This transmitter and receiver will closely resemble a modem utilizing Quadrature Amplitude Modulation (QAM). QAM allows data to be sent at relatively high speeds in situations where data must be sent in a narrow bandwidth channel, such as a coaxial-based network or POTS (Plain Old Telephone System). A QAM transmitter is a multilevel modulated signal generator that can take either two binary inputs at a time or a single binary input that will be processed to two demultiplexed binary inputs. By using amplitude and phase modulation this will allow much more information to be transmitted in a limited bandwidth. In this transmitter/receiver, the type of QAM used will be 16-QAM. This will allow 4 bits to be transferred every symbol interval by using a multilevel signal output.

The receiver will use either a PLL (Phase Locked Loop) or a BPF (Bandpass Filter) to synchronize itself to the transmitted signal to correctly decode the transmitted signal. 
 

Applications

• Computer to computer communication over 2 wire POTS.
• Coaxial full-duplex communication possible (may not be implemented)

• Designed to match CCITT V.22bis to V.29 transfer rates and modulation.
• Data rates of up to 9600 bits/s. Baud rate up to 2400 baud.
• Single DSP design.
• Transmitter can take either independent or baseband processed inputs.
• Easy to implement interface with single data ports for inputs and outputs on both transmitter and receiver. RCA jacks for I/O.