Day 2: Transponder & TT&C Flashcards
A communication path or ‘channel’ rather than a specific piece of equipment
Transponder
What are the primary functions of transponders?
- Amplifying the received input signal
- Translates the frequency of the input signal to avoid the interference between the transmitted and received signals
Regenerative / On-Board XPDR adds what compared to transparent/bent pipe?
FEC/signal correction
Advantages of Regenerative / On-board XPDR
- Better link quality
- Harder to jam
- Direct connection between terminals
Path management for specified communication signals
Channelizing
Channelizing Techniques
- Fan in
- Fan out
Digital signal processor that routes between any uplink subchannel to any downlink subchannel
Digital channelizer
Transmission path from a satellite to Earth stations
Downlink footprint
Transmission path from an Earth station (ground-based transmitter) to a satellite
Uplink footprint
A location is within the uplink footprint means it’s in the downlink footprint
False
Large footprint - covers 1/3 of earth
Earth Coverage Beam Advantage
Does not cover polar regions
Earth Coverage Beam Disadvantage
Easy to place a jammer in the footprint
Earth Coverage Beam Disadvantage
More resistant to jamming since individual elements can be switched on/off
Multi Beam Arrays
Cannot follow mobile forces
Fixed Spot Beams
Can follow mobile forces and shape to geographical location
Steerable Spot Beams
Much more complex design, more costly
Phased Array
Information conveyed by satellite subsystem to the TT&C subsystem (e.g. resources, health, altitude, mode, payload data, etc.) where it is then encoded and transmitted to a user in space for ground segment
Telemetry
A one-way process (downlink only)
Telemetry
Used by satellite operators to precisely determine a satellites orbit
Tracking
Two-way ranging from ground station common
Tracking
Permits the satellite to be reconfigured in response to RF signals that are sent from the ground
Command
