Ettus USRP Family hardware¶
You can run OsmoTRX using the Ettus USRP family of devices.
All Ettus Research devices are supported.
- almost all models except the USRP1 are suppored using UHD.
- for USRP1 you need a special driver, see below.
|USRP1||Requires legacy libusrp driver and clocking modification|
|USRP2||10 MHz external reference required|
|B200||GPSDO or 10 MHz external reference recommended|
|B210||Dual channel, 10 MHz external reference recommended|
The USRP1 is now considered a legacy device in that only maintenance development takes place with no new features scheduled to become available.
For use with OsmoTRX, the USRP1 requires hardware modification and non-official driver software and firmware.
As an older device, USRP1 hardware does not support flexible device clocking or external 10 MHz referencing like more recent products.
The internal crystal oscillator is too imprecise for any reliable GSM operation and cannot be externally referenced. Consequently, the internal USRP1 clock must be replaced or driven by an external 52 MHz clock signal. Typical clocking options include the following.
To accommodate any of these clock sources, hardware modification involves soldering a new SMA connector and shifting various small resistors and capacitors.
Modification instructions and illustrations can be found on the Fairwaves ClockTamer website.
The official / new Ettus driver stack "UHD" supports the USRP1, but it does not support FPGA timestamp functionality on it. As a result, an alternative FPGA firmware and driver configuration is required for using the USRP1 with OpenBTS. The alternative configuration is based on a customized FPGA image and the now deprecated 'libusrp' driver found in early versions of GNU Radio.
The last release version of GNU Radio to contain the libusrp driver is 3.4.2. Note that this version of GNU Radio is not maintained, and installation on recent Linux distributions may be difficult - detailed setup instructions are no longer available
As a result, Osmocom has packaged this libusrp from gnuradio 3.4.2 as a stand-alone library which can be built on modern Linux distributions. The sorce code can be found at https://gitea.osmocom.org/sdr/libusrp and the libusrp binary packages are part of the Osmocom Binary_Packages feed.
In order to run osmo-trx with a USRP1 you need to install
Ettus USRP B2x0¶
Ettus B2x0 output signal levels
|band||arfcn||tx-attenuation||signal level (dBm)|
these values were measured by sysmocom on a agilent E4406 with an ettus B210