A few questions on Ka

1) Is Ka approved to be used for non-police usage? e.g. door opener?
2) Is there other source of Ka false besides Cobra leakage?
3) Does anyone know the actual freq of Cobra Ka leakage? Is it other than the 33.8, 34.7, or 35.5 actually used by radar manufactuers?

Re: A few questions on Ka

Quote:

Originally Posted by JonnyZero

1) Is Ka approved to be used for non-police usage? e.g. door opener?

Yes, there's nothing which specifically prohibits other devices from operating in that band. BUT, there's currently only one or two FCC Approved devices other than police radar which operate in that band, and those are not in widespread use.

Quote:

Originally Posted by JonnyZero

2) Is there other source of Ka false besides Cobra leakage?

Leakage from cheap detectors is by far the greatest source of Ka false alerts. But there's a few other sources too, such as leakage from local oscillators of some satellite receivers.

Quote:

Originally Posted by JonnyZero

3) Does anyone know the actual freq of Cobra Ka leakage? Is it other than the 33.8, 34.7, or 35.5 actually used by radar manufactuers?

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: (according to Mike B)

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.

Thanks Jim.

What are these FCC approved non-police radar devices?

There's a couple of FCC approved non-police devices used for ballistics analysis:
http://www.infinition.com/English/products.html

Another is perimiter surveillance radar made by this company:
http://www.amphitech.com/

Luckily, nothing as common as the X and K band motion sensors that cause all of the false alerts....

Something else I forget to mention: some cheap detectors will sometimes misidentify radar in other bands as Ka.