3D1X3 Self Test Questions Vol. 3 Unit 3

Front 1

What is the purpose of the space segment?

Back 1

To provide the downlink information encompassing an area of coverage required by the program mission or
the program Operational Requirements Document.

Front 2

Define telemetry?

Back 2

The science of measuring physical properties and other phenomena onboard mission satellites and
transmitting these measurements to ground receiving elements.

Front 3

t types of information do the telemetry, tracking, and command status contain?

Back 3

Data on the receiver and demodulator units, command decryptor unit, downlink transmitter, telemetry
formatting and encoding unit, telemetry encryptor, and satellite antenna configuration.

Front 4

What are the two major sections of a basic satellite?

Back 4

(1) The mission (or missions) payload.
(2) The spacecraft bus.

Front 5

Why is stability important to the satellite?

Back 5

Because it allows the payload to operate with accuracy and the satellite bus to receive commands and
uploaded data with reliability.

Front 6

For what types of satellites are position and orientation control especially critical?

Back 6

Those using highly directional antennas.

Front 7

What is the function of the C2 segment?

Back 7

To support the satellites and enhance the downlinked mission data for the user segment.

Front 8

What do all satellites require, regardless of the program?

Back 8

Telemetry, tracking and commanding support.

Front 9

What is the purpose of antenna pointing data?

Back 9

It is used to drive motors to move the antenna to the specific acquisition angles.

Front 10

Why is satellite command verification so important?

Back 10

To make sure commands have been executed properly.

Front 11

Why is using the same reference time between the C2 segment and the satellite so important?

Back 11

Without it, operations—such as commanding mission satellites, processing and evaluating tracking data, or
processing telemetry data—would be impossible.

Front 12

What is the purpose of the user segment?

Back 12

To receive, process, use, or distribute mission data as required by program taskings.

Front 13

What is the purpose of the DMSP user segment?

Back 13

To receive, process, and distribute global weather data to support Air Force, Army, Navy, and Marine
Corps operations worldwide.

Front 14

In the DSP program, what agency operates SBIRS satellites?

Back 14

The 460th Space Wing at Buckley AFB, Colorado.

Front 15

Where do the DSP early warning centers forward their data?

Back 15

To various agencies and operation areas around the world, varying with the Air Force’s changing mission.

Front 16

What is the purpose of the GPS user segment?

Back 16

To enable users to passively receive the satellite broadcast position, velocity, and time data for their
operational mission.

Front 17

What is the primary purpose of Milstar?

Back 17

To support the National Command Authority and provide the Navy, Army, and Air Force with
interoperable command, control, and communications (C3) at all levels of conflict for both strategic and
tactical forces.

Front 18

For what purposes do we use a satellite beacon?

Back 18

To locate, identify, and track a satellite.

Front 19

How does telemetry differ from the satellite beacons?

Back 19

Telemetry refers to the data sent by the satellite to give on-board equipment status.

Front 20

What is ephemeris data?

Back 20

Data showing the calculated positions of a satellite at regular intervals of time.

Front 21

How does computer programmed tracking differ from automatic signal tracking?

Back 21

In computer programmed tracking, the position of the satellite is computed and the pointing signal is
generated from that information. Automatic tracking follows the apparent position of the satellite based on
the actual signals from the satellite.

Front 22

Which autotracking method cannot sense the satellite location without moving off the satellite
main beam?

Back 22

Random step track.

Front 23

What two IF frequencies are used by the DSCS earth terminal? What’s their nominal signal level?

Back 23

(1) 70 MHz at –10 dBm.
(2) 700 MHz at –13 dBm.

Front 24

How are the HPAs cooled in a DSCS earth terminal?

Back 24

Air cooled.

Front 25

What’s the downlink frequency range of a DSCS earth terminal?

Back 25

7.25 to 7.75 GHz.

Front 26

What’s the size of an AN/GSC–52 antenna reflector, and what are the azimuth and elevation
limitations?

Back 26

38-foot dish, ±174 degrees in AZ and from –1 to 92.5 degrees in EL.

Front 27

How many feedhorns does a AN/GSC–52 terminal use to determine tracking errors?

Back 27

Four.

Front 28

Which downconverter is designated as the tracking downconverter?

Back 28

Downconverter 1 in Downconverter Rack 1.

Front 29

What’s the purpose of the memory-tracking mode in a DSCS earth terminal?

Back 29

Maintains a 24-hour record of antenna movements by the memory track unit. This data can be used to
control the antenna in memory track mode in the event of an autotrack failure.

Front 30

What type of frequency standard is used in a DSCS earth terminal and what are its outputs?

Back 30

Cesium. 5 MHz, 1 MHz, and 1 pps.

Front 31

How does the operator control the AN/GSC–52 terminal?

Back 31

Locally by the TP or RTP, or remotely by an ECE or the laptop from any of the terminal access ports (EER,
pedestal base, etc.).

Front 32

What feedhorns are in the AN/GSC–52 feedhorn assembly?

Back 32

One center sum (communication) feedhorn and four peripheral error (tracking) feedhorns.

Front 33

The AIA develops AZ and EL tracking error signals. What is done with those signals?

Back 33

The tracking-error data from the AIA is sent to TS-B and is used to create antenna velocity commands.
These velocity commands are sent to the antenna’s servo amplifier via the AIA. The servo amplifier
converts the velocity commands to drive power outputs to move the antenna, and/or to correct for tracking
error.

Front 34

What type of HPA does the AN/GSC–52 use?

Back 34

Traveling wave tube.

Front 35

How many HPAs are normally operating at one time?

Back 35

Three are active online, and one is in standby mode.

Front 36

What happens if one of the AN/GSC–52 converters fails?

Back 36

TS-A commands the appropriate switch assembly (DSA or USA) to automatically switch from the
defective converter to the backup converter.

Front 37

Which converter (up or down) is normally dedicated to auto-switchover?

Back 37

Number 8 in each rack.

Front 38

What is the purpose of the FTS?

Back 38

To generate and distribute precise 1 MHz and 5 MHz reference frequencies and 1 pps timing signals.

Front 39

What is the purpose of the terminal servers?

Back 39

To serve as interfaces to separate individual subsystems within the equipment complex. Each terminal
server is responsible for control and status of specific groups of terminal equipment, and must be
operational to allow for any remote control of these specific equipment groups.

Front 40

What can the terminal operator do with the terminal processor?

Back 40

Manually configure the terminal equipment that will be online for any given operational plan up to the
equipment complement. Receive audible and visual notification of terminal major and minor alarms. Direct
testing of the system utilizing the rack-mounted test equipment.