Communication Subsystem. Introduction Hardware Protocol Description Interface Examples Test Link...

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: 2W@9.6V 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 i rcu 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 Structure

O 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 ran spo r tC on tro lle r

C hanne ls

D e -Mu ltip le xe r

T55X Transport Layer

Channels 16 Channels

Priorities Fixed Priorities

Pause / Resume

Example

Application Channel 2Channel 1De-MulSchedulerChannel 1Channel 2 Application

Data-APacket-A1

Packet-A1Packet-A1

Data-B

Data-B

Packet-A2

Packet-B1

Packet-B1

Packet-B1

Packet-A2

Packet-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 Communication

while(true) dosendConLess(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 Chart

Groundapplications

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 dBHz

b

MHz

f

Km

d

T

GEIRP

N

E

o

b

tt GPEIRP

dBdBK

KdB

T

G8)

1

251log(1016

Link Budget Max distance to satellite

Using Pythagoras:

Inserting into the equation

dBdBdBdBdBdBdBN

E

o

b 7.268.397.520.6915.19680

283063786002600

Re)(Re

2

22

hd

Effective Throughput I frame size: 24 - 276 bytes

23 bytes overhead S frame size: 19 bytes

Effective Throughput Data:

Beacon:

%6,16253

25319276

Data

Data) - frame S frame (I

%7,8253

253275

Data

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