Ka filtering

**amoney** · 04-21-2006, 08:57 AM

Originally Posted by ghz1

So then why do the bells false like crazy over here on ka? Really they do.
Dont get this wrong they are good radar detectors it's the Ka false's that get me. So i asked what have the done about it? Do they filter Ka at all?

Some others have said that they live in paradise (where you live) because they only need Ka, and they hardly ever ever ever get a Ka false, and so when it does alert Ka there always is a cop somewhere.

However, if memory is right, they have the Escort unit, but I would expect the same performance from Beltronics.

Perhaps it is just in your specific location, and everyone has crappy radar detectors.

Then again I am even confused when GTO says he got a fair shar of Ka flases with his old 985, but I never recieved a Ka false with my 985, even with my friends Cobra parked next to me, go figure.

You just might have a sensitive Bel. :?

**ghz1** · 04-21-2006, 05:09 PM

I had a 990 int which did false abit on Ka, when bell relaesed the Rx 65 i was first in the shop with my hand up

. I had the rx65 for no more than 1 month. It falsed on ka like 10x a day. then i got the "service requird" and then i took it back and got a V1.813.
So have bell fixed the Rx65 Ka falseing? It's a good detector but Ka falseing gave me the Sh!ts i had to run it in tech display mode just to know if it was a cop or not. As the dectors get better Ka detection the makers will have to find some filtering to stop the Ka false alert's right. VR have and are doing this with "Ka guard" and also "Junk" alert. So i was just woundering what have bell done.
I am very interested in the Sti and would like to buy one as soon as bell sort the Ka falseing out. So if someone know's what bell do pls fill me in.
Thanks

GTO
The V1 looks for certain 3rd order X band harmonics that fall into the Ka band. When those are present, the source is likely a LO from a leaky Crapra or Uniden and the alert is suppressed. POP detection makes it more complicated. In POP mode you don't necessarily want to suppress short alerts, so certain short alerts are reported and later "J'ed out" if the harmonics are found. BTW Valentine has a patent on it's false alarm guard.

Would this mean bell can not use this type of Ka filtering?

**cervan** · 04-21-2006, 09:44 PM

ive had my rx-65 about 3 months and have only had about 4 ka falses

**jimbonzzz** · 04-21-2006, 11:12 PM

All of the detector use similar basic methods of Ka filtering, like I mentioned on the GOL website. The main methods are:

-Suppressing Ka alerts when a signal is also detected at 1/3 and/or 2/3 the frequency of a Ka radar received by the detector: When a detector with an LO in the ~11 GHz range is producing a harmonic in the Ka band, the the fundemental and second harmonic will also (ideally) be present. But, these signal are not present with real police radar.

-Suppressing alerts to short-duration Ka signals, which are characteristic of the harmonics from the sweeping LO of another detector. Examples of this can be seen in Michael B's lab measurements.

-Suppressing Ka alerts if a detected Ka signal changes frequency significantly, which is also characteristic of harmonics from the sweeping LO of another detector. (some detectors)

The main differences in the way the manufacturers suppress Ka false alerts lies in the details of how they actually apply the techniques outlined above, such as the hardware utilized, signal processing, signal level threshold comparison, timing, etc etc...

Jim

**ghz1** · 04-22-2006, 02:35 AM

Thanks Jim i understand what you are saying. Bell do use Ka filtering to some level. Strange thing is some poeple say they never get Ka false alert's with them and some poeple say they get way too much im in the to much area. I would really love to see some more post to do with Ka filtering in the bell forum as this makes interesting reading as it did in the V1 forum. Thanks to all the people who replyed to this thread.
What it's done for me is to except that bell have good Ka filtering and that alot has happened in 2 years at bell :wink:

**amoney** · 04-22-2006, 04:41 AM

Originally Posted by ghz1

Thanks Jim i understand what you are saying. Bell do use Ka filtering to some level. Strange thing is some poeple say they never get Ka false alert's with them and some poeple say they get way too much im in the to much area. I would really love to see some more post to do with Ka filtering in the bell forum as this makes interesting reading as it did in the V1 forum. Thanks to all the people who replyed to this thread.
What it's done for me is to except that bell have good Ka filtering and that alot has happened in 2 years at bell :wink:

You know it is a difficult thing because I live where I live, GTO lives where he lives, you live where you live and other forum members live in your contry but in different parts, then add in the fact we have different ditectors, GTO has his I have mine, too many variables. I belive that you like others get Ka falses, but if it is do to specific location or the detector just being sensitive or worst having the combination of the two to result in lots of Ka falses. Its a crap shoot.