01/10/2013 Ebro Observatory, October 1st, 2013 New Technology involved in SWING: Software Radio and...
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- Slide 1
- 01/10/2013 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 With the support
of the Prevention, Preparedness and Consequence Management of
Terrorism and other Security-related Risks Programme European
Commission - Directorate-General Home Affairs
- Slide 2
- 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;
- Slide 3
- 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.
- Slide 4
- 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 InterfaceBlock diagram
include terminals, functions, constants, structures, and wires,
which transfer data among other block diagram objects.
- Slide 5
- 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 Transmitter LFTX daughterboard NI USRPN210 Receiver
LFRX daughterboard Gigabit Ethernet Connections to Host PC
- Slide 6
- 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.
- Slide 7
- Aim of the experiment Convert Message to Bits Generate
PacketsMap Bits to Symbol Resample to IQ rate Apply Pulse Shaping
FilterUpconvert and transmit NI USRPn210 HW (FPGA, DAC, ADC, LFTX
daughterboard) Communications Channel Receive and Downconvert
Synchronization And Demodulation Rearrange Packets Desplay Message
Host PC Message
- Slide 8
- 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; E b /N 0 : Specifies the desired E b /N 0 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; TX Parameters Set USRP hardware parameters, and Tx
Parameters.
- Slide 9
- 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;
Order Constellation Graph: Shows how the detected symbol locations
and the transitions between those symbols are modified by the
presence of the noise.
- Slide 10
- 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
modulation Sets the type of modulation and parameters for a pulse
shaping filter.
- Slide 11
- Error out: Represents error information; Spectrum with noise :
Spectrum of transmitted base- band complex waveform with noise;
Debug
- Slide 12
- RX Display Despalys 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
- Slide 13
- Error out: Represents error information; Sync Found: Checks for
valid packet; Correct Packet Rx Represents the number of the
correct received packets; Debug
- Slide 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.