Rev.
ECO
Description
Author
01
37-292
Initial release
02
37-306
Add hardware functionality
Approved
Date
ZKhan
14/Jul/2015
RFG
8/Aug/2015
TESS
Spacecraft Simulator Functional Description
Dwg. No. 37-60104
Revision 02
3/August/2015
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Table of Contents
1
Introduction ............................................................................................................. 1
2
Spacecraft Simulator Functions ............................................................................ 2
3
Spacecraft Simulator Description ......................................................................... 2
3.1
3.2
3.3
3.4
3.5
Inputs .......................................................................................................................... 2
Outputs ....................................................................................................................... 2
Hardware Description ................................................................................................ 3
Firmware Description ................................................................................................ 3
Software Description ................................................................................................. 4
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Preface
This is the TESS Spacecraft Simulator Functional Description.
Revision 01 is the initial release.
Revision 02 added a lot of discrete hardware interface details.
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1 Introduction
The Spacecraft Simulator is a system to simulate the Master Avionics Unit (MAU)
interface and the Ka-band transmitter (KaTx) interface to the Instrument DHU during
development of the TESS Instrument DHU. This document describes the interfaces and
basic functions of the Spacecraft Simulator. The hardware, firmware and software of the
Spacecraft Simulator system are also described in detail. Figure 1 shows the test setup
in which the simulator will be used.
This simulator will be used with the DHU EDU as well as the flight DHU.
Figure 1 - DHU Test Setup
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2 Spacecraft Simulator Functions
The primary functions of the spacecraft simulator are as follows:

Communicate with the DHU over the primary RS422 interface

Send (4) discrete commands to the DHU

Send 1 Pulse-per-second (PPS) pulse to the DHU

Receive (4) discrete telemetry and (8) active analog telemetry from the DHU

Receive and transmit information to the EGSE RS422 interface

Transmit data to the boot-program RS422 interface

Provide (3) 28VDC power services to the DHU

Receive data from the DHU through 8-bit parallel interface
3 Spacecraft Simulator Description
3.1 Functional Inputs
From DHU Test Console (Ethernet interface):

Commands (3 UDP ports)
o Primary s/c command channel, CCSDS packets
o EGSE port
o Boot RAM port
From DHU:

Instrument SOH data over primary RS422 interface

Quaternions over primary RS422 interface

Four discrete telemetry bits

Eight active analog telemetry values

Instrument Data (SFDUs) over the Ka-band interface
From GSE power supply: 28 VDC
3.2
Outputs
To DHU Test Console (Ethernet interface):

Spacecraft simulator housekeeping
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
Instrument SOH data

Quaternions

Discrete instrument telemetry

Active analog instrument telemetry

Instrument Data (SFDUs)
To DHU:

1 PPS signal

State data over RS422 interface

Ancillary data over RS422 interface

Commands over RS422 interface

Discrete commands

20 - 36 VDC, 7.0 Amps
3.3
Hardware Description

Zynq single board computer:
o Kintex 7 board with
 Processor
 Programmable Logic
 1GB block RAM
o Mezzanine card:
 Connectors to DHU interface per EICD
 In-house design: TBD
o 1G Ethernet port

Simulator housing
o External Connections
 28VDC Input (Male 9-pin D-sub)
 28VDC output to DHU power (Female 9-pin D-Sub)
(J101)
 28VDC output to Camera power (Female 9-pin D-sub)
(J701)
 28VDC output to Survival power (Female 9-pin D-sub)



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MAU Interface (MWDM2L-51S) (J201)
Ka-band interface (MWDM2L-51P) (J202)
External RTD interface (MWDM2L-25S) (J703)
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o
o
o
o
o
o
o
3.4
 Active Analog Telemetry (MWDM2L-9P) (J704)
 1 Gbps Ethernet port
LEDs for four discrete inputs
LEDs for four discreet outputs
Enable switch for 1PPS
Inhibit switch for Survival Power
Enable switch for 28VDC DHU Power
Enable switch for 28VDC Camera Power
Enable weitch for 28VDC Survival Power
Firmware Description
TBD
3.5
Software Description
TBD
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