1 Auroc III Telemetry Sytem Steven S. Pietrobon 6 Firt Avenue, Payneham South SA 5070, Autralia teven@world.com.au 9th Annual ASRI Conference (ASRI 99) Canberra, Autralia 3 5 December 1999
2 Introduction The Auroc III Telemetry Sytem i deigned to tranmit information of the tate of the Auroc III ounding rocket before and during launch. On payload eparation, the ytem tranmit data from the payload. The information include preure, temperature, actuator poition, valve poition, flow rate, train, propellant level, flight computer data and experimental data from the payload. The tranmitted data i received on the ground where it i imultaneouly tored and diplayed on PC for ue in the launch control centre. The ytem wa tarted a a tudent project at the Univerity of South Autralia in 1989, culminating in 1994 with tudent Vince Roe (enor conditioning module), Troy Zierch (data acquiition module), and David Mullin (telemetry encoder unit).
3 The Original Sytem The original Auroc III Telemetry Sytem conit of three eparate module: Senor Conditioning Module (): Collect analog enor data and convert it to a tandard 5 to +5 V ignal. Each can condition up to eight enor on a 3U 160 mm eurocard with a mall daughter board for temperature conditioning. Data Acquiition Module (DAM): Convert tandard ignal data from up to two and/or 12 on/off ignal into 12 bit ample on a 3U 160 mm eurocard. Telemetry Encoder Unit (TEU): The TEU command up to 16 DAM to convert and tranmit ampled data to the TEU which combine it into a 250 kbit/ tream. The TEU alo collect and end data to the Flight Computer and tranmit payload data after payload eparation. A 3U 160 mm eurocard wa ued.
4 Sytem Block Diagram e n o r DAM DAM DATA RS 485 Bu Payload TEU Tranmitter e n o r DAM CLK Flight Computer L Band up to 256 enor up to 16 unit up to 8 unit
5 Telemetry Format The telemetry format that i tranmitted to the ground follow tandard technique with frame and ub frame. Each ub frame conit of 24 word (originally 54 word) with 13 bit in each word. The firt two word are ynchroniation word, followed a frame count, ub frame count, and 20 data word. There are 20 (originally 16) ub frame per frame. Synch Word 0 = 1111 1010 0110 1 Synch Word 1 = 0110 0110 0000 0 Frame Count = 0 4095 (12 bit) with 1 odd parity bit Sub Frame Count = 0 19 (12 bit) with 1 odd parity bit Data Word = 12 bit per ample with 1 odd parity bit Frame Frequency = 5 Hz (22.258 Hz originally) Sub Frame Frequency = 100 Hz (356.13 Hz originally) Word Frequency = 2400 Hz (19,230.7 Hz originally) Bit Frequency = 31,200 Hz (250,000 Hz originally)
6 Telemetry Format (cont d) The word rate and frame ize were changed o a to have ampling rate of 10 and 100 Hz. Each Auroc III i expected to have 8 enor at 100 Hz for the motor and 62 enor at 10 Hz for the ret of the vehicle. Thi allowed the data rate to be greatly reduced. Original deign with Xilinx XC3064, three 2Kx8 EPROM, and two dual port RAM (for FC) redeigned with Xilinx XCS05, one EPROM, and one 1Kx8 dual port RAM. Minor Frame Sync 0 Sync 1 Frame Cnt Sub Frame 0 Word 0 Word 19 Sync 0 Sync 1 Frame Cnt Sub Frame 1 Word 0 Word 19 Major Frame Sync 0 Sync 1 Frame Cnt Sub Frame 19 Word 0 Word 19
7 Flight Computer Interface The interface from the TEU to the Flight Computer (FC) i via a 1Kx8 dual port RAM. Each enor word require two addre location (for the low and high byte). With up to 256 enor the firt 512 byte are for ending enor data to the FC. The remaining 512 byte are for ending FC data to the TEU. The BUSY ignal i ued by the TEU to check if the FC i writing data to the location that i being read. If o, the TEU invert the parity bit to indicate that the data could be corrupted. I/O[7:0] I/O[7:0] Telemetry Encoder Unit A[9:0] WE BUSY 1Kx8 DPRAM A[9:0] WE BUSY Flight Computer
8 Payload Interface On payload eparation, a wire path i broken to indicate that enor data i to be replaced by payload data. If eparation i not detected, then a timer ignal i ued to indicate tart of payload operation. The payload provide it own tream and clock to the TEU. Thi allow the payload to tranmit data to the ground at it own data rate. Connector Wire Auroc III Separation Telemetry Encoder Unit Payload Separation Data Clock Payload Separation Plane Payload Fairing
9 RS 485 Bu Protocol During each word period (416.7 ) the TEU erially end an eight bit addre to the data bu. The firt four bit elect the DAM and the next four bit elect the enor for that DAM. Senor addre 0 can alo be ued to elect the 12 on/off ignal. Once elected, the DAM convert the analog data to digital and erially end the 12 bit ample and odd parity bit to the data bu. A eparate clock ignal from the TEU keep the ignal ynchronied. TEU A7 A6 A5 A4 A3 A2 A1 A0 P DAM TEU DAM D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 P
10 Implementation Iue The original DAM ued a Xilinx XC3030, a 16 to 1 analog multiplexer and a 12 bit MAX122 analog to digital (A/D) converter. Currently, the XC3030 ha been replaced with an XCS05. To reduce power (from 230 to 66 mw) and cot (from $60 to $30) the multiplexer and A/D will be replaced with two A/D converter with eight analog input. The input voltage range will change from 5 to +5 V to 0 to 4.096 V (with 1 mv per diviion). Each Auroc III will have five /DAM unit (Boattail, Intertank 1, Intertank 2, Payload Fairing, and Noe Cone). Four of thee have 16 enor with the Noe Cone having 8 enor. Thu, to reduce ize and ma, two will be implemented on a 6U 160 mm eurocard, with up to eight temperature enor. The DAM, TEU and power upply will alo be implemented on a 6U 160 mm eurocard (only one unit will have the TEU loaded).
11 Concluion A telemetry ytem for Auroc III ha been deigned that allow enor, flight computer, and payload data to be tranmitted to the ground. Thi ytem i currently being redeigned for flight uing indutrial grade component. Improvement have been made to reduce component count, cot and power. Hardware and oftware to tore and diplay the received telemetry on the ground till need to be performed. The telemetry ytem can alo be ued in other vehicle (uch a Auroc IV) due to it flexibility and programmability.