Transcript New Technology involved in SWING: Software Radio and HF Links

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
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
01/10/2013
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;
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.
Reduced Simulated Scenario
•Connection type: point-to-point;
•Carrier frequency : single;
•Modulation type: PSK.
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
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
USRP and HF band
Block diagram include terminals, functions,
constants, structures, and wires, which
transfer data among other block diagram
objects.
Ideal candidate for the implementation of HF communication
because it can directly sample the entire HF band.
Theoretical and Practical
implementation: Experiment
Requirements of the HF link
•Connection type: point-to-point;
•Carrier frequency: single;
•Modulation type: PSK.
Experiment Setup
NI USRPN210
Receiver
LFRX
daughterboard
NI USRPN210
Transmitter
LFTX
daughterboard
Gigabit Ethernet
Connections 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.
Resample to IQ rate
Map Bits to Symbol
Generate Packets
Convert Message to Bits
DAC,
Message
NI USRPn210 HW (FPGA,
ADC, LFTX daughterboard)
Upconvert and transmit
Apply Pulse Shaping Filter
Host PC
Desplay
Message
Rearrange
Packets
Synchronization
And
Demodulation
Receive and
Downconvert
Aim of the experiment
Communications Channel
Message
TX Parameters
Set USRP hardware parameters, and Tx Parameters.
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 Parameters
Refers to a Tx/Rx values supported
by the device.
Constellation Graph:
Specifies the detected symbol
locations and the transitions
between those symbols;
Packet Parameters
Sets 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;
Constellation Graph:
Shows how the detected
symbol locations and the
transitions between those
symbols are modified by the
presence of the noise.
Type of modulation
Sets the type of modulation and
parameters for a pulse shaping
filter.
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 baseband complex waveform without
noise at transmitter;
Debug
Error out:
Represents error information;
Spectrum with noise :
Spectrum of transmitted baseband complex waveform with
noise;
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
Debug
Correct Packet Rx
Represents the number
of the correct received
packets;
Error out:
Represents error information;
Sync Found:
Checks for valid packet;
Conclusions
•Theoretical and Practical implementation of a HF communication link have been
studied;
•A reduced simulated scenario has been evaluated;
•Connection type: point-to-point;
•Carrier frequency : single;
•Modulation type: PSK.
•USRP hardware and LabVIEW have been used;
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.
•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.