QUESTIONS: Is the RF transmitters traceable

[mushaima]

HI

I have some Qs about the RF transmitters:

Are they traceable? I mean can someone follow a certain frequency and know where it's broadcasted from?

And If that can be done, is it possiple to make filters or encoders to prevent the trace of the broadcast?

THNX

 

[toonafishy]

Yes.
Spreadspectrum below the noise floor isone way to go.

 

[PaulHolland]

Hi, Any form of transmission can be intercepted but if you do not have the propper equipment than some forms of communication are very difficult to track. The person before me was talking about Spread Spectrum and in special case DSSS but you also have different forms of SS (Short for Spread Spectrum) like HFSS (Frequency Hopping Spread Spectrum) or CSS (Chirp Spread Spectrum) Most of the time military systems use HFSS with hop rates up- to 100K/sec. (100000 hops per second) over a very wide frequency range.

The best trich for transmitting a signal when no person will find it is the following: On short wave you have many powerfull transmitters but all are transmitting in AM with a lower frequency audio of 300 Hz upto 3.4KHz if you make a very stable transmitter FM modulated and you put your frequency 150Hz from the carrier frequency of the SW transmitter and you transmit like 10Bits/s you will be undetected and have a very very long range since no person is on that frequency since it high power channel uses all (not all) the channel. ... Its possible since I know people who did use this.

Paul.

 

[Element_115]

Sure. Signal strength! I know this CB-er that was talking trash with some
truckers and the truckers kept him talking while they drove around and found
the TX signal strength get larger (A meter that's on CB's). They ultimately
saw the only CB antenna in the area and that was the last time my friend
talked trash for more that a minute or so .

Cheers

 

[the_risk_master]

Yes they are, with the use of RDF (radio direction finder) it measures field strength and calculates the range of a radio signal source

 

[artem]

The best trich for transmitting a signal when no person will find it is the following: On short wave you have many powerfull transmitters but all are transmitting in AM with a lower frequency audio of 300 Hz upto 3.4KHz if you make a very stable transmitter FM modulated and you put your frequency 150Hz from the carrier

Paul.

imho it is not practical - any SSB receiver will detect modulation (if we talk about manual tracking). Special autotracking equipment can calculate RF signal spectrum to estimate its modulation type and information nature .

And not only transmitters abut receivers can also be tracked if poorly designed. in 70th avax system claim to detect superheterodyne receiver signals.

Added after 11 minutes:

Sure. Signal strength! I know this CB-er that was talking trash with some
truckers and the truckers kept him talking while they drove around and found
the TX signal strength get larger (A meter that's on CB's). They ultimately
saw the only CB antenna in the area and that was the last time my friend
talked trash for more that a minute or so .

Cheers

very sophisticated truckers indeed) - RF strenght measurement is one of the oldest surveilance methods .

I suppose R&S was the one of the pioneers in this area.
But since tech is developing what can modern 007's can do? May be just listen to internet traffic, and tracking 3rd countries poor stuff )

 

[madengr]

Yes, in fact each transmitter can be finger printed due to start up transients in the oscillators or PA. Let's say you steal a cell phone and switch the ESN, you can still be identified by the RF hardware. There is commercial harwdare available to do this and has been used to bust cell phone theft rings.

https://www.scs.carleton.ca/~kranakis/Papers/RFFPaper3.pdf

 

[mushaima]

Thnx guys for replying

But you only answered one Question, leaving the other one.
I'm talking about experienced people with a lot of money to track a RF

can I make a circuit that can filter their tracking device and stop it from detecting?

I'm thinking like 007 and the bad guys.

PaulHolland

special case DSSS but you also have different forms of SS (Short for Spread Spectrum) like HFSS (Frequency Hopping Spread Spectrum) or CSS (Chirp Spread Spectrum) Most of the time military systems use HFSS with hop rates up- to 100K/sec. (100000 hops per second) over a very wide frequency range.

You lost me
can you explain more please?

Added after 10 minutes:

forgot to say that even when banning the RDF I want to transmitte to my radio contacts at the same time

 

[sinip]

Thnx guys for replying

But you only answered one Question, leaving the other one.
I'm talking about experienced people with a lot of money to track a RF

One doesn't need a lot of money to get involved into RF tracking.

can I make a circuit that can filter their tracking device and stop it from detecting?

No

I'm thinking like 007 and the bad guys.

Not everything you see in the movies is actually true.

 

[mushaima]

Ok one last question, how long does it take for one to trak an RF signal if he had advanced technology.

Are we talking about finding the signal Immediately or do they take time to locate it.

I will be thankful if you can give me an Approximate time.

THNX any way

 

[PaulHolland]

A few seconds and they can find your location ! I have seen advanced HF location equipment finding transmissions within 2 seconds !!!!! realtime. Over a distance of 1000Km !.

Paul.

Added after 1 minutes:

The best trich for transmitting a signal when no person will find it is the following: On short wave you have many powerfull transmitters but all are transmitting in AM with a lower frequency audio of 300 Hz upto 3.4KHz if you make a very stable transmitter FM modulated and you put your frequency 150Hz from the carrier

Paul.

imho it is not practical - any SSB receiver will detect modulation (if we talk about manual tracking). Special autotracking equipment can calculate RF signal spectrum to estimate its modulation type and information nature .

And not only transmitters abut receivers can also be tracked if poorly designed. in 70th avax system claim to detect superheterodyne receiver signals.

If your signal is FM modulated than NO SSB receiver will see anything, just a carrier !!.