30-03-2018, 03:18 PM
FM pre-emphasis: The process of increasing the treble signals is called pre-emphasis, and reducing the in the receiver is called de-emphasis. The rate of pre-emphasis and de-emphasis is expressed as a time constant. It is the time constant of the capacitor-resistor network used to give the required level of change. In the UK, Europe and Australia the time constant is 50 µs, in North America it is 75 µs.
VHF FM receivers have the de-emphasis circuitry - consisting of a simple CR network built into the circuitry immediately after the FM demodulator. In this way it is not incorporated into an amplifier that may be used for other audio sources that would not require the de-emphasis applied to VHF FM transmissions.
Geordie McBoyne.
VHF FM receivers have the de-emphasis circuitry - consisting of a simple CR network built into the circuitry immediately after the FM demodulator. In this way it is not incorporated into an amplifier that may be used for other audio sources that would not require the de-emphasis applied to VHF FM transmissions.
Geordie McBoyne.
