Difference between revisions of "ODR-DabMod"

From OpenDigitalRadio
Jump to navigationJump to search
m (→‎Description: wrong link)
 
(3 intermediate revisions by 2 users not shown)
Line 1: Line 1:
 
==About ODR-DabMod==
 
==About ODR-DabMod==
 
ODR-DabMod is the DAB OFDM modulator initially developed by Communication Research Center (CRC) from Canada, and subsequently forked
 
ODR-DabMod is the DAB OFDM modulator initially developed by Communication Research Center (CRC) from Canada, and subsequently forked
−
by opendigitalradio.
+
by Opendigitalradio.
  
 
CRC have stopped releasing new versions.
 
CRC have stopped releasing new versions.
−
The development is now pursued by opendigitalradio on [http://github.com/Opendigitalradio GitHub] with releases available ad interim on http://mpb.li
+
The development is now pursued by opendigitalradio on [http://github.com/Opendigitalradio GitHub] with releases available as git tags. The git master branch always points to the latest release, the next branch is where development happens.
  
 
The main communication channel is the [https://groups.google.com/forum/#!forum/crc-mmbtools CRC-mmbTools Google Group mailing list]
 
The main communication channel is the [https://groups.google.com/forum/#!forum/crc-mmbtools CRC-mmbTools Google Group mailing list]
  
−
Original CRC version [[http://web.archive.org/web/20131031110313/http://mmbtools.crc.ca/content/view/44/71/ CRC-DabMod description and source code] archived on the MMBTools website
+
Original CRC version [http://web.archive.org/web/20131031110313/http://mmbtools.crc.ca/content/view/44/71/ CRC-DabMod description and source code] archived on the MMBTools website
  
 
==Description==
 
==Description==
  
−
ODR-DabMod takes an [[Ensemble Transport Interface]] (ETI) stream as input and outputs a complex baseband stream of interlaced 16 bits I/Q samples with a default sampling frequency of 2.048MHz. It can also directly communicate to the Ettus USRPs using the UHD driver.
+
ODR-DabMod takes an [[Ensemble Transport Interface]] (ETI) stream as input and outputs a complex baseband stream of interlaced I/Q samples with a default sampling frequency of 2.048MHz. It can also directly drive SDR devices through Ettus' UHD driver, [https://github.com/pothosware/SoapySDR/wiki SoapySDR] and LimeSuite.
  
−
The USRP1 will require resampling to 3.2Msps, which will requires high CPU usage but cannot be avoided. Newer USRPs have a more flexible clocking system.
+
Some devices require resampling to another sampling rate, which increases CPU requirements and can be done internally by ODR-DabMod.
  
 
==Build information==
 
==Build information==
Line 22: Line 22:
 
===Prerequisites===
 
===Prerequisites===
  
−
You will need boost at least version 1.42. The one from your distribution is probably fine, and if you have installed GNURadio or UHD, you will already have it.
+
You will need boost at least version 1.54. The one from your distribution is probably fine, and if you have installed GNURadio or UHD, you will already have it.
  
−
You need uhd, don't forget to also install the -dev package from your distribution.
+
You need uhd and/or soapy (including drivers for your SDR device), don't forget to also install the -dev package from your distribution.
  
−
If you want to use the zeromq inputs or outputs, you need a recent (4.0.4 or later) version of [http://zeromq.org/ ZeroMQ], preferably installed from your distribution's repository.
+
You need a recent (4.0.4 or later) version of [http://zeromq.org/ ZeroMQ], preferably installed from your distribution's repository. Also don't forget the -dev package.
  
 
===Building odr-dabmod===
 
===Building odr-dabmod===
Line 36: Line 36:
 
Build and install according to the instructions in the README.
 
Build and install according to the instructions in the README.
  
−
test with:
+
 
−
odr-dabmod -h
 
  
 
to update to latest upstream:
 
to update to latest upstream:
Line 45: Line 44:
  
 
==Usage==
 
==Usage==
−
There are two ways of using ODR-DabMod: through command line arguments or with a configuration file:
+
There are two ways of using ODR-DabMod: with a configuration file, and a smaller set of features is available through command line arguments. Use the -h option to see all options:
  
−
===Command line arguments===
+
odr-dabmod -h
  
−
Example with command-line interface:
+
For the configuration file, start with the example configuration inside the doc folder: [https://github.com/Opendigitalradio/ODR-DabMod/blob/master/doc/example.ini doc/example.ini]
−
ord-dabmod ./racor.eti -l -g1 -r3200000
 
  
−
This modulates the racor.eti file, performs OFDM modulation on baseband at a sampling frequency of 3.2Msamples/sec. Output is sent to the standard output. It can be redirected into a file, or piped into a baseband player ([[CRC-Dwap.py]]).
+
This example file describes and explains all supported settings.
  
−
When using a USRP, the integrated UHD output can be used. This requires the definition and usage of a configuration file.
+
Several settings can be modified while the modulator is running by enabling the '''remotecontrol''', see [https://github.com/Opendigitalradio/ODR-DabMod/blob/master/doc/README-RC.md doc/README-RC.md] for more details.
  
−
===Configuration file===
+
Once you have defined a configuration file (let's call it modulator.ini), you can call:
−
 
 
−
Take the example configuration from GitHub: [https://github.com/Opendigitalradio/ODR-DabMod/blob/master/doc/example.ini example.ini]
 
−
 
 
−
The '''input''' section defines if you want to read a file or ETI over ZeroMQ. The ZeroMQ must point to a odr-dabmux ZeroMQ output.
 
−
The '''modulator''' section sets parameters for the modulator which are described below.
 
  
−
'''firfilter''' enables the filter that was previously done in the baseband player. It reduces out of band energy, and will increase signal quality, and reduce energy waste in the mask filter. The filter taps can be generated with the helper script in doc/fir-filter
+
odr-dabmod modulator.ini
  
−
For each possible output, there is a section: '''outputuhd''' and '''outputfile'''. '''outputfile''' only defines the filename. '''outputuhd''' is more interesting: it defines the device flags, the TX frequency, the PGA gain, and what clocking source you want to use. In case of refclk loss, it is possible to make the modulator crash so as to avoid transmitting a corrupt signal, maybe even on the wrong frequency.
+
See also [[DAB hardware]]
−
 
 
−
The parameter
 
−
device=master_clock_rate=32768000,type=b100
 
−
is valid for USRP B100, and the master_clock_rate allows us to avoid resampling the 2048000sps signal. It is used as UHD device parameter without modification. There are other USRPs supported: See [[DAB hardware]]
 
−
 
 
−
The txgain can be modified while the modulator runs by enabling the '''remotecontrol'''
 
−
 
 
−
Once you have defined a configuration file (let's call it modulator.ini), you can call:
 
−
odr-dabmod -C modulator.ini
 
  
 
==Additional information concerning the options==
 
==Additional information concerning the options==
Line 82: Line 66:
 
This filter is used on the FPGA for up-sampling to 128MHz.
 
This filter is used on the FPGA for up-sampling to 128MHz.
 
This pre-correction filter is only enabled when the -c option is used.
 
This pre-correction filter is only enabled when the -c option is used.
−
You should use -c128000000 for regular USRP1 only.
+
You should use -c128000000 for the old USRP1 device only.
  
 
-g, or '''gainmode''': Gain computation mode
 
-g, or '''gainmode''': Gain computation mode

Latest revision as of 07:38, 7 April 2020

About ODR-DabMod

ODR-DabMod is the DAB OFDM modulator initially developed by Communication Research Center (CRC) from Canada, and subsequently forked by Opendigitalradio.

CRC have stopped releasing new versions. The development is now pursued by opendigitalradio on GitHub with releases available as git tags. The git master branch always points to the latest release, the next branch is where development happens.

The main communication channel is the CRC-mmbTools Google Group mailing list

Original CRC version CRC-DabMod description and source code archived on the MMBTools website

Description

ODR-DabMod takes an Ensemble Transport Interface (ETI) stream as input and outputs a complex baseband stream of interlaced I/Q samples with a default sampling frequency of 2.048MHz. It can also directly drive SDR devices through Ettus' UHD driver, SoapySDR and LimeSuite.

Some devices require resampling to another sampling rate, which increases CPU requirements and can be done internally by ODR-DabMod.

Build information

If you run debian, have a look at the Installer scripts

Prerequisites

You will need boost at least version 1.54. The one from your distribution is probably fine, and if you have installed GNURadio or UHD, you will already have it.

You need uhd and/or soapy (including drivers for your SDR device), don't forget to also install the -dev package from your distribution.

You need a recent (4.0.4 or later) version of ZeroMQ, preferably installed from your distribution's repository. Also don't forget the -dev package.

Building odr-dabmod

First get it via the package or git repository: 

git clone https://github.com/Opendigitalradio/ODR-DabMod
cd ODR-DabMod

Build and install according to the instructions in the README.


to update to latest upstream: 

git pull

and do the bootstrap configure make again.

Usage

There are two ways of using ODR-DabMod: with a configuration file, and a smaller set of features is available through command line arguments. Use the -h option to see all options: 

odr-dabmod -h

For the configuration file, start with the example configuration inside the doc folder: doc/example.ini

This example file describes and explains all supported settings.

Several settings can be modified while the modulator is running by enabling the remotecontrol, see doc/README-RC.md for more details.

Once you have defined a configuration file (let's call it modulator.ini), you can call: 

odr-dabmod modulator.ini

See also DAB hardware

Additional information concerning the options

-c, or dac_clk_rate: Pre-correction for the CIC filter in the USRP:

This filter is used on the FPGA for up-sampling to 128MHz. This pre-correction filter is only enabled when the -c option is used. You should use -c128000000 for the old USRP1 device only.

-g, or gainmode: Gain computation mode

The gainmode option controls how ODR-Dabmod computes the OFDM symbol gain.

mode 0 (FIX) uses a fixed factor and is really not recommended. It is more useful on an academic perspective for people trying to understand the DAB modulation.

mode 1 (MAX) is the normalization of every OFDM symbol. No overshoot, no truncating, but varying output power (around 3dB) which might not be the best for some power amplifier.

mode 2 (VAR) uses the method specified in ETSI 300 798. This method normalizes to 4 times the standard deviation for an approximation of the RMS power. So around 6/100000 samples will be truncated and will introduce some really minor distortion. But this mode also maximizes the output power. This is the gain mode recommended for real world operation as it is based on a DAB standard; the only difference is that ODR-Dabmod uses a better resolution with 16 bits in place of 8 bits.

(Additional info taken from google groups discussion, originally written by Pascal Charest, CRC)

Retrieved from "https://wiki.opendigitalradio.org/index.php?title=ODR-DabMod&oldid=1498"