Remove the paragraph about writing to the Free Software Foundation's
mailing address. The FSF has changed addresses in the past, and may do
so again. In 2021 this is not useful, let's rather have a bit less
boilerplate at the start of source files.
Change-Id: I73be012c01c0108fb6951dbff91d50eb19b40c51
I intentionally do not use 'Downlink' and 'Uplink' terms in this project
because both MS and BTS transmit and receive on the opposite directions.
A burst coming from demodulator may be a Downlink or an Uplink burst
depending on the context, so we definitely need more precise terms.
Back then when I started to work on TRX toolkit, I decided to use the
'TRX2L1' and 'L12TRX' for receive and transmit directions respectively.
Now I find them hard to read, so let's replace them with 'Rx' and 'Tx'.
Change-Id: I688f24a3c09dd7e1cc00b5530ec26c8e8cfd8f7c
Related: OS#4006, SYS#4895
We do have TRXC/TRXD documentation in osmo-gsm-manuals repository.
These big comments are out of sync with what we have in the manuals,
so let's better remove them to avoid maintaining docs in several places.
Change-Id: I47786cf3039f712efadc85bc4e1c3ae89e79ff25
Related: OS#4006, SYS#4895
Before using DATA_MSG.HDR_LEN, we need to make sure that a parsed
header version is known and supported. Otherwise we will get an
IndexError exception.
Change-Id: Ie1887aa8709da1a2a287aa58a7873e72c0b4ed33
Unlike DATA_MSG.HDR_LEN, the CHDR_LEN is a constant that defines
length of the common header, which is mandatory for every version.
DATA_MSG.HDR_LEN in its turn defines length of the whole header,
including the version specific fields. Thus we need to know the
header version before using it.
In DATA_MSG.parse_msg() we need to parse the common header first,
so then we know the version and length of the whole header. After
that we can safely use DATA_MSG.HDR_LEN.
Change-Id: I2809f5f96209eed64bdabf7a15575144313f7cc9
Raising exceptions is a Pythonic way to handle errors, which in this
particular case will help us to know *why* exactly a given message
is incorrect or incomplete.
Change-Id: Ia961f83c717066af61699c80536468392b8ce064
Since version 0x01, the burst bits are encoded as L16V,
so appending two dummy octets doesn't make sense.
Change-Id: I4d6c0bf54649d636ea6cb3fa2f37486b6619d5b3
The new version adds the following fields to the TRX2L1 message,
keeping the L12TRX message unchanged:
+------+-----+-----+-----+--------------------+
| RSSI | ToA | MTS | C/I | soft-bits (254..0) |
+------+-----+-----+-----+--------------------+
- MTS (1 octet) - Modulation and Training Sequence info, and
- C/I (2 octets) - Carrier-to-Interference ratio (big endian).
== Coding of MTS: Modulation and Training Sequence info
3GPP TS 45.002 version 15.1.0 defines several modulation types,
and a few sets of training sequences for each type. The most
common are GMSK and 8-PSK (which is used in EDGE).
+-----------------+---------------------------------------+
| 7 6 5 4 3 2 1 0 | bit numbers (value range) |
+-----------------+---------------------------------------+
| . . . . . X X X | Training Sequence Code (0..7) |
+-----------------+---------------------------------------+
| . X X X X . . . | Modulation, TS set number (see below) |
+-----------------+---------------------------------------+
| X . . . . . . . | IDLE / nope frame indication (0 or 1) |
+-----------------+---------------------------------------+
The bit number 7 (MSB) is set to high when either nothing has been
detected, or during IDLE frames, so we can deliver noise levels,
and avoid clock gaps on the L1 side. Other bits are ignored,
and should be set to low (0) in this case.
== Coding of modulation and TS set number
GMSK has 4 sets of training sequences (see tables 5.2.3a-d),
while 8-PSK (see tables 5.2.3f-g) and the others have 2 sets.
Access and Synchronization bursts also have several synch.
sequences.
+-----------------+---------------------------------------+
| 7 6 5 4 3 2 1 0 | bit numbers (value range) |
+-----------------+---------------------------------------+
| . 0 0 X X . . . | GMSK, 4 TS sets (0..3) |
+-----------------+---------------------------------------+
| . 0 1 0 X . . . | 8-PSK, 2 TS sets (0..1) |
+-----------------+---------------------------------------+
| . 0 1 1 X . . . | AQPSK, 2 TS sets (0..1) |
+-----------------+---------------------------------------+
| . 1 0 0 X . . . | 16QAM, 2 TS sets (0..1) |
+-----------------+---------------------------------------+
| . 1 0 1 X . . . | 32QAM, 2 TS sets (0..1) |
+-----------------+---------------------------------------+
| . 1 1 1 X . . . | RESERVED (0) |
+-----------------+---------------------------------------+
== C/I: Carrier-to-Interference ratio
The C/I value is computed from the training sequence of each burst,
where we can compare the "ideal" training sequence with the actual
training sequence, and then express that difference in centiBels.
Change-Id: Ie810c5a482d1c908994e8cdd32a2ea641ae7cedd
Related: OS#4006, OS#1855
It may be necessary to extend the message specific header with
more information. Since this is not a TLV-based protocol, we
need to include the header format version.
+-----------------+------------------------+
| 7 6 5 4 3 2 1 0 | bit numbers |
+-----------------+------------------------+
| X X X X . . . . | header version (0..15) |
+-----------------+------------------------+
| . . . . . X X X | TDMA TN (0..7) |
+-----------------+------------------------+
| . . . . X . . . | RESERVED (0) |
+-----------------+------------------------+
Instead of prepending an additional byte, it was decided to use
4 MSB bits of the first octet, which used to be zero-initialized
due to the value range of TDMA TN. Therefore, the current header
format has implicit version 0x00.
Otherwise Wireshark (or trx_sniff.py) would need to guess the
header version, or alternatively follow the control channel
looking for the version setting command.
The reserved bit number 3 can be used in the future to extend
the TDMA TN range to (0..15), in case anybody would need
to transfer UMTS bursts.
Change-Id: Idb0377d66290eb9c15d6998a5806a84fa2e5dd02
Related: OS#4006
Both functions are never used outside of both gen_msg() and parse_msg().
AFAIR, they were more complicated until we started to use struct, but
now they can be easily inlined.
Change-Id: Ie64b271cf502f3df23b32f4b14a1e2b551a0f794
Having fn = 1024 and tn = 0 in all tests decreases the chances
to spot encoding / decoding bugs of higher or lower values.
Let's randomize the reference data before all the tests.
Change-Id: Id3c5be9faaf0bef727b975c7182098af0cec6e71
The old TOA256 range was bigger than we can actually store:
struct.error: 'h' format requires -32768 <= number <= 32767
Change-Id: I5d4e1fea9d07f2c49f01e6644d1c0d1dc8cf4e40
Some transceivers (e.g. OsmoTRX) have inherited a rudiment from
OpenBTS - two dummy bytes at the end of TRX2L1 messages. Despite
they are absolutely useless, some L1 implementations, such as
trxcon and OpenBTS, still do expect them when checking
the message length.
Let's add an optional (disabled by default) argument to gen_msg(),
that would enable adding those two dummy bytes.
Change-Id: I0cf1314c399411886420176704cadd6e6d84787f
The built-in struct module is already used for toa256 decoding,
so let's use it for toa256 encoding, and TDMA frame number
coding too - no need to (re)implement the wheel!
Change-Id: I10d2e15ac57a0524e9bc1c80ed6a0f6f5a263436
There are multiple advantages of using Python's logging module:
- advanced message formatting (file name, line number, etc.),
- multiple logging targets (e.g. stderr, file, socket),
- logging levels (e.g. DEBUG, INFO, ERROR),
- the pythonic way ;)
so, let's replace multiple print() calls by logging calls,
add use the following logging message format by default:
[%(levelname)s] %(filename)s:%(lineno)d %(message)s
Examples:
[INFO] ctrl_if_bts.py:57 Starting transceiver...
[DEBUG] clck_gen.py:87 IND CLOCK 26826
[DEBUG] ctrl_if_bts.py:71 Recv POWEROFF cmd
[INFO] ctrl_if_bts.py:73 Stopping transceiver...
[INFO] fake_trx.py:127 Shutting down...
Please note that there is no way to filter messages by logging
level yet. This is to be introduced soon, together with argparse.
Change-Id: I7fcafabafe8323b58990997a47afdd48b6d1f357
This toolkit has branched out into several different tools for
TRX interface hacking, and creating a virtual Um-interface
(FakeTRX) is only one of its potential applications.
Change-Id: I56bcbc76b9c273d6b469a2bb68ddc46f3980e835
Oliver Smith
Vadim Yanitskiy
Pau Espin
Vadim Yanitskiy