The current version of the 8PSK modulator is configured for 600Mb/s operation. One may select an internal data generator which outputs three pseudo random data streams separated in time as well as a 200Mb/s baud rate clock. Similarly one may select two cable differential external data and clock inputs at ECL levels. The selected data and clock inputs are routed to a modulo eight differential encoder. The encoder output is then processed by baseband circuitry to produce four level I and Q outputs. The I and Q signals are then square root Nyquist filtered with X/sinX compensation. The filtered I and Q signals are routed to the RF modulator to produce 600Mb/s 8PSK at 720Mhz. The modulated output is then amplified and routed through a variable attenuator to produce the final output at programmable levels on the rear panel. Local and remote IEEE 488 monitor and control are provided.