Hi there, I wanna distinguish all signals that I see in the spectrum, Like WIFI, 4G, 3G signals and so on. what are the methods? and which one is more suitable for my needs?
thanks for your attention
Dear Ali,
There are some radio signal detectors;
-There the socalled energy detector which the signal strength and these detectors are the simplest type but they can nor identify the type of the radio signal
- There is the cyclostationary detectors which identify the periodicity of the autocorrelation function. And so it can identify the signals by their cyclostationatity signature. This detector is very suitable for you.
- There is also the correlator method which correlates a locally generated copy with the the received signal. This is also one method which can be used provided that the signal is known.
- The last one is the matched filter method which is very similar to the correlator method
The matched filter also requires the signal to be known and so can identify the received wireless signal.
There are wealth of literature that you can get fro the web.
May be the best method for you is the cyclostationarity detection.
Best wishes
Make use of antennas to detect RF signals. Once received look at them on spectrum analyser. If you want to receive only some bands then use filters to allow or stop the bands.
"all signals" might be a bit "ambitious" :)
There are 2 basic approaches (that in the end are not too different):
- Sweep the frequency band of interest with a (relatively) narrow-band receiver.
- Monitor the band of interest with a wideband ("panorama") receiver.
In both cases, the further processing of the signal(s) can be done by
- (speculative) application of demodulation schemes. The one consuming all artefacts and giving the smallest number of decoding errors is most likely the correct scheme.
- judge on the spectrum: every modulation creates over time a quite typical modulation scheme that's e.g. identifyable in a waterfall display.
Judging on the modulation scheme (which allows to derive the service using a particular frequency (band)) requires knowledge about the modulation scheme(s). If you know nothing about the modulation schemes used for particular services, it is not possible to discern services using the same frequency band (as e.g. WiFi, Bluetooth X.Y and some more services use the same band, but with differing bandwidths, center frequencies etc.)
Please read my work
Communication Engineering Laboratories in Universities of England (part 1)
Communication Engineering Laboratories in Universities of England (part 2)
I think you can find a good answer.
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