Hi Pep. I am using the djx11 in I/Q mode with fcdp-tetra_demod.py. I leave sample rate @ 96000 but low-pass filter (-L) 12.5Khz (gr firdes lp filter in complex gives + - 12.5khz = bandwidth of 25khz). this gives me excellent constellation and works fine on demod. I hope this helps. Regards. Graham.
Hope some members of this list will find interesting this paper & source code.
Recent research paper that analyzed the security features of the APCO Project 25 (P25) digital two-way radio system. P25 radios are widely deployed in the United States by state, local and federal agencies, first responders, and other public safety organizations.
http://www.usenix.org/events/sec11/tech/full_papers/Clark.pdf
Digital Speech decoder an open source software package that decodes several digital speech formats: P25, ProVoice, NEXEDGE/IDAS and MOTOTRBO (Based on ETSI DMR Standard of especial interested for those of us in Europe given is strongly promoted as a cheap alternative to TETRA).
Also worth to mention that supporting mbelib implement IMBE/AMBE Codec.
http://wiki.radioreference.com/index.php/Digital_Speech_Decoder_(software_pa...)
Hi, Thanks for the report, I was looking for it.I read about it yesterday, it is quiet fascinating isn't it? What scared me the most about the report was this:
In a study we conducted over a two year period in several US metropolitan areas, we found that a significant fraction of the “encrypted” P25 tactical radio traffic sent by federal law enforcement surveillance operatives is actually sent in the clear, in spite of their users’ belief that they are encrypted, and often reveals such sensitive data as the names of informants in criminal investigations.
People spend years of their lives creating and testing those algorithms but in the end, the end user completely ignores them! I believe it is the same with TETRA systems as well, if the user decides not to activate the encryption, the whole 'security' aspect of the product is lost.
I really wonder if this can cause an outcry from the legislators in the US and Europe to enforce more strict ruling against Software Radio 'capable' products. I really hope not, but you never know,
BR, /Farhad
From: Mccauley mccauley@gmx.net To: tetra@lists.osmocom.org Sent: Friday, August 19, 2011 10:18 PM Subject: Off-topic resources on digital voice radio
Hope some members of this list will find interesting this paper & source code.
Recent research paper that analyzed the security features of the APCO Project 25 (P25) digital two-way radio system. P25 radios are widely deployed in the United States by state, local and federal agencies, first responders, and other public safety organizations.
http://www.usenix.org/events/sec11/tech/full_papers/Clark.pdf
Digital Speech decoder an open source software package that decodes several digital speech formats: P25, ProVoice, NEXEDGE/IDAS and MOTOTRBO (Based on ETSI DMR Standard of especial interested for those of us in Europe given is strongly promoted as a cheap alternative to TETRA).
Also worth to mention that supporting mbelib implement IMBE/AMBE Codec.
http://wiki.radioreference.com/index.php/Digital_Speech_Decoder_(software_pa...)
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Farhad Abdolian -
Graham Palmer -
Mccauley