Loran Integrity Performance Panel Loran Integrity & Performance Panel (LORIPP) Per Enge, Stanford...
-
Upload
sherilyn-dean -
Category
Documents
-
view
220 -
download
1
Transcript of Loran Integrity Performance Panel Loran Integrity & Performance Panel (LORIPP) Per Enge, Stanford...
Loran Integrity Performance Panel
Loran Integrity & Performance Panel (LORIPP)
Per Enge, Stanford University, November 2003
Based on the work of: Federal Aviation Administration, U.S. Coast Guard,
Peterson Integrated Geopositioning, Booz Allen Hamilton, Ohio University,JJMA, ITT, University of Wales, Reelektronika & Stanford University
But the opinions may be mine alone & and the mistakes certainly are!
Loran Integrity Performance Panel 2
RNP 0.3 Requirements
Performance Requirement Value
Accuracy (target) 307 meters
Monitor Limit (target) (HAL) 556 meters
Integrity • for all users in the coverage area (cannot
average Boulder against Colorado Springs)• at all times (cannot average solar peak
against quiet times)• under all conditions (in the presence of
hazards)
10-7/hour
Time-to-alert 10 seconds
Availability at primary or alternate airport (minimum/target)
99.9/ 99.99%
Continuity (minimum/target) 99.9/ 99.99%
Integrity Hazards(from Sherman Lo)
TransmitterBias& Jitter
SkywaveInterference
Atmospheric Noise
Propagation Prediction Errors
Local Noise, P-static,Receiver Noise & Bias
LORIPP work is organized around these hazards with a system engineering group predicting coverage.
Loran Integrity Performance Panel 4
10-7?10-7 means:• Use the best available engineering to think
through the corner cases. • Find the data that describes the hazard.• If the right data does not exist, collect some. • Design monitors to address any real integrity
issues.• Remember, over design hurts continuity,
availability and coverage.
Loran Integrity Performance Panel 5
Error Bounds, Not Accuracy
One or more cycle errors:• Envelope TOA at short ranges• Residuals test at long ranges
2
All cycles correct, but
fails to overbound the true error.
i i i i i ii i i
HPL K K K
Prob(HPE > HPL) < 10-7 per hour
are unbiased
& independent:i are completely
correlatedi are potentially
correlated or biasedi
transmitter
receiver noise & RFI
temporal ASF residual of temporal ASF
spatial ASF
Loran Integrity Performance Panel 6
Integrity Analysis
• is best taught by example.
• My favorite example (hazards) are: evil waveforms for GPS early skywave for Loran remember these are only two examples from two
long hazard lists.
Loran Integrity Performance Panel 7
DGPS Position Error Measured by Trimble at the 1993 Oshkosh Air Show
SV19 Visibility Period
Alt
itu
de
(met
ers)
Local time of day19 0 5 10 15
Differential vertical errorup to 8.5 meters
Loran Integrity Performance Panel 8
C/A and P(Y) Measurement from Camp Parks
Loran Integrity Performance Panel 9
C/A and P(Y) Measurement from Camp Parks
Loran Integrity Performance Panel 10
Modeling Evil Waveforms(from Eric Phelts)
-1.5 -1 -0.5 0 0.5 1 1.5
0
0.2
0.4
0.6
0.8
1
Correlation Peaks
Code Offset (chips)
Nor
mal
ized
Am
plitu
de0 1 2 3 4 5 6
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
C/A PRN Codes
Chips
Vol
ts
1/fd
Loran Integrity Performance Panel 11
Signal Quality Monitoring(from Eric Phelts)
SQM2b
SQM2b E-L Spacings:
0.1 chips*
0.15 chips
0.2 chips
Spacing (chips)
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
0
0.2
0.4
0.6
0.8
1
48 Correlator Receiver Spacings
Nor
mal
ized
Mag
nit
ud
e
Loran Integrity Performance Panel 12
WAAS Safety Processor
WREs, level D
SV orbitdetermination& corrections
Iono.correct.& GIVE
UDRERange
DomainPositionDomain
+
CNMP
UDRE
+ +
+ +
Safety ProcessorDO 178 level B
L1/L2Biases
GIVE
Corrections ProcessorDO 178, level D
Loran Integrity Performance Panel 13
Error Bounds, Not Accuracy(from Sherman Lo)
LORAN WAAS with Latency Removed
Loran Integrity Performance Panel 14
Back to Loran – Early Skywave
0 10 20 30 40 50 60Timeus1.5
1
0.5
0
0.5
1
naroL
tnerruCGroundwave and Early Skywave
Loran Integrity Performance Panel 15
ECD Perturbations at Fairbanks(from Bob Wenzel)
7960-Z ECD at Fairbanks 11-12 January 2002
-0.5
0
0.5
1
1.5
2
2.5
11.65 11.7 11.75 11.8 11.85 11.9 11.95 12 12.05 12.1
Large solar proton event on Jan. 10
time in days UT (n.0 is early afternoon on n-1 in Western Alaska)
Loran Integrity Performance Panel 16
TD Perturbations at Fairbanks(from Bob Wenzel)
7960-Z TD at Fairbanks 11-12 January 2002
49922.65
49922.7
49922.75
49922.8
49922.85
49922.9
49922.95
11.65 11.7 11.75 11.8 11.85 11.9 11.95 12 12.05 12.1
300
nsec
time in days UT (n.0 is early afternoon on n-1 in Western Alaska)
Loran Integrity Performance Panel 17
Previous plots blown up
Caribou (9960W) to Sandy Hook 463NM or
857 km
from Bob Wenzel
7960-Z ECD at Fairbanks 10-11 January 2002
0
0.5
1
1.5
2
2.5
10.65 10.75 10.85 10.95 11.05 11.15 11.25 11.35 11.45
9960-W ECD at Sandy Hook January 2002
-1.5
-1
-0.5
0
0.5
1
10.65 10.75 10.85 10.95 11.05 11.15 11.25 11.35 11.45
Loran Integrity Performance Panel 18
Monitor Using 228 Paths < 900 NM(from Ben Peterson)
-130 -120 -110 -100 -90 -80 -70 -60 -50
25
30
35
40
45
50
55
+ Caribou
+ Nantucket
+ Cape Race
+ Fox Harbor+ Williams L
+ Shoal Cove
+ George
+ Port Hardy
+ Malone + Grangevlle
+ Raymondvll+ Jupiter
+ Carolina B
+ Havre + Baudette
+ Boise City
+ Gillette
+ Dana + Fallon + Middletown
+ Searchlght
+ Las Cruces
+ Seneca
+ Comfort Cv
+ Point Pinos
+ Point Cabrl + Grand Junct
+ Bismarck + Spokane
+ Sandspit
+ Whidbey Is.
+ Cape Eliz
+ Montague
+ St Anthony
+ Red Head
+ Mayport + New Orleans
+ Destin
+ Dunbar For
+ Plumbrook
+ Little Rock
+ Midland
+ Sandy Hook
Loran Integrity Performance Panel 19
Early Skywave Cures
• Monitor at LorStas and SAMs (not at airports!)
• Range limits• Sample earlier (at 20 or 25 microseconds) &
maybe speed the rise time of the pulse.• Channel sounding pulse• Receiver autonomous detectionSee talks by Peter Morris, Bob Wenzel, Frenand
Le Roux & Ben Peterson for much more.
Loran Integrity Performance Panel 20
Summary10-7 means:• Use the best available engineering to think through the
corner cases. • Find the data that describes the hazard.• If the right data does not exist, collect some. • Design monitors to address any real integrity issues.• Remember, over design hurts continuity, availability and
coverage.For Loran• We are well underway.• We have the right people, working the right issues.• But it is a big job
Loran Integrity Performance Panel 21
Backup Viewgraphs
Loran Integrity Performance Panel 22
Major Hazards
1. Temporal Variations of Groundwave including ASF, ECD and SS
2. Spatial Variations of ASF, ECD & SS3. Weather related noise (p-static & atmospheric)4. Early skywave5. Aircraft dynamics6. Man-made RFI7. Transmitter Hazards
LORIPP work is organized around these hazards with a system engineering group predicting coverage.
Loran Integrity Performance Panel 23
-15 -10 -5 0 5 10 1510
-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
SNR = 6dB
SNR = -6dB
Probability density of TOA for average over 500 pulses
usec relative to selected zero crossing
Typical Distributions of TOA Measurement(from Ben Peterson)
Prob
abil
ity
Den
sity
of
TO
A
Accuracy = fn(Phase
uncertainty)
Pcycle error = fn(Envelope uncertainty)
Blue - Low SNR, Red - High SNR
Loran Integrity Performance Panel 24
Threat Flow from GPS Work
Ground controlsegment• upload
GPSsatellite• nav. message• signal dist.
ionosphere& troposphere
Airborneradioenviron.• RFI• multipath
Groundradioenviron.• RFI• multipath
Ref. rcvr.• Level D code• cycle slips
Faultdetection
Databroadcast
Datafaults
Airbornercvr.
Airbornefault
detection
Loran Integrity Performance Panel 25
Monitor Performancenominalprob. densityfunction
faultedprob. densityfunction
Pr(false alarm)
Pr(miss detect)
Loran Integrity Performance Panel 26
Simulation Data for Locus LRS IIID (from Bob Wenzel)