The OBM100 is an out of band data modulator for use with the SCT2X4 headend satellite to cable transcoder. The purpose of the OBM100 is to provide a one-way data channel from the headend to a universe of set top boxes that are being served by the headend. Usually program guide and conditional access control information will be sent through this channel.

The OBM100 provides two functions in the data management process. First of all it accepts an ASI transport stream from the SCT2X4 data output connector. This is data that is sent over the satellite path to the headend. The OBM100 takes this low data rate stream and without making any changes to the data, outputs the data through an Ethernet connection to the headend control PC.

After the headend PC constructs a complete data stream for the set tops, derived from the satellite delivered data and from locally generated data, the resulting stream is output from the headend control PC back to the OBM100 on the same Ethernet cable that is passing the satellite delivered data in the other direction. The OMB100 accepts this incoming data and performs its second function – transmitting this data stream to the set top boxes.

The OBM100 generates a QPSK modulated signal, modulated by the data stream from the headend controller, at a data rate of approximately 3 Mbps. This signal is upconverted to any operator-selected frequency between 70 and 130 MHz for transmission throughout the cable plant.