Does anyone have circuit to detect RF frequency(300-500MHz)?

em4095 sniffer

Hi.

I am looking for a RF detector/sniffer circuit which is able to detect frequency from 300-500MHz). The purpose of such circuit is to detect any jammer frequency which interferes with my 433MHz wireless alarm sensor.

Any ideas of such circuit is very appreciated. Thanks.


regards

Re: Does anyone have circuit to detect RF frequency(300-500M

One method is to buy another receiver and put an audio amplifier on the detector output.

If you are in UK, then the most probable jamming is from the 426MHz .

Try to get yourself a narrow band receiver.... that will help.

hi.

i think its quite costly if i get another receiver module n plug it in.

but can narrow band receiver managed to detect wide frequency from 300MHz to 500MHz?

In spore or malaysia, there are wireless remote control at 315MHz or 330MHz or 433MHz frequencies. Thats why i need to have a RF detector to detect or sniff if someone trying to jam my wireless receiver.

Re: Does anyone have circuit to detect RF frequency(300-500M

Here are some interesting ideas:
http://www.linear.com/pc/downloadDocument.do?navId=H0,C2,C1161,C1186,D4576
and
**broken link removed**

narrow band receiver is only to trap your necessary frequency with a sharp bandwidth, so it cannot detect other frequencies, but with better receiving performance.

I think those frequencies mentioned is only for data transmission and cannot transmit continuously for a long period of time. So mostly not someone to jam you but using the same frequency spectrum.

To prevent jamming of the same frequency, either change the house code (digital data) of the alarm or simply change the frequency.

hi trigger74,

i am building an ASK wireless sensor transmitter for wireless home security system. if someone try to break into the house by jamming (continuously enabling the transmitter), i think my wireless receiver sure will not be able to detect the signal send out by the wireless sensor.

so the purpose of this rf detector circuit is to pre-warn/sound the alarm/indicator that there is strong rf jammer frequency nearby.

anyone has such circuit? i just need to detect for the presence of such rf frequencies and send signal to the control board.

regards

Just an idea..... at the receiver part, add an rectifier circuit..... when there is a strong RF frequency, that part will output a dc voltage..... use a counter to count the duration of that RF signal... if the duration is too long then activate the alarm. Supposedly, no signal will last for a few minutes..... so you can use this as the source to determine your system being jammed or not

Re: Does anyone have circuit to detect RF frequency(300-500M

I have found an RF detector that covers a wider range than you might need.
This was published in Radio Electronics June 1989 issue.
The article consists of 3 pages but only the one with the diagram I will include.
If u need the whole article I can scan and post it.

hi platonas,

can you post all the three pages of the article. thank you very much. your help is greatly appreciated.

regards

Re: Does anyone have circuit to detect RF frequency(300-500M

Allow me a couple of days to find time to scan it.
Is this resolution OK?

Added after 5 hours 21 minutes:

Here is the rest of the article. Total of 3,5 pages

Re: Does anyone have circuit to detect RF frequency(300-500M

If you are talking about Singapore and Malaysia, there's no need for a RF Detector to trigger an alarm if someone tired to jammed your system.

Almost all alarm wireless transmitter are build with code hopping either from Microchip(Keeloq) or self programmed Rolling-code to able/disabled your alarm and transmitter are capable of transmiting upto 100m away,and in HDB flats where mass population staying in a single building and most are using the same frequency and a 10m transmitter is still too far if you are sure that 10 family around you are not using the same transmitter, will trigger a false alarm anyway, If you building a RF detector dont forget to build a Data logger as well.(assume nobody at home and someone tried to Jam your reciever)

I've read from the web that someone had 'Cracked' Keeloq code, I wouldn't believed till I've found a working model, and Microchip claims it's unbreakable!I dont know..
Using the Ugly Wire to hook up your Motion sensor could save you alot of trouble!

I wanted to design a alarm system using 433mhz RF first but end up using RFID...
A picture of my homebrew alarm (rework) build last year.. now with EM4095 RFID (upto 10cm), Sec. Keycode ,MT8880 DTMF and using AVR processor.