VG-2 detecting Stalker Radar

**KnightHawk** · 06-12-2007, 07:46 AM

I was running VG-2 yesterday and was approaching a hill and my VG-2 started screaming with full bars. So i thought it was just a crapie radar detector that it detected. Soon after, i saw LEO and nobody behind him. I thought that was strange a VG-2 detectin LEO.

So i did some testing this morning with my VG-2 and stalker ATR. Surely enough, every time a press the trigger with the ATR, the VG-2 alerts to full bars with the ATR pointed away from the VG-2. I have the kustom golden eagle Ka band onboard and every time i use it, VG-2 was silent. I just thought to share this with you guys about my findings lately. I just wondered if the VG-2 would interfere with the stalkers.

Jimbonzz, any thoughts?

**bauzer71487** · 06-12-2007, 07:49 AM

It surely wouldn't interfere as the vg2 is merely a receiver just like an RD. . it doesn't transmit anything for its use, although it does leak.

Although this is extremely weird. . I guess we know a leo won't be running a stalker ATR and vg2

**KnightHawk** · 06-12-2007, 07:57 AM

Originally Posted by bauzer71487

Although this is extremely weird. . I guess we know a leo won't be running a stalker ATR and vg2

Not only the ATR's but any stalker Ka band. LEO was using the stalker Dual SL. I will do some testing later on how far the VG-2 will pick up the stalkers. This will be an interesting find and compare it with my X50 and V1. Imagine a VG-2 picking up a good signal from stalkers over the hill?

**kpatz** · 06-12-2007, 07:58 AM

VG-2 looks for LO emissions in the 11.4-11.6 GHz range, specifically 11.558 GHz. Stalker ATR operates around 34.7 GHz. One of the lower harmonics of 34.7 is 11.567 Ghz, which is within the detection range of VG-2.

I believe Jimbonzzz will say the same thing.

That said, now that I have a VG-2 and an ATR, I'll have to do some tests.

P.S. I read that Spectre apparently scans parts of the Ka band, particularly around 34.7 Ghz, so running a Spectre and a Stalker at the same time would be impossible.

**jimbonzzz** · 06-12-2007, 08:32 AM

The most likely cause is the strong 34.7 GHz signal producing images in the VG-2 which are in the VG-2's detection range. Although the Stalker doesn't emit any lower harmonics, once the VG-2 receives it, it mixes the Ka signal with the oscillator signal causing sum and difference signals of everything in the mixer.

Most likely what is happening is the 34.7 Ka signal mixes directly with the 3rd harmonic of the VG-2's LO @ (for example) 34.674. 34.7-34.674=26 MHz, well within the VG-2's IF (assuming 200 MHz or so).

The same thing won't happen with 35.5 guns, since the signal produced would be at 826 MHz. And on 33.8, it would be 874 MHz. Both well outside of the VG-2's IF.

As far as I know, the US version of Spectre doesn't scan any portion of the Ka band directly. But the same thing that is happening here might happen with all Ka guns on Spectre, since it sweeps a much wider range.

**kpatz** · 06-12-2007, 12:59 PM

Hey, I knew it had something to do with harmonics.

So radar guns don't produce harmonics? They produce a perfect "sine wave" microwave signal? Or are harmonics always higher than the base frequency (not lower)?

**jimbonzzz** · 06-12-2007, 01:12 PM

Originally Posted by kpatz

Hey, I knew it had something to do with harmonics.

So radar guns don't produce harmonics? They produce a perfect "sine wave" microwave signal? Or are harmonics always higher than the base frequency (not lower)?

Yeah but they they produce multiples of the fundamental, so a Stalker 34.7 gun would produce harmonics at 69.4, 104.1, etc...