This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://firstname.lastname@example.org/.Balint balint256 at hotmail.com
Hi all, Firstly, thank you to Max for the Slashdot mention! I'd like to continue the ultra-cheap SDR theme with this video that demonstrates the RTL2832 USB DVB-T dongle successfully receiving an encrypted P25 signal, which is then decrypted and decoded by OP25 (represented by the new 'OP25 Decoder' GRC block in gr-baz <http://wiki.spench.net/wiki/gr-baz#rtl_source_c> ), and sent to the soundcard: http://www.youtube.com/watch?v=wShOLgW2tmI The block lets you specify a key to enable DES-OFB decryption of an incoming stream. As Matt Robert suggested, this could be further developed by having a 'key map file', that contains the correct key for a specific AlgID/etc. All the RTL2832 code is in gr-baz. The patch enabling decryption support is from a rather old version of the source (r219), so if anyone would like to make it current for submission into the repo, please let me know and I can send it out! I also added another new block called 'Message Callback', which is used to trigger callbacks in the GRC generated code based on messages sent by other blocks to messages queues. If you watch the video or visit my wiki, you'll see all the tuning/channel selection/filtering/audio is done by the appropriate blocks in GRC - separate from the OP25 code (this is different from it all being in the one Python file, e.g. audio_p25_rx). You may recall the FSK4 block outputs auto-tuning messages to the Frequency Translating FIR filter (channel selection block) before the FSK4 block. This feedback loop is handled internally in the existing stand-alone Python files, but needs to be replicated in GRC - hence the new block. The 'Message Callback' block connects to the 'tuning' output of the OP25 Decoder block, and is told about the 'auto_tune_freq' GRC variable to update when a message arrives with a new value. This GRC variable is subsequently used to update the Centre Frequency in the Frequency Translating FIR filter (channel selection block) to fulfil the FSK4 block's request. If you're into GNU Radio, I just posted a much longer update with the latest RTL2832 developments (including a completely re-written 'librtl2832++') to the GNU Radio Discussion list. Kind regards, Balint @spenchdotnet <http://twitter.com/spenchdotnet> From: op25-dev at yahoogroups.com [mailto:op25-dev at yahoogroups.com] On Behalf Of ikj1234i Sent: Sunday, 1 April 2012 10:20 PM To: op25-dev at yahoogroups.com Subject: [op25-dev] congrats to Balint: on Slashdot ! ! ! http://hardware.slashdot.org/story/12/03/31/1914217/software-defined-radio-f or-11 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/op25-dev/attachments/20120405/63b04abe/attachment.htm> -------------- next part -------------- A non-text attachment was scrubbed... Name: image001.jpg Type: image/jpeg Size: 359 bytes Desc: not available URL: <http://lists.osmocom.org/pipermail/op25-dev/attachments/20120405/63b04abe/attachment.jpg> -------------- next part -------------- A non-text attachment was scrubbed... Name: image002.jpg Type: image/jpeg Size: 332 bytes Desc: not available URL: <http://lists.osmocom.org/pipermail/op25-dev/attachments/20120405/63b04abe/attachment-0001.jpg>