Toulouse/Montauban, France, July 16 – 26, 2012 INTERNATIONAL SUMMER SCHOOL ON GNSS GNSS Signals Christopher J. Hegarty The MITRE Corporation
Toulouse/Montauban, France, July 16 26, 2012
INTERNATIONAL SUMMER SCHOOL ON GNSS
GNSS Signals
Christopher J. Hegarty
The MITRE Corporation
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 2
OVERVIEW
Modulation basics GPS signals GLONASS signals GALILEO signals COMPASS signals IRNSS signals QZSS signals
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 3
OVERVIEW
Modulation basics GPS signals GLONASS signals GALILEO signals COMPASS signals IRNSS signals QZSS signals
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 4
Binary Phase Shift Keying (BPSK)
carrier
T0
=
data bits, d(t)
(+1 or -1)
BPSK signal, s(t)
(180 deg phase
shift when data
bit changes)
Td
f0= 1/T0 = carrier frequency (Hz) Rd= 1/Td = data rate (bits/s)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 5
Direct Sequence Spread Spectrum
=
carrier
spread spectrum
waveform
Tc
Td
data waveform
modulated spread
spectrum signal
Rc= 1/Tc = chipping rate (chips/s)
T0
f0= 1/T0 = carrier frequency (Hz)
Rd= 1/Td = data rate (bits/s)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 6
Autocorrelation and Power Spectrum
Let s(t) be a BPSK signal created with random data waveform d(t).
Autocorrelation of data waveform:
else
TT
tdtdER
dd
,0
,1
)()()(
Power spectrum:
2
2
2
)(
)(sin
)()(
d
dd
fj
fT
fTT
deRfS
Power spectrum describes how total power in signal is distributed in frequency domain.
Note that ~90% of a BPSKs signal power is within +/-Rd Hz of carrier.
R()
0 Td -Td
S(f)
f Rd -Rd
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 7
Why Spread?
Direct sequence spreading allows precise ranging
Use of different spreading waveforms for each satellite can provide a multiple access capability Multiple satellites can broadcast ranging signals at same
frequencies
Interference rejection
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 8
DSSS Autocorrelation
Tc
Received signal:
Receiver replica:
Received signal
Receiver replica
Integrate & Dump
Out Out
-Tc Tc
Autocorrelation
+1
-1 -1
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 9
DSSS Cross-correlation
Tc
Received signal (SV
j):
Receiver replica (SV
kj):
Received signal
Receiver replica
Integrate & Dump
Out
Out
Cross-correlation
+1
-1 -1
One code selection goal is to select codes for each satellite to minimize cross-correlation.
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 10
Pseudorandom Sequences
Sequence of bits generated at chip rate to produce spread spectrum waveform Periodic for open (unencrypted) signals, aperiodic
for encrypted signals
Desired attributes: Good autocorrelation and cross-correlation
properties low amplitude sidelobes Balanced equal number of ones and zeros
Also known as pseudorandom noise (PRN) sequences, spread spectrum sequences
Often generated with linear feedback shift registers (LFSRs)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 11
LFSR Example
One Code Period
1 2 3 4
Code length = 24 - 1 = 15
G(x) = 1 + x1 + x4
Note: state (0,0,0,0) does not occur
State 1 2 3 4
1 1 1 1 1
2 0 1 1 1
3 1 0 1 1
4 0 1 0 1
5 1 0 1 0
6 1 1 0 1
7 0 1 1 0
8 0 0 1 1
9 1 0 0 1
10 0 1 0 0
11 0 0 1 0
12 0 0 0 1
13 1 0 0 0
14 1 1 0 0
15 1 1 1 0
1 1 1 1 1 Code repeats
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 12
Some PRN Sequence Families
m is an arbitrary positive integer
Source: No and Kumar, IEEE Trans. Info. Theory, March 1989.
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 13
Binary Offset Carrier Modulation
=
Carrier
Spreading code
Square wave
Data
BOC signal*
*Shown at baseband, i.e., without carrier.
Tsq
fsq= 1/Tsq = subcarrier frequency (Hz)
By convention, BOC(m,n) refers to a binary offset carrier modulation with m 1.023 MHz square wave subcarrier frequency and a n 1.023 MHz chipping rate.
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
Sine-phased vs Cosine-Phased BOC
14
Spreading code
Square wave
Sine-phasing
Spreading code
Square wave
Cosine-phasing
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
Multiplexing
Many GNSS satellites broadcast two or more signals on each carrier frequency
So that efficient switching-class amplifiers can be used on the spacecraft, multiplexing techniques that maintain constant envelope are preferred
Such techniques include: Phase quadrature for two signals on a carrier frequency, one
multiplies a sine the other a cosine
Interplexing for three signals (Butman and Timor, IEEE Trans Comm., 1972)
Majority vote for any odd number of signals
Time division multiplexing
Alternative BOC (ALTBOC)
15
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
Constant Envelope
16
Constant envelope
Not constant envelope
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
Dataless (Pilot) Components
Many modern GNSS signals include a component that is not modulated by navigation data Both signal components are still modulated by a PRN
Motivation allows carrier phase to be tracked using a phase locked loop (PLL) instead of a Costas loop A PLL can reliably track in 6 dB lower signal-to-noise ratio (SNR)
conditions
So, if one-half of the signal power is devoted to a dataless component, there is a net 3 dB SNR benefit
Data demodulation suffers a power loss, but this can be overcome by forward error correction
Data-modulated and dataless components are multiplexed on same carrier
17
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
Secondary Codes
Secondary codes with lengths up to 1800 bits are used in many modern GNSS signal designs Each repetition of the spreading waveform is kept as is or
inverted following a deterministic pattern
Also referred to as synchronization code
Benefits: Reduces cross-correlation between signals
Helps receiver synchronize with data bits
Reduces impact of narrowband interference
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 19
Polarization
Current and planned GNSS signals are right hand circularly polarized (RHCP)
User antenna should be also
+
+
+
-
-
-
+
+
+
-
-
-
Linear Polarization
1
0
RHCP
E-field
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 20
Relativistic Effects
GNSS satellite clocks are set slow to appear at the desired
frequencies to an observer on the ground.
Source: Ashby, N., www.livingreviews.org
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 21
OVERVIEW
Modulation basics GPS signals GLONASS signals GALILEO signals COMPASS signals IRNSS signals QZSS signals
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 22
GPS Navigation Signals
Today - 2 navigation frequencies, 3 signals L1 = 1575.42 MHz (154 10.23 MHz)
Coarse Acquisition (C/A) code
Precision (P(Y)) code
L2 = 1227.6 MHz (120 10.23 MHz) P(Y) code
Future - 3 navigation frequencies, 8 signals L1 C/A, C, P(Y), and M-code
L2 C, P(Y), and M-code
L5 = 1176.45 MHz (115 10.23 MHz)
L2C, M-code, and L5 are being broadcast by a growing subset of the satellites in the
GPS constellation.
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 23
GPS Signal Evolution
1227 MHz 1575 MHz 1176 MHz
L2 L1 L5
P(Y)
P(Y)
C/A
P(Y)
L2C M M
Present Signals
Signals After
Modernization
C/A
P(Y)
L1C
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 24
GPS Spreading Codes
Signal Chipping Rate Carrier frequency Comments
(Mchip/s) (MHz)
C/A 1.023 1575.42 (L1) 1023 chip Gold codes repeat
every 1 ms
L2C 1.023 1227.6 (L2) 2 codes per SV each at 511.5
kHz, future
P(Y) 10.23 L1 and L2 Repeats 1/week. When P-
code is encrypted, referred to
as Y-code
L5 10.23 1176.45 (L5) 2 codes per SV, future
M 5.115 L1 and L2 BOC(10,5) modulation
future
L1C 1.023 L1 BOC(1,1)/BOC(6,1) - future
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 25
Signal Power Spectra
Notes: (1) C/A codes actually have line spectra - continuous approximation shown.
(2) L5 signal spectrum resembles P(Y), except that L5 is also a line spectrum.
-15 -10 -5 0 5 10 150
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1x 10
-6
Offset from Carrier Frequency (MHz)
Norm
aliz
ed P
ow
er S
pectrum
(W
/Hz)
C/A or L2C
L1C
P(Y)-code M-code
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 26
C/A Code (PRN2) Spectrum
2000190018001700160015001400130012001100100090080070060050040030020010000-100
-90
-80
-70
-60
-50
-40
-30
-20
Frequency Offset from L1 (kHz)
Pow
er
Spe
ctr
al
Dens
ity (
dB
c/H
z)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 27
Spacecraft Signal Generation
Frequency Synthesizer
(10.23 MHz)
Navigation Data
Unit
C/A
P(Y)
L1 modulator/
Power Amplifiers/
Synthesizer
L2 modulator/
Power Amplifiers/
Synthesizer
Atomic clocks
Combiner
Phased
array
antenna
Nuclear detonation
detection
signal (L3)
Timing for all signals derived from 10.23 MHz atomic clock-based frequency
synthesizer. Note that C/A and P(Y) are in quadrature on L1.
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 28
C/A Code Generation
SHIFT REGISTER
G GENERATOR 1
1 2 3 4 5 6 7 8 9 10
G GENERATOR 2
SET TO
"ALL ONES"
+
+
+
1 2 3 4 5 6 7 8 9 10
1.023
MBPS
CLOCK
SHIFT REGISTER
+
G = ---10101111111111 1
G = ---01001111111111 2
1023
DECODE
20 50 BPS DATA
CLOCK
G EPOCH
1kBPS
GOLD CODE XG (t)
C/A CODE i
XG
C/A CODE 2 2i G
S 1 S 2
PHASE
SELECTOR
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 29
C/A Code Timing Relationships
1023 etc.
X1 Epoch @ 2/3 bps
0 1 2 18 19 0
1 ms 1023 BIT Gold Code @ 1023 kbps
1023 1023 1023 1023
Gold Code Epochs @ 1000/s
Data @ 50 cps
20 ms
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 30
P-code Generation
Generator based on four
12-stage shift registers
10.23 Mchips per second
Reset once/week
For details, see Interface
Specification IS-GPS-200F
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 31
Received Minimum Signal Levels
-155.5
-158.5
-161.5
-164.5
0 o 5 o 20 o 40 o 60 o 80 o 100 o 90 o
USER ELEVATION ANGLE (DEG)
RE
CE
IVE
D P
OW
ER
OU
T O
F 3
dB
il U
SE
R A
NT
EN
NA
(dB
W)
C/A - L 1
P - L 1
P - L 2 or
C/A - L 2
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 32
Typical GPS L1 C/A Link Budget
Power in dBW = 10 log10 (Power in W)
Power in dBm = 10 log10 (Power in mW)
1 mW = 0.001 W = 0 dBm = -30 dBW
EARTH
Free space
path loss:
-184.7 dB
Transmit power:
40 W
= 16 dBW
Antenna gain:
12 dB
Received Signal:
2 10-16 W = -157 dBW
Received signal power is less than the thermal noise power in the receiver.
Thermal Noise
(2 MHz bandwidth):
1.4 10-14 W = -138.5 dBW
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 33
C/A and P(Y) Navigation Data
Each subframe is 300 bits (6 s @ 50 bps). Entire message repeats every 12.5 min
(5 subframes 300 bits/subframe 25 pages = 37500 bits/message)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 34
L2C Characteristics Summary
L2 = 1227.6 MHz Minimum received power = -160 dBW PRN code chipping rate = 511.5 kHz for each
of two codes
Time Division Multiplexed (TDM) Signal Chip by chip multiplexing of two PRN sequences
Total chip rate: 1.023 MHz
Specification: IS-GPS-200F
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 35
L2 Civil Signal Definitions
L2C the L2 civil signal CM the L2C moderate length code
10,230 chips, 20 milliseconds
CL the L2C long code 767,250 chips, 1.5 second
NAV the legacy navigation message provided by C/A and P(Y)
CNAV improved L2C and L5 navigation data message format and contents
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 36
IIF L2C Signal Generation
C/A Code
Generator
10,230 Chip
Code Generator
767,250 Chip
Code Generator
L5-Like CNAV
Message
25 bits/sec
Chip by Chip
Multiplexer
1.023 MHz
Clock
Transmitted
Signal1/2
A1
A2B1
B2
Rate 1/2 FEC
Legacy NAV
Message
50 bits/sec
511.5 kHz Clock
CM
Code
CL
Code
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 37
L2C Code Characteristics
Codes are disjoint segments of a long-period maximal length code
27-stage linear feedback shift register with multiple taps is short-cycled to get desired
period
Selected to have perfect balance
Separate shift registers for each of the two codes
1 cycle of CL & 75 cycles of CM every 1.5 s
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 38
L2C Code Generator
DELAY
NUMBERS
SHIFT DIRECTION
OUTPUT
INITIAL CONDITIONS ARE A FUNCTION OF PRN AND CODE PERIOD (MODERATE/LONG)
1 3 1 1 3 3 2 3 3 2 2 3
Linear shift register generator with 27 stages and 12 taps
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 39
L5 Characteristics Summary
L5 = 1176.45 MHz Minimum received power = -154.9 dBW Code chipping rate = 10.23 MHz QPSK Signal
In-Phase (I5) = Data Channel
Quadraphase (Q5) = Data-Free Channel
Equal Power in I5 and Q5 (-157.9 dBW)
Independent spreading codes on I5 and Q5
Specification: IS-GPS-705
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 40
L5 Characteristics Summary (contd)
I and Q Modulation (1 kbps) Forward Error Correction (FEC) encoded 50 bps data on I5
(100 sps)
Further encoded with 10-bit Neuman-Hofman Code
Q5 encoded with 20-bit Neuman-Hofman Code
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 41
L5 Codes
Codes with 2 - 13 stage shift registers Length of one (XA code) = 8190 chips
Length of second (XB code) = 8191 chips
Exclusive-ord together to generate longer code
Chipping rate of 10.23 MHz Reset with 1 ms epochs (10,230 chips)
Two codes per satellite (4096 available) One for I5, one for Q5
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 42
L5 I and Q Code Generators
1 2 3 4 5 6 7 8 9 10 11 12 13
1 2 3 4 5 6 7 8 9 10 11 12 13
Exclusive OR
Initial XBI State
Exclusive OR
All 1's
1 ms Epoch
Code Clock
XA(t)
XBI(t+niT
c)
XIi(t)
XA Coder
XBI Coder
XBI State for SV i
ResetXQ
i(t)
XBQ(t+niT
c)
1 2 3 4 5 6 7 8 9 10 11 12 13
Initial XBQ State
Exclusive OR
XBQ Coder
XBQ State for SV i
Decode 1111111111101
Reset to all 1s on next clock
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 43
L5 Neuman-Hofman Codes
Encoded symbols and carrier Modulate at PRN code epoch rate
Spreads PRN code 1 kHz spectral lines to 50 Hz spectral lines (including FEC)
Reduces effect of narrowband interference by 13 dB
Reduces SV cross-correlation most of the time
Provides more robust symbol/bit synchronization
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 44
10-ms Neuman-Hofman Code on I5
-1.5
-1
-0.5
0
0.5
1
1.5
0 1 2 3 4 5 6 7 8 9 10
Code Delay - Milliseconds
Neu
man
-Ho
ffm
an
Co
de V
alu
e
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 45
20-ms Neuman-Hofman Code on Q5
-1.5
-1
-0.5
0
0.5
1
1.5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Code Delay - Milliseconds
Neu
man
-Ho
ffm
an
Co
de V
alu
e
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 46
L5 Data Content and Format
Six-Second 300-bit Messages Format with 24-bit cyclic redundancy code (CRC)
(same as satellite-based augmentation systems)
Convolutionally encoded: rate , length-7
Messages scheduled for optimum receiver performance
Lined up with L1 sub-frame epochs
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 47
M-code
Unlike current GPS signals, M-code is generated with four components 10.23 MHz square wave, in addition to carrier, spreading
waveform, and data
Creates an effect similar to amplitude modulation - double sideband (AM-DSB) i.e., moves signal energy away from carrier to upper and lower
sidebands
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 48
M-code Generation
=
Carrier (L1 or
L2)
5.115 Mchip/s
spreading code
10.23 MHz
square wave
Data
M-code signal*
*Shown at baseband, i.e., without carrier.
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 49
M-code Autocorrelation
Note the presence of multiple peaks due to the square wave subcarrier.
-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Auto
corr
ela
tion
Delay (microseconds)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 50
L5, L2C, and M-code Nav Data
Improvements made to clock and ephemeris representation
Clock resolution significantly enhanced Legacy message resolution ~ .5 ns
Ephemeris Resolution enhanced
Rate terms added for semi-major axis, mean motion, and inclination improve curve fit
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 51
L1C
New L1 civil signal on GPS IIIA+ Interoperable with GALILEO L1 signal
Modulation is multiplexing of BOC(1,1) and BOC(6,1) symbols referred to as multiplexed BOC (MBOC)
Planned features: Dataless component, powerful forward error correction,
length-10230 PRN codes
Specified in IS-GPS-800
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 52
L1C MBOC
-15 -10 -5 0 5 10 15-95
-90
-85
-80
-75
-70
-65
-60
-55
Frequency (MHz)
Pow
er S
pect
ral D
ensi
ty (d
BW
/Hz)
C/A Code
BOC(1,1)
TMBOC
-15 -10 -5 0 5 10 15-95
-90
-85
-80
-75
-70
-65
-60
-55
Frequency (MHz)
Pow
er S
pect
ral D
ensi
ty (d
BW
/Hz)
C/A Code
BOC(1,1)
TMBOC
(1,1) (6,1)29 4
33 33Pilot BOC BOCf f f
(1,1)Data BOCf f
(1,1) (6,1)
3 1
4 4
10 1
11 11
Signal Pilot Data
BOC BOC
f f f
f f
25% Power Data Component
75% Power Pilot Component
BOC(1,1) BOC(6,1)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 54
OVERVIEW
Modulation basics GPS signals GLONASS signals GALILEO signals COMPASS signals IRNSS signals QZSS signals
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 55
Current GLONASS Signals
DSSS modulation Frequency Division Multiple Access (FDMA)
scheme with multiple carriers in two sub-bands
Standard accuracy signal - 511 kHz chip rate, length-511 maximal-length codes
High accuracy signal 5.11 MHz chip rate, encrypted
Data at 50 bps, Manchester-encoded
1 1602 0.5625 MHzKf K
2 17 / 9K Kf f
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 56
Standard Accuracy PRN Generation
See GLONASS Interface Control Document, version 5.1 for further signal details.
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 57
Evolution of GLONASS Signals
GLONASS-K1 (launched Feb 2011) is broadcasting a test 10.23 MHz chip
rate CDMA signal at 1202.025 MHz. CDMA signals for L1, L2, L3 and
planned for future satellites.
Frequency (MHz)
L1 (~1593 1612) L2 (~1238 1593) L3
(1164 1215 MHz band)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 58
OVERVIEW
Modulation basics GPS signals GLONASS signals GALILEO signals COMPASS signals IRNSS signals QZSS signals
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 59
Galileo Frequency Bands
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 60
Frequencies and Power Levels
CS = Commercial Service
SoL = Safety of Life Service
Note that carrier frequencies were selected to be integer
multiples of 10.23 MHz for interoperability with GPS.
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 61
PRN Codes
E5 primary codes may be generated with LFSRs or stored in memory
E1 primary codes are stored in memory E6 codes are not disclosed in Galileo OS ICD
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 62
E5 Signal Characteristics
E5 is a wideband signal, centered at 1191.795 MHz Generated using alternative BOC (AltBOC) technique Similar in appearance to two coherently generated DSSS
signals with 10.23 MHz chip rates and centered at +/-
15.345 MHz from 1191.795 MHz
E5a at 1176.45 MHz E5b at 1207.14 MHz E5a and E5b each have data and pilot components
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 63
E6 Signal Characteristics
E6 includes 3 components: A (for Public Regulated Service), B & C (for Commercial Service)
CS signal is DSSS modulated with 5.115 MHz chip rate High rate data: 500 bps/1000 sps Data and pilot components
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 64
E1 Signal Characteristics
E1 includes 3 components: A (for Public Regulated Service), B & C (for Open, Safety of Life, and Commercial
Services)
B&C components represent Galileos implementation of MBOC (interoperable with GPS L1C)
Composite BOC (CBOC) technique used to achieve mixture (in power) of 10/11 BOC(1,1) and 1/11 BOC(6,1)
Data (125 bps/250 sps) and pilot components (50-50% power split)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 65
OVERVIEW
Modulation basics GPS signals GLONASS signals GALILEO signals COMPASS signals IRNSS signals QZSS signals
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
COMPASS Signals
66
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 67
OVERVIEW
Modulation basics GPS signals GLONASS signals GALILEO signals COMPASS signals IRNSS signals QZSS signals
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
IRNSS Signal Characteristics
68
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 69
OVERVIEW
Modulation basics GPS signals GLONASS signals GALILEO signals COMPASS signals IRNSS signals QZSS signals
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
QZSS Signal Characteristics
70
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE
Summary of GNSS Signal Plans
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300
Frequency (MHz)
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300
Frequency (MHz)
Future CDMA signal
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300
Frequency (MHz)
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300
Frequency (MHz)
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300
Frequency (MHz)
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300
Frequency (MHz)
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300
Frequency (MHz)
SBAS
QZSS (Japan)
IRNSS (India)
COMPASS (China)
Galileo (Europe)
GLONASS (Russia)
GPS (US)
L1 L5 L2
Compass & IRNSS In S-band
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300
Frequency (MHz)
ESA INTERNATIONAL SUMMER SCHOOL ON GNSS
MITRE 72
1. Kaplan, E., and C. Hegarty (Eds.), Understanding GPS: Principles and Applications, 2nd Edition, Artech House, 2006.
2. Misra, P., and P. Enge, Global Positioning System: Signals, Measurements, and Performance, 2nd Edition, Ganga-Jumana Press, 2006.
3. GPS Interface Specifications, available from www.gps.gov 4. GALILEO Open Service Signal in Space Interface Control
Document, available from www.gsa.europa.eu
5. GLONASS Interface Control Document, available from www.glonass-ianc.rsa.ru
6. COMPASS information from: www.unoosa.org/pdf/icg/2010/ICG5/18october/04.pdf
7. IRNSS information from: www.unoosa.org/pdf/icg/2010/ICG5/18october/05.pdf
8. QZSS ICD available from: qzss.jaxa.jp/is-qzss/index_e.html
References