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Ebro Observatory, October 1st, 2013

New Technology involved in SWING: Software Radio and HF Links. A.L. Saverino A.Capria , F.Berizzi , M . Martorella, E. Dalle Mese. Ebro Observatory, October 1st, 2013. With the support of the Prevention, Preparedness and Consequence Management

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Ebro Observatory, October 1st, 2013

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  1. New Technology involved in SWING: Software Radio and HF Links A.L. Saverino A.Capria, F.Berizzi, M. Martorella, E. Dalle Mese Ebro Observatory, October 1st, 2013 With the support of the Prevention, Preparedness and Consequence Management of Terrorism and other Security-related Risks Programme European Commission - Directorate-General Home Affairs

  2. Aim and Contents How to realize a HF communication link between the ECIs and the CGA by using the USRP hardware and LabVIEW. Aim HF communication link Scenario; USRP and LabVIEW environment; Contents Theoretical and Practical implementation: Experiment;

  3. HF Communication Link Scenario Ionospheric Channel Properties Long haul communications in the HF band Ionospheric Channel Constraints • Signal loss due to the dispersion of the propagation medium; • Formation of multiple beams because of the refraction from different ionospheric layers (the phenomenon of multipath); • Strong presence of external noise (atmospheric, cosmic and man-made); • Congestion of HF band. ReducedSimulated Scenario • Connection type: point-to-point; • Carrier frequency : single; • Modulation type: PSK.

  4. USRP and LabVIEW Environment USRP Definition Universal Software Defined Radio Peripheral • General purpose hardware for SDR implementation; • Low cost and extremely flexible solution. USRP Software USRP and HF band Ideal candidate for the implementation of HF communication because it can directly sample the entire HF band. GNU radio, Simulink and LabVIEW NI LabVIEW Environment Definition: LabVIEW is a powerful graphical software development environment which can be used for acquisition, analysis, display and store data and for instrument control. LabVIEW Programs: Virtual Instruments or VIs (Front Panel and Block Diagram) User Interface Block diagram include terminals, functions, constants, structures, and wires, which transfer data among other block diagram objects.

  5. Theoretical and Practical implementation: Experiment • Connection type: point-to-point; • Carrier frequency: single; • Modulation type: PSK. Requirements of the HF link Experiment Setup NI USRPN210 Receiver LFRX daughterboard NI USRPN210 Transmitter LFTX daughterboard Gigabit Ethernet Connections to Host PC

  6. TypicalBlockDiagram of USRP device Transmitter Block of USRP • Host PC generates in baseband the modulated waveforms; • The Gigabit Ethernet transfers the waveform to the FPGA of the USRP; • The FPGA sets the sample rate according to the rates of the DACs and the Ethernet network; • Two 16-bit DACs at 400Ms/s convert the digital I/Q components into the analog domain; • The mixer up-converts the signal to RF Receiver Block of USRP • A quadrature mixer extracts the complex envelope; • Two 14-bit ADCs samples the I/Q component with a rate of 100Ms/s: • Two DDC decimates the ADCs sampling rate; • The Ethernet network transfers the I/Q samples of complex envelope to the Host PC; • The Host PC processes the signal.

  7. Aim of the experiment Message NI USRPn210 HW (FPGA, DAC, ADC, LFTX daughterboard) Map Bits to Symbol Generate Packets Apply Pulse Shaping Filter Resample to IQ rate Convert Message to Bits Upconvert and transmit Host PC Communications Channel Synchronization And Demodulation Receive and Downconvert Rearrange Packets Desplay Message Message

  8. TX Parameters Set USRP hardware parameters, and Tx Parameters. Actual TX Parameters Refers to a Tx/Rx values supported by the device. USRP IP Address Constellation Graph: Specifies the detected symbol locations and the transitions between those symbols; • I/Q rate: Specifies the sample rate of the baseband I/Q data for Tx or Rx in samples per second (S/s); • Frequency Carrier: Carrier frequency in Hz of the RF signal; • Gain: Specifies the gain, in dB, applied to the RF signal for Rx and Tx;. • Tx antenna: Refers to the connectors on the device front panel; Eb/N0: Specifies the desired Eb/N0 of the output complex waveform in dB;

  9. Packet Parameters Sets the lengths of the bit fields that comprise the packets to transmit. Constellation Graph: Shows how the detected symbol locations and the transitions between those symbols are modified by the presence of the noise. Guard Band: Protects against the filter effect Sync Seq: Is the sequence for the carrier and clock recovery ; Order Packet Number: Is used to reorder the packets and to detect missing packets Data: Represents the length of the useful data; Pad Data: Represents the number of the samples appended at the end of the signal in order to have a constant packet size;

  10. Type of modulation Sets the type of modulation and parameters for a pulse shaping filter. Spectrum without noise: Spectrum of transmitted base-band complex waveform without noise at transmitter; Modulation Type Pulse Shaping Filter: This filter is applied to each symbol to: • Reduce the amplitude and phase transition of modulated signal (the majority of the channel power is now limited to a specific defined bandwidth); • Reduce Inter-Symbol Interference (ISI)

  11. Debug Error out: Represents error information; Spectrum with noise : Spectrum of transmitted base-band complex waveform with noise;

  12. RX Display Despalys the resulting recovered text message, the live raw / received signal and a constellation graph of one of the recovered packets. Raw Received Signal Received Message Constellation Graph

  13. Debug Correct Packet Rx Represents the number of the correct received packets; Error out: Represents error information; Sync Found: Checks for valid packet;

  14. Conclusions • Theoretical and Practical implementation of a HF communication link have been studied; • A reduced simulated scenario has been evaluated; • USRP hardware and LabVIEW have been used; • The functionality of the system has been experimentally demonstrated in a closed-loop configuration. Moreover the effect of additive white Gaussian noise has been evaluated by using a set of different signal to noise ratio. • Connection type: point-to-point; • Carrier frequency : single; • Modulation type: PSK. USRP Features: • General purpose hardware for SDR implementation; • Low cost and extremely flexible solution. LabVIEW Features: • General purpose software for data processing and instruments control.

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