National Space Development Agency of Japan (NASDA) is to perform experimental operations to acquire necessary technology for the future inter-satellite communications configured with a data relay satellite. This paper intends to overview functions of the experimental ground system which NASDA has developed for the Engineering Test Satellite VI (ETS-VI) Data Relay and Tracking Experiment, and to introduce Space Network System Operations Procedure (SNSOP) method with an example of Ka-band Single Access (KSA) acquisition sequence. To reduce operational load, SNSOP is developed with the concept of automated control and monitor of both ground terminal and data relay satellite. To perform acquisition and tracking operations fluently, the information exchange with user spacecraft controllers is automated by SNSOP functions

Ishihara, Kiyoomi

Sugawara, Masayuki

English

NASA Technical Reports Server

. N95- 17184
i: '
:i!i_i!Lili¸_
!!i!_i_o_:il_-
_-H. ,
<i<'i
iL< <IC
•. <i,
. i /i _
>) <i ),
i_!i_I i_ ii_
ii_il:!_!!i<iil
:i_<_,:j! ii_
• ,i_:i'
<:
_ ,L,<_
Attempt of automated space network operations
at ETS-VI experimental data relay system
Kiyoomi ISHIHARA Masayuki SUGAWARA
National Space Development Agency of Japan (NASDA)
Tsukuba, Japan
o
/,'
ABSTRACT
National Space Development Agency of Japan
(NASDA) is to perform experimental
operations to acquire necessary technology for
the future inter-satellite communications
configured with data relay satellite. This paper
intends to overview functions of the
experimental ground system which NASDA
has developed for the En_neering Test Satellite
VI (ETS-VI) Data Relay and Tracking
Experiment, and to introduce Space Network
System Operations Procedure (SNSOP)
method with an example of Ka-band Single
Access (KSA) acquisition sequence. To reduce
operational load, SNSOP is developed with the
concept of automated control and monitor of
both ground terminal and data relay satellite. To
perform acquisition and tracking operations
fluently, the information exchange with user
spacecraft controllers is automated by SNSOP
functions
1. INTRODUCTION
NASDA has launched several types of satellites
since 1975. The tracking and data acquisition
operations for these satellites have been
conducted by using NASDA's ground stations
network, four S-band ground tracking stations,
3 stations in Japan and one in Sweden, but
with no space network. NASDA has yet no
experience of performing the satellite mission
operations with a space network.
ETS-VI Space Network system described in
this paper has been developed by NASDA
under the Space Operations and Data System
(SODS) program, as an experimental system to
obtain the necessary technology for the inter-
satellite communications. As a follow -on
program, NASDA will launch COMETS in
1997 and enhance NASDA's space network
technology of ETS-VI for the future operational
system.
2. ETS-VI SN SYSTEM
ETS-VI Space Network (SN) system consists
of space segment and ground segment. Figure-
1 illustrates the ETS-VI SN system.
2.1 Space Segment
ETS-VI will be launched by H-II launch
vehicle in 1994 . It will be located at I53.8
degrees East longitude. ETS-VI mounts two
experiment equipments for the experiment: S-
band Inter-satellite Communications Equipment
(SIC) and Ka-band Single Access Equipment
(KSA).
SIC can provide one forward service and two
return services simultaneously to support user
spacecraft on low earth orbit. The 19
elements phased array antenna attached to the
body of spacecraft provides return link service
for up to 2 users simultaneously. Only 16 of
the 19 elements are used to provide forward
link service to one user. The SIC operates on a
fixed frequency ( 2106.4 MHz forward/2287.5
MHz return)
KSA provides high-data rate support by using
new frequency band: 23 GHz forward/26 GHz
return. The 23/26 GHz KSA will be the first
inter-satellite communications equipment on
orbit. For experiments, only 80 cm parabolic
antenna provides one forward and one return
link services at a time.
2.2 Ground Segment
ETS-VI SN ground segment is located in
Tsukuba Space Center. It consists of 6 major
functions.
41
https://ntrs.nasa.gov/search.jsp?R=19950010769 2020-06-16T08:57:55+00:00Z
ETS-VI ADEOS
SNMS [ ESS I [ OADss 1 S'B3nd_ _ _and
#2LAN DSS
USER TERMINAL SYSTEM TERMINAL
DSS-OCS Figure-! : ETS-V! Space Network System
(1) Experimental Ground Station (EGS)
The EGS provides the telemetry and command
functions for ETS-VI and also provides the
telecommunication functions necessary for
transmitting and receiving user data through the
ETS-VI. The EGS interfaces with the ETS-VI
through Ka-band (30 GHz uplink/20 GHz
downlink) Space-to-Ground Feeder Link.
These uplinks and downlinks are done through
a 5-meter antenna.
(3) Space Network Management Subsystem
The SNMS is a core of the ETS-VI SN ground
segment. ETS-VI SN system control is
provided by the SNMS, which consists of a
configuration of computer setup to control and
monitor the ETS-VI and the EGS. The SNMS
also provides a interface with the User
Operations Control Center (OCC), through a
user terminal for the scheduling and real time
operations.
(2) Dummy Satellite Station (DSS)
The DSS provides the telecommunication
equipments to emulate the user spacecraft. The
DSS has functions of receiving SIC/KSA
forward links and transmitting SIC/KSA return
links to ETS-VI. The SIC forward/return
services are sent/received through a 3-meter
antenna, KSA services use a 2-meter antenna.
The DSS is normally located in the Tsukuba
Space Center, Japan, and is transportable for
experimental purposes.
(4) Orbit Determination/Acquisition and
Tracking Support Subsystem (OD/ATSS)
The OD provides orbit computation for earth
orbiting spacecraft and tracking performance
assessments for the SN.
The ATSS provides all system calculations
necessary for the initial acquisition and tracking
operations. One computer (EWS) is shared
between OD and ATSS.
42
(5)ExperimentSupportSubsystem(ESS)
TheESSprovidesthefollowing functions.
-Accumulationof theexperimentdata
-Analysisof theexperimentdata
-FaultIsolationanalysis(KSA system)
(6) DSS-OCS
The Dummy Satellite Station-Operations
Control Subsystem(DSS-OCS)providesDSS
control.Its primaryfunctionsis to monitorthe
DSSconditionsandgeneratethecommandsto
theDSS.
3.ACQUISITION SEQUENCE
Duringtheinitial acquisition,manycomplicated
processesoccurin combinationwith theuser
OCC, the ETS-VI, and the userspacecraftin
order to establish the inter-satellite
communicationlinksbetweenthetwosatellites.
Understandingof theseprocessesis required.
Obtaining theseoperationstechniquesis oneof
the most important objectives of the
experiments.
The acquisition and tracking operationsfor
spacenetworkis muchcomplexin comparison
to the usualdirect communicationswith the
groundstationnetwork.The last tendencyof
mass data and high rate transmission, for
example,requiresdata relay satellite to have
antenna bigger and frequency higher, and
eventually make the operations more
complicated.In fact,althoughtheKSA antenna
of EFS-VI is only 80-cm in diameter, the KSA
has a very narrow radiation beam because the
frequency band is so high, 23/26 GHz band.
Eventually the KSA is required to point its
antenna precisely toward the user spacecraft
during acquisition.
For the ETS-VI SN experiments, NASDA
plans to use the Advanced Earth Observation
Satellite (ADEOS), as a user spacecraft, which
will be launched in 1996 from Tanegashima
Space Center, NASDA. Table-1 shows the
KSA typical acquisition sequence between the
two satellites.
The acquisition sequence shown in table-1 is
nominal procedure. However in case ETS-VI
fails,for example, to acquire the return beacon
signal from ADEOS at step E4, ETS-VI will
start the antenna movement for signal search.
Table-l: Typical Acquisition Sequence
ETS-VI ADEOS
Step-E1
Update orbit elements
stored at onboad
computer
Step-E2
Antenna point toward
ADEOS
Step-E3
Transmit Forward
beacon signal
Step-E4
Acq. RTN signal
Start ANT auto
track
Step-A1
Update orbit elements
Step-A2
Antenna point toward
ETS-VI
Step-A3
Acq. ForwardBeacon
Start Antenna auto
tracking mode
Step-A4
Transmit Return
signal
|1 I II I II
I s,a Fo ar and,Re,urn,,Se ,ces,]
4. AUTOMATED SN OPERATIONS
4.1 Automated SN operations
Establishing an automated SN operations
system is one of the key-elements that NASDA
intends to develop by the era of our operational
Data Relay Satellite System. NASDA thus
made an attempt to develop a new automatic
operations method, SNSOP (Space Network
System Operations Procedure), as a
experimental method at the ETS-VI
Experimental SN ground system. This method
concentrated on the following points:
- To control both ETS-VI and EGS
automatically in accordance with the pre-
determined acquisition sequence.
43
-To monitor the network conditions
effectively.
- To move into recovery procedures
automatically as much as possible if any of
the checks fail
- To create/modify the operations sequences
easily.
- To exchange the operational information
with the user OCC timely.
for other ground elements
- Check Box : Defines the TLM# to compare
with data base value.
- Branch Box : Defines the branch condition.
- Loop Box : Defines the loop process based
on a branch condition.
- Store Box : Defines the stored CMDs for
ETS-VI
- StoreExe Box: Defines the execution of
stored commands
- Sub-SOP Box: Defines the sub/mini-SOP#
- SN/OpsMSG Box:Defines SN or OpsMsglD
4.2 Hardware
All control and monitor of the EGS and ETS-
VI is performed by SNSOP installed in the
SNMS, although manual intervention is still
possible. The SNMS consists of the host
computer and two EWSs (one for SIC, the
other for KSA). The SNSOP process can be
divided into two processes; (1) a client process
in the EWS, (2) a server process in the host
computer. Figure-2 shows their functional
assignments.
4.3 SNSOP
The SNSOP is a flow chart list which consists
of the combination of process boxes and flow
lines. The process box can define a statement,
an arithmetic expression, a lo_cal expression,
a control command for SNSOP and so forth.
The flow line is a line, which can define one-
way direction, for connecting between two
process boxes. The SNSOP can be composed
of a main-SOP, a sub-SOP and a mini-SOP
structurally. The SNMS provides a MMI for
creating and modifying the SNSOP easily.
Process boxes used in the ETS-VI SN system
are shown in figure-3 and as follows:
- Exec2 Box
- Exec3 Box
- Start Box : States the start of main-SOP
- End Box : States the end of main-SOP
- Entry Box : States the start of sub/mini-SOP
- Return Box : States the end of sub/mini-SOP
- Process Box: Defines the free text
(ex.arithrnetic expression,etc.)
- Execl Box : Defines the execute command
for ETS-VI
: Defines the execute command
for EGS
: Defines the execute command
EVVS HOST COMPUTER
SNSOP Edition --
SNSOP Execution ..
MMI
SNSOP Data Base
TLM Data base
,_ _ CMD Data Base
_- TLM Processing
k
CMD Processing
CLIENT SERVER
Figure-2 '. SNMS functional assignment
Connect
Point
Figure-3 : Process Box
44
4A Operation Description Data (ODD)
The ODD is a unique language developed by
NASDA to be used in SNSOP. The system
operator can easily describe a free text ,e.g., an
arithmetic expression, a logical expression,
branch condition, etc., in a process box by
using the ODD. It can basically be divided into
following groups:
(1) Arithmetic Assignment
- Constant
- Variable
- Array
- Arithmetic operator (+,-,x,/)
- Functions
- Assignment
(2) Logical Assignment
The assignment method is the same as
arithmetic assignment.
- Logical operator
and, or, not, xor
(3) Judgement condition
>, <, >----, <--, --, !----
(4) SNSOP control commands
The control commands used at ETS-VI SN
system are as follows;
Test : Compare the received TLM with
canned value in data-base.
Wait : Wait before moving to the next step
for an appointed period of time.
Wake : Break the current job and restart at
the appointed time.
Input : Input the value to the appointed
variable name.
Display : Display the value in the appointed
variable name.
Print : Print the value in the appointed
variable name.
Interrupt: Prohibit the interruption, or release it.
GetTLM: Set the appointed TLM value to the
appointed variable name.
StoreCancel: Cancel the stored commands
Save : Store the value in the appointed
variable name to the appointed file
Load : Get the value into the appointed
variable name.
Beep : Sound buzzer for the appointed time
Exec I : Execute the commands for ETS-VI
Exec2 : Execute the commands for EGS
Exec3 : Execute the commands for other
ground elements
Store : Store the ETS-VI commands
StoreExe: Execute the stored commands
OpsMsgGet: Get the operation message
4.5 Execution of SNSOP
The SNSOP is executed one after another
automatically in accordance with the flow chart
list, and the manual operation is also possible.
The automatic execution will be stopped
temporally when the system operator selects
"Pause Mode" or sets a break point on the
expected process box of flow chart list, or
when the system operator is asked for his
judgement by SNSOP. Following are the
threee modes during manual operation:
Step Exec. mode
Step Skip mode
Box Skip mode
: Execute one step only.
: Skip one step only.
: Skip one process box.
The transition from manual to automatic mode
is performed by choosing" Restart Mode" ,and
"Abort mode" is for the SNSOP forced end.
4.6 Control Requests from user-OCC
The changes to the operating conditions or
configurations of the ETS-VI SN ground
segment can be initiated by the "Operations-
Control" message from user-OCC to the
SNMS. These messages are categorized into
two groups: Class A and Class B,
The class A Ops-control message is executed
automatically after completing the valid check at
SNMS. The class B is performed with the SN
operator's decision.
The operating SNSOP will be interrupted after
the completion of validity check when the Ops-
control message is received at SNMS, and
another SNSOP for an Ops-control message
will be called and started automatically.
4.7 Monitor requests from user-OCC
The real-time monitoring of SN _ound system
at user-OCC is achieved via "SN message" and
"SN message ID". The SN message is a
telemetry data of ETS-VI SN system, and is
sent to user-OCC every 2 seconds during
support period. The SN message ID is used
when the SN system wants to notify the key
event of the current executing sequence,e.g.,
45
:; i_
2 ¸ , •
/ ,i_;;'¸
<
!_i; _:i___
:_•_ ;;:5 i
f ?
Completion of EGS setup, Bringing forward
beacon signal up, etc., to the user-OCC.
The message ID is sent to user-OCC by
SNSOP.
The user-OCC can get information of which
step the SN system is executing at a certain
time via the SN message and SN message ID.
_. SNSOP DATA BASE
A total number of 61 main-SNSOPs are stored
in the data base of SNMS. Many sub and mini-
SOPs are linked with the main-SOP. The main-
SOP can be classified as follows:
(1) System Operations SOP
There are 11 SOPs for system operations, e.g.,
EGS initial setup, Pilot links on/off, TT&C
links on/off, etc.
(2) KSA Service SOP
4 SOPs are prepared for the KSA service
operations based on the combination of types
of initial acquisition sequence mode
(Sequence#I, Sequence#2A, Sequence#2B)
and KSA antenna pointing modes( CPU mode,
Direct mode).
(3) SIC Service SOP
4 SOPs are prepared for the SIC forward/return
service operations based on the SIC antenna
pointing modes (Orbit elements mode, Program
mode, Real time mode, Direct mode).
(4) Recovery SOP
The recovery SOP is called when any of the
checks in the main-SOP fails. I 1 SOPs are
stored in the data base.
(5) Ops-Control SOP
30 SOPs are stored in the data base. The Ops-
control SOP is used when it is requested from
the user-OCC.
_iiii_
Figure-4 shows the KSA service operations
display for CPU/sequence#2A mode. The left
window shows the main-SOP and the fight is
the sub-SOP of the second process box from
the top of main-SOP.
46
6. SN Real-Time OPERATIONS
The real-time operations period is the time
frame in which the user-OCC and the SN
system perform necessary activities to support
the command , telemetry, and tracking
operations of a user spacecraft. These
operations can be categorized as those
occurring prior to the scheduled support start
time, those occurring during the real support
period, and those occurring post-support.
The following are the typical operations of each
phase with an example of the KSA service
operation (CPU mode).
6.1Pre-support Phase
(1) User-OCC
a. Sending the KSA service requests to the
SNMS by at least 30 minutes prior to
scheduled start of service,through the user
terminal.
(2) ATSS
a. Receiving the state vectors of both ETS-VI
and user spacecraft if updated.
b. Processing of them by 30 minutes prior to
C.
the scheduled start of service.
Calculating the parameters necessary for
the acquisition and tracking operations, and
sending them to the SNMS when required
from the SNMS.
(3) SNMS
a. Choosing the next support service by at
least 30 minutes prior to the scheduled start
time.
b. Sending the calculation request of
acquisition parameters to the ATSS and
receiving it from the ATSS within a certain
time.
c. Setting the parameters calculated at step b
into the system variables of KSA service
SOP.
d. Configuring the ETS-VI by SNSOP.
(4) EGS
a. Configuring the EGS by SNSOP.
6.2 Support Phase
(1) SNMS
a. Controlling KSA antenna operations by
/::<: : </: ;'::<:;:h< >: . >::: :.. :><. < :;;.,::- • • < :5::: • >>• : r,:::: :<:• ::>:. •• / • : '• ' :• :;; : : ' : : : ..... :•> ": _:>! : < :::;> ••;:::::C:<%:;::: ::¸ :i: :::<•• ::h;<<::::;<:C:•::_>>>•::::::;::::::::.::`:_:!:_:_:_;_:i:_:_:!:i:_:::::i;i;i:i:{:i:i:i:i:i:i:i:i:i::::::::::::::::::::::_:_:_:_:_:i:{:_:_:_:_:_:_:i_!;_:_:_:_:
• :_i<i!/i:
<i _/ • L_
:i_ki!_/!:7>I_<L
kili_i/!!<:!/
L ii:i L >'
,/<i:/_ /
L_ _ if< _
<!<ilC 
j/k::< F• .'
H
c
<i ,i_
_
ili;ii_iL<fL
• ::ii_::i:J_
SNSOP.
b. Initiatin_terminating the services by
SNSOP.
c. Generating and transmitting the SN
message and SN message ID to the user
terminal located at the user-OCC.
d. Operating service.
e. Monitoring the SN performance.
f. Verifying and processing the Ops-control
from the user-OCC through user terminal if
received.
g. Initiating the recovery operations based on
the recovery SOP if any of the checks fails.
(2) EGS
a. Acquisition of service channel.
b. Operating service.
c. Reconfigurin_reacquisition service.
d. Receiving and logging the tracking data if
required.
(3) User-OCC
a. Monitoring the SN performance via SN
message and message ID.
b. Sending the Ops-control if needed.
6.3 Post-support Phase
(1) SNMS
a. Dumping the operations history
b. Conducting post-support debriefing with
the user-OCC.
(2) OD/ATSS
a. Receiving and logging the tracking data
from the EGS in accordance with the
direction from the SNMS.
7. CONCLUSION
NASDA is now in its final process of the ETS-
VI launch scheduled on August '94. The
experiment will be_n from November '94 after
completing the initial mission checkouts on
orbit. We would like to verify the availability of
the SNSOP method through the ETS-VI data
relay experiment period and reflect it to our
future data relay satellite system.
ETS-YI Experiment £_z'0und System _ . SOR MONITOR SOP-_NdE: KSA.SUBSOP/gHECK I(SA
g4 System Terlnirm|
Uonlt_ Sub
_/ode : Operation
Data : Realti,.___ee
UTC 94/182 08:44:12
3ST _4/182 1]:/.4:12
rt
Qpe _-t Sctze _- I Oata _'- I _-I I I
08:21:33 _/._/._._?_ _ 7 4) I_0 K _1
08:21:41 SN • SOPrZs:7)bf:- F
_J
IE_LL _ _ F C1;
HISTORY MONITOA
Ol:_r.J_r ZON TEXT STATUS
sr_ar
sr_r
SF._gF
STC_qT
Stt_9[
Figure-4 : KSA service operations display
SF_T I<._/],lq:R ___
Ct_L "Y,.__ $t,,I]_13OiK._ _S/,/$13P SE TU_;
ENTRY ;
INTEI_LIPT NO
CALL "Y-..__SU6SOP/Y-_ _S_tSOP_SE TLP";
C/_LL "KS__ SLi]SSP/EHEtX_ KS_";
ENFF_
Opera t I o_1 uon I tot"
_er lo : _c_1 Ivu_ _t_rt : S4/1_ _:E4:OO
I'l,-,It_nm _ss_a_ to _1_207S40000001 iv_t Step :S4/I_. 1o:oo:oo
v J I/AIH I/[I_IITDII _i_-N/IE: KSA,/I/IffR_A_2A
_-I SN Ii_l I tot
its ] OR::3,:I: O_
IIIIOR:_:2_
47
%
5-
ON. SOP CONTROl
STEP )
BSKI, )
SSKIP )
RESTART )
ABORT )
P_INT I
END


Attempt of automated space network operations at ETS-VI experimental data relay system

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server