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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 7 of GJB 1198.
This part replaces GJB 1198.7-1991 Telemetry tracking command and data handling for satellite: Packet telecommand.
This part is formulated by reference to the following CCSDS standards, which are consistent in technical content and simplified in text:
——CCSDS 201.0-B-3 2000;
——CCSDS 202.0-B-3 2001;
——CCSDS 202.1-B-2 2001;
——CCSDS 203.0-B-2 2001;
The following main changes have been made in this part with respect to the previous edition:
a) The definition of segmentation layer is extended, and the concepts of telecommand user data unit and telecommand frame data unit are introduced;
b) Among the three command operations procedures, COP-1 is recommended, COP-0 and COP-2 are only briefly described, and a subcategory of urgent service is added;
c) Chinese wording of the control command of the original transfer layer is changed;
d) Randomized processing of telecommand data is added;
e) The tail sequence code image of the command link transmission unit is modified;
f) Support for transfer network datagrams is added;
g) The channel coding block length is fixed at 64bit;
h) The application scope is extended to all spacecrafts.
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 7: Packet telecommand
1 Scope
This part specifies the data structure, format and necessary operations of packet telecommand system for spacecraft.
This part is applicable to spacecraft telecommand system using packet telecommand system, telecommand interface between corresponding spacecraft and earth station, and interactive support of international space data system in packet telecommand.
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 1198.6A-2004 Telemetry tracking command and data handling for spacecraft - Part 6: Packet telemetry
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
packet telecommand
open-type PCM telecommand system for multi-source and multi-user telecommand data transmission through layered and dynamic data management in the form of packet
3.2
telecommand user data unit
user data structure of a finite length suitable for transferring telecommand application data from the ground to spacecraft in packet telecommand. It can be a telecommand packet conforming to the format specified in 5.2 of this part, or other user-defined format
3.3
telecommand transfer frame
transfer-oriented standard data structure suitable for transferring telecommand data to spacecraft in packet telecommand. It consists of a frame header, a frame data field and an optional frame error control field, in a format conforming to 7.2 of this part
3.4
telecommand frame data unit
standard data structure that is suitable for being placed in the transfer frame data field in packet telecommand, It can be a telecommand segment in a format conforming to 6.2 of this part, one or more telecommand packets in a format conforming to 5.2 of this part, or a single telecommand user data unit
3.5
command link transmission unit
error control protocol-based standard data structure that is established in packet telecommand and suitable for reliable transmission of telecommand data in noisy channels. It consists of block code block of one or more transfer frames, start sequence and tail sequence, in a format conforming to 8.2 of this part
3.6
virtual channel
dynamic transmission management mechanism that enables multiple sources and users to share the same physical channel. By uniformly allocating the "virtual channel identifier word" which designates the transfer frame header and implementing dynamic management according to the user's needs and the actual situations of the channel, different user application data alternately occupy the physical channel in a time-shared manner, i.e., dividing a single channel into multiple virtual branches
3.7
file of packets
ordered set of relevant telecommand user data units corresponding to a single control function or an independent control process of a spacecraft. It should include three basic characteristics: file name, file size and transmission integrity
3.8
command operations procedure (COP)
closed-loop operation protocol that is used to keep the telecommand sending and receiving ends working synchronously. Depending on this protocol, the correctness, integrity and sequence of telecommand application data transmitted in error channel are guaranteed
3.9
control command
specific telecommand transfer frame, which carries control instruction in its data field, and is used to establish the internal operating parameters required for establishment of the command operations procedures
3.10
command link control word
relevant information of the telecommand receiving end is reported in the packet telemetry transfer layer to the sending end through packet telemetry to support effective command operation. It is a standard format data unit specified for such report information
3.11
multiplexer access point
transmission management mechanism that enables multiple sources and users to share the same virtual channel. By uniformly allocating the "multiplexer access point" which designates the header of the telecommand segment, and implementing transmission management according to different priorities of user’s needs, different user application data alternately occupy the virtual channel in a time-shared manner, i.e., subdividing a single virtual channel into multiple transmission paths
4 General provisions
4.1 Bit sequencing convention
The bit sequencing convention is shown in Figure 1. In an N-bit data field: the first bit transferred (i.e., the most left justified in Figure 1) is defined to be Bit 0 (B0), the following bit is defined to be Bit 1 (B1) and so on up to Bit N-1 (BN-1). When this field is used to express a binary value, the most significant bit shall be the first bit of the field, i.e., Bit 0 (B0).
All fields mentioned in this part are 8-bit words.
Figure 1 Bit sequencing convention
4.2 Data stream of packet telecommand
The information processing process of packet telecommand shall be hierarchical, and the telecommand application data sent from the source side shall be sent to the telecommand user on the spacecraft after five layers of processing and inverse processing, as shown in Figure 2.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General provisions
5 Pack layer
6 Segmentation layer
7 Transfer layer
8 Channel coding layer
9 Physical layer
