Device for the automatic testing of digital filters in moving-target indicators
AssigneeThomson-CSF
InventorsGuy Lepere, Didier Duval
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Abstract
One or more digital filters in the output of an echo detector in a radar or sonar system are periodically checked for correct operation by the application of a test signal to their input and the comparison of a resulting output signal with a predetermined response code stored in a read-only memory. If the comparison fails, a visual indicator is actuated; if the defective filter is one of a plurality, it is blocked and the gain of the echo detector is adjusted to compensate for the reduction in signal level. With two filters in respective circuit branches carrying detected echo signals in relative quadrature, these filters are tested alternately; failure of either of them may cause its automatic replacement by a standby filter.
Claims12
In an electromagnetic echo-detection system comprising a receiver with output means carrying digitized periodic samples of detected echo signals and filter means connected to said output means for suppressing signals due to fixed-target echoes,
- the combination therewith of a device for checking the operation of said filter means, said device comprising:
- a generator of predetermined test signals;
- timing means synchronized with said receiver for periodically activating said generator to feed a test signal to said filter means;
- memory means for storing a code representing a predetermined response of said filter means to said test signals;
- comparison means connected to said filter means and to said memory means for emitting a failure signal upon detecting a discrepancy between an output signal of said filter means and the stored code read out from said memory means upon activation of said generator;
- and
- malfunction-indicating means connected to said comparison means for actuation by said failure signal.
Dependencies are inferred from the claim text.