Batboard

Hello,

I have done some experimenting and to me, radio audio sounds better on the Rx side if Rx De-Emphasis is off, and Tx audio sounds a little bit better but not a drastic difference.

What is the standard?
Should it be on or off?

What radio and what are you going to do with it?
Standard is both on.
*Most* older radios the De-emp applies to an accessory port rather than the speaker.
Really depends on what you are trying to do.

The function of pre-emphasis/de-emphasis is to improve SNR on voice transmission by pre-emphasis boosting high frequencies on the TX side so RX de-emphasis rolls off the noise on a non-quieting signal and restores the normal voice frequency response. So both should be on for voice.

If no TX pre-emphasis voice will be muffled. If RX de-emphasis is off voice will sound tinny with high frequency noise. If no TX pre-emphasis nor RX de-emphasis then overall SNR is degraded.

But "flat audio" (no pre/de- emphasis) is needed for data and best tone paging results. This is often done at the TX side with a flat audio input (separate from the mic input) for data and paging tones and on the RX side flat audio to the aux port with de-emphasis on speaker audio. The RX aux port is often programmable so de-emphasis is off for a data device but can be on if it feeds an audio device like an external speaker.