Microchip Technology DM183037 Data Sheet

 2012 Microchip Technology Inc.

DS30575A-page 235

The Data Signal Modulator (DSM) is a peripheral which
allows the user to mix a data stream, also known as a
modulator signal, with a carrier signal to produce a
modulated output.
Both the carrier and the modulator signals are supplied
to the DSM module, either internally from the output of
a peripheral, or externally through an input pin.
The carrier signal is comprised of two distinct and
separate signals: a Carrier High (CARH) signal and a
Carrier Low (CARL) signal. During the time in which the
Modulator (MOD) signal is in a logic high state, the DSM
mixes the Carrier High signal with the Modulator signal.
When the Modulator signal is in a logic low state, the
DSM mixes the Carrier Low signal with the Modulator
signal. 

Using this method, the DSM can generate the following
types of key modulation schemes:
• Frequency-Shift Keying (FSK)
• Phase-Shift Keying (PSK)
• On-Off Keying (OOK)
Additionally, the following features are provided within
the DSM module:
• Carrier Synchronization
• Carrier Source Polarity Select
• Carrier Source Pin Disable
• Programmable Modulator Data
• Modulator Source Pin Disable
• Modulator Output Polarity Select
• Slew Rate Control 

 shows a simplified block diagram of the

Data Signal Modulator peripheral.