The Wideband Test Modulator – Multirate – Ultra High Rate (WTM-MR-UHR) provides 720 Mhz OQPSK modulated signals at four different data rates (typically in the 100 Mb/s to 600 Mb/s). The unit provides internal clock generation, data generation of two PN sequences as well as OQPSK modulation. Thus the functionality of four pieces of rack mount hardware are combined into one unit. A block diagram of the WTM-MR-UHR is provided in figure 1. In the internal data mode, one can select one of four baud rates and also, one of four different maximum length PN sequences. The selected PN sequence is processed by delay circuitry to produce two essentially uncorrelated I and Q outputs.

One selects between external two cable differential I data, Q data, and clock inputs or the internal I and Q data and clock. The selected signal is then processed by randomizer circuitry and modulo 2 differential encoders (if selected locally or remotely) and converted to antipodal I and Q signals. The antipodal I and Q signals are then processed by lowpass filters and routed to the RF modulator. In the RF modulator, each I and Q signal is double sideband up converted in quadrature to 720 Mhz using I/Q quadrature modulator circuitry. The sum of these signals is the desired OQPSK output. The desired output level is selected locally or remotely. A multi-mode TCP/IP interface (ASCII quarry / response and http) is provided to remotely control and monitor the modulator. The TCP/IP physical interface is 10/100 base T via an RJ-45 connector. Local status and control is also provided on the front panel. All electrical connections are provided on the back panel.

Figure 1, Wideband Test Modulator – Multirate – Ultra high Rate Block Diagram