How do you identify/decode different tones received ?

VK2FBIG

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Hi everyone, I've enjoyed analogue scanning for many many years but now moving into digital with the SDS100 and also playing with the RTL-SDR and several apps.

I'm really curious about all the "digital" tones received when listening using analogue mode and scanning across frequencies.

Is there any way to identify what system each transmission is using, and then perhaps decode them too ?

I've enabled P25 and DMR on the SDS100 so can decode them, but what could all the other tones be ? (Sorry I don't have a recorded examples so they would be difficult to explain)

I have tuned DSD+ with the RTL-SDR which has a few decoders but they don't recognise most of the digital transmissions I find.

I am also guessing they could be propriety systems like the hand-held screens used by couriers, taxis, electricity co, etc etc etc.

Does anyone have any tricks or resources to better understand the various "digital" transmissions out there ?

Thanks heaps.
AM.
 

bob550

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Consider downloading MultiPSK, and using Virtual Audio Cable or similar to connect to your SDR. There's a free and paid version available, the paid decoding more modes. There's several other decoders available for specific modes. You can use a website such as Signal Identification Wiki to assist in identifying the mode using the waterfall on your SDR.
 
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nd5y

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Search for "digital mode sound samples". There used to be some web sites with recordings of various modes.
It appears that you are in Australia. You should be able to search frequencies on the ACMA web site and at least find the licensed users in a particular area.
 

ka3jjz

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Are you talking about tones you found with your SDS100 or with the RTL?

One site that is used by numerous folks is the Signal Identification wiki at


It will never have them all (to paraphrase Pokeman) but it's a place to start.

Mike
 

ka3jjz

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Just a side note - if you're in Australia, you should know that this board is in the US. Consequently our band allocations above 30 Mhz - and in some cases, modes used - won't be the same as yours. As I understand it, TETRA and MPT-1327 are common in Australia, but not so much here. MultiPSK really won't help in this case.

Mike
 

VK2FBIG

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Thanks for your reply everyone. I will have a look at that Wiki and try MultiPSK. I haven't found those resources during my web searching.

I find the tones using the scanner or the RTL-SDR by either a normal scan through a frequency range; or close call; or even by entering the frequencies registered on ACMA (the Australian Communications and Media Authority).
 
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