Technical Expert's Explanation Of Why NOT To Operate Multiple RD's Simulataneously
Below is an explanation from an RD INDUSTRY TECHNICAL EXPERT on why it is not a good idea to operate multiple RD's simultaneously M3 or any other platform
"All superheterodyne radar detectors use a combination of local oscillators to enable conversion of the radar signals to a lower frequency for processing. These oscillators can combine (mix) in various ways inside the detector to produce signals that are in the same frequency bands as those being detected. Some of the signals track the receiving frequency of the detector offset by the final IF frequency being used. Since the final IF frequency is usually quite low, the "tracking interference" signals appear very close to the instantaneous tuning frequency of the offending detector. Since most all detectors are swept, the up-converted final-LO signals are swept throughout the bands being received. Two identical detectors operating near each other can receive each other's LO mixing products if one detector happens to be tuned to a frequency offset from the other detector by the IF frequency. This circumstance may seem to be very improbable to occur in practice, but it happens quite frequently. Since even two detectors of the same, exact type are rarely identical in sweep rate due to tolerances in manufacturing, there will be a phenomenon where the differences in sweep rate will cause the mixed LO products to "crawl" past the receiving frequency of the other detector over a period of time.
I first observed the process described above when simultaneously testing two original Escort detectors in the late 1970's. The sweep rates were controlled in each Escort by quartz watch crystals which provided nearly identical sweep rates. Every few minutes, one of the Escorts would begin to alert while the other would be silent. Then, the alert would pass and the other Escort would begin to alert. A few seconds later both detectors would be silent. This cycle would repeat a few minutes later. The interval between disturbances would be longer if the sweep rates were closer to identical. One can think of the process as a beat note between two musical instruments tuned to nearly the same note. In perfect tune, the beat note disappears.
Of course, if the detectors are of different types, the beat notes between sweep rates will be very rapid and continuous interference is quite evident. It's only two detectors with nearly identical sweep rates that produce this minute-to-minute style of intermittent interference."
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Originally Posted by dtraill27
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