TSKS01 Digital Communication

Transcription

1 Made by Ettus Research TSKS01 Digital Communication - Lecture 5 Introduction to Python TSKS01 Digital Communication - Lecture 5 Fixed replaceable RF frontends Programmable FPGA for base-band manipulations USB interface to PC Running stuff Used for Software Defined Radio research Suitable for prototyping Mostly open-source design Normal PC used for signal processing 2 TSKS01 Digital Communication - Lecture Lab System Overview : USRP Universal Software Radio Peripheral The industry is interested in SDR. Vision: Flexible radio equipment, easy updates. Wide-band sampling Can be a problem. Idea: As much as possible in software Provides flexibility Connecting stuff The software GNU radio The hardware USRP Abstraction layers My first impressions Lab system overview Introduction to software defined radio Outline of the Lecture Div. of Communication Systems Department of EE (ISY) Mikael Olofsson Software Defined Radio TSKS01 Digital Communication Lecture 5 Introduction to SDR

2 Lab System Overview: GNU Radio Open-source software framework for SDR Runs on standard Linux/Windows computers Flowgraphs define signal processing chains Primitive blocks written in C++ Flowgraph models in Python TSKS01 Digital Communication - Lecture 5 5 Overview: Interaction Flexibility: Do as much of the signal processing as possible in software. Software on host computer Programmable digital hardware Manually selectable analog hardware Signal generation Settings Signal processing USB Interpolating filters Decimating filters MUX MUX D/A 128 MS/s D/A A/D 64 MS/s A/D Further signal manipulation Further signal manipulation Initial signal manipulation Initial signal manipulation GNU-Radio code USRP motherboard Daughter boards TSKS01 Digital Communication - Lecture 5 6 First Impressions SWIG Documentation? Python USB Yikes!! C++ VHDL Hardware Tutorials? TSKS01 Digital Communication - Lecture 5 7 Abstraction Layers Python code Connecting blocks Host computer SWIG Glue between Python and C++ C++ modules Definition of blocks VHDL code on FPGA Programmable filters USRP Hardware Electrical signals TSKS01 Digital Communication - Lecture 5 8

3 The USRP Front Panel TSKS01 Digital Communication - Lecture 5 9 The USRP Mother Board FPGA Connector to Rx daughterboard B Connector to Tx daughterboard A A/D and D/A converters A/D and D/A converters Connector to Tx daughterboard B Connector to Rx daughterboard A USB interface TSKS01 Digital Communication - Lecture 5 10 USRP Mother Board Functionality TSKS01 Digital Communication - Lecture 5 11 USRP Mother Board Block Diagram TSKS01 Digital Communication - Lecture 5 12

4 The USRP USB Interface USB capabilities USB 2.0: 480 Mbit/s FPGA firmware: 32 MB/s (= 256 Mbit/s) useful data rate 32 bit complex samples (16 bits each for real/imag) Limit: 8 MS/s (combined for all tx/rx streams on one computer) USB transmission order: I0 Q0 I1 Q1 I0 Q0 I1 Q1 16 bits 16 bits 16 bits 16 bits 16 bits 16 bits 16 bits 16 bits TSKS01 Digital Communication - Lecture 5 13 The USRP Daughter Boards 1(2) Base-band boards: BasicTX/BasicRX, LFTX/LFRX Bandwidth: 250 MHz (Basic), 30 MHz (LF) Can not connect directly to antenna WBX - Wide-band transceiver 50 MHz 2.2 GHz Relatively poor performance TVRX MHz receiver Bandwidth: 6 MHz Suitable for receiving TV signals RFX-series - General full-duplex transceivers Bandwidth: 30 MHz Bands: MHz, MHz, MHz, GHz, GHz Used in lab TSKS01 Digital Communication - Lecture 5 14 The USRP Daughter Boards 2(2) LFTX RFX-2400 LFRX TSKS01 Digital Communication - Lecture 5 15 GNU Radio Software Layers Config & UI Python Glue SWIG SWIG SWIG Signal Processing Primitives C++ C++ C++ Data flow Buffers on all block outputs Hardware USRP USRP TSKS01 Digital Communication - Lecture 5 16

5 GNU Radio Flowgraphs Data types may vary along a flowgraph. Bits Complex symbols Complex samples Data source Error control Framer Bit mapper Modulator Filter USRP Data types must match in each connection TSKS01 Digital Communication - Lecture 5 17 GNU Radio Hello World! from gnuradio import gr from gnuradio import audio class my_top_block(gr.top_block): def init (self): gr.top_block. init (self) gr.sig_source_f gr.sig_source_f audio.sink sample_rate = ampl = 0.1 src0 = gr.sig_source_f(sample_rate, gr.gr_sin_wave, 350, ampl) src1 = gr.sig_source_f(sample_rate, gr.gr_sin_wave, 440, ampl) dst = audio.sink(sample_rate) self.connect(src0, (dst, 0)) self.connect(src1, (dst, 1)) tb = my_top_block() tb.run() TSKS01 Digital Communication - Lecture 5 18 GNU Radio Block Naming Convention Block names: lib.block_suffix lib is the library: gr for most primitive signal processing blocks blks2 for high-level signal processing blocks usrp for USRP interfacing blocks audio for audio sources and sinks qtgui for GUI library (relatively bare) wxgui for old GUI library Projects usually use their own library suffix determines port types b for byte, s for 16-bit int,ifor 32-bit int,ffor 32-bit float, c for 64-bit complex x for sources and sinks xx for two-port blocks xxx for parameterized blocks (e.g. ccf for FIR filter with complex data and float coefficients) vx,vxx for blocks with vector ports TSKS01 Digital Communication - Lecture 5 19 GNU Radio Some Useful Blocks gr.noise_source_f : Generates random float samples with specified distribution. gr.add_cc : Adds two streams of complex samples. gr.nlog10_ff : Computes db of a stream of floats. gr.fir_filter_ccc : FIR filter with complex input, output and coefficients. audio.source : Stream of floats from line-in/mic. usrp.sink_c : USRP sink for complex stream. qtgui.sink_c : GUI element with oscilloscope, FFT and constellation diagram TSKS01 Digital Communication - Lecture 5 20

6 GNU Radio Nested Blocks Gr.hier_block2 Block1 Block4 Block3 Block2 class my_hier_block(gr.hier_block2): def init (self): gr.hier_block2. init (self, my_hier_block, gr.io_signature(1, 1, gr.sizeof_char), gr.io_signature(1, 1, gr.sizeof_gr_complex) ) # Block definitions self.connect(self,...) self.connect(..., self) TSKS01 Digital Communication - Lecture 5 21 GNU Radio Connecting Blocks Block1 Block2 Block3 self.connect(block1, Block2, Block3) Block2 Block1 self.connect(block1, Block2) self.connect(block1, Block3) Block3 Restriction: Both Block2 and Block3 must consume the data. If Block2 does not, then Block3 will stall TSKS01 Digital Communication - Lecture 5 22 GNU Radio Run-Time Behaviour Heavily threaded Each block runs in separate thread Most blocks have threadsafe configuration functions Starting a flow graph: gr.top_block.run(): Spawns threads, waits for completion gr.top_block.start(): Spawns threads and returns Stopping it: gr.top_block.stop() from gnuradio import gr from gnuradio import audio class my_top_block(gr.top_block): def init (self): gr.top_block. init (self) self.src = gr.sig_source_f(48000, gr.gr_sin_wave, 350, 0.1) self.dst = audio.sink(48000) self.connect(self.src0, self.dst) tb = my_top_block() tb.start() f = 440 while f>0: c = raw_input( Enter frequency: ) f = float(c) tb.src.set_frequency(f) tb.stop() TSKS01 Digital Communication - Lecture 5 23 Python Python is A full-blown high-level programming language Half-compiled, half-interpreted Python supports Object-oriented programming Procedural programming Functional programming (to some extent) Interactive testing of code Python is used for Scripting Web-development Full-blown computer applications with GUIs and what-not. Python is used by Google, YouTube, NASA, Disney, Hubble, CommSys, TSKS01 Digital Communication - Lecture 5 24

7 TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture 5 28

8 TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture 5 32

9 TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture 5 36

10 TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture 5 40

11 TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture 5 44

12 TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture 5 48

13 TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture TSKS01 Digital Communication - Lecture 5 52

14 TSKS01 Digital Communication - Lecture 5 53