Detecting spread spectrum

[John Connor]

I was reading about the trellis modulation here in this sub forum and decided to look into it further on Wikipedia. Then I was reading about all the different types of spread spectrum modulation; FHSS DSSS, CSS and THSS.

I'm into radio communications has a hobby, mostly scanner and shortwave and have been really curious about spread spectrum. I know a company that makes frequency counters called Optoelectronics, but I don't recall a device to detect spread spectrum. Is there a device that can detect spread spectrum signals?

 

[John Connor]

Found something! http://www.optoelectronics.com/#!digital-scout/c1pqp

 

[esun]

Well detecting it is just a matter of having a receiver sensitive enough to see the spread signal. For example if you point a big enough dish at a GPS satellite you'll be able to see the chips being sent down directly (while normally you'd just see noise from a small antenna).

Of course if the signal is spread widely enough then it could be pushed below any noise floor theoretically in which case you wouldn't be able to detect it unless you knew the spreading sequence.

Actually you'll notice that the device you linked to can't detect CDMA/DSSS which seems natural since there's no way to tell a DSSS signal from just a high rate uncoded signal. You can imagine detecting a FHSS signal by looking for rapid narrowband pulses and THSS by looking for rapid broadband pulses.

 

[AD5MB]

with a spectrum analyzer. bring money.

 

[John Connor]

Can you give a link to one?

Would one of these work? http://www.home.agilent.com/en/pc-1...ectrum-analyzer-signal-analyzer?&cc=US&lc=eng

 

[AD5MB]

yes, those are spectrum analyzers. the third from the left seems to be showing a spread spectrum signal. you look for a big wide hump in the noise floor. narrowband signals show up as a spike sticking up out of the noise floor.

 

[Z15CAM]

Are you one of these fanatics with a Big Tower when energized my Radio Ham Neighbor starts all the cars with remote starters and run them until empty of gas the next morning. My wife accused me of midnight rendezvous and it took about 5 tanks of gas and totally insane ostracism before I ripped out the remote. The FCC and Town Council just laughed at me.

Understand this: First of all I'm a LIAR when I tell her I filled the tank last night and then she goes to drive the kid to Kindergarten the next morning the vehicle wont start because its outta gas; you had better hold on to your britches because you got Blue Balls and it happened to me time after time.

So you might say I have some experience about Detecting Spread Spectrum and believe me no one was siphoning my gas.

PS: One thing I do know are Radar Detectors - I was and probably always will be a Driver aside from my Wife's prospective.

MOREL: Know your Bands and don't get caught by the UNEXPECTED.

 

[John Connor]

Sound like a neighbor is on the same remote control channel. Try changing the channel.