AM/SSB and NBFM:
On the main control panel, audio tab, the "de-emp" menu to the right of the volume control
has been greatly improved. For AM/SSB modes the traditional 75 uS (N.Am) and 50 uS (EU)
filter profiles are available. For NBFM a 20 dB / decade (= 6 dB / octave) is available,
with or without ("+LF") attenuation below 400 Hz (e.g. to suppress PL tone etc).
The de-emp menu settings are stored and persistent across page reloads.
Comments welcome. These filters are now FIR-based and designed with Octave from a
frequency response profile. So they are easy to adjust.
A second spectrum peak hold is available. The "Pk" button on the WF tab has been replaced by
"P1" and "P2". Each click on Pk cycled between off/clear(wht) and hold(grn).
But P1 and P2 cycle between three states: off(wht) - on(grn) - hold(red).
This is so one can be in hold mode while the other is on. P1 is the yellow trace and P2 cyan.
The momentary zero icon of the left of the squelch slider has been changed to a toggle.
The default FAX passband has been lowered from 2200 Hz to 1200 Hz. It was observed that for weak
signals this slightly reduced the background noise in the image without lowering the overall
contrast, indicating that the extra passband width was just increasing the noise floor.
Comments welcome. You can type "/2200" or "/2k" in the frequency box to re-widen the passband.