R12

New features

CESSB

CESSB (Controlled Envelope Single Sideband) is a technique used to increase the average power and perceived loudness of an SSB transmission by carefully clipping and filtering the signal to reduce its peak-to-average ratio while maintaining spectral purity.
Many thanks @ki9ng for idea.

Controls:

• ON/OFF,
• power up level (dB)

Power up controls increasing RF level before clipping. There is a trade-off between average output power and distortion level.
KI9NG measurements:

Setting	Avg power improvement	Notes
Conservative (p99)	+2.4 dB	Barely audible processing
Recommended (p97)	+3.7 dB	Clean, no pumping
Aggressive (p95)	+4.3 dB	Slight "processed" sound

If your TX level configured well (https://github.com/gdyuldin/x6100_base_patch#installing) - after enabling CESSB your ALC level should not exceed 1.0 for a long time, most time it should be 0.1-0.3 or below.

Even without increasing power up (set it to 0) CESSB helps to prevent overloading (and out-of-band emissions) output transistors and amplifier (if you are using it).

VOX

Vox uses only handle microphone (or any microphone, which is connected to MIC socket).
Internal microphone uses a phantom power, which turning on only during TX. During RX it doesn't produce any signal and can't be used for VOX.
VOX will not work, if you choose internal mic in settings.

Controls:

• ON/OFF,
• Vox gain (more value - more sensitivity, I tested with ~ 50),
• Antivox gain (to prevent TX on loud sound received). Zero - ignoring output audio.
• Delay (to prevent switching to RX on pauses).

When VOX enabled - voice transmitted with a small delay to prevent the transceiver from cutting off the start of speech.
In LSB/USB VOX "listens" handle microphone and line in (usb soundcard).
In digital modes it only listens line in.

VOX has some "handover" timeout to prevent too fast TX/RX/TX switching.

CW Peak filter

It's a simple resonant filter on the CW key frequency with adjustable Q. I was impressed by the same function on HDSDR. It helps to slightly increases level on a weak signal. On high Q values filter starts ringing.

Controls:

• ON/OFF,
• Q value

Fixes and changes:

• NR stability improvement
• SSB RX bandwidth increased to 5000 Hz (was 3300)
• DC blocker for incoming audio moved to AIC3204 chip (bit less MCU load)
• Output audio level to the linux-based part increased at 29 dB. It allows to reduce SNR on APP part (recordings, CW decoding, FT4/8 decoding, etc)