Universal Software Radio Peripheral
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The Universal Software Radio Peripheral (USRP) is a high-speed USB-based board for making software radios.
The USRP is intended to be a comparatively inexpensive hardware device facilitating the building of a software radio. The USRP has an open design, with freely available schematics (provided approved tools are used for downloading) and drivers, and free software to integrate with GNU Radio. It is also designed to be flexible, allowing developers to make their own daughterboards for specific needs with regard to connectors, different frequency bands, etc.
The USRP is developed by a team led by Matt Ettus.
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[edit] Technical Details
The USRP consists of:
- Four high-speed analog-to-digital converters, each capable of 64 MS/s at a resolution of 12 bit, 85dB SFDR (AD9862).
- Four high-speed digital-to-analog converters, each capable of 128 MS/s at a resolution of 14 bit, 83dB SFDR (AD9862).
- An Altera Cyclone EP1C12Q240C8 FPGA.
- A Cypress EZ-USB FX2 High-speed USB 2.0 controller.
- 4 extension sockets (2 TX, 2 RX) in order to connect 2-4 daughterboards.
- 64 GPIO pins available through 4 BasicTX/BasicRX daughterboards (16 pins each).
- some glue logic.
[edit] USRP boot sequence
When the USRP is powered up, it puts the AD9862 is a low power state, and blinks the led 3 times per second. The host (computer) detects a USB device 04b4:8613, and therefore knows it is an unconfigured FX2 device. The driver will now load a firmware into the FX2, and when it boots up, the host will now detect a different USB device of fffe:0002. Using a capability of the newly loaded FX2 firmware, the driver will now initialize the FPGA. Once that is done, boot is complete, and the device is ready for tuning.[1]
[edit] USRP2
The next version, USRP2, was made available in early September 2008. It was made clear that the USRP2 is not intended to replace the original USRP, which will continue to be manufactured and sold in parallel to the USRP2.
USRP2 contains:
- A Xilinx Spartan 3-2000 FPGA (instead of the Altera FPGA)
- Gigabit Ethernet interface (instead of USB 2.0)
- Two 100 MS/s, 14 bit, analog-to-digital converters.
- Two 400 MS/s, 16 bit, digital-to-analog converters.
- SD-card reader.
- etc.
Xilinx's free programming tool, ISE WebPACK, is not compatible with the FPGA used for USRP. None of Xilinx's tools are open source, and the compatible tool (ISE Foundation) is not free of cost, so it is harder to compile the USRP2 firmware.[2][3]
[edit] Daughterboards
Daughterboards serve as the RF frontend. They allow the output signal to be modulated to a higher frequency and an input signal to be stripped of its carrier. Several classes of boards exist: Receivers, Transmitters and Transceivers.
Receivers only support RX and consume only one RX port:
- BasicRX, 1-250 MHz Receiver, for use with external RF hardware.
- LFRX, DC to 30MHz Receiver
- TVRX, 50 MHz to 870 MHz Receiver
- DBSRX, 800 MHz to 2.4 GHz Receiver
Transmitters only support TX and consume one TX port:
- BasicTX, 1-250 MHz Transmitter, for use with external RF hardware.
- LFTX, DC to 30MHz Transmitter.
Transceivers are both TX and RX and consume 2 ports (all come with 70dB AGC unless specified otherwise):
- WBX0510, 50 MHz - 1 GHz Transceiver, 100mW output.
- RFX400, 400-500 MHz Transceiver, 100+mW output, 45dB AGC. Can be changed to cover 200 MHz up to 800 MHz with a hardware mod.
- RFX900, 800-1000 MHz Transceiver, 200+mW output (can be changed into a RFX1800 with basic soldering and flash update).
- RFX1200, 1150-1450 MHz Transceiver, 200+mW output.
- RFX1800, 1.5-2.1 GHz Transceiver, 100+mW output (can be changed into a RFX900 with a flash update).
- RFX2400, 2.3-2.9 GHz Transceiver, 20+mW output (can be changed into a RFX1200 with basic soldering and flash update).
- XCVR2450, Dual-band Transceiver, 100+mW output at 2.4-2.5 GHz and 50+mW output 4.9-5.85 GHz.
- 800 MHz - 2.2 GHz Transceiver.
Together, daughterboards allow the USRP to use the entire spectrum. However, when several daughterboards are used together in the same USRP case, some shielding may be required in order to reduce cross-talk between the daugherboards when a full-duplex application requires a high degree of receiver sensitivity (see OpenBTS Black Rock City Field Trial).
[edit] Uses
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Please be aware that transmitting on radio frequencies without a special permit is illegal in most of the world. There are certain bands which allow unlicensed usage, but in some countries you need a licensed device in order to use these bands. USRP is sold as a test equipment and is not a licensed transmitter, therefore you may not connect it to an antenna unless you have a specific permit to do so. Amateur Radio licenses are one type of licenses that allow you to use USRP as a transmitter on some parts of the spectrum.
In addition, receiving transmissions not intended to you are illegal in many countries under anti-eavesdropping laws. In particular, IMSI catching, and military bands are off-limits. In the US, some hams may be licensed to use military bands (MARS) on some conditions.
The USRP has been used as:
- RFID reader
- testing equipment
- a cellular GSM base station[4]
- a GPS receiver[5]
- an FM radio receiver[6]
- an FM radio transmitter[7]
- a digital television decoder[8]
- passive radar
- synthetic aperture radar
- an amateur radio
- a teaching aid[9]
[edit] References
- ^ http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html#fm-receiver
- ^ http://www.ettus.com/downloads/ettus_ds_usrp2_v2.pdf
- ^ http://toolbox.xilinx.com/docsan/xilinx10/books/docs/irn/irn.pdf
- ^ http://openbts.sourceforge.net/
- ^ http://www.gps-sdr.com/
- ^ http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html#fm-receiver
- ^ http://juha.vierinen.net/mp3tofm.html
- ^ http://www.ruby-forum.com/topic/60548
- ^ http://www.wired.com/science/discoveries/news/2006/06/70933
[edit] External links
- The GNU Radio wiki
- Ettus Research LLC, makers of the USRP.
- A Wired Article on USRP
- Using the USRP for digital communications Tools4SDR
