trunked signals

I believe the noise I hear on a regular scanner are trucked signals ,some sound like a running diesel engine ,others like an gasoline engine ( revving up ) with a knock in it. I guess this is the data , but exactly how is this data hidden in these sounds.
I've heard digital signals before on the radio and they sound like data ,not a car or truck engine ?

What makes this data sound this way ... I am hearing it on an analog scanner.


Al

alok said:

but exactly how is this data hidden in these sounds.

Click to expand...

P25, DMR and NXDN use 4-level FSK (Frequency Shift Keying)
https://en.wikipedia.org/wiki/Frequency-shift_keying

What frequencies? There are a lot of digital signals that aren't trunked. When you say "running engine" sound, digital paging comes to mind.

This link may be of interest: Digital Modes Samples

computers

they can talk different languages.
and they all sound different to us.
1's and 0's look the same but don't sound the same.