RF detector circuit help

Depending on the dynamic range as well as the frequency range, the AD8362, LTC5505, LTC5507, LTC5534 come to my mind. There may be a few more at Analog Devices and Linear Technology.

Rene

Hello Mike,

Use Google to look for "RF sniffer", "field strength meter" and stuff like that. This should be all you need, plus threshold detector, buzzer, battery etc.

As Joe said you need to be concerned about foreign signals that create false alarms. Either by coding or by using a narrow enough bandwidth, the latter getting quite expensive the more you lower it.

Regards, Joerg

Detecting RF transmitter using a RF detector.... even a simple RF diode with tuned circuit or one of the better RF detector IC's is for detecting RF signal strength is OK.

RF signal strength is proportional to 1/(distance x distance)

However... within the same RF band there may be other unwanted signals - which a RF detector can not discriminate - apart from possible RF signal strength.

A keyfob for remote control sends a "coded" stream and the receiver decoder and discriminated between different keyfobs OR interference in the same RF band.

So both RF level detection and a coded signal would be more reliable.

If the RF Tx used On/Off keying (OOK, or Amplitude keying) then the RF level detector could possible decode the OOK (modulated) code as well as the RF level.

JG

I read in sci.electronics.design that Joerg wrote (in ) about 'RF detector circuit help', on Thu, 29 Sep 2005:

For narrow-band, use, if possible, a direct-conversion receiver with a low-pass filter.

In article , Joe G \\(Home\\) wrote: [...]

This is not true when the reciever and transmitter are very close to each other. Calibrate the system at the trigger distance not by bringing the units very close together.

A very narrow bandwidth helps in this. If you can, make the bandwidth narrow.

In article , John Woodgate wrote: [...]

If simply narrowing the RF bandwidth can't be done, you can AM modulate the transmitter at lets say 1KHz and put a 1KHz band pass filter after the RF detector. It ins't nearly as good as a real narrow band but it is better than nothing.

I am not sure the that the most important concept here has been identified.

How do you determine that you are "too far away"? Is it by signal being below a threshold? Do you measure signal strength and then calculate that "I have traversed an excessive distance"?

These issues came up repeatedly when I worked for a major defense contractor and our group was building autonomous vehicles.

Good luck, Dave

I am not sure the that the most important concept here has been identified.

How do you determine that you are "too far away"? Is it by signal being below a threshold? Do you measure signal strength and then calculate that "I have traversed an excessive distance"?

These issues came up repeatedly when I worked for a major defense contractor and our group was building autonomous vehicles.

Good luck, Dave

I've long made jokes about how all the appliances of the world are wired together. Ready to communicate and revolt. :>) :>)

You silly man. It's more about mundane things like troop-supply convoys that won't require legions of unarmed drivers, such as those supplying the troops in Iraq who were killed or captured. Eventually it'll be about automated trucks, buses and taxis.

I saw something kinda spooky yesterday (Sunday) on TeeVee - one, I saw the last half of the movie "Maximum Overdrive," which is a fanciful tale about all of the machines somehow acquiring a "mind of their own" (I guess there was some telepathic alien comet or something, to try to make it 'plausible'), and try to take over the world. Later that evening, I saw a TeeVee Nooz program reporting on a race between "autonomous" vehicles - essentially, robots on wheels. It was funded by DOD, and it was actually kind of scary - send machines to do your killing remotely and all that. There's a Klingon saying, "He who kills without showing his face has no honor."

Thanks! Rich

I read in sci.electronics.design that Winfield Hill wrote (in ) about 'RF detector circuit help', on Mon, 10 Oct 2005:

Some I have bought were revolting as soon as switched on. (;-)

How would that be morally any different from other remote things we're comfortable with now in war, such as torpedoes, guided bombs and missiles, cruise missiles, and armed drone planes?

Those applications indeed are the short-term goals. But don't discount the perspective of intelligently moving vehicles used to do the actual "dirty work" in a war zone. Seeing how every single one of a few killed US solders is a PR disaster in itself this is something we must definetely be aware of.

Technologically, the step from a land mine to an intelligent "kill vehicle" is a big one, but conceptually it isn't.

robert

It's not. They're all evil.

Thanks, Rich

On 11 Oct 2005 15:04:03 -0700, Winfield Hill wrote in Msg.

I never claimed it would. Rich Grise called the scenario "scary", which prompted you to call him a "silly man" (implying that autonomous, armed combat vehicles were not an application intended by the DoD).

Besides, I'm not exactly "comfortable" with any of the things you listed above.

robert