I've mentioned this idea in passing in other threads, but now I'm actually building one, thus this new thread.
Long story short, this is how it works.
The device is connected to the jammer so that it knows when the jammer is firing. For example, it may be connected to the radio mute output on an LI, or the alert LED. The device is also connected to the brake pedal switch so it knows when you are braking. When it senses the jammer firing, and you apply and then release the brakes while jamming (presumably to drop speed to PSL) the device will switch on a relay which is wired to the jammer's park/jam switch, or to disconnect power to the jammer entirely, thus preventing JTG.
After a 30 second delay, the device re-enables the jammer.
In addition, I'll have an accessible button and two status LEDs. The button will serve different purposes. If pressed while jamming, it will immediately kill the jammer. If pressed after the jammer has been killed, it will immediately re-enable the jammer. I'll also provide additional functions if the button is held or clicked multiple times, such as, setting the unit to always be in parking mode/jammer disabled (valet/pull-over mode), setting it to always be in jamming mode (for JTG testing), providing programming settings such as changing the delay time, adapting it to your particular car/jammer, etc.
The LEDs will indicate: jammer enabled or disabled, jamming, and whether you're in JTG mode.
Since, once I perfect this device, I may offer them to rd.net members, I was wondering what other features you might want in such a device.