[randombits0]

> It's also the only state to prohibit radar detectors

Which is arguably outside of the state’s jurisdiction. Only the FCC has the authority to regulate the airwaves and specifically transmitters and receivers.

I bet that cop’s radar gun has an FCC sticker on it.

[novok]

Maybe they are not regulating radio receiver usage, but the just the possession of it, which would be a separate kind of regulatory space.

[blantonl]

All radio receivers have local oscillators built into their receiving circuitry that actually transmits energy that can be detected by specialized receivers.

[xxpor]

Not only are there radar detector detectors, but then there are radar detector detector detectors, and radar detector detector detector detectors. A hilarious arms race.

[ianhawes]

You should be fine with a trace buster.

[worik]

> All radio receivers have local oscillators built into their receiving circuitry that actually transmits energy that can be detected by specialized receivers.

All efficient radio receivers....

It is possible to build radio receivers without such. I built a crystal set as a child that could power an air piece without a battery using only the AM signal.

[someguydave]

Not so much with modern ADC based receivers, it is possible that the only oscillator is at a fixed frequency and the only “tuning” happens in a computer.

[hammock]

That is accurate. Your vehicle is not allowed to be equipped with a radar detector that is powered or accessible to the driver.

The police even have radar detector detectors.

[cjrp]

I can’t be the only one thinking “so how do you build a radar detector detector detector?”

[VistaBrokeMyPC]

It's basically just a more sensitive radar detector. Instead of picking up the main frequencies radar guns use, it picks up the harmonics emitted by the oscillating crystal inside the radar detectors. All radar detectors leak on harmonic frequencies of the frequency they pick up on, it's just a matter of how much. Those cheap Walmart radar detectors leak so badly they detect each other. Pricier ones are more sophisticated in how they shield.

[function_seven]

Could one build an SDR version of a radar detector that doesn't have a detectable oscillator? (Or, if it does, it's oscillating at a much higher frequency?)

I'm no RF guy, so I'm clueless on this stuff. But my understanding is that SDRs aren't radio receivers in the traditional sense. That's the whole "SD" part of it, the device scoops up everything and FFTs it or something.

[RF_Savage]

Radenso Theia does that.

But they are suffering from the chip shortage. I was interested in using it as an X-band and K-band capable SDR receiver, which is a supported use case according to their media. But we'll see when it ships.

[krapht]

It would be way cheaper to design the radar detector to have better RF isolation than to go towards an SDR solution.

A modern radar gun operates in the Ka-band, Google says between 33.4 and 36 GHz. Assuming 12 bit samples, your proposed solution needs to process a minimum 3.9 gigabits per second, or ~500 megabytes per second. To do this work in software would require a workstation.

Not to mention I'm not even sure if you can operate most ADCs above the 1st Nyquist zone like would be needed here.

[randombits0]

You could tune an antenna to trip a detector detector (side note: which would be some great civil disobedience!), but I don’t think you can get to the detector detector detector without an interaction with law enforcement. Layer eight problem.

[CodeAndCuffs]

Some Troopers have a Radar-detector detector (such as the VG-2).

There are Radar Detectors that have VG-2 (Radar detector detector) detectors on them.

I haven't heard of a radar detector detector detector detector. Such a thing would be pretty useless for a cop's intent and purposes.

[Wistar]

How do radar detector detectors work? A video.

https://m.youtube.com/watch?v=upCm4ONlvBY

[throwaway0a5e]

Which is stupid if the goal is safety. A radar detector makes the user slow down for a much longer area than the sight of a cop car does.