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Communication Subsystem
Communication Subsystem
Introduction Hardware Protocol Description Interface Examples Test Link Budget Conclusion
Table of Contents Hardware Protocol Description Interface Examples Test Link Budget Conclusion
Hardware OSSS Vital Part Testing
MIL-STD-1540 Power Interface?
Specifications Frequency: 430-450 MHz Bitrate: 9600 baud Voltage: 3.3-5 V and 7.5-12 V Power output: [email protected] Current Drain:
Transmitting: 940mA@2W Receiving: 60mA
Mass: 100 g
Interface
D ata Bus
Addres s Bus
D 0:7
A0:1
A d d res s D eco d eC ircu i tA2:7
D 0:7
A0:1
A2:7
RD
IRQ
W R
RD
IRQ
W R
M O D E MC
Ground Station Modem from OSSS No Final Solution Yagi Antenna 16 dB gain NOVA Rotor Control Price 10.000 - 20.000 Kr. Brian Lodahl from KOM
Table of Contents Hardware Protocol Description Interface Examples Test Link Budget Conclusion
Requirements Flawless Link Support Call-names Pause / Resume Prioritizing Channels Half Duplex
Layer StructureO S I Layers
Applic ation
N etw ork
P hys ic al
D ata Link
S es s ion
P res entation
T rans port
G round S tation
Radio
AX .25
T 55X
A1. .An
S atellite
Radio
AX .25
T 55X
A1. .An
AX.25 Error Detection Supports Call-names Supports Half Duplex Connections Widely Used Well Documented
T55X Structure
T 55XT ra n spo r tC on tro lle r
C hanne ls
De -Mu ltip le xe r
T55X Transport Layer Channels
16 Channels Priorities
Fixed Priorities Pause / Resume
ExampleApplication Channel 2Channel 1De-MulSchedulerChannel 1Channel 2 Application
Data-APacket-A1
Packet-A1Packet-A1
Data-B
Data-B
Packet-A2Packet-B1
Packet-B1Packet-B1
Packet-A2Packet-A2
Data-A
Table of Contents Hardware Protocol Description Interface Examples Test Link Budget Conclusion
Interface Callback Functions
Receive Data Receive Events / Beacon
Send Connection Less Data Send Data Connect / Disconnect Complete API on WWW
www.control.auc.dk/~01gr555/api/
Table of Contents Hardware Protocol Description Interface Examples Test Link Budget Conclusion
Start Communicationwhile(true) do
sendConLess(housekeeping) sleep(rtt+ct)if status=CONNECTED then breaksleep(30 s)
Satellite:
SetupCall-back(handleEvent(type, data))
handleEvent(type,data) {If type=DATA_RECEIVED then
store(data)connect
}
Ground Station:
Sequence ChartGroundapplications
Groundprotocol
Satelliteprotocol
Satelliteapplications
sendConLess
Lost in spacegetStatus
sendConLess
getStatus
handleEvent
connect
30 sec
Send/Receive
Start:createChannel(8,receiveImage)createChannel(2,commandChannel)
Main:.......sendData(2,Take Picture)........
Callback:receiveImage(data){
Save(data)sendEventToAdmin(Received Image)
}
Ground Station:
Send/Receive
Start:createChannel(8,imageChannel)createChannel(2,receiveCommand)
Callback:receiveCommand(data){
if data=’take image’ thentakeImagesendData(8,image)
}
Satellite:
Time Synchronization Several Solutions
Connection Less Channel With Estimation
No Requirements Yet
Table of Contents Hardware Protocol Description Interface Examples Test Link Budget Conclusion
Modelling and Verification Why?
Short Implementation Test Time New Protocol Satellite
What: SDL Modelling Exhaustive Testing Code Generation
Tools: ObjectGeode
Table of Contents Hardware Protocol Description Interface Examples Test Link Budget Conclusion
Link Budget Link Budget equation or Ebno
EIRP: (Equivalent Isotropically Radiated Power)
G/T: Quality factor of receiver
])[1
log(10)1
log(20)1
log(2015,196 dBHzb
MHzf
Kmd
TGEIRP
NE
o
b
tt GPEIRP
dBdBKKdB
TG 8)
1251log(1016
Link Budget Max distance to satellite
Using Pythagoras:
Inserting into the equationdBdBdBdBdBdBdB
NE
o
b 7.268.397.520.6915.19680
283063786002600
Re)(Re2
22
hd
Effective Throughput I frame size: 24 - 276 bytes
23 bytes overhead S frame size: 19 bytes
Effective Throughput Data:
Beacon:
%6,16253
25319276Data
Data) - frame S frame (I
%7,8253
253275Data
Data) - frame (UI
Table of Contents Hardware Protocol Description Interface Examples Test Link Budget Conclusion
Conclusion Work So Far:
Analysis / Design / Modelling / API Hardware
To Do: Implementation Verification / Test Purchase from OSSS Ground Station
