Demodulator

In that same system, a second demodulator, the Z demodulator, also extracts an additive combination of U plus V, but in a different ratio.

Amateurs used their existing receivers for RTTY operation but needed to add a terminal unit, sometimes called a demodulator, to convert the received audio signals to DC signals for the teleprinter.

A modem (from modulator–demodulator) can perform both operations.

A single digital-to-analog converter (DAC) was shared by all six ports providing voltage compare functions for the modulators and feeding sample and hold circuits for the demodulator outputs.

As is common to all digital communication systems, the design of both the modulator and demodulator must be done simultaneously.

DPSK can be significantly simpler to implement than ordinary PSK, since there is no need for the demodulator to have a copy of the reference signal to determine the exact phase of the received signal (it is a non-coherent scheme).

Implementation using the FFT algorithm The orthogonality allows for efficient modulator and demodulator implementation using the FFT algorithm on the receiver side, and inverse FFT on the sender side.

In newer sets, this new carrier at the offset frequency was allowed to remain as intercarrier sound, and it was sent to an FM demodulator to recover the basic sound signal.

In some sets made before 1948, this was filtered out, and the sound IF of about 22 MHz was sent to an FM demodulator to recover the basic sound signal.

In this system, the demodulator determines the changes in the phase of the received signal rather than the phase (relative to a reference wave) itself.

On the receiver side a demodulator is used to detect the signal and reverse the modulation process.

The demodulator extracts the audio or other modulation from the IF radio frequency; the extracted signal is then amplified by the audio amplifier.

These tones are fed to the demodulator part of the modem, which processes them through a series of filters and detectors to recreate the original digital signal.

This modulation is the most robust of all the PSKs since it takes the highest level of noise or distortion to make the demodulator reach an incorrect decision.