Transcript QPSK TLM Modes CCSDS 401 2.4.11 DRAFT 10/15/04 RFM_05-06 Not

QPSK TLM Modes
CCSDS 401 2.4.11
DRAFT 10/15/04 RFM_05-06
Single Data Source
Aligned bits
Staggered (offset) bits
Coded
Dual encoders
Single encoder
Uncoded
Not covered by 2.4.11
Dual Data Source (Note 1 says … single, serial data stream …)
with Same data rate on each channel
with Different data rate on each channel (2.4.11 a) says coherent)
1
2.4.11
PHASE-AMBIGUITY RESOLUTION FOR QPSK MODULATION SYSTEMS 1
The CCSDS,
considering
(a)
that resolution of phase ambiguities in the earth station's receiver is an inherent problem with systems
using coherent Quaternary Phase-Shift-Keying (QPSK) modulation;
(b)
that coding (Constellation convention, but not decoding) conventions for QPSK systems are
unambiguously defined in CCSDS
Recommendation 401 (2.4.10);
(c)
that the phase ambiguity results from the lack of transmission of reference phase information, thus
making it impossible for the receiver's carrier recovery circuitry to select the correct reference phase
from the four possible stable lock points (Table 2.4.11-1);
(d)
that the phase-ambiguity can be resolved by using the techniques listed in Figure 2.4.11-1;
(e)
that the several methods for resolving the phase ambiguity depicted in Figure 2.4.11-1 are evaluated in
Table 2.4.11-2;
(f)
that most space agencies currently employ differential encoding and synchronization (sync) markers for
framed data transmission;
(g)
that any of the four possible phase states result in an unambiguously identifiable unique word pattern
according to Table 2.4.11-1 which can be used to resolve the phase ambiguity;
(h)
that the sync markers already existing in the framed data transmission can be used as the unique words
for resolving the phase ambiguity;
Note 1
… single, serial data stream …
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Can be supported by equipment commonly available for GN
High Rate Telemetry Single Data Source, Coded
Space Segment
Single Data Source
Data
RS Code
Interleave
I/Q switch gives
½ bit delay.
Actual circuit may
use parallel load
Transition
Generator,
Randomizer
Frame Synch
not randomized
Ground Segment
Mission Operation Center (MOC)
Frame
Data RS Decode Synch and
Deinterleave Data derandomizer
Frame Synch
not randomized
Data Format
Conversion
(NRZ-L to
NRZ-M)
Convolutional
Encode
High
Rate
QPSK
Put differential format
before convolutional encode
Data Format
Conversion
(NRZ-L to
NRZ-M)
+
Transmit
Convolutional
Encode
Q channel delay implied by
commutator at left
Format Convolutional
Bit/Symbol
Conversion
(Viterbi)
Synchronizer
(NRZ-M to
Decode
NRZ-L)
Ground Station
Receive
Analog bits
Format Convolutional
(Viterbi)
Conversion
Bit/Symbol
Decode
(NRZ-M to
Synchronizer
NRZ-L)
Staggered bits
and Differential Format
Resolves ambiguity
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Can be supported by equipment commonly available for GN
High Rate Telemetry Single Data Source, Coded
Space Segment
Single Data Source
Data
I/Q switch gives
½ bit delay.
Actual circuit may
use parallel load
Transition
RS Code
Generator,
Not requred
Randomizer
Frame Synch
not randomized
Ground Segment
Mission Operation Center (MOC)
Frame
Data RS Decode Synch and
Not required Data derandomizer
Frame Synch
not randomized
Data Format
Conversion
Not required
Convolutional
or LDPC
Encode
Put differential format
before convolutional encode
Data Format
Conversion
Not required
LDPC
Decode
Convolutional
or LDPC
Encode
Frame
Synch
(soft bits)
Ground Station
LDPC
Decode
Frame
Synch
(soft bits)
Staggered bits
and Frame Synch
Resolves ambiguity
High
Rate
QPSK
+
Transmit
Q channel delay implied by
commutator at left
Bit/Symbol
Synchronizer
Receive
Analog bits
Bit/Symbol
Synchronizer
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V. Sank 10/15/04
Can be supported by equipment commonly available for GN
High Rate Telemetry Single Data Source, No inner code
Space Segment
Single Data Source
Data
RS Code
Interleave
I/Q switch gives
½ bit delay.
Actual circuit may
use parallel load
Transition
Generator,
Randomizer
Frame Synch
not randomized
Ground Segment
Mission Operation Center (MOC)
Frame
Data RS Decode Synch and
Deinterleave Data derandomizer
Frame Synch
not randomized
Data Format
Conversion
(NRZ-L to
NRZ-M)
High
Rate
QPSK
Put differential format
before convolutional encode
Data Format
Conversion
(NRZ-L to
NRZ-M)
+
Transmit
Q channel delay implied by
commutator at left
Format
Conversion
(NRZ-M to
NRZ-L)
Bit/Symbol
Synchronizer
Ground Station
Format
Conversion
(NRZ-M to
NRZ-L)
Staggered bits
and Differential Format
Resolves ambiguity
Receive
Analog bits
Bit/Symbol
Synchronizer
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Not currently supported by GN but can also be supported by equipment available for GN. Supported by USN for Jason
Low Rate Telemetry with Single Encoder
Space Segment
Single Data Source
Data RS Code Transition
Generator,
Interleave
Randomizer
Data Format
Conversion
(NRZ-L to
NRZ-M)
g1
Convolutional
Encode
g2
Low
Rate
QPSK
+
Transmit
Frame Synch
not randomized
Q channel delay ½ symbol
SQPSK
Ground Segment
Mission Operation Center (MOC)
Frame
Data RS Decode Synch and
Deinterleave Data derandomizer
Frame Synch
not randomized
Format
Conversion
(NRZ-M to
NRZ-L)
_ or
Convolutional g1
g1 or
Bit/Symbol
(Viterbi)
g2
_ or
Synchronizer
g2
Decode
(I/Q swap (node synch)
and inversion
(polarity) must
be resolved.
Metric growth
resolves swap
and inversion,
SNR impact)
g2
_ or
g2
_ or
g1 or
g1
Ground Station
Analog
bits
Receive
Bit/Symbol
Synchronizer
If no convolutional coding, Frame Marker can be used to resolve alternate bit inversion.
This will increase acquisition time and have a SNR performance impact.
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Not currently supported by GN but can also be supported by equipment available for GN. Supported by USN for Jason
Low Rate Telemetry, Uncoded
Space Segment
Single Data Source
Data RS Code Transition
Generator,
Interleave
Randomizer
Data Format
Conversion
(NRZ-L to
NRZ-M)
No
Convolutional
Code
Bit n
Bit n+1
Low
Rate
QPSK
+
Transmit
Frame Synch
not randomized
Q channel delay ½ symbol
SQPSK
Ground Segment
Data is all true
or all inverted,
use Frame Synch
to resolve.
Frame
Data RS Decode Synch and
Deinterleave Data derandomizer
Frame Synch
not randomized
Format
Conversion
(NRZ-M to
NRZ-L)
Convolutional n_ or
n or
Bit/Symbol
(Viterbi)
n+1 or
__
Synchronizer
n+1
Decode
Bypass
I or Q (exclusive)
inversion
(polarity) must
be resolved.
SNR impact
n+1 or
__
_n+1 or
n or
n
Receive
Analog bits
Bit/Symbol
Synchronizer
I/Q swap is not an issue because stagger insures correct time ordering of the bits.
If no convolutional coding, Frame Marker can be used to resolve alternate bit inversion.
This will increase acquisition time and have a SNR performance impact.
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Not currently supported by GN but can also be supported by equipment available for GN. Supported by USN for Jason
Low Rate Telemetry, Uncoded
Space Segment
DRAFT
Single Data Source
Data RS Code Transition
Generator,
Interleave
Randomizer
Data
Format
(NRZ
L to M)
Data
Format
(NRZ
L to M)
No
Convolutional
Code
Bit n
Bit n+1
Low
Rate
QPSK
+
Transmit
Frame Synch
not randomized
Q channel delay ½ symbol
SQPSK
Ground Segment
Data is all true
or all inverted
Frame
Data RS Decode Synch and Format Format
(NRZ
(NRZ
Deinterleave Data deM to L) M to L)
randomizer
Frame Synch
not randomized
n_ or
Convolutional n or
Bit/Symbol
n+1
or
__
(Viterbi)
Synchronizer
n+1
Decode
Bypass
Analog bits
Receive
n+1 or
__
n+1 or
_
I or Q (exclusive) n or
inversion
(polarity) must
be resolved.
SNR impact
n
Bit/Symbol
Synchronizer
If no convolutional coding, Frame Marker can be used to resolve alternate bit inversion.
OR a double L to M and M to L format conversion will resolve the ambiguity.
This has an additional .3 dB SNR performance impact.
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Back Up Slides
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High Rate Telemetry Dual Data Source
Space Segment
Data 1
Transition
RS Code
Generator,
Interleave
Randomizer
Dual Data Source
Data 2
Frame Synch
not randomized
Transition
RS Code
Generator,
Interleave
Randomizer
Data Format
Conversion
(NRZ-L to
NRZ-M)
Convolutional
Encode
High
Rate
QPSK
Put differential format
before convolutional encode
Data Format
Conversion
(NRZ-L to
NRZ-M)
+
Transmit
Convolutional
Encode
Q channel delay arbitrary
due to data rate difference
Ground Segment
Frame
Data 1 or 2 RS Decode Synch and
Deinterleave Data derandomizer
Frame Synch
not randomized
Frame
Data 2 or 1 RS Decode Synch and
Deinterleave Data derandomizer
Format Convolutional
Bit/Symbol
Conversion
(Viterbi)
Synchronizer
(NRZ-M to
Decode
NRZ-L)
Receive
Analog bits
Format Convolutional
(Viterbi)
Conversion
Bit/Symbol
Decode
(NRZ-M to
Synchronizer
NRZ-L)
If Data 1 and Data 2 have different data rate, Sort by data rate at bit synchronizer.
If data rates are the same and Frame marker is the same sort by VCID.
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C/NOFS, Swift, GLAST Low Rate Telemetry with Single Encoder
Space Segment
Single Data Channel
20 Kbps
PN Transmitter
Often purchased
as component.
40 Ksps
40 Ksps
Data
RS Code
Interleave
Transition
Generator,
Randomizer
Data Format
Conversion
(NRZ-L to
NRZ-M)
g1
Convolutional
Encoder
_
g2
Low
Rate
QPSK
40 Ksps
Frame Synch
not randomized
Bit/Symbol
Synchronizer
Frame Synch
not randomized
Format
Conversion
(NRZ-M to
NRZ-L)
Inversion
Convolutional
must be
(Viterbi)
resolved
Decode
Transmit
I and Q
PN codes
out of phase.
Ground Segment
Frame
Data RS Decode Synch and
Deinterleave Data derandomizer
+
g1g2
_ _ or
g1g2
_ _ or
g1g2 or
g1g2
300 Ksps max
40 Ksps
Receive
Analog bits
Bit/Symbol
Synchronizer
40 Ksps
g1g2
_ _ or
g1g2 or
_g1g2
_ or
g1g2
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TDRSS High Rate Telemetry Signal Flow Block Diagram
Section B.3.3.1 a)
Space Segment
Single Data Channel
Data
RS Code
Interleave
I/Q switch gives
½ bit delay.
Actual circuit may
use parallel load
Transition
Generator,
Randomizer
Frame Synch
not randomized
Ground Segment
Frame
Data RS Decode Synch and
Deinterleave Data derandomizer
Frame Synch
not randomized
Figure references are to the SNUG Rev 8
Fig B-6
Data
Source
Data Format
Conversion
(NRZ-L to
NRZ-M)
Fig B-6
Data
Conditioner
g1g1g1g1…g2g2g2g2…
Convolutional
Encode (up to 8
encoders,
Fig B-8
Fig B-10 lower left)
Put differential format
before convolutional encode
Fig B-6
Data
Source
Data Format
Conversion
(NRZ-L to
NRZ-M)
Format
Conversion
(NRZ-M to
NRZ-L)
Fig B-8
Fig B-6
Data
Conditioner
Convolutional
Encode (up to 8
encoders,
Fig B-10 lower left)
Fig B-6
DG2
High
Rate
QPSK
Transmitter
Often purchased
as component.
+
Transmit
Fig B-6
DG2
Q channel delay implied by
Commutator at left, SQPSK
300 Msps max
Convolutional
Bit/Symbol
(Viterbi)
Synchronizer
Decode
(Up to 8)
Receive
Analog bits
Format
Conversion
(NRZ-M to
NRZ-L)
Convolutional
(Viterbi)
Bit/Symbol
Decode
Synchronizer
(Up to 8)
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Can NOT be supported by equipment commonly available for GN due to DG1, spread spectrum
TDRSS Low Rate Telemetry Signal Flow Block Diagram
Section B.3.2.1 a)
Space Segment
Single Data Channel
Data RS Code Transition
Generator,
Interleave
Randomizer
Frame Synch
not randomized
Identical data on I and Q but
not BPSK due to spreading.
Convo symbols serial, not staggered
Data Format
Conversion
(NRZ-L to
NRZ-M)
g1
Convolutional
Encoder
Data Conditioner Fig B-7
Transmitter
Often purchased
as component.
Fig B-6
DG1
Low
Rate
QPSK
_
g2
+
Transmit
Fig B-6
DG1
Q channel delay ½ chip
for spectral reasons
KSA, SSA, MA, SMA and DAS
300 Ksps max
Ground Segment
Frame
Data RS Decode Synch and
Deinterleave Data derandomizer
Format
Conversion
(NRZ-M to
NRZ-L)
Analog
bits
Convolutional
(Viterbi)
Decode
Bit/Symbol
Synchronizer
Inversion
resolved
at PN level
Frame Synch
not randomized
Balanced Power Single Data Source Identical Data on I/Q Channels
Figure references are to the SNUG Rev 8
Receive
g1g2
_ _ or
g1g2 or
_g1g2
_ or
g1g2
(KSA, SSAR, MA, SMA, DAS)
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Can NOT be supported by equipment commonly available for GN due to DG1, spread spectrum
TDRSS S Low Rate Telemetry Signal Flow Block Diagram
Section B.3.2.1 b)
Space Segment
I/Q switch gives ½ bit delay.
Used for reciever
Fig B-7
Data
Re-interleaving.
Data Format Conditioner
Actual circuit may
use parallel load
Conversion
Single Data Channel
SSA and HIJ only for MA
Data
RS Code
Interleave
Transition
Generator,
Randomizer
Frame Synch
not randomized
Not available on DAS
Ground Segment
Frame
Data RS Decode Synch and
Deinterleave Data derandomizer
Frame Synch
not randomized
Fig B6
Data
Source
(NRZ-L to
NRZ-M)
Fig B6
Data
Source
Data Format
Conversion
(NRZ-L to
NRZ-M)
Format
Conversion
(NRZ-M to
NRZ-L)
Transmitter
Often purchased
as component.
Fig B-6
DG1
Low
Rate
QPSK
Put differential format
before convolutional encode
Convolutional
Encode,
(Fig B-10 upper left)
Fig B-7
Data
Conditioner
+
Transmit
Fig B-6
DG1
Q channel delay ½ chip
for spectral reasons, SQPN
300 Ksps max
Convolutional
Bit/Symbol
(Viterbi)
Synchronizer
Decode
Receive
Analog bits
Format
Conversion
(NRZ-M to
NRZ-L)
Balanced Power Single Data Source Alternate I/Q Bits
Figure references are to the SNUG Rev 8
Convolutional
Encode
(Fig B-10 upper left)
Convolutional
(Viterbi)
Bit/Symbol
Decode
Synchronizer
(SMAR, SSAR, DG1 Mode 1 or 2, Nor available on MA or DAS)
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