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Publication Date: 2015-May-13
Document File: 5 page(s) / 1M

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Synthetic Approach To Multi-Beam Payload Testing

Mario Lisi

Charles Van Lingen



Payload test system (PLTS) and RF test equipment (RFTE) systems typically require a network analyzer as the base instrument for performing and acquiring calibration and a substantial number of measurements.  

 According to the present disclosure, a synthetic network analyzer (NA) is configured using a programmable signal generator, an arbitrary waveform generator (AWG) and digitizers such as oscilloscopes or digitizer/down converters. The test set (reflectometer) is placed remote from the instruments close to the unit under test (UUT), and thus the VNA function can be dispersive and more easily operable in a parallel mode. The benefits of such a synthetic approach to multi-beam payload testing include the ability to perform S-Parameter calibration and characterization to existing bent pipe measurements such as gain, gain transfer, and group delay, wideband real stimulus tests such as error vector magnitude (EVM) and simultaneous multitones for gain monitoring and loading tests. Furthermore, most of the parameters can be generated by one stimulus and one capture, and then analyzed off line.

 Figure 1 illustrates a test assembly according to the present disclosure that enables routing of parametric and functional signals.  The test assembly includes splitter/combiner 110, reflectometer 120 and switch matrix 130 arranged to allow simultaneous multiple tone injections in a non-blocking manner. During parametric testing, for the satellite uplink test signals are generated by the test system sources and routed through the reflectometer 120 which discerns the signals for network analysis of the calibrations and measurements.  An output from the reflectometer 120 is routed to switch matrix 130. A path through switch matrix 130 may be selected to provide the test signal to the satellite (not shown). For the satellite downlink, the return signal from the payload is provided to switch matrix 130.  A path through switch matrix 130 may be selected to route the return signal to the downlink reflectometer 120 which discerns the downlink signals for network analysis of the calibrations and measurements.  The output of reflectometer 120 then provides to the instrumentation the signals for detection and analysis.  During functional testing, uplink signals are simulated to resemble real stimulus formats such as the carrier modulation signals typical for satellite communication. These real stimulation signals can follow a similar routing as described above, where the switch matrix 130 provides simultaneous routing of the stimulus signals from the splitter/combiner 110.  The path through switch matrix 130 is selected to be non-blocking, thus providing the required functional multitone signals to the satellite payload simultaneously.  For the satellite downlinks, the retu...