Currently we have 2 out parameters, but in forthcoming commits will add
a third one. All those functions already have too many parameters, so
let's put together all the output params in a struct to pass them easily
and make it easier to understand they are the estimated output values.
Related: OS#4006
Change-Id: I05cfa0ceaa2e633a5e6e404e2eae497ff4442dea
Make the interface using trx_ul_burst_ind more implementation agnostic
as well as easier to use. For instance, we don't care about SoftVector
size one returned from pullRadioVector(); we want to use nbits instead.
As a result, we no longer spend time normalizing guard periods. While at
it, change vectorSLicer to return void since it always returns true.
Change-Id: I726e5a98a43367a22c9a4ca5cbd9eb87e6765c7a
This is a preparatory change that enables a possibility to choose
the amount of synch. sequences to be used for Access Burst (RACH)
detection. The VTY flag will be introduced in further changes.
There are two correlation types now:
- RACH (default) - TS0 only;
- EXT_RACH - all TS0, TS1, and TS2 together.
Change-Id: Ia4f20524350bb8c380d7e10360758eddae8b03e9
Related: OS#3054
Also remove entirely completely unused calls. Most of these
calls have been around since OpenBTS conception. Nearly a
decade is long enough time for deprecation.
Change-Id: Ifc122aaff23414c363b4b00f99061eed8a6902d0
demodCommon() used to scale input vector in place which changed original data.
That's a bad practice and is not really necessary, so I've changed the code to
scale burst after it's copied to a new vector during a delay operation.
Change-Id: Ic45f71b634e48808356d68925bb9f5783e0bf0d3
The file seem to be using "2 spaces" indent, bt some lines are using
tabs which breaks formatting.
Change-Id: I7718cca45c245c9e91250ab2877f5436d4029698
This makes it similar to 8-PSK demod and also saves a bit of lines ofcode and
should give us a tiny improvement in performance.
Ideally we need to remove vector slicing at all, because in osmo-bts-trx
we convert back to +-1.0 again (actually to +-127, but it doesn't mater).
So we should rather transmit +-1.0 values to avoid double conversion.
Change-Id: If9ed6f0f80fbe88c994b2f9c3cae91d0d57f4442
Documentation in sigProcLib.h was noticeably out of sync with the actual
implementation - e.g. not all arguments were documented and arguments
which are already removed are still in the documentation. Also argument
names were different between declaration in .h and implementation in .cpp
which was confusing.
I've fixed this for detect*Burst() functions.
Change-Id: I4dfd07125d9a1e9a42a78b79faff539f003deb16
Previously MAXDLY value was applied to Normal Bursts, which was nice
when working with sloppy test equipment like CMD57, but useless for
real world usage. At the same time documentation and de facto usage
of MAXDLY in OsmoBTS and OpenBTS assumed that it actually applies to
Access Bursts (RACH). So this patch changes osmo-rx behavior to apply
MAXDLY to RACH bursts and introduces a new command MAXDLYNB for the
old behavior.
Setup generators for empty, random, and dummy bursts. This moves error
prone burst length handling out of the Transceiver and into the signal
processing core.
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
Create EDGE slot type in the Transceiver. When EDGE mode is enabled
for a particular slot, blind detection will be performed by
correlating against EDGE followed by normal bursts if no EDGE burst
is found.
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
Setup correlator and detection process similar to the GMSK
receiver chain. Require 4 SPS sampling on both Rx and Tx paths
as 1 SPS sampling adds too much distoration for 8-PSK recovery.
Core receiver operations still run at 1 SPS with the exception
of fractional delay filtering, which runs at the higher rate.
Perform linear equalization to handle the Gaussian pulse
induced ISI. The fixed impulse response used for equalizer tap
calculation consists of combined EDGE pulse shape filter and
effects of the downsampling filter. Note that the non-adaptive
equalizer corrects for modulation induced band limiting and
does not account for or compensate for fading channel effects.
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
DFE equalizer is unused and has been experiencing code rot for
multiple years. The effect is a significant amount of baggage being
carried in the Transceiver and interfaces.
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
Samples per symbol used by the transceiver is not configurable through
the socket interface once running, so stop pretending like it could be.
Initialize all tables and midambles at start.
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
As a side change - get rid of passing toa and amp arguments as pointers and use
references instead.
The commit doesn't change behaviour, but makes the code cleaner.
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
Alert user of overdriven burst input indicated by a positive
threshold detector result. This indication serves as notification
that the receive RF gain level is too high for the configured
transceiver setup.
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
Allow non-in-place use of the delay setting. Internally, the delay call
creates a new vector and copies the contents back into the original.
Instead, provide the option to return the computed output vector
directly and remove an an extra copy in the process.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
This prevents the use of a copy constructor in the downlink
modulator and prevents a secondary memory allocation during
the convolution. Avoid both cases by dynamically allocating
with preloaded head room. The latter provides enough memory
before the first sample in the burst to cover the length
of the filter taps.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
This patch applies oversampling, when selected with 4 sps,
to the downlink only, while running the receiver with
minimal sampling at 1 sps. These split sample rates allow
us to run a highly accurate downlink signal with minimal
distortion, while keeping receive path channel filtering
on the FPGA.
Without this patch, we oversample the receive path and
require a steep receive filter to get similar adjacent
channel suppression as the FPGA halfband / CIC filter
combination, which comes with a high computational cost.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
Replace the polyphase filter and resampler with a separate
implementation using SSE enabled convolution. The USRP2 (including
derived devices N200, N210) are the only supported devices that
require sample rate conversion, so set the default resampling
parameters for the 100 MHz FPGA clock. This changes the previous
resampling ratios.
270.833 kHz -> 400 kHz (65 / 96)
270.833 kHz -> 390.625 kHz (52 / 75)
The new resampling factor uses a USRP resampling factor of 256
instead of 250. On the device, this allows two halfband filters to
be used rather than one. The end result is reduced distortial and
aliasing effecits from CIC filter rolloff.
B100 and USRP1 will no be supported at 400 ksps with these changes.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
This large patch replaced the convolve() call with an SSE vector
enabled version. The lower C and SSE intrinsic based code operates
on fixed and aligned vectors for the filter taps. The storage format
of interleaved I/Q for both complex and real vectors is maintained.
SSE filter tap values must:
1. Start 16-byte aligned
2. Number with a multiple of 4 between 4 and 20 for real taps
3. Number with a multiple of 4 for complex taps
Non-compliant values will fall back to non-SSE usage. Fixed length
iterators mean that head and tail cases may require reallocation of
the input vector, which is automatically handled by the upper C++
interface.
Other calls are affected by these changes and adjusted or rewritten
accordingly. The underlying algorithms, however, are unchanged.
generateGSMPulse()
analyzeTrafficBurst()
detectRACHBurst()
Intel SSE configuration is automatically detected and configured at
build time with Autoconf macros.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
There is no temporal dependency on when the RACH sequence is generated,
so there is no need for transceiver to create it in response to a
command from GSM core. If we power on the transceiver, we will need
the RACH sequence, so just allocate it during initialization.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
There is no reason expose the pulse shaping filter outside of the
signal processing calls. The main transceiver object makes no use
of the filter and there's no reason to pass it around.
Initialize the pulse shape with the signal processing library, and
maintain an internal static member like many of the other library
variables. Similarly destroy the object when the library is closed.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
Because repeatedly typing mSamplesPerSymbol is giving me
carpal tunnel syndrome. Replace with the much shorter,
easier to type, and just as clear name of 'sps'.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
Remove radio clock and vector interfaces into their own
files. This clears up and simplifies the radio interface
and, additionaly, prepares for a further split of the I/O
portion for optional resampler use.
Signed-off-by: Thomas Tsou <ttsou@vt.edu>
git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@2669 19bc5d8c-e614-43d4-8b26-e1612bc8e597
Sylvain Munaut
Martin Hauke
Pau Espin
Vadim Yanitskiy