This standard specifies the system and interface of the ground equipment of the space-to-earth VHF digital communication system in the manned spacecraft flight test. This standard applies to the design, development and production of the ground equipment of the space-to-earth VHF digital communication system. SJ 20816-2002 System and interface of the ground equipment of the space-to-earth VHF digital communication system SJ20816-2002 Standard download decompression password: www.bzxz.net

Military Standard of the Electronic Industry of the People's Republic of China FL5821
SJ20816—2002
System and interface on surface equipment forVHF digital communication between heaven and earth
System and interface on surface equipment forVHF digital communication between heaven and earth earth2002-01-31 issued
2002-05-01 implementation
approved by the Ministry of Information Industry of the People's Republic of China 1 Scope.
1.1 Subject content
1.2 Scope of application
2 Reference documents
3 Definitions
4 General requirements
4.1 System structure
4.2 Equipment composition and interface
Monitoring center equipment composition and main interfaces
5 Detailed requirements
5.1 System and interface
Detailed requirements of the interface
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1 Scope
Electronic industry military standard of the People's Republic of China System for VHF digital communication between heaven and earth
System and interface on surface equipment forVHF digital communication between heaven and earth 1.1 Subject Content
SJ20816—2002
This standard specifies the system and interface of the ground equipment of the VHF digital communication system between heaven and earth in the flight test of manned spacecraft. 1.2 Scope of Application
This standard applies to the design, development and production of ground equipment of the VHF digital communication system between heaven and earth. 2 Reference Documents
GB/T34541982 Interface Circuit Definition Table between Data Terminal Equipment (DTE) and Data Circuit Terminating Equipment (DCE) GB/T6107—1985 Interface between Data Terminal Equipment and Data Circuit Terminating Equipment for Binary Data Exchange GB/11014—1989 Electrical Characteristics of Balanced Voltage Digital Interface Circuit 3 Definitions
3.1 Terms
3.1.1 VHF Digital Voice Communication System between Heaven and Earth A communication system between manned spacecraft and ground equipment operating in the VHF frequency band. 3.1.2 Ground equipment equipment on surface equipment in the earth station and monitoring center of the space-earth VHF digital communication system. 3.1.3 Earth station station on earth
VHF tracking communication equipment.
3.1.4 Monitoring center monitor control centre Equipment for monitoring and controlling the status and parameters of each VHF earth station in the system. 3.1.5 CCSDs services CCSDS services
Services that comply with the CCSDS space data link. 4 General requirements
4.1 System structure
The structure of the space-earth VHF digital communication system is shown in Figure 1. It consists of digital communication equipment on manned spacecraft, several VHF communication earth stations and a monitoring center. Under the supervision, control and management of the monitoring center, the system uses a VHF communication earth station close to the sub-satellite point of the manned spacecraft to achieve ground-to-space VHF communication. The earth station should ensure the synchronous tracking and capture of the communication system. Monitoring
Command voice
Digital service
4.2 Equipment composition and interface
4.2.1 Equipment composition
VHF earth station equipment generally consists of:
Antenna, servo subsystem:
Transceiver:
Ground equipment
Earth station-1
Earth station-2
Earth station-n
Figure 1 Structure of the ground-earth VHF digital communication system
Manned spacecraft
Data terminal (including voice terminal, data multiplexer, confidentiality machine, CCSDS service interface unit); monitoring subsystem;
Power supply.
4.2.2 Equipment Interface
The equipment interface of VHF earth station is divided as shown in Figure 2: KAoNiKAca-
Four-wire speech
Two-wire speech
Digital voice terminal
Time signal
Multi-core
Remote encrypted group signal
Remote monitoring data
Monitoring equipment
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Secrecy machine
Device/demodulator
And transmitter/ Receiving
CCSDS service
Interface unit
Note: A-remote voice interface: B-digital service interface; C, D, E-group signal interface: F-intermediate frequency interface: G-RF interface: H-monitoring interface G
Duplexer
CCSDS service
Figure 2 Schematic diagram of earth station equipment interface division of earth-to-earth VHF digital communication system 4.2.2.1 Remote voice interface
Four-wire voice signal interface:
Two-wire voice signal interface.
4.2.2.2 Digital service interface
a: Balanced digital voice serial interface:
b. Balanced digital service serial interface.
4.2.2.3 Group signal interface
a. Balanced group signal application interface;
b. Balanced remote encrypted group signal serial interface. 4.2.2.4CCSDS service interface
Supports the following service types of CCSDS network.
a. Insertion;
Virtual channel access.
4.2.2.5Intermediate frequency interface
Uplink interface;
b. Downlink interface.
4.2.2.6RF interface
Uplink interface;
Downlink interface.
Monitoring interface
a. Balanced remote monitoring data serial interface: b. Network interface.
4.3 Equipment composition and main interfaces of the monitoring center 4.3.1 Equipment composition
The equipment composition of the monitoring center is shown in Figure 3:
Four-wire telephone
4.3.2 Main interfaces
Digital voice terminal
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Data multiplexer
Voice unit monitoring
Secrecy machine
Remote encrypted group signal
Monitoring and recording
Remote monitoring
Figure 3 Equipment composition of the monitoring center
Remote monitoring data
The main interfaces are shown as "A", "D", "H" and "I" in Figure 3, which respectively represent the following four interfaces: a.
Two/four-wire voice interface;
b. Balanced encrypted group signal serial interface: balanced data serial interface
Network interface.
Detailed requirements
System and interface
5.1.1 Communication frequency band
Use the frequency band of 250MHz~310MHz in the VHF band, or use the frequency band that complies with relevant specifications or development contracts. 5.1.2 Modulation and demodulation
5.1.2.1 Two-phase continuous phase frequency shift keying (2CPFSK) The characteristics of the two-phase continuous frequency shift keying method are detailed in Table 1: iKANiKAca
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Main characteristics of the two-phase continuous frequency shift keying method Recommended characteristics
Two-phase continuous phase frequency shift keying (2CPFSK) Modulation index 0.7
Positive voltage → positive frequency shift
Incoherent frequency demodulation
Demodulation channel bandwidth B-1.1/T
Note: FSK can also be used.
Phase shift keying (2DPSK or 4DPSK)
Phase shift keying characteristics are detailed in Table 2 and Table 3:
It has the advantages of narrow bandwidth, constant envelope, and easy detection method. The modulator input voltage controls the carrier frequency shift
The output voltage of the signature frequency detector is restored after integral judgment. The data code T is the code element (if the code is a sign bit) width. The main characteristics of the two-phase phase shift keying (2DPSK) method are shown in Table 2
Recommended characteristics
2DPSK Differential phase shift keying (0/1 phase modulation) Positive voltage → positive phase shift
Square wave signal transmission --- space ratio should be between 0.98 and 1.02 Carrier suppression>20dB
Coherent detection
Differential coherent detection
Data is first differentiated, then 0/1 phase modulation, there are two methods for demodulation: coherent detection and differential coherent detection
Modulator input controls carrier phase shift
After detection, the differential signal needs to be restored to the baseband data signal. This detection The best test effect
After detection, it is the baseband data signal
The main characteristics of the four-phase phase shift keying (4DPSK) method are shown in Table 3
Recommended characteristics
Four-phase phase shift keying (4DPSK)
00 represents 0°
01 represents 90°
11 represents 180°
10 represents 270°
Coherent detection (polarity comparison method)
Differential coherent detection (phase comparison Method)
The square wave signal-space ratio should be between 0.98 and 1.02. Carrier suppression>20dB
Positive voltage→positive phase shift
5.1.2.32DPSK/DS or 4DPSK/DS mode. The characteristics of 2DPSK/DS or 4DPSK/DS mode are detailed in Table 4: Description
The data is first differentiated and then phase modulated. Two orthogonal 2DPSK signals can be synthesized
The detection output is restored to the baseband data signal through logical exchange. This method has the best detection effect
The detection output can directly obtain the baseband data signal. This method has a good detection effect
Modulator input controls the carrier phase shift
2DPSK/DS
4DPSK/DS
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Table 42DPSK/DS or 4D7SK/DS mode main characteristics recommendations
Information (symbol) code element width and
Spread spectrum code period keep integer multiples
Transmission signal bandwidth B=2Rb
(R is the spread spectrum code rate ）
Carrier suppression>25dB
Spread spectrum loss<0.8dB
Note: 2DPSK, 4DPSK modulation and demodulation requirements are shown in 5.1.2.2.5.1.3 Data multiplexing and demultiplexing
Differential phase keying, direct sequence spread spectrum
Easy to extract bit synchronization
If conditions permit, B=3Rb
If conditions permit, 1dB
The data multiplexing and demultiplexing device synchronously inserts digital voice, time signal and digital service signal (telegraph, telemetry signal), and synchronously extracts digital voice and digital service signal. Its output/input group signal rate is selected according to the business volume. The equipment on the service side of the interface is digital voice terminal, telegraph terminal and telemetry terminal. 5.1.4 Digital service
Digital service content: digital voice, time signal, telemetry, telegraph. 5.1.4.1 Service type
Uplink transmission of digital voice, time signal, telegram: a.
b. Downlink transmission of digital voice, time signal, telemetry data, telegram. 5.1.4.2 Rate
Digital voice rate: 16/32kb/s;
Telemetry signal rate range: 4800~19200b/s: Telegram signal rate: 2400b/s.
5.1.5CCSDS network service
Has the ability to access the CCSDS main network or CCSDS space link subnet. 5.2 Detailed requirements of the interface
5.2.1 Group signal interface
5.2.1.1 Rate
The group signal rate selected according to the service volume is: 24/32/64kb/s. 5.2.1.2 Interface signal
There are two types of signals passing in both the sending and receiving directions. a. Group signal
This signal is a binary code with a duty cycle of 100%. When the information signal is "0", the output terminal A of the generator is positive relative to the terminal B, and the voltage difference between the receiver terminals A and B' is ≥0.3V: When the information signal is "1", the output terminal A of the generator is negative relative to the terminal B, and the voltage difference between the receiver terminals A and B is ≤0.3V.
b. Timing signal of group signal
This signal is a rectangular pulse with a duty cycle of 50%, and the leading edge of the clock positive pulse is aligned with the leading edge of the information signal. As shown in Figure 4: 6
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5.2.1.3 Interface type
Timing signal
Information signal
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Figure 4 Information and timing signal
There are two types of interface types: unidirectional interface and reverse interface. a. Same-direction interface
The group signal and its corresponding timing signal through the interface are transmitted in the same direction, as shown in Figure 5: Data multiplexing
Information signal
Timing signal
Figure 5 Same-direction interface
Reverse interface
Secret machine
The timing signals of the two transmission directions through the interface are transmitted toward the secret machine, as shown in Figure 6: Data multiplexing
Information signal
Timing signal
Figure 6 Reverse interface
5.2.1.4 Electrical characteristics
Should comply with the provisions of 5.2.4.3.
5.2.1.5 Mechanical characteristicsWww.bzxZ.net
Should comply with the provisions of D-type 37-core connector in 5.2.4.2.1. 5.2.2 Voice signal interface
5.2.2.1 Audio four-wire interface
a. Passband: 300～3400Hz;
Secrecy machine
b. Relative power level:
Send: -14dBr
Receive: +4dBr:
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Note: The current equipment allows sending: -16dBr receiving: 7dBr. Impedance: 6002, balanced;
Return loss: ≥15dB (300~600Hz); d.
≥20dB (600~3400Hz).
Audio two-wire interface
Passband: 300~3400Hz;
Relative power level: Send: 0~-5dBr; b.
Receive: -2~7.5dBr;
Impedance: 6000, balanced:
Note: Allowed when necessary: ​​9000, balanced: 6000+2.16μF, balanced
900Q+2.16μF, balanced
Return loss: ≥12dB (300~600Hz); ≥15dB (600~3400Hz)
5.2.3 Unbalanced data signal serial communication interface is used to connect various devices inside the earth station, and its requirements should comply with GB6107. 5.2.3.1 Data signal rate
Data signal rate: 0~19200b/s.
5.2.3.2 Mechanical characteristics of the interface
The interface between the data terminal equipment (DTE) and the data circuit terminating equipment (DCE) is set at the signal interface point of a pluggable connector between the two devices. The female connector is connected to the data circuit terminating equipment. The data terminal equipment should provide an extension cable with a male connector. It is recommended to use short cables (less than 15m each). See Table 5 for the pin signal allocation table of D-type 25-pin connector: 8
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Pin number
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Table 5 D-type 25-pin connector pin signal allocation Interface circuit
Function of interface circuit
Protective ground
Send data
Receive data
Request to send
Ready to send
Data equipment ready
Signal ground or common return line
Data channel receiving line signal detector
(Reserved for data equipment testing)
(Reserved for data equipment testing)
Unspecified
Sub-channel receiving line signal detector||tt ||Subchannel ready
Subchannel sends data
Transmitter signal symbol timing (DCE source)
Subchannel receives data
Receiver signal symbol timing (DCE source)
Unspecified
Send subchannel line signal
Data terminal ready
Data signal quality detector
Call indicator
Data signal rate selector (DTE/DCE source)Transmitter signal symbol timing (DTE source)
Unspecified
The interface circuits between data terminal equipment and data circuit terminating equipment are divided into four categories a.
Ground and common return line:
Data circuit:
c. Control circuit;
Timing circuit.
See Table 6 for circuit categories and interface circuit numbers
Interface circuit
Protection ground
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Table 6 Circuit categories and interface circuit numbers
Signal ground or common return line
Send data
Receive data
Request to send
Ready to send
Data equipment ready
Data terminal ready
Call indicator
Data channel receive line signal detector
Data signal quality detector
Data signal rate selection (DTE)
Data signal rate selector (DCE)
Transmitter signal symbol timing (DTE)
Transmitter signal symbol timing (DCE)
Receiver signal symbol timing (DCE)
Sub-channel transmit data
Sub-channel receive data
Send sub-channel line signal
Sub-channel ready
Channel receive line signal detector
Balanced data signal serial communication interface
Balanced data signal The line communication interface is used to connect the units (which can also be components or devices) shown in Table 7. Table 7 Balanced data signal serial communication interface application service
Digital voice
Digital service
Group signal
Monitoring data
Remote encrypted group signal
Encrypted signal
5.2.4.1 Input/output
Unit A
Voice terminal
Service terminal
Multiplexer
Monitoring equipment
Monitoring center
Secrecy machine
Rectangular, polarized binary data.
5.2.4.2 Mechanical characteristics of the interface and connector pin function assignment 10
Unit B
Multiplexer
Multiplexer
Secrecy machine
Monitoring center
CCSDS interface unit
CCSDS interface unit
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Transmission rate (kb/s)
2.4/4.8/9.6
24/32/64
4.8/9.6/19.2
24/32/64
24/32/64
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