Cobra-induced false alarms

**Doc What, son?** · 08-07-2007, 09:04 PM

Is there any particular frequency or range of frequencies on which Cobras leak their evil false alarms?

In the city I have my bel on tech (frequency read-out) mode.

Thanks

**jdong** · 08-07-2007, 09:12 PM

Originally Posted by Doc What, son?

Is there any particular frequency or range of frequencies on which Cobras leak their evil false alarms?

In the city I have my bel on tech (frequency read-out) mode.

Thanks

I don't know exact frequencies, but it's on K or Ka band, depending on which Cobra model and whether or not it's in VG2 mode.

**jdong** · 08-07-2007, 09:13 PM

Errr actually:

http://www.radardetector.net/viewtopic.php?t=17324

Yay Prof. Jim

Cobras might leak a variety of frequencies because of the sweeping LO. But, they periodically "park" during their sweep at different intervals, this causes much of the interference.

The majority of the leakage is on the following freqs:

9 Band models = 12.180 GHz (Produces harmonics at 24.36 and 36.54 GHz)
10 Band models = 11.350 GHz (Produces harmonics at 22.7 GHz and 34.05 GHz)
11 Band Models = 11.1 GHz (Produces harmonics at 22.2 and 33.3 Ghz) and 10.950 GHz (Produces harmonics at 21.9 GHz and 32.85 GHz)

Even if a harmonic is slightly outside the police radar band, it still might be detected as police radar, since all detectors scan slightly beyond the police radar bands to compensate for oscillator drift.

**Orbital75** · 08-07-2007, 09:20 PM

yep..... Jim never ceases to amaze me.

I'll take Radar Detectors for 500 Alex.........

**Doc What, son?** · 08-07-2007, 09:22 PM

JDong,

Thanks for your helpful reply.

I've been getting Ka band signals of late and unable to locate a police source. Sometimes there's been another car near me, and I wondered if it could be a leaky crapra.

Generally Ka seems pretty specific for detecting the real McCoy.

**Doc What, son?** · 08-07-2007, 09:25 PM

Originally Posted by Orbital75

yep..... Jim never ceases to amaze me.

I'll take Radar Detectors for 500 Alex.........

Oh yeah, and watch a fist fight break out with the Bel vs. the V.1-weilding fellow contestants... meanwhile, the Cobra owner just stands there, not quite understanding what is happening.

I just can't believe it -- a pal of mine bought a cobra last week for a hundred bucks or so. FOOL!

Stealthcb · 08-07-2007, 09:26 PM

I can't remember the last RD-induced false I saw. The filtering on the Pro-78 is amazing. Michael B might be able to add to the Professor's info, though.

**Orbital75** · 08-07-2007, 09:34 PM

Yeah, I'd say the Filtering is pretty amazing on the X50 as well.
However, I do recall sitting at a redlight a few weeks or so and
getting a blap blap on my detector. I looked in my rear view and
saw a Cobra in the car behind me. I was like, can't you get behind
someone else.

**jdong** · 08-07-2007, 09:46 PM

Originally Posted by Stealthcb

I can't remember the last RD-induced false I saw. The filtering on the Pro-78 is amazing. Michael B might be able to add to the Professor's info, though.

I agree,

In FILTER 2 on my XTR-690 I cannot pick up my XRS-9300 cobra unless I place the cobra RIGHT next to my XTR-690....

With regular FILTER mode it'll pick up the Cobra from at least a driveway's distance away. Definitely wait-500ms filtering is effective at eliminating Cobra falses.