Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GJB 1198 consists of the following eight parts under the general title Telemetry tracking command and data handling for spacecraft:
——Part 1: PCM telecommand;
——Part 2: PCM telemetry
——Part 3: Telemetry channel coding;
——Part 4: Ranging;
——Part 5: Radio frequency and modulation;
——Part 6: Packet telemetry;
——Part 7: Packet telecommand;
——Part 8: Onboard data handling interface.
This part is Part 2 of GJB 1198.
This part replaces GJB 1198.2-1991 Telemetry tracking command and data handling for satellite: PCM telemetry.
The following main changes have been made in this part with respect to the previous edition:
a) The format is rearranged according to the relevant provisions of the national military standard;
b) Supplementary provisions for use are made for the vacancy of individual clauses such as 6.10 “Frame count word”;
c) The representation of some charts and tables is improved;
d) To avoid duplication with other standards, some clauses are revised to make them more accurate and rigorous.
Annex A of this part is informative.
This part was proposed by China Aerospace Science and Technology Corporation.
This part is under the jurisdiction of China Astronautics Standards Institute.
This part was firstly issued in October 1991, and firstly revised this time.
Telemetry tracking command and data handling for spacecraft
Part 2: PCM telemetry
1 Scope
This part specifies the telemetry channel, modulation characteristics, standard telemetry format, establishment of telemetry format and technical requirements of float format for spacecraft PCM telemetry.
This part is applicable to the spacecraft PCM telemetry system, as well as the telemetry interface between the spacecraft and the earth station.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part. For dated reference, subsequent amendments to (excluding any corrigendum), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest editions apply to this part.
GJB 727A-1998 Terms and acronyms of space tracking telemetry and command system
GJB 1198.3A-2004 Telemetry tracking command and data handling for spacecraft — Part 3: Telemetry channel coding
GJB 1198.5A-2004 Telemetry tracking command and data handling for spacecraft Part 5: Radio frequency and modulation
GJB 1198.8A-2004 Telemetry tracking command and data handling for spacecraft— Part 8: Onboard data handling interface
3 Terms and definitions
For the purposes of this part, the terms and definitions established in GJB 727A-1998 and the following ones apply.
3.1
telemetry channel
interface channel that can independently input a measured signal in telemetry system
3.2
PCM data stream
serial PCM telemetry information stream generated according to the structural hierarchy of bit, telemetry word, frame and format
3.3
telemetry word
basic unit, which is composed of successive 8 bits and is used to compose telemetry frames, also called path
3.4
pair of telemetry words
telemetry word pair formed by every two adjacent telemetry words starting with an even-numbered serial number, also called path pair
3.5
frame
ordered set of telemetry words between the starting points of two adjacent frame synchronization code blocks in PCM telemetry data stream, with the number of telemetry words contained in a frame called the frame length
3.6
format
ordered set of a group of telemetry frames sent one after another with the frame count word as synchronization and identification marks
3.7
float format
special information zone composed of some telemetry words in standard telemetry format, used to transmit irregular independent data segments
4 Telemetry channel
4.1 Classification
4.1.1 General
Telemetry channels are classified into analog channels, digital channels, bi-level channels and timing channels. Technical requirements for interfaces of various channels shall comply with GJB 1198.8A-2004.
4.1.2 Analog channel
4.1.2.1 General
The input is the voltage that continuously changes between the specified upper and lower limits, which is sampled and quantized to form telemetry words.
The analog channel is classified into single-ended analog channel and double-ended analog channel according to its hardware interface mode.
4.1.2.2 Single-ended analog channel
The reference end of the input telemetry signal is connected to the ground reference point of the telemetry coder. The input signal is positive with respect to its reference end.
4.1.2.3 Dual-ended analog channel
The input signal end and its reference end are connected to the high end and the low end of the channel respectively. They are in a high impedance state with the ground reference point of the telemetry coder. The input signal is positive with respect to its reference end.
4.1.3 Digital channel
4.1.3.1 General
It is a telemetry channel for acquisition of digital signals. It is classified into serial digital channel and parallel digital channel according to interface mode.
4.1.3.2 Serial digital channel
Telemetry information is serially input into telemetry channel in the form of PCM NRZ-L, which completes serial data acquisition by means of gating signal and clock signal, and can receive 8Nbit (where N is a positive integer) of input data for each sampling. Gating signals and clock signals are provided by telemetry equipment. The width of the gating signal can meet the requirement of receiving 8Nbit.
4.1.3.3 Parallel digital channel
Telemetry information is input into telemetry channel in 8bit parallel form. The length of data can be 8Nbit (where N is a positive integer). The data is acquired by means of a gating signal and a clock signal. The gating signal gates N sampling pulses, each of which is used to acquire parallel 8bit information.
4.1.4 Bi-level digital channel
Also known as state quantity channel, used to acquire discrete status bits. Each bi-level channel can only acquire 1 bit of information at a time. The level signal is expressed in the form of voltage, and its voltage has only two different values relative to the ground reference point, namely, an on level ("1" level) and an off level ("0" level).
4.1.5 Timing channel
It represents the occurrence time of an event in the form of a single event pulse. When it appears, it samples the contents of the on-board time counter, and then arranges it in the telemetry data stream at a specified position with a length of 8Nbit. It is a special type of telemetry channel.
4.2 Sampling
4.2.1 General
Sampling of telemetry channel input is classified into super frame rate sampling, frame rate sampling and low rate sampling.
4.2.2 Super frame rate sampling
The channel input signal is sampled more than once per frame.
4.2.3 Frame rate sampling
The channel input signal is sampled once every frame.
4.2.4 Low rate sampling
The channel input signal is sampled at a rate lower than sampling once per frame but at least once per format.
5 Modulation characteristics
5.1 PCM characteristics
5.1.1 PCM code form
See GJB 1198.5A-2004 for the recommended PCM code form and corresponding waveform expression.
5.1.2 Waveform symmetry
The width ratio between the high-level and low-level symbols in the PCM output waveform shall be between 0.998 and 1.002.
5.1.3 Jump intensity
See GJB 1198.5A-2004 for data jump intensity.
5.1.4 Bit error rate
The bit error rate of telemetry system transmission shall be no more than 1×10-5.
5.1.5 Bit rate
See GJB 1198.5A-2004 for the bit rate.
5.1.6 Frequency stability of PCM data stream
The frequency stability of PCM data stream is the same as that required for PSK subcarrier, as shown in 5.2.4.
5.1.7 Change of data rate
In the process of telemetry data transmission, only the earth station is allowed to send remote telecommands to change the bit rate. For a given telemetry format, the time when the data bit rate actually changes can only be at the starting point of the format in the output information stream, that is, the starting point of F0W0B0.
When it is possible to change the transmission rate, data indicating the bit rate used shall be arranged in the telemetry data.
5.2 Telemetry video signal
5.2.1 General
Telemetry video signal sent to RF transmitter can be PCM waveform or PCM modulated phase shift keying (PSK) subcarrier. The modulation of telemetry video signal to RF carrier shall comply with GJB 1198.5A-2004.
5.2.2 Waveform of PSK subcarrier
The waveform of PSK subcarrier is sinusoidal or square wave.
5.2.3 Coherence between PSK and PCM telemetry signals
The frequency and phase of PSK subcarrier shall be directly coherent with the clock of PCM information. See GJB 1198.5A-2004 for the ratio of subcarrier frequency to bit rate.
Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 Telemetry channel 5 Modulation characteristics 6 Standard telemetry format 7 Establishment of telemetry format 8 Float format Annex A (Informative) Concept of float format
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GJB 1198 consists of the following eight parts under the general title Telemetry tracking command and data handling for spacecraft:
——Part 1: PCM telecommand;
——Part 2: PCM telemetry
——Part 3: Telemetry channel coding;
——Part 4: Ranging;
——Part 5: Radio frequency and modulation;
——Part 6: Packet telemetry;
——Part 7: Packet telecommand;
——Part 8: Onboard data handling interface.
This part is Part 2 of GJB 1198.
This part replaces GJB 1198.2-1991 Telemetry tracking command and data handling for satellite: PCM telemetry.
The following main changes have been made in this part with respect to the previous edition:
a) The format is rearranged according to the relevant provisions of the national military standard;
b) Supplementary provisions for use are made for the vacancy of individual clauses such as 6.10 “Frame count word”;
c) The representation of some charts and tables is improved;
d) To avoid duplication with other standards, some clauses are revised to make them more accurate and rigorous.
Annex A of this part is informative.
This part was proposed by China Aerospace Science and Technology Corporation.
This part is under the jurisdiction of China Astronautics Standards Institute.
This part was firstly issued in October 1991, and firstly revised this time.
Telemetry tracking command and data handling for spacecraft
Part 2: PCM telemetry
1 Scope
This part specifies the telemetry channel, modulation characteristics, standard telemetry format, establishment of telemetry format and technical requirements of float format for spacecraft PCM telemetry.
This part is applicable to the spacecraft PCM telemetry system, as well as the telemetry interface between the spacecraft and the earth station.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part. For dated reference, subsequent amendments to (excluding any corrigendum), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest editions apply to this part.
GJB 727A-1998 Terms and acronyms of space tracking telemetry and command system
GJB 1198.3A-2004 Telemetry tracking command and data handling for spacecraft — Part 3: Telemetry channel coding
GJB 1198.5A-2004 Telemetry tracking command and data handling for spacecraft Part 5: Radio frequency and modulation
GJB 1198.8A-2004 Telemetry tracking command and data handling for spacecraft— Part 8: Onboard data handling interface
3 Terms and definitions
For the purposes of this part, the terms and definitions established in GJB 727A-1998 and the following ones apply.
3.1
telemetry channel
interface channel that can independently input a measured signal in telemetry system
3.2
PCM data stream
serial PCM telemetry information stream generated according to the structural hierarchy of bit, telemetry word, frame and format
3.3
telemetry word
basic unit, which is composed of successive 8 bits and is used to compose telemetry frames, also called path
3.4
pair of telemetry words
telemetry word pair formed by every two adjacent telemetry words starting with an even-numbered serial number, also called path pair
3.5
frame
ordered set of telemetry words between the starting points of two adjacent frame synchronization code blocks in PCM telemetry data stream, with the number of telemetry words contained in a frame called the frame length
3.6
format
ordered set of a group of telemetry frames sent one after another with the frame count word as synchronization and identification marks
3.7
float format
special information zone composed of some telemetry words in standard telemetry format, used to transmit irregular independent data segments
4 Telemetry channel
4.1 Classification
4.1.1 General
Telemetry channels are classified into analog channels, digital channels, bi-level channels and timing channels. Technical requirements for interfaces of various channels shall comply with GJB 1198.8A-2004.
4.1.2 Analog channel
4.1.2.1 General
The input is the voltage that continuously changes between the specified upper and lower limits, which is sampled and quantized to form telemetry words.
The analog channel is classified into single-ended analog channel and double-ended analog channel according to its hardware interface mode.
4.1.2.2 Single-ended analog channel
The reference end of the input telemetry signal is connected to the ground reference point of the telemetry coder. The input signal is positive with respect to its reference end.
4.1.2.3 Dual-ended analog channel
The input signal end and its reference end are connected to the high end and the low end of the channel respectively. They are in a high impedance state with the ground reference point of the telemetry coder. The input signal is positive with respect to its reference end.
4.1.3 Digital channel
4.1.3.1 General
It is a telemetry channel for acquisition of digital signals. It is classified into serial digital channel and parallel digital channel according to interface mode.
4.1.3.2 Serial digital channel
Telemetry information is serially input into telemetry channel in the form of PCM NRZ-L, which completes serial data acquisition by means of gating signal and clock signal, and can receive 8Nbit (where N is a positive integer) of input data for each sampling. Gating signals and clock signals are provided by telemetry equipment. The width of the gating signal can meet the requirement of receiving 8Nbit.
4.1.3.3 Parallel digital channel
Telemetry information is input into telemetry channel in 8bit parallel form. The length of data can be 8Nbit (where N is a positive integer). The data is acquired by means of a gating signal and a clock signal. The gating signal gates N sampling pulses, each of which is used to acquire parallel 8bit information.
4.1.4 Bi-level digital channel
Also known as state quantity channel, used to acquire discrete status bits. Each bi-level channel can only acquire 1 bit of information at a time. The level signal is expressed in the form of voltage, and its voltage has only two different values relative to the ground reference point, namely, an on level ("1" level) and an off level ("0" level).
4.1.5 Timing channel
It represents the occurrence time of an event in the form of a single event pulse. When it appears, it samples the contents of the on-board time counter, and then arranges it in the telemetry data stream at a specified position with a length of 8Nbit. It is a special type of telemetry channel.
4.2 Sampling
4.2.1 General
Sampling of telemetry channel input is classified into super frame rate sampling, frame rate sampling and low rate sampling.
4.2.2 Super frame rate sampling
The channel input signal is sampled more than once per frame.
4.2.3 Frame rate sampling
The channel input signal is sampled once every frame.
4.2.4 Low rate sampling
The channel input signal is sampled at a rate lower than sampling once per frame but at least once per format.
5 Modulation characteristics
5.1 PCM characteristics
5.1.1 PCM code form
See GJB 1198.5A-2004 for the recommended PCM code form and corresponding waveform expression.
5.1.2 Waveform symmetry
The width ratio between the high-level and low-level symbols in the PCM output waveform shall be between 0.998 and 1.002.
5.1.3 Jump intensity
See GJB 1198.5A-2004 for data jump intensity.
5.1.4 Bit error rate
The bit error rate of telemetry system transmission shall be no more than 1×10-5.
5.1.5 Bit rate
See GJB 1198.5A-2004 for the bit rate.
5.1.6 Frequency stability of PCM data stream
The frequency stability of PCM data stream is the same as that required for PSK subcarrier, as shown in 5.2.4.
5.1.7 Change of data rate
In the process of telemetry data transmission, only the earth station is allowed to send remote telecommands to change the bit rate. For a given telemetry format, the time when the data bit rate actually changes can only be at the starting point of the format in the output information stream, that is, the starting point of F0W0B0.
When it is possible to change the transmission rate, data indicating the bit rate used shall be arranged in the telemetry data.
5.2 Telemetry video signal
5.2.1 General
Telemetry video signal sent to RF transmitter can be PCM waveform or PCM modulated phase shift keying (PSK) subcarrier. The modulation of telemetry video signal to RF carrier shall comply with GJB 1198.5A-2004.
5.2.2 Waveform of PSK subcarrier
The waveform of PSK subcarrier is sinusoidal or square wave.
5.2.3 Coherence between PSK and PCM telemetry signals
The frequency and phase of PSK subcarrier shall be directly coherent with the clock of PCM information. See GJB 1198.5A-2004 for the ratio of subcarrier frequency to bit rate.
Contents of GJB 1198.2A-2004
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Telemetry channel
5 Modulation characteristics
6 Standard telemetry format
7 Establishment of telemetry format
8 Float format
Annex A (Informative) Concept of float format
