Term
| 413-1. What is the purpose of the space segment? |
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Definition
To provide the downlink information encompassing an area of coverage required by the program mission or
the program Operational Requirements Document. |
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Term
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Definition
The science of measuring physical properties and other phenomena onboard mission satellites and
transmitting these measurements to ground receiving elements. |
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Term
| 413-3. What types of information do the telemetry, tracking, and command status contain? |
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Definition
Data on the receiver and demodulator units, command decryptor unit, downlink transmitter, telemetry
formatting and encoding unit, telemetry encryptor, and satellite antenna configuration. |
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Term
| 413-4. What are the two major sections of a basic satellite? |
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Definition
(1) The mission (or missions) payload.
(2) The spacecraft bus. |
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Term
| 413-5. Why is stability important to the satellite? |
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Definition
Because it allows the payload to operate with accuracy and the satellite bus to receive commands and
uploaded data with reliability. |
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Term
| 413-6. For what types of satellites are position and orientation control especially critical? |
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Definition
| Those using highly directional antennas. |
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Term
| 414-1. What is the function of the C2 segment? |
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Definition
| To support the satellites and enhance the downlinked mission data for the user segment. |
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Term
| 414-2. What do all satellites require, regardless of the program? |
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Definition
| Telemetry, tracking and commanding support. |
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Term
| 414-3. What is the purpose of antenna pointing data? |
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Definition
| It is used to drive motors to move the antenna to the specific acquisition angles. |
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Term
| 414-4. Why is satellite command verification so important? |
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Definition
| To make sure commands have been executed properly. |
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Term
| 414-5. Why is using the same reference time between the C2 segment and the satellite so important? |
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Definition
Without it, operations—such as commanding mission satellites, processing and evaluating tracking data, or
processing telemetry data—would be impossible. |
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Term
| 415-1. What is the purpose of the user segment? |
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Definition
| To receive, process, use, or distribute mission data as required by program taskings |
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Term
| 415-2. What is the purpose of the DMSP user segment? |
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Definition
To receive, process, and distribute global weather data to support Air Force, Army, Navy, and Marine
Corps operations worldwide. |
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Term
| 415-3. In the DSP program, what agency operates SBIRS satellites? |
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Definition
| The 460th Space Wing at Buckley AFB, Colorado. |
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Term
| 415-4. Where do the DSP early warning centers forward their data? |
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Definition
| To various agencies and operation areas around the world, varying with the Air Force’s changing mission. |
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Term
| 415-5. What is the purpose of the GPS user segment? |
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Definition
To enable users to passively receive the satellite broadcast position, velocity, and time data for their
operational mission. |
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Term
| 415-6. What is the primary purpose of Milstar? |
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Definition
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. |
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Term
| 416-1. For what purposes do we use a satellite beacon? |
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Definition
| To locate, identify, and track a satellite. |
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Term
| 416-2. How does telemetry differ from the satellite beacons? |
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Definition
| Telemetry refers to the data sent by the satellite to give on-board equipment status. |
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Term
| 416-3. What is ephemeris data? |
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Definition
| Data showing the calculated positions of a satellite at regular intervals of time. |
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Term
| 416-4. How does computer programmed tracking differ from automatic signal tracking? |
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Definition
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. |
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Term
416-5. Which autotracking method cannot sense the satellite location without moving off the satellite
main beam? |
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Definition
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Term
| 417-1. What two IF frequencies are used by the DSCS earth terminal? What’s their nominal signal level? |
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Definition
(1) 70 MHz at –10 dBm.
(2) 700 MHz at –13 dBm. |
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Term
| 417-2. How are the HPAs cooled in a DSCS earth terminal? |
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Definition
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Term
| 417-3. What’s the downlink frequency range of a DSCS earth terminal? |
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Definition
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Term
417-4. What’s the size of an AN/GSC–52 antenna reflector, and what are the azimuth and elevation
limitations? |
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Definition
| 38-foot dish, ±174 degrees in AZ and from –1 to 92.5 degrees in EL. |
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Term
| 417-5. How many feedhorns does a AN/GSC–52 terminal use to determine tracking errors? |
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Definition
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Term
| 417-6. Which downconverter is designated as the tracking downconverter? |
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Definition
| Downconverter 1 in Downconverter Rack 1. |
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Term
| 417-7. What’s the purpose of the memory-tracking mode in a DSCS earth terminal? |
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Definition
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. |
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Term
| 417-8. What type of frequency standard is used in a DSCS earth terminal and what are its outputs? |
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Definition
| Cesium. 5 MHz, 1 MHz, and 1 pps. |
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Term
| 417-9. How does the operator control the AN/GSC–52 terminal? |
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Definition
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.). |
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Term
| 418-1. What feedhorns are in the AN/GSC–52 feedhorn assembly? |
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Definition
| One center sum (communication) feedhorn and four peripheral error (tracking) feedhorns. |
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Term
| 418-2. The AIA develops AZ and EL tracking error signals. What is done with those signals? |
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Definition
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. |
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Term
| 418-3. What type of HPA does the AN/GSC–52 use? |
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Definition
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Term
| 418-4. How many HPAs are normally operating at one time? |
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Definition
| Three are active online, and one is in standby mode. |
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Term
| 418-5. What happens if one of the AN/GSC–52 converters fails? |
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Definition
TS-A commands the appropriate switch assembly (DSA or USA) to automatically switch from the
defective converter to the backup converter. |
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Term
| 418-6. Which converter (up or down) is normally dedicated to auto-switchover? |
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Definition
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Term
| 418-7. What is the purpose of the FTS? |
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Definition
| To generate and distribute precise 1 MHz and 5 MHz reference frequencies and 1 pps timing signals. |
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Term
| 418-8. What is the purpose of the terminal servers? |
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Definition
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. |
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Term
| 418-9. What can the terminal operator do with the terminal processor? |
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Definition
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. |
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