would permit try transmitting.<br><br>So if you either find a legal way to =
include the ETSI code at build time, or<br>preferable write a GPL compatibl=
e audio decoder, I think we would be happy to<br>include it in the git repo=
sitory.<br><br>cheers<br> holger<br><br><br>Hello
Pepijn,<br><br>On Sat, 24 Sep 2011 15:49:37 +0200, "Pepijn van den Berkhof=
" <<a ymailto=3D"mailto:vandenberkhof.pepijn@gmail.com" href=3D"mailto:v=
andenberkhof.pepijn(a)gmail.com">vandenberkhof.pepijn(a)gmail.com</a>> wrote=
:<br>> <br>> But do you actually hear output from a real life network=
? Because I<br>> tried the examples attached to the ETSI document regard=
ing the testing<br>> of the codec. They work very nicely, but no luck on=
real life networks<br>> so far. (yes, no encryption)<br><br>I know that=
others have used the current code to decode speech, maybe<br>someone can c=
onfirm it.<br><br>I haven't worked with the code for a while and so can't c=
onfirm it,<br>but it has worked for me in the past.<br><br>Maybe I find the=
time to try it within the next few weeks, if possible<br>I will also try t=
o provide a sample capture from a test TETRA network<br>so everyone can try=
the sample. "Test TETRA Network" means from a<br>network under our
control run in a faraday cage so that there are<br>no legal issues providi=
ng the capture.<br><br>Best regards,<br> Dieter<br>-- <br>Dieter Spaa=
r, Germany &n=
bsp; <a ymailto=3D"mailto:spaar@mirider.augusta.de" h=
ref=3D"mailto:spaar@mirider.augusta.de">spaar(a)mirider.augusta.de</a><br><br=
><br><div id=3D"yiv1108789824">is that could help us for voice decoding : ?=
<br><br><a rel=3D"nofollow" target=3D"_blank" href=3D"http://www.joys99.com=
/d-4784.html">http://www.joys99.com/d-4784.html</a><br clear=3D"all"><br>--=
<br><br>=0A</div><br>_______________________________________________<br>te=
tra mailing list<br><a ymailto=3D"mailto:tetra@lists.osmocom.org" href=3D"m=
ailto:tetra@lists.osmocom.org">tetra(a)lists.osmocom.org</a><br><a href=3D"ht=
tps://lists.osmocom.org/mailman/listinfo/tetra" target=3D"_blank">https://l=ists.osmocom.org/mailman/listinfo/tetra</a><br><br><br></div></div></div></=
body></html>
--1668814050-976982791-1316890565=:17022--
=========
The BCCH is used for two types of broadcast control channel:
* BSCH (broadcast sync channel)
* Broadcast Network Chanenl (BNCH)
These channels, whcih are present only on the downlink, transmit information
about the serving base station. The BSCH transmits the SYNC message. This
provides physical layer synchronization information, including an
extended training sequence for synchronisation and slot alignment, frequency
correction bits to set the carrier frequency, along with MAC layer information
on frame timing (i.e. the number of the current slot, frame and multiframe) as
well as network layer information. Due to the physical layer synchronisation,
the BSCH is transmitted on a synchronisation burst rather than a normal
downlink burst.
The BNCH either carries the ACCESS-DEFINE message or the SYSINFO message.
The SYSINFO message fives the main carrier frequency so that mobiles can tune
to it after picking up any SYSINFO message infromation on any secondary control
channels, power information and network layer information.
The broadcast control channels are normally transmitted in frame 18. Each takes
up to one block of 216 bits, leaving the other block withing the burst for the
corresponding assigned channel or for the base station to send signalling to
other mobiles. O each slot, the sequence shon win figure 7.45 is used, and the
sequence is offset b yone for each slot in the frame, so that every frame 18
has one BSCH and one BNCH. However, transmitting the network information takes
several half-slot BNCH instances, and it will take some time therefore for a
mobile to acquire all the information it needs. This is not normally a concern
since mobiles will be switched on before they are used and an initial delay can
be tolerated. The standards allow the option of transmitting the BNCH in other
physical control channels (indicated by the AACH) as neccessary. Mobiles
continue to monitor the BCCH after they are switched on and also during
transmissions so as to ensure that they receive network information and remain
synchronised.
Multiframe number 1 2 3 4
DL Frame 18, first half slot BSCH*
DL Frame 18, second half slot * BNCH
* = Transmitted on a Synchronisation Burst
Figure 7.45 BSCH and BNCH transmission sequence.
==============
--
- Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
(ETSI EN 300 175-7 Ch. A6)
Hi Kevin,
On Fri, Nov 05, 2021 at 02:18:14PM +0100, Kévin Redon wrote:
> I'm also happy to help with the recording and streaming of the public talks for those not able to join on site.
thanks for that, as usual.
--
- Harald Welte <laforge(a)osmocom.org> http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
(ETSI EN 300 175-7 Ch. A6)
I have worked on several satellite projects, such as SATCOM. Based on my
past experience, satellite signals usually have high SNRs (or LOS signals)
compared to cellular signals in the city environment, The received
satellite signal's SNR would be approximately 10dB ~ 20dB, or even higher.
I am currently working on a TETRA project, which would be some low earth
orbit signals (terrestrial signals). What could be the range of TETRA
signal SNRs? The received signal's SNR plays a very important role on the
receiver structure design.
Hi, I'm just getting started with the osmo-tetra, and following the wiki (https://osmocom.org/projects/tetra/wiki/Osmo-tetra).
However, I do not see the python scripts in the git source code.
For example, I cannot find:
src/demod/python/tetra-demod.py
* call demodulator on a 'cfile' containing complex baseband samples
src/demod/python/usrp1-tetra_demod.py
* use demodulator in realtime with a USRP1 SDR
src/demod/python/usrp2-tetra_demod.py
* use demodulator in realtime with a USRP2 SDR
Jeff
Dear fellow Osmocom developers,
as you all know, we've sadly had to postpone OsmoDevCon 2020 back in
April this year. At the time, we discussed to re-visit the situation
in October 2020.
While legally it is no problem at all to host an event with ~ 20
participants in Berlin/Germany (specific regulations really only start
from 50+ participants) - I'm not entirely convinced it would be the
smartest move.
Legality and public health regulations are only one part of the equation
- common sense and profound care for the key members of our community
for sure are more relevant considerations to me.
I'm not 100% in favour and not 100% against. Hence, I would like to get
your input. Should we
a) try to get an event organized on-site in Berlin? We'd have to move
to a larger venue than IN-Berlin with proper ventilation and sufficient
space so we can keep physical distance, but I think that's
manageable for sysmocom as organizer.
b) simply postpone to 2021? I'm convinced the situation will not change
significantly (in a positive way) until late April 2021, so it's not
really a "solution" as it will likely mean we have to think of late
2021 or 2022.
c) plan some kind of online conference? To be honest, I think this
model works fine for events where a single speaker wants to give
lectures to hundreds or thousands of participants. But OsmoDevCon
is much more interactive. We could record or live-stream some talks
or screencasts from home, sure. But that only captures one part of
the event. We could also try to set a date for a collaborative
mumble, or the like - for the "hallway track".
What are your thoughts? Let's avoid cross-posting the discussion to all
of the mailing lists and simply have it on openbsc(a)lists.osmocom.org.
Regards,
Harald
--
- Harald Welte <laforge(a)osmocom.org> http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
(ETSI EN 300 175-7 Ch. A6)
There is an urgent need to migrate our most important public
infrastructure to a new server, and I will be doing that on
*Sunday, July 19 2020*, starting about 9am CEST.
The migration involves redmine (main osmocom.org website), jenkins, gerrit,
git, and cgit.
In theory, the migration should be quick. I would expect (significantly)
less than one hour of downtime. However, we all know Murphys law.
Services not affected are mail (including mailman lists), ftp, dns. So in case
of doubt, we can still use mailing lists to communicate.
In case anyone urgently needs osmocom source code on Sunday morning
during the downtime: There are public mirrors available on github.
Regards,
Harald
--
- Harald Welte <laforge(a)osmocom.org> http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
(ETSI EN 300 175-7 Ch. A6)
Hi,
Thanks for the add, I have been hinted this place, and im looking forward
to digging deeper into the realm of TETRA / DQPSK.
What im trying to do is write a C# program for demodulation of TETRA. and
have come so far as to be able to view the IQ vector run around on the
unity circle, but it appears a bit distorted. I think its due to a crude
low pass filter i used on the I/Q signal causing this. From reading books
and sites i find that I should probably used a raised cosine filter to keep
the signal form beeing distorted (ISI). am i correct in my assumption? and
do you have the open source code i can inspect, regardless if programming
language.
I know there is tons of programs out there that can decode and even produce
audio from TETRA DQPSK signals, and I have one installed, but i want to
have an edge to this, i need to understand and learn first hand. It may
take time, but thats how it is.
I have what is required regarding programming skills and radio knowledge -
I am radio Amateur, and 20 years ago i did have Digital communication
classes at Engineering college - But thats 20 years ago, and the equations
in the books are kind of far away in my head.. but the theory sticks.
Please help me get up to speed in decoding DQPSK, im not expecting to do
this quickly, but will be in steps when i have time, and will lead to
questions. But at some point i could be on your frontier digging into TETRA
as a whole.
Best Regards
Kim Mortensen
Dear fellow Osmocom developers,
I would like to invite all developers and contributors to Osmocom [sub]projects
to register for OsmoDevCon 2020 (held on April 24th-27th, 2020 in Berlin).
For details known so far, please check
http://osmocom.org/projects/osmo-dev-con/wiki/OsmoDevCon2020
Please enter your name at
https://osmocom.org/projects/osmo-dev-con/wiki/OsmoDevCon2020#Requested
in case you would like to attend. Registering early allows proper
planning. Thanks!
Looking forward to meeting old and new Osmocom developers in April 2020.
Regards,
Harald
--
- Harald Welte <laforge(a)osmocom.org> http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
(ETSI EN 300 175-7 Ch. A6)
I was interested in getting involved in some open source development. With
a signal processing background, I thought osmo-tetra might be a good
project. Looking at some data from the New Jersey Transit Authority I
noticed something odd though. Some of the Broadcast PDUs had a type of 3,
which in the spec is only listed as "Reserved." What's more, the control
channels there seem to be missing SYSINFO messages. I'm guessing that
somehow their system does a modified SYSINFO (which is normally broadcast
type 0) and labels it 3? Is anyone familiar with the format they use for
that message? Thanks.
