Communications Design Review
13
Communications Design Review SSE-122 Morehead State University Morehead, KY Prof. Bob Twiggs [email protected]
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Communications Design Review. Morehead State University Morehead, KY Prof. Bob Twiggs [email protected]. SSE-122. Design Review. How are you going to transmit data up/down?. How often will you be over a single ground station with a LEO orbit?. - PowerPoint PPT Presentation
Transcript of Communications Design Review
Communications Design Review
SSE-122
Morehead State UniversityMorehead, KY
Prof. Bob [email protected]
2
Design Review
Will your link margin allow you to communicate horizon to horizon?
What do you do if you get errors in your communication data?
How much of the contact time will you need to use for commanding satellite?
How are you going to transmit data up/down?
How often will you be over a single ground station with a LEO orbit?
How much time will you have to transmit during passes?
SSE-122
3
Design Review
How are you going to transmit data up/down?
How often will you be over a single ground station with a LEO orbit?
What do you need to know to determine this?
SSE-122
How much time will you have to transmit during passes?
Will your link margin allow you to communicate horizon to horizon?
What do you do if you get errors in your communication data?
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Design Review
How much of the contact time will you need to use for commanding satellite?
SSE-122
If you can not get all of the data down with a single ground station and you can not add any more stations, what are your options?How will your down loading data have an impact on the power system?What kind of analysis do you need to do now with the EPS?
5
Design Review
SSE-122
Will this operational scenario affect the thermal system?
What about the charging and discharging of the battery?
Where is the heat coming from?
6
Design Review
Do a Comm System Design
SSE-122
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Design Review
Make some assumptions – verify my assumptions and recalculateOrbit: 600 km, circular
- 6 passes/day- get ~ 13 minutes view time horiz. to
horiz. on zenith pass.- get ~ two passes with 6 minutes, one
before and one after zenith.- this pattern will occur twice a day.
Link margin:- assume you must take one minute to connect on each pass and one minute
to terminate comm at end of each pass.
SSE-122
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Design Review
More assumptions – verify my assumptions and recalculate
Data volume:- assume you have a 20% overhead required to correct errors.- if you use FEC you must have a 100% overhead.Data conversion: analog - digitalResolution needed:
Temperatures, voltages: accuracy 5%
Currents: battery: accuracy 10%Currents: solar panel accuracy –
5%Currents: subsystem accuracy –
3%All others: - 10%
SSE-122
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Design Review
More assumptions – verify my assumptions and recalculate
Discrete bits to monitor:25 discrete bits for states in satellite
busDuty cycle:
You decide as a bus engineer what you need
to diagnoses anomalies.
SSE-122
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Design Review
Analysis:1.From data collection, find total data collected each 12 hours.
2.Assume you have 1 watt on satellite with a -3dBi gain antenna. Transmitter line loss is 0.3dB.
3.You are operating at 435MHz.
4.Your ground antenna has a gain of 18dBi.
5.Your ground antenna line has a loss of 1.5 dB
6.You have an average 2 degree pointing error.
SSE-122
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Design Review
Continued Analysis:
a.Can you get all of the data down for the contact time given?
b.If not, what can you change to get data down that is reasonable?
c.Maybe you need to reduce the amount of data collected.
d.Change duty cycle?
7.The BER must be 10-5 or better.
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Design Review
Continued Analysis:
e.Change sample frequency?
f.Change resolution?
g.Change BER?
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Design Review
Got all the information you need here to do this analysis?
SSE-122
