GGNNUU RRaaddiioo UUssiinngg RRaaddiioo442200 ( (P Pi ic co oS SD DR R, , u uS SD DR R4 42 2x x, , A AS SP P4 42 2x x S Sy ys st te em ms s) ) M Ma ar rc ch h 2 20 01 13 3 Revision history RevisionDateComments 0.9February 2013First released revision 1.0March 2013Linguistic revision 1Installation This chapter presents the requirements and the procedure to install GNU Radio. 1.1Requirements The following hardware and software requirements must be met to use GNU Radio on Fedora 17. 1.1.1Hardware 1 Nutaq SDR 1 male-to-male MMCX cable 4 MMCX antennas 1 Ethernet cable 1 Gigabit Ethernet network adapter 1.1.2Software Nutaq ADP 6 software and latest Fedora 17 installed on a x86 computer 1.2Installing GNU Radio on Fedora 17 To install GNU Radio: 1.Install GNU Radio by running the following command: wget http://www.sbrac.org/files/build-gnuradio && chmod a+x ./build-gnuradio && ./build-gnuradio -v -ja It will download a script and execute it. This script will build the GNU Radio toolkit including its dependencies from source and install it to the system. 2.If not already done, install the Nutaq ADP6 software. You may have to configure the path to the Nutaq ADP6 libraries using the following command: For a 64-bit computer export LD_LIBRARY_PATH=/opt/Nutaq/ADP6/ADP_MicroTCA/sdk/lib64/ For a 32-bit computer export LD_LIBRARY_PATH=/opt/Nutaq/ADP6/ADP_MicroTCA/sdk/lib/ 3.After expanding the gr-radio420 archive, run the install.sh script located in the gr-radio420 folder: ./install.sh It will ask for your password so that it can install the Radio420 software using the administrative privilege. 4.In the default Radio420 configuration, the Ethernet communication use jumbo frames of 8192 bytes. Make sure that the Ethernet card can support jumbo frames and is configured correctly. The figure below shows the current configuration of the Ethernet card. Make sure that the MTU value is higher than 8192. If not, set the Ethernet card MTU to 9000 as follows: ifconfig your_ethernet_device_name mtu 9000 (for example,ifconfig em1 mtu 9000). Verify that the MTU configuration worked properly using the ifconfig command. If there is an invalid argument error, it is possible that the Ethernet card cannot support jumbo frames. If it is the case, it still possible to use the GNU Radio420 plugin but the effective bandwidth of Ethernet communication can be limited by the host computer. To reduce the Ethernet packet size, open the radio420_api.h file located in the gr-radio420/lib/ folder. Find the following line: #define RTDEX_PACKET_SIZE (8192) and modify the 8192 value to a smaller power of 2 value such as 1024. Make sure that the new value is supported by the Ethernet card. Save the file and restart the script: ./install.sh 2Running GNU Radio It is possible to generate your own bitstream on a Windows computer with Xilinx ISE 13.4 and ADP6 software or your can use the default bitstream provided inside the bin folder of the GNU Radio420 plugin. Section 2.1 and 2.2 present the procedures to generate your own bitstream using respectively EDK and System Generator. If you do not want to generate your own bitstream, proceed to the section 2.3. 2.1Generating bitstream with EDK 1.Using EDK Platform Studio, browse to the ADPROOT\examples_perseus6010\perseus6010_radio420x_rtdex_record_playback\edk\ folder and open the perseus6010_radio420x_record_playback.xmp project. 2.On the Device Configuration menu, click Update Bitstream. This will generate a bitstream (*.bit) required to run the GNU Radio software. Xilinx Platform Studio window for bitstream generation 2.2Generating bitstream with System Generator 1.In Windows, open System Generator linked with MATLAB 2011b. 2.Browse to the ADPROOT\matlab\examples\perseus601x\ folder and open the perseus601x_radio420x_fpga.mdl model. 3.Double click on the System Generator icon, select your FPGA part number and click on the Generate button. This will generate a bitstream (*.bit) required to run the GNU Radio software. In the System Generator model figure below, only blocks outlined in red are used for the GNU Radio streaming example. Section 1 contains the configuration blocks Sections 2 and 3 contain Custom Registers Section 4 contains the RTDEx RX synchronization logic for the MIMO configuration Sections 5 and 6 connect the RTDEx RX blocks with the Radio420 DAC interfaces. Sections 7 and 8 connect the Radio420 ADC interfaces with the RTDEx TX blocks. System Generator bitstream generation 2.3FPGAlogic description The bitstream generated with EDK, with System Generator and the precompiled bitstream all implement the same logic. The FPGA logic allows the user to run examples demonstrating the use of Record/Playback, DDS generation and streaming with the Ethernet port. In the GNU Radio420 plug-in, only the streaming configuration is used. The Custom Register 1 value must be set to 6 to connect the RTDEx RX signals with the Radio420 DAC interface. The Custom Register 3 value is used to allow writes to the RTDEx TX buffer. Once the RTDEx communication is setup by the host computer, this register must be set to 1. The Custom Register 4 is used to synchronize both RTDEx RX channel together when in the MIMO configuration. When this register is set to 1, both RTDEx RX fifos must contain samples before they start sending there samples to the DAC interface. In SISO configuration, this register must be set to 0. 2.4Programming the FPGA and launching GNU Radio 4.In Windows, using the Xilinx Impact software, load the bitstream onto the Xilinx FPGA.Alternatively, in Fedora 17, you can use the CLI command fpgaflash to program in the flash a bitsteam that will be loaded at the Perseus power up. Refer to the CLI (Command Line Interface) documentation for more information about fpgaflash. 5.You may now run the gnuradio-companion software located at in the /usr/local/bin/gnuradio-companion folder. You will need to run gnuradio-companion as root so that it is able to inject a raw Ethernet packet onto the network that will be used to send and receive signals when communicating with the Radio420 carrier. 6.Before starting gnuradio-companion make sure that the following paths are set correctly for the root user: LD_LIBRARY_PATH must contain the Nutaq sdk library path (for example, /opt/Nutaq/ADP6/ADP_MicroTCA/sdk/lib64/) and the GNU Radio library path (for example, /usr/local/lib64/). PYTHONPATH must contain the Python package path (for example, /usr/local/lib64/python2.7/site-packages). Note: Each time a new root terminal is started, the environment variables can be reset. Some scripts are present in the gr-radio420 folder to set the environment variables before starting gnuradio-compagnion. For a 64-bit computer, use launch_gnuradio_companion_x86_64.sh; for a 32-bit computer use launch_gnuradio_companion_i686.sh. 7.Once gnuradio-companion is started, you can find our example project files in the gr-radio420/examples folder. 3Examples This chapter presents two examples of the use of GNU Radio with Radio420. 3.1Digital Voice Transmission Example 3.1.1Procedure 1.Open the voice_gmsk.grc project file. 2.Double-click Radio420 GigE: Global block. A window containing the settings for the Radio420 opens. Depending on the network configuration, you will need to reconfigure the IP address of the Radio420 carrier (Perseus board) by changing the field named IP Address. 3.Connect an MMCX antenna to ports TX and RX of the Radio420. Alternatively, you can use a male-to-male MMCX cable, but you will have to adjust the gain manually. 4.Start the example by click the Execute the flow graph button. 3.1.2Expected Results 1.Make sure the data displayed in the scope does not saturate. The dynamic range of the Radio420 source block is between -1 and 1. If the received signal exceeds or almost exceeds the dynamic range, lower the RX or the TX gain. The GMSK Demodulation and Packet Decoder blocks will not be able to properly decode the recorded voice if the signal saturates.If the GMSK Demodulation and Packet Decoder blocks work properly, you should see the FFT of the decoded signal in the FFT Plot window. If the FFT Plot window is empty, try different gains or move you antennas. 2.Make sure the volume of the microphone and the speakers are correctly set. If no sound is heard, try turning up their volume or using another speaker peripheral. If only noise is heard, try turning down the volume of your microphone. 3.1.3How It Works This model transmits a digitally encoded audio signal recorded from the computer microphone, recodes it using GMSK encoding, and transmits it through the Radio420. At the other end, the Radio420 receives the signal. The computer decodes the GMSK signal and plays it back on the computer speakers. TX path 1.Reads from the default audio input of the computer and outputs the signal as float so that it is available to other signal processing blocks. 2.Packetizes data at its input. It adds a preamble so that the beginning of the packet is detected. When no data is available to be read, it writes filler data so that data is always available to be sent to the transceiver. 3.Encodes data using GMSK (Gaussian minimum shift keying). 4.Sends data to the SDR unit using Gigabit Ethernet. RX path 1.Receives data from the SDR unit using Gigabit Ethernet. 2.Demodulates the signal that was encoded using GMSK encoding. 3.Detects preambles in the data stream and records the data following the preamble. 4.Sends data to the default audio output. 5.Analyzes data by doing a fast Fourier transform and displays it as a frequency domain graph in real-time. 6.Displays the data in real-time as a time domain. 3.2MIMO Loopback Example 3.2.1Procedure 1.Open the sinkandsource_mimo.grc project file. 2.Double-click Radio420 GigE: Global block. A window containing the settings for the Radio420 opens. Depending on the network configuration, you will need to reconfigure the IP address of the Radio420 carrier (Perseus board) by changing the field named IP Address. 3.Connect to an MMCX antenna to all TX and RX ports of the Radio420. Alternatively, you can use male-to-male MMCX cables, but you will have to adjust the gain manually. 4.Using a male-to-male MMCX cable, connect the RefOut port of card 1 to the RefIn of card 2. This provides clock synchronization to the second Radio420. 5.Start the example by clicking the Execute the flow graph button. 3.2.2Expected Results

1.Make sure the received data does not saturate. The dynamic range of the Radio420 source block is between -1 and 1. If the received signal exceeds or almost exceeds the dynamic range, the displayed FFTs in the FFT Plot windows can be dramatically altered. 2.If a lot of harmonics are seen in the FFT Plot windows, try lowering the gains, or moving the antennas apart. 3.If only noise is seen in the FFT Plots, try increasing the gains, or try moving the antennas closer.