Ka Guard

[stevescivic]

What is Ka Guard for? I'm assuming its an advance filtering system to reduce falsing?

By disabling it does it give much better Ka detection range?

Thanks

[sethy]

It will give you ebtter KA response time, but it will increase KA falses

[jimbonzzz]

Here's basically how the Ka guard works:

Many old/cheap detectors had a local oscillator of 11.55 GHz, and the third harmonic of this is in the Ka band (11.55 GHz x 3=34.65 GHz). This caused Ka false alerts. So, in order to suppress alerts from this, V1 looks for the second harmonic at ~23.1 GHz (11.55x2), which would also normally be present with an interfering detector, but not police radar. If it sees this harmonic slightly before or at the same time the Ka is detected, the alert is suppressed.

This is realted to the "J" feature:
Because of K bandpass filtering in some of these detectors, the second harmonic might be too weak to detect initially. So the V1 errs on the side of caution and reports the alert. But if the harmonic is detected later when the alert is already in progress, V1 terminates the alert with a "J", ideally so the alert isn't left "unresolved" with you still looking for a cop.

BEL/Escort detectors use their own version of this system that works in a similar manner.

[Holla]

It will give you ebtter KA response time, but it will increase KA falses

Then you get the 3.851 V1 for instant KA response time as seen on video :D

[ghz1]

BEL/Escort detectors use their own version of this system that works in a similar manner.[/quote]



I think i like VR Ka filtering over Bells hands down 8)

Say that would be a interesting pole sure wise i knew how to create one :cry:

[GTO_04]

Here's basically how the Ka guard works:

Many old/cheap detectors had a local oscillator of 11.55 GHz, and the third harmonic of this is in the Ka band (11.55 GHz x 3=34.65 GHz). This caused Ka false alerts. So, in order to suppress alerts from this, V1 looks for the second harmonic at ~23.1 GHz (11.55x2), which would also normally be present with an interfering detector, but not police radar. If it sees this harmonic slightly before or at the same time the Ka is detected, the alert is suppressed.

This is realted to the "J" feature:
Because of K bandpass filtering in some of these detectors, the second harmonic might be too weak to detect initially. So the V1 errs on the side of caution and reports the alert. But if the harmonic is detected later when the alert is already in progress, V1 terminates the alert with a "J", ideally so the alert isn't left "unresolved" with you still looking for a cop.

BEL/Escort detectors use their own version of this system that works in a similar manner.

Good explanation! The way they explain it in the patent is a little obscure to say the least. But I think they do that on purpose so only the patent attorneys can completely understand it.

I always wondered how BEL did their Ka false alert suppresion since VR has the patent on the false alarm guard. So many others report fewer Ka falses than V1, but from my experience the BEL has more Ka false alerts. I thought BEL relied more on Accusweep/USA mode and ignoring shorter bursts of Ka.

GTO_04