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 of 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 1 of GJB 1198.
This part replaces GJB 1198.1-1991 Telemetry tracking command and data handling for satellite: PCM telecommand.
The following main changes have been made in this part with respect to the original edition:
a) Clause 3 Terms and definitions is added to define three probabilities;
b) 6.6 changes the original ending word into ending sequence, and recommend the picture system to be changed into code word in line with international standards, because the original l6bit is too short, which is easy to produce false ending;
c) Clause 7 "Randomized processing” is added, which is consistent with international standards. In fact, this method is also used in China, but the random sequence selection is different, which is suitable for standardization;
d) Clause 8 "Telecommand data security protection” is added, the concept of which is consistent with international standards, but the specific format of which is self-defined. It is necessary to include this content in the standard. At present, the different practices of different models have caused some problems;
e) Clause 10 “Telecommand operation" is added, which refers to the standard of packet telecommand, but is compiled according to the PCM telecommand practice in China.
This part was proposed by China Aerospace Science & 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 1: PCM telecommand
1 Scope
This part specifies the main functions, performance, standard data structure, decoding and execution, and necessary remote control operation of PCM telecommand system for spacecraft.
This part is applicable to spacecraft telecommand system using PCM telecommand system in S frequency band, and the interface between corresponding spacecraft and ground telecommand. The telecommand system using spacecraft service frequency band can also be adopted by reference.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this part. However, parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the normative documents 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 1198.5A-2004 Telemetry tracking command and data handling for spacecraft Part 5: Radio frequency and modulation
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
lost probability of receiving
probability of the spacecraft telecommand system to lose a piece of complete telecommand information after the earth station correctly sends it to the spacecraft
3.2
error probability of receiving
probability of the spacecraft telecommand system to receive a piece of complete telecommand information but restore a different piece of information after the earth station correctly sends the former information to the spacecraft
3.3
false probability of receiving
probability of the spacecraft telecommand system to output a piece of telecommand information in case that the earth station has not sent any piece of telecommand information to the spacecraft
4 General provisions
4.1 Basic composition of system
The basic structure of PCM telecommand system is as shown in Figure 1.
4.2 Main functions of system
4.2.1 Telecommand switch command
In order to ensure that the telecommand switch command is sent from the ground to the spacecraft with high reliability, the switch command information must be coded and formatted according to the provisions of this part on the ground, and the telecommand decoder is used for receiving, decoding and checking on the spacecraft, and the restored switch command pulse is output to the users on the spacecraft.
4.2.2 Data injection
In order to ensure that the control data (including users' working parameters, working procedures and delay switch command, etc.) are sent from the ground to the spacecraft with high reliability, the data must be formatted and packaged on the ground according to the provisions of this part, and received, unpacked and checked on the spacecraft through the telecommand decoder, and the restored data are sent to the spacecraft users.
Figure 1 Basic structure of PCM telecommand system
5 Main performance of system
The design of telecommand system shall meet the following main performance requirements:
a) The lost probability of receiving of any telecommand switch command or any telecommand injection data frame is lower than 1×10-6;
b) The error probability of receiving of any telecommand switch command or any telecommand injection data frame is lower than 1×10-8;
c) The false probability of receiving Pf of any telecommand switch command or any telecommand injection data frame in the design life of spacecraft is:
Pf<10-4 (non-important function command);
Pf<10-6 (important function command).
The support condition required by the above two points (a) and (b) is that the bit error rate of channel transmission is lower than 5×10-6.
All the above requirements are applicable to general switch commands or general injection data. For switch commands and injected data that may lead to major faults of spacecraft, design indexes can be improved or reused application schemes can be adopted.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General provisions
5 Main performance of system
6 Standard data structure
7 Randomized processing
8 Telecommand data security protection
9 Decoding and execution
10 Telecommand operation
