Multiple Telemetry Site Signal Source Synchronization

Flight test missions that traverse multiple Test Ranges (e.g. hypersonic vehicles/weapons, cruise missiles, long-range weapon systems etc.) or that require different test support infrastructures (e.g. sea range, targets, threat simulators, etc.) at remote Test Ranges, require telemetry receive stations along the flight paths to receive real-time telemetry and then relay that data via ground networks to the control room monitoring the mission. In past mission pre-flight scenarios, remote telemetry receive site to control room links were checked individually. This was accomplished with a local bore sight signal simulator that transmitted a known test pattern at the center frequency of the actual test article. The telemetry receive site would receive the radio frequency signal, demodulate/decode it, then send the data via Internet protocol (IP) networks to the control room. In the control room the received data was verified to be correct as the bit pattern received could be compared to the bit pattern transmitted. This was accomplished for each local and remote telemetry receive site prior to the mission.During the test, each local and remote telemetry receive site would send data to the control room and a manual switch would be accomplished between each data source based on data quality that was determined manually. Note, this selection was not automated.With the invent of best source selection using data quality metrics transferred over IP networks via data quality encapsulation [1], no longer is election of multiple data sources done manually. Telemetry receivers now assess received data quality and assign a bit error probability to a packet of data prior to sending it to the best source selector in the control room. A best source selector (BSS) inputs these multiple streams, performs time alignment, then using the data quality metric, selects the best data to output on a bit-by-bit basis. This output is the best data using all available data streams from diverse receive sites.Though higher quality, near error-free data is now provided to the control room, the addition of the BSS has revealed a shortfall. The entire data path from remote receive sites to transport through best source selection to control room cannot be tested as a complete system to assess mission readiness. The traditional method of pre-flight checks cannot be used. Why? The best source selector will not be able to correlate the multiple data streams from remote sites as the signal sources will not be correlated. This results in the configuration and operation of the BSS being unknown until the test mission. The proposed work will focus on solving this shortfall resulting in a networked, synchronized telemetry validation system capable of simulating a test vehicle's telemetry signal at multiple ground stations simultaneously. Stated another way, the proposed system must simulate the test article signal as if all telemetry receive stations could “see” the test article and simultaneously receive the telemetry signal. This capability will allow test ranges to perform pre-mission verification of the entire telemetry infrastructure. This would include all participating receive antennas, distribution networks, and best source selector(s) to control room displays to ensure full system connectivity and performance before supporting a live mission.