Pirazzi Gabriele Intecs S.p.A Bruxelles, 10/04/2008 “Study of an SDR GNSS receiver” Chapter of Rome M.Sc. In Advanced Communication and Navigation Satellite Systems AFCEA’s Student Conference 2008

Slide 2 of 20 Agenda SDR Definitions SDR Applications GNSS receiver Acquisition Phase GPS Giove-A(Galileo) SBAS Tracking Phase GPS Giove-A(Galileo) SBAS Space Software Receiver

Slide 3 of 20 Definitions Software Radio: the digitization is at the antenna and all of the processing required is performed for the radio by software. Software Defined Radio: the digitization is performed at some stage downstream from the antenna, typically after wideband filtering, low noise amplification, and down conversion to a lower frequency in subsequent stages.

Slide 4 of 20 SDR purpose The purpose of the Software Radio: Move the ADC (analog-to-digital) as close as possible to the antenna. Elaborate the samples obtained through a reprogrammable processor. Advantages: Removing analog components with non-linear characteristics, depending on the temperature and age. Single antenna for multi-constellation, multiband and multi- modes systems. High flexibility in the implementation of new algorithms: update software without replace hardware. Reducing costs and maintaining

Slide 5 of 20 Applications (1) Telecommunication RadarNavigation SDR One Terminal, multiple Applications.

Slide 6 of 20 Applications (2) User Terminal Hardware Layer Software Layer (management, control and configuration) Application Layer Installing, upgrading software module GPS Galileo UAV Radar SatCom Control Center

Slide 7 of 20 GNSS Receiver Structure Channel n Software Correlator Canale 2 Software Correlator Down conversion Frequency synthesizer Reference oscillator LNA A/D converter AGC Channel 1 Software Correlator IF Analogue RF Acquisition Tracking IF Digital Navigation processing HardwareSoftware

Slide 8 of 20 RF Carrier: Single IF conversion: Bandwidth (-3dB): 2 bit ADC (sign and mag) Sampling frequency: AGC TCXO Front-end

Slide 9 of 20 Acquisition phase Acquisition scope: Determinate the number of visible satellites. Coarse estimate of the beginning C/A code. Coarse estimate of the carrier included Doppler.

Slide 10 of 20 GPS, Giove-A real data acquisition

Slide 11 of 20 Incoherent Integration SBAS

Slide 12 of 20 Unexpected Signal: GAGAN! Geostationary satellite acquired, tracked and decoded:  AOR-E  Artemis  IOR-W  Gagan Constellatio n NamePRN Orbital Position Egnos Inmarsat-3-F2 (AOR-E) °W EgnosArtemis °E Egnos Inmarsat-3-F5 (IOR-W) 12625°E WAASAnik F1R °W WAASGalaxy °W MSASMTSAT-1R129140°E MSASMTSAT °E GaganInmarsat-4-F112764°E First signal transmitted at the end of December 2007 Analisis of Message 18 (Ionosperic Grid Points Mask, IGP) and Message 9 (Geo Navigation Message) confirm it’s Gagan! EGNOS GAGAN

Slide 13 of 20 Tracking Tracking scope:  Tracking over time the carrier and the GPS code. Implemented Tracking closed loop:  PLL (Phase Lock Loops) Costas 2° order.  DLL (Delay Lock Loops) incoherent 2° order.  FLL (Frequency Lock Loops) del 1° order.

Slide 14 of 20 Tracking Giove-A E1B

Slide 15 of 20 Tracking GPS real data

Slide 16 of 20 Giove-A Message Decoded (Viterbi) Packets 5-8 First Frame Packets 1-4 Packets 5-8 Carrier StatusNav. Data Health

Slide 17 of 20 MIOSat mission MIssione Ottica su microSATellite

Slide 18 of 20 SSR Requirements FunctionValue Dimensions100x100x90mm Weight<0.7 Kg Antenna weight<50g (cable excluded) Power5 V Power consumption<12W Antenna gain> 5 dBi at Zenith Noise figure< 2.5 dB Operative frequencyL1 GPS e GALILEO GNSS systemsGPS (GALILEO HW-ready) Receiver linearityTBD ADC quantization bits1 AGCEmbedded in the receiver Sampling frequency16.8 MHz (TBC) Oscillator stabilityTCXO typical Electric interfaceRS 422 Launch vibrations complianceTBD (reference VEGA launcher suggested) Mission lifetime6 months ground, 2.5 years in flight Operating temperature-20°/+50° Radiation tolerance>10 Krad

Slide 19 of 20 SSR Scheme Satellite or System on Chip (SoC). Less volume and mass. Reduced power consumption. Fewer interconnects, solder joints e bound wires. Soft-core CPU: Leon3

Slide 20 of 20 Pirazzi Gabriele Intecs S.p.A. Bruxelles, 10/04/08 “Study of an SDR GNSS receiver” Q & A SESSION Thank you for your attention