01/10/2013

Ebro Observatory, October 1st, 2013

Short Wave critical Infrastructure Network based on new Generation of high survival radio communication system

New Technology involved in SWING: Software Radio and HF Links

A.L. Saverino

A.Capria, F.Berizzi, M. Martorella, E. Dalle Mese

With the support of the Prevention, Preparedness and Consequence Management of Terrorism and other Security-related Risks ProgrammeEuropean Commission - Directorate-General Home Affairs

Aim and Contents

Aim How to realize a HF communication link between the ECIs and the

CGA by using the USRP hardware and LabVIEW.

HF communication link Scenario;

Contents USRP and LabVIEW environment;

Theoretical and Practical implementation: Experiment;

Ionospheric Channel Constraints

Long haul communications in the HF band

•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.

HF Communication Link Scenario

Ionospheric Channel Properties

Reduced Simulated Scenario

•Connection type: point-to-point;•Carrier frequency : single; •Modulation type: PSK.

Universal Software Defined Radio Peripheral

USRP and LabVIEW Environment

USRP Definition

• General purpose hardware for SDR implementation;

• Low cost and extremely flexible solution.

USRP and HF band Ideal candidate for the implementation of HF communication because it can directly sample the entire HF band.

USRP Software 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.

Theoretical and Practical implementation: Experiment

Requirements of the HF link

•Connection type: point-to-point;•Carrier frequency: single; •Modulation type: PSK.

Experiment Setup

NI USRPN210Transmitter

LFTX daughterboard

NI USRPN210Receiver

LFRXdaughterboard

Gigabit EthernetConnections to Host PC

Typical Block Diagram 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.

Aim of the experiment

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Communications Channel

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Messag

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Host PC

Message

Message

USRP IP Address

1.I/Q rate:Specifies the sample rate of the baseband I/Q data for Tx or Rx in samples per second (S/s);

2. Frequency Carrier:Carrier frequency in Hz of the RF signal;

3.Gain:Specifies the gain, in dB, applied to the RF signal for Rx and Tx;.

4.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;

Actual TX ParametersRefers to a Tx/Rx values supported by the device.

Constellation Graph:Specifies the detected symbol locations and the transitions between those symbols;

TX ParametersSet USRP hardware parameters, and Tx Parameters.

Packet ParametersSets the lengths of the bit fields that comprise the packets to transmit.

Guard Band:Protects against the filter effect

Sync Seq:Is the sequence for the carrier and clock recovery ;

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;

Order

Constellation Graph:Shows how the detected symbol locations and the transitions between those symbols are modified by the presence of the noise.

Modulation Type

Pulse Shaping Filter:This filter is applied to each symbol to:1.Reduce the amplitude and

phase transition of modulated signal (the majority of the channel power is now limited to a specific defined bandwidth);

2.Reduce Inter-Symbol Interference (ISI)

Spectrum without noise:Spectrum of transmitted base-band complex waveform without noise at transmitter;

Type of modulationSets the type of modulation and parameters for a pulse shaping filter.

Error out:Represents error information;

Spectrum with noise :Spectrum of transmitted base-band complex waveform with noise;

Debug

RX DisplayDespalys the resulting recovered text message, the live raw / received signal and a constellation graph of one of the recovered packets.

Received Message

Raw Received Signal

Constellation Graph

Error out:Represents error information;

Sync Found:Checks for valid packet;

Correct Packet RxRepresents the number of the correct received packets;

Debug

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.