This is an ISA expansion card with associated software that adds several functions to a type approval test set for satellite voice and data communications. The original test set was incapable of testing some parameters, particularly transmit burst timing, with sufficient accuracy. This card monitors a number of test points from the test set, and generates accurate timing reference signals.
Other functions generate modulation inputs for a vector signal generator, and allow various errors and other impairments to be applied to the signal to test the demodulator under specific conditions. As the card is aware of the frame structure of the signal, more specific impairments can be generated than would be possible with a general-purpose channel simulator. For instance blockages or error bursts can be precisely targeted at specific parts of the frame.
The large ICs are Xilinx programmable gate arrays. These are RAM-based, and can be dynamically reprogrammed. The arrays are loaded by the control software via the PC's expansion bus. This feature is used to support the different type approval tests, reconfiguring the card "on the fly".
Both simple command-line and menu-based control programs were produced. The menu-based program included support for a simple command language, and remote control via the PC's serial port.
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