1. Performance requirements update
26/08/2014

2. Overview

3. Time-to-first-fix (PAR#5)
New values for other receiver classes (stand-alone GNSS and A-GNSS)
New user dynamics (pedestrian) for indoor environments according to (table 5.1 to be amended with a column for indoor/outdoor)
Tables updated

4. Robustness to Interference (PAR#8)
Jammer scenarios definition
Identification of applicable classes of positioning terminals for simulations
Performance parameters definition
Post-processing of the results and minimum performance requirements derivation for the applicable classes

5. Jammer scenarios
Based on PPDs (Personal Privacy Devices) surveys available on literature
D. Borio, J. Fortuny-Gausch and C. O’Driscoll "Characterization of GNSS Jammers", Coordinates, Vol. XI, Issue 5, May 2013, pp. 8-16
T. Kraus et al., Survey of In-Car Jammers — Analysis and Modeling of the RF Signals and IF Samples (Suitable for Active Signal Cancelation), Proceedings of ION-GNSS 2011 September 2011
Mitch, R. H., Dougherty, R. C., Psiaki, M. L., Powell, S. P., O’Hanlon, B. W., Bhatti, B. W. and Humphreys T. E. (2011). Signal characteristics of civil GPS jammers. Proceedings of the 24th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION/GNSS), pages , Portland, OR.
Pullen, S. and Gao G. (2012). GNSS jamming in the name of privacy. Inside GNSS, pages
Chirp signals with different characteristics
No.
Class
Center frequency
Bandwidth
Sweep time(s)
PPeak [dBm] 1 I
GHz
0.92 kHz -
-12.1 dBm 2 II
GHz
11.82 MHz
TSW = 11.71µs
-14.4 dBm 3
GHz
44.9 MHz
TSW = 18.97µs
-9.6 dBm 4
GHz
-25.6 dBm 5
III
GHz
10.02 MHz
TSW1 = 8.7 µs (TSW1,up = 6.8µs, TSW1,down = 1.9µs) TSW2 = 34.8µs
-19.3 dBm 6 IV
GHz
( GHz)
11.31 MHz
(– MHz)
TSW1 = 8,7408µs TSW4,1 = ms TSW2 = 43.78µs TSW4,2 = ms TSW3 = 139.9– 183.7µs TSW4,3 = ms
-9.5 dBm 7
GHz
10.72 MHz
TSW = 8.62µs
-30.8 dBm

6. Jammer position and relative power
Testing scenario defined as a repetition of N successive overtaking of the jammer
Relative power accounts for free space propagation losses and the initial jammer power
relative Doppler is negligible if compared to the frequency range swept by the jammer
DoA of the jammer considered for Beam-forming antenna
Class
Center Frequency
Bandwidth
Sweep time(s)
Peak [dBm]
Chirp signal with one saw-tooth function – case 1
MHz
11.82 MHz
11.71µs
-14.4
Chirp signal with one saw-tooth function – case 2
44.9 MHz
18.97 µs
-9.6

7. Performance parameter definitions
Availability of the position fix
Accuracy degradation of the position fix in dependence of the interference power level (jammer distance and J/S)
Loss of lock and reacquisition probability according to the interference power level (jammer distance and J/S)

8. Test results
Test results with different high sensitivity receivers (only GPS L1) -160 dBm trk. Sensitivity and narrowband (can filter out part of the jammer power)
UBLOX: Ublox 5H, 5T
Mediatek MT3329 (Fastrax IT500)
STM TeseoII (Fastrax IT600) with notch filter
NOKIA N8 GPS
NovAtel OEM4

9. Single frequency position accuracy
The solution availability when the maximum J/S was around 25 dB was only 16%

10. Applicable classes of terminals
Standard GNSS receiver single constellation
Standard GNSS receiver multiple constellation (the impact of the jammer is not the same at the same time on all the satellites – different instantaneous spectral separation coefficients. It depends on the sweeping time of the jammer and on its bandwidth)
Standard GNSS receiver multiple constellation + Notch filters (expected gain of 5 dB)
Standard GNSS receiver multiple constellation + Notch filters + beam-forming antenna

11. Notch filter analysis – based on STM Teseo II
Multi-constellation receiver (GPS + Galileo + GLONASS)
notch filter to track and eliminate narrow-band interferers from the GPS/Galileo and GLONASS RF paths
Command to enable / disable notch
proprietary message that reports the current status of the notch filter indicating the intermediate frequency value tracked by the notch filter and estimated power of the interferer

12. Beam forming antenna Antenna Solutions:
CRPA (Controlled Radiation Pattern Antenna) - null steering or sidelobe cancellation
Adaptive Beamforming - beamforming the receiver antenna towards GPS satellites
Example (military applications) for Controlled Reception Pattern Antenna: Novatel GAJT (Anti-Jam Antenna)
7 antenna elements (Maximal 6 interferers simultaneous)
Interference suppression 40 dB (typical)
Way-forward for simulation:
definition of a beam-nulling or forming algorithm
Computation of the beam and reduction of the Jammer and SV signals

13. GNSS Sensitivity (PAR#10)
Defined scenarios based on AWGN channel with decreased GNSS SV signal power
Simulation to be finished

14. Position Integrity Protection Level and Position Integrity Time-to-Alert (TTA) and (PAR#11 & 12)
To be completed (not yet started)