NC-10 USRP Channelizer
of Channels with
Wideband receivers & digital channelization in one
Channelization and Channelized Receivers
NC-10 USRP Channelizer combines excellent performance with low cost and small footprint. It provides four 80 MHz RF-inputs and can channelize phase coherently on all inputs, making it possible to create direction finding systems and many other types of applications.
Spectrum monitoring and signal analysis have many application areas, both civilian and military. The RF spectrum is getting crowded and having the right tools to acquire and analyze the wireless environment is crucial.
When monitoring a wideband source, many different signals of interest must be analyzed, demodulated, decoded, or processed in other ways. However, processing the entire wideband source for every signal of interest is not effective. Instead, the signals of interest should be extracted from the wideband source so that each signal is processed individually.
This extraction can be achieved by filtering and decimating the wideband signal, resulting in a lower sample rate that contains only the signal of interest. By using channelization, it is possible to use a single wideband receiver and still analyze hundreds of signals.
NC-10 USRP Channelizer is a toolkit for USRP-2955. It contains software as well as FPGA-bitfiles to turn the device into a powerful channelized receiver, allowing users and system integrators to extract signals of interest from four phase synchronized RF-inputs.
The USRP 2955 supports sharing LOs between the RF inputs which gives phase synchronized acquisition. This combined with phase synchronized channelization allows the user to create powerful direction finding application with up to 128 direction finding channels.
The four RF inputs can be configured individually and cover four separate bands of 80 MHz. Up to 512 channels in total can be extracted from the inputs. The channels will continuously stream the channelized data for further processing. Because the stream is continuous it is possible to use it for demodulation of signals and listen to traffic.
High Channel Count Systems
More synchronized RF inputs and channels leads to higher accuracy in many algorithms. By using the octoclock clock distributor module it is possible to synchronize channelization across multiple USRP devices making it possible to connect large arrays of antennas.
GPS timestamping and positioning can be used to synchronize systems across large distances. Direction finding applications can, together with other DF-systems provide a geo location by using triangulation techniques.
The USRP 2955, with its’ four RF-inputs, is capable to alone, or stacked with several USRPs’, provide beamforming capabilities. This means that an otherwise omnidirectional antenna lobe can be electronically manipulated to obtain directivity features.
Directivity features can be used to enhance reception of signals in desired directions and to discriminate signals in undesired directions.
Reducing Data Rates
Due to data bandwidth limitations, reducing the data rate is important when transferring data between different locations. Covering a wide RF bandwidth means large data rates and 80 MHz is approximately 400 MBps. By extracting the signals of interests and discarding undesired data, the data rate can be drastically decreased.
NC-10 USRP is a building block for larger systems and is designed to easily be integrated into other environments. NC-10 USRP can be connected to Windows computers with a PCIe or Expresscard-slot and connected to other systems in different ways.
To increase the streaming rate an additional network interface card with SFP+ connections can be added to the computer to stream the data (B).
If processing needs to be distributed across multiple computers, the SFP+ connections can be connected to a switch instead and the data is distributed across the network (C).
NC-10 can also be used as a channelization server and the computer connected to the USRP via PCIe is then also connected to a network and receives commands from other computers, telling NC-10 server which frequencies to channelize (D).
The USRP-2955 features four two-stage superheterodyne receiver channels. Each of the four inputs have a real-time bandwidth of 80 MHz and are tunable in a span from 10 MHz to 6 GHz. The inputs can be configured to share LO to enable phase coherent acquisition, or independently to be able to cover a larger frequency span. Data from the RF inputs can be streamed from the USRP to be analyzed and identify signals of interest.
The heart of NC-10 USRP is the FPGA-based channelization and the user can configure up 512 channels in total with no restrictions on which RF input the channels use as source. The channels can be made to overlap, have different bandwidth and are independent of each other, unless they are configured for phase synchronized channelization. The channels can be reallocated dynamically when running and modifying one channel does not affect the operation of the other ones. The channelized data is output as IQ-data that is sent for analysis with the streaming interfaces.
Data can be streamed either through the PCIe-link or the two SFP+ ports. Both RFdata as well as channelized data can be streamed through the two different interfaces. Data sent through the SFP+ ports are sent as VITA49 UDP packages and can be routed over long distances either through switches or by connecting fiber optic cables to the SFP+ ports. The UDP packaging is performed directly on the FPGA and each channel can be sent to a specific address and UDP port, making it easier for processing nodes to filter out channels of interest. The 512 channels could for example be streamed to 512 different UDP ports. Other streaming protocols such as Xilinx Aurora are available on request.
The software is used to configure all the parameters of the hardware such as the RF frontend settings, channelization settings as well as the streaming location and many more parameters. The NC-10 software (including FPGA personality) can be used in three different ways, either locally by calling a DLL, using LabVIEW or as a server, receiving commands via TCP/IP. All three methods allows you to integrate NC-10 USRP into your own application.
The DLL can be called from any programming language capable of loading a DLL, such as C and Python. To help you get started more quickly, ready to run examples can be obtained in the following languages:
Apart for configuring the RF frontend and channelization, with the LabVIEW API it is possible to connect NC-10 to other hardware from National Instruments. Through peerto-peer streaming data can be streamed to additional FPGA boards to process the RF data or the channelized data.
Included in the software package is also a server software that is ready-to-run. This software runs on a Windows computer connected to the USRP and communicates with other systems using TCP/IP. Via an open protocol it is possible to configure the different parameters of the system.
The server is running on a Windows computer but the systems communicating with the server can be running any operating system. The only requirement is that it is possible to communicate with TCP/IP commands.
Examples of how to communicate, what commands to send and in which order are included in the protocol documentation.
From the server software it is also possible to stream spectrum-data from the inputs via UDP, which gives a good overview of the present signals.
For USRP 2955 specifications please visit National Instruments homepage www.ni.com
|Number of RF inputs||4|
|Number of output channels||512|
|Output channel center frequency resolution||<1 hZ|
|Output channel sample rate||Min: 3k MSps|
|Max 50 MSps|
|Spurious-free dynamic range||>100 dBFS|
|Signal to noise and distortion ratio||>90 dB|
Mechanical / Enviromental
|Dimensions (L x W x B)||26.67 cm x 4.06 cm x 21.84 cm|
|(10.5 in x 1.6 in x 8.6 in)|
|Weight||1.59 kg (3.50 Ib)|
|Ambient Temperature||0-55 °C|
|Maximum altitude||2 000 m (800 mbar @ 25 °C amb temp)|
|input Voltage||9-16 VDC|
|Input Current||7.5 A (max)|
|Power Consumption||38-44 W (depending on application)|