Simultaneous signal detection for IFM (Instantaneous Frequency Measurement) receivers by transient detection

The instantaneous frequency measurement (IFM) receiver is highly susceptible to erroneously reporting frequency if two or more signals are overlapped in time. This problem is extremely important when the receiver is presented to detect simultaneous signals which overlap in the critical frequency encode strobe. In essence, during the pulse overlap condition, a transient will occur on the video output lines of the receiver. These lines are monitored during the transient period and compared with predetermined values which are obtained from a single signal condition. If a transient is detected, a simultaneous signal detect flag is raised and this flag is sent to an associated processor. In this special design, the receiver will measure the frequency again at approximately 200 ms from the first measurement. The transient detection is also performed on the second measurement.