lincoln@eosp1.UUCP (Dick Lincoln) (08/20/84)
> A cheap radar detector does not have to emit much energy for it to be > detected by another nearby radar detector when there is no real radar > signal present.... Also, a simple continuous-wave microwave signal > in the right frequency range is enough for a radar detector to decide > that there is a transmitter out there somewhere..... Radar detectors > just look for the presence of a signal which is assumed to mean that > there is a radar unit nearby..... Not so with relatively recent vintage Escorts from Cincinnatti Microwave. They have circuitry to be sure they are receiving pulse modulated signals, as any real range or velocity measuring radar device must use. Leakage from super-het receiver oscillators is an unmodulated signal which can block an Escort by saturating its RF front end, but not trigger a "false alarm". The biggest source of spurious alarms from Escorts are commercial X-band burglar alarms that also use (hopefully) very low power radar as motion detectors. Such radar is, of course, pulse modulated, and thus very hard to distinguish from police radar.
dmmartindale@watcgl.UUCP (Dave Martindale) (08/21/84)
From: lincoln@eosp1.UUCP (Dick Lincoln) > A cheap radar detector does not have to emit much energy for it to be > detected by another nearby radar detector when there is no real radar > signal present.... Not so with relatively recent vintage Escorts from Cincinnatti Microwave. They have circuitry to be sure they are receiving pulse modulated signals, as any real range or velocity measuring radar device must use..... Yes, I know this. I was trying to explain why a cheap radar detector may be able to set off other radar detectors and still be quite incapable of jamming a real radar gun. Did I really need to write "another nearby radar detector which can be falseley triggered, (which means most detectors other than recent Escorts)" instead of simply "another nearby radar detector"? I was simplifying the truth, since the fine detail of the truth was irrelevant to answering the question that was asked.
wetcw@pyuxa.UUCP (T C Wheeler) (08/21/84)
The CAT scan seems to set radar detectors off near one of our hospitals. Or maybe it is one of the other gadgets, but there are constant reports of radar around the hospital yet noone ever sees a bear. T. C. Wheeler
dmmartindale@watcgl.UUCP (Dave Martindale) (08/22/84)
A CAT scanner uses X-rays - not very likely to affect a radar detector. But do you have an NMR scanner? Those use very high frequency RF, I believe.
dw@rocksvax.UUCP (Don Wegeng) (08/26/84)
Has anyone else noticed that the Ultrasonic (or whatever) transmitters
which are used to trigger automatic door openers at many hospitals, airports,
and even supermarkets will set off a Radar Detector? Maybe this is
the source of the signals, not a CAT scanner or NMR scanner.
As an aside, I've noticed that this sets off my Escort with STOP circuitry.
A friend of mine has also noticed this, so I'm not inclined to believe
that my unit is broken. Any ideas as to why the STOP circuitry does not
filter these signals?
--
/Don
arpa: Wegeng.Henr@Xerox.ARPA
uucp: {allegra,princeton,rochester,amd,sunybcs}!rocksvax!dwdave@rocksvax.UUCP (Dave Sewhuk) (08/26/84)
The STOP circuit cannot discriminate between the CW radar signal and
the CW door opener because the signals at the antenna look the
same.
The way I understand the STOP circuit is as follows, the radiating
radar detectors are scanning the two bands much like the Escort does, but
the local oscillator in the polluting units leaks out the receiver
antenna setting off those radar detectors without a STOP circuit.
So the signal appears as a rapidly drifting signal in the X and K bands.
When the Escort hears RF coming in it looks to see if there has been a RF
hit in the other band detector within the last few milliseconds. If so
then it assumes that something just swept through its passband and ignores
the signal. If you have ever used an Escort without STOP you usually
hear those polluting detectors as signals that beep and bop through
both bands.
--
Dave
arpa: Sewhuk.HENR@Xerox.ARPA
uucp: {allegra,rochester,amd,sunybcs}!rocksvax!dave