Missile Telemetry Data Interface Circuit
Patent, Filed 8 Apr 96, Patented 5 Aug 97
DEPARTMENT OF THE NAVY WASHINGTON DC
Pagination or Media Count:
An interface circuit which receives a PCM telemetry data stream comprising a waveform divided into 100 words including a three word frame sync signal. The PCM data stream is supplied to a comparator which converts input telemetry signal to a TTL compatible signal. When the PCM data is unencrypted, the PCM data stream is supplied to a de-randomizer circuit which de-randomizes the randomized data. A bit sync circuit which also receives the PCM data stream generates a 320 kHz clock signal which is synchronized to the incoming PCM data stream. The de-randomized PCM telemetry data stream which is in a serial format and the 320 kHz clock signal pass through a digital multiplexer to a universal synchronous asynchronous receiver transmitter. When the receiver transmitter detects a PCM frame sync signal for a frame of PCM data, it interrupts a master microprocessor which then retrieves each word of PCM data from the frame. The master microprocessor writes the frame of PCM data into one bank of a dual Port RAM. The master microprocessor then sends a command to a slave microprocessor to retrieve the frame of PCM data stored in the dual port RAM. The slave microprocessor processes each word of the PCM data stream in accordance with a predetermined algorithm which scales the PCM data providing at least one ten hit digital equivalent word for each channel of PCM data. The ten bit digital words for the one hundred channels of a frame of PCM data are then output to a missile subsystem test set along with the appropriate channel identifications.