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Operations Tracking (cont’d)

Operations Tracking (cont’d). Figure 13-12 shows the Iridium ground station in Yellowknife, Canada which is one of several that tracks the Iridium constellation of sixty-six satellites. Operations Command and Control.

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Operations Tracking (cont’d)

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  1. OperationsTracking (cont’d) • Figure 13-12 shows the Iridium ground station in Yellowknife, Canada which is one of several that tracks the Iridium constellation of sixty-six satellites. Unit 4, Chapter 13, Lesson 13: Space Operations

  2. OperationsCommand and Control • Commands are instruction sets telling the onboard computers to take some action or update some critical part of the software. • Commands can tell the spacecraft to charge batteries, fire rockets, or point at a new target. • Commands can either be real-time or stored. • Real-time commands implemented on receipt • Stored commands carried out • At a time an operator determines • After a certain event Unit 4, Chapter 13, Lesson 13: Space Operations

  3. OperationsCommand and Control (cont’d) • Important commands are sent in two stages: • The command travels to spacecraft through an uplink. • The communication subsystem echoes it back to the operators through the downlink. • After operators confirm the command received is the one sent, they send a second command to enable it in the spacecraft’s onboard software. • Two stage commands ensure important information doesn’t get garbled during transmission and provides some security from outside interference. Unit 4, Chapter 13, Lesson 13: Space Operations

  4. OperationsCommand and Control (cont’d) • Because the spacecraft communication links are so important to mission performance, most spacecraft have built-in commands to follow if they lose a communication link. • A simple timing switch or “watch-dog timer” onboard keeps track of the time a spacecraft goes without communication. • If this time exceeds a certain preset amount, the spacecraft puts itself into a “safe mode” to make it easier to restore the communication link and resume the mission. Unit 4, Chapter 13, Lesson 13: Space Operations

  5. CommunicationElements of Communication • Radio communication is like carrying on a conversation in several key ways: • Distance • Language • Speed • Environment Unit 4, Chapter 13, Lesson 13: Space Operations

  6. CommunicationElements of CommunicationDistance • For a conversation, participants should be within hearing distance so each person’s words reach the other. • The more distance between participants, the louder they must talk to be heard. • If they are too far away to hear each other, they can’t communicate. • To communicate effectively from one spacecraft to another or to a ground station, we must consider the distance or range between the speaker (called the transmitter) and the listener (called the receiver). Unit 4, Chapter 13, Lesson 13: Space Operations

  7. CommunicationElements of CommunicationLanguage • For a conversation, the language must be one that both participants can understand and speak fluently. • For radio communications, the transmitter and receiver must understand the language or code that each uses. Unit 4, Chapter 13, Lesson 13: Space Operations

  8. CommunicationElements of CommunicationSpeed • In a conversation if people speak too rapidly, it’s hard to process the words fast enough to understand their message. • For radio communication, the receiver must handle the transmitter’s message speed or data rate. Unit 4, Chapter 13, Lesson 13: Space Operations

  9. CommunicationElements of CommunicationEnvironment • If a conversation occurs in a crowded football stadium, the crowd generates noise. To overcome the noise, participants must talk louder—increase the strength of their signal. • For radio communication, the signal strength must be higher than the noise level—the signal-to-noise ratio must be greater than one. • The important quantity for communication is the ratio of the volume of your speech to the volume of their noise. Unit 4, Chapter 13, Lesson 13: Space Operations

  10. Communication (cont’d) • The receiver must handle the transmitters message speed or data rate. • The volume or signal strength at the receiver must be higher than the overall noise in the system. Unit 4, Chapter 13, Lesson 13: Space Operations

  11. Communication (cont’d) • When turned on, the car radio receives signals from the radio station in the form of electromagnetic (EM) radiation. • EM radiation comes from an accelerating charge. • As charges accelerate in the radio station’s transmitter antenna, an electric field forms and induces a magnetic field. • The magnetic field induces an electric field. • The frequency at which this charge accelerates determines the frequency of the EM radiation. The faster the charge accelerates, the higher the frequency. Unit 4, Chapter 13, Lesson 13: Space Operations

  12. CommunicationCar radio example • A radio station broadcasts carrier signal at specified frequency regulated and licensed by the Federal Communication Commission (FCC). • The transmitter then places the message being sent on top of carrier signal, using some type of modulation. We’re most familiar with: • amplitude modulation (AM) • frequency modulation (FM) • Signal travels from station antenna to car antenna. • Receiver re-translates it to the original signal and separates message from the carrier signal (demodulates). • Receiver amplifies the original signal and—behold—music comes from the speakers. Unit 4, Chapter 13, Lesson 13: Space Operations

  13. CommunicationCar radio example (cont’d) • Spacecraft applications use other schemes as well. • This signal travels outward from the station’s antenna and hits the car radio’s antenna. There more charges accelerate. • The receiver detects this charge movement in the antenna and re-translates it to the original signal. • The receiver “demodulates” the AM or FM signal to separate the message from the carrier signal. Unit 4, Chapter 13, Lesson 13: Space Operations

  14. CommunicationCar radio example (cont’d) Unit 4, Chapter 13, Lesson 13: Space Operations

  15. CommunicationBasic Principles • Similar to a radio transmitter, a light bulb emits EM radiation, but at a different frequency—visible light. • A light bulb placed in the center of a room radiates outward in all directions (assuming it’s a perfect bulb with no light blockage). Unit 4, Chapter 13, Lesson 13: Space Operations

  16. OperationsTracking (cont’d) • Figure 13-12 shows the Iridium ground station in Yellowknife, Canada which is one of several that tracks the Iridium constellation of sixty-six satellites. Unit 4, Chapter 13, Lesson 13: Space Operations

  17. OperationsCommand and Control • Commands are instruction sets telling the onboard computers to take some action or update some critical part of the software. • Commands can tell the spacecraft to charge batteries, fire rockets, or point at a new target. • Commands can either be real-time or stored. • Real-time commands implemented on receipt • Stored commands carried out • At a time an operator determines • After a certain event Unit 4, Chapter 13, Lesson 13: Space Operations

  18. OperationsCommand and Control (cont’d) • Important commands are sent in two stages: • The command travels to spacecraft through an uplink. • The communication subsystem echoes it back to the operators through the downlink. • After operators confirm the command received is the one sent, they send a second command to enable it in the spacecraft’s onboard software. • Two stage commands ensure important information doesn’t get garbled during transmission and provides some security from outside interference. Unit 4, Chapter 13, Lesson 13: Space Operations

  19. OperationsCommand and Control (cont’d) • Because the spacecraft communication links are so important to mission performance, most spacecraft have built-in commands to follow if they lose a communication link. • A simple timing switch or “watch-dog timer” onboard keeps track of the time a spacecraft goes without communication. • If this time exceeds a certain preset amount, the spacecraft puts itself into a “safe mode” to make it easier to restore the communication link and resume the mission. Unit 4, Chapter 13, Lesson 13: Space Operations

  20. CommunicationElements of Communication • Radio communication is like carrying on a conversation in several key ways: • Distance • Language • Speed • Environment Unit 4, Chapter 13, Lesson 13: Space Operations

  21. CommunicationElements of CommunicationDistance • For a conversation, participants should be within hearing distance so each person’s words reach the other. • The more distance between participants, the louder they must talk to be heard. • If they are too far away to hear each other, they can’t communicate. • To communicate effectively from one spacecraft to another or to a ground station, we must consider the distance or range between the speaker (called the transmitter) and the listener (called the receiver). Unit 4, Chapter 13, Lesson 13: Space Operations

  22. CommunicationElements of CommunicationLanguage • For a conversation, the language must be one that both participants can understand and speak fluently. • For radio communications, the transmitter and receiver must understand the language or code that each uses. Unit 4, Chapter 13, Lesson 13: Space Operations

  23. CommunicationElements of CommunicationSpeed • In a conversation if people speak too rapidly, it’s hard to process the words fast enough to understand their message. • For radio communication, the receiver must handle the transmitter’s message speed or data rate. Unit 4, Chapter 13, Lesson 13: Space Operations

  24. CommunicationElements of CommunicationEnvironment • If a conversation occurs in a crowded football stadium, the crowd generates noise. To overcome the noise, participants must talk louder—increase the strength of their signal. • For radio communication, the signal strength must be higher than the noise level—the signal-to-noise ratio must be greater than one. • The important quantity for communication is the ratio of the volume of your speech to the volume of their noise. Unit 4, Chapter 13, Lesson 13: Space Operations

  25. Communication (cont’d) • The receiver must handle the transmitters message speed or data rate. • The volume or signal strength at the receiver must be higher than the overall noise in the system. Unit 4, Chapter 13, Lesson 13: Space Operations

  26. Communication (cont’d) • When turned on, the car radio receives signals from the radio station in the form of electromagnetic (EM) radiation. • EM radiation comes from an accelerating charge. • As charges accelerate in the radio station’s transmitter antenna, an electric field forms and induces a magnetic field. • The magnetic field induces an electric field. • The frequency at which this charge accelerates determines the frequency of the EM radiation. The faster the charge accelerates, the higher the frequency. Unit 4, Chapter 13, Lesson 13: Space Operations

  27. CommunicationCar radio example • A radio station broadcasts carrier signal at specified frequency regulated and licensed by the Federal Communication Commission (FCC). • The transmitter then places the message being sent on top of carrier signal, using some type of modulation. We’re most familiar with: • amplitude modulation (AM) • frequency modulation (FM) • Signal travels from station antenna to car antenna. • Receiver re-translates it to the original signal and separates message from the carrier signal (demodulates). • Receiver amplifies the original signal and—behold—music comes from the speakers. Unit 4, Chapter 13, Lesson 13: Space Operations

  28. CommunicationCar radio example (cont’d) • Spacecraft applications use other schemes as well. • This signal travels outward from the station’s antenna and hits the car radio’s antenna. There more charges accelerate. • The receiver detects this charge movement in the antenna and re-translates it to the original signal. • The receiver “demodulates” the AM or FM signal to separate the message from the carrier signal. Unit 4, Chapter 13, Lesson 13: Space Operations

  29. CommunicationCar radio example (cont’d) Unit 4, Chapter 13, Lesson 13: Space Operations

  30. CommunicationBasic Principles • Similar to a radio transmitter, a light bulb emits EM radiation, but at a different frequency—visible light. • A light bulb placed in the center of a room radiates outward in all directions (assuming it’s a perfect bulb with no light blockage). Unit 4, Chapter 13, Lesson 13: Space Operations

  31. CommunicationBasic Principles (cont’d) • The light’s intensity or brightness at some distance from the bulb is called the power-flux density (“F” in Figure 13-14). • The farther away from the light bulb we go, the dimmer it appears. • In other words, the power-flux densityperceived as brightnessdecreases the farther we go from the light bulb. • Radiation (“R” in Figure 13-14), moving equally in all directions as in the light-bulb example, is called omni-directional. Unit 4, Chapter 13, Lesson 13: Space Operations

  32. CommunicationBasic Principles—Gain • To increase the brightness or power-flux density in only one direction using the same bulb would require the light to be focused, as in a flashlight. • Putting a parabola-shaped mirror on one side of the light bulb will focus its light. • Most of the light in one direction reflects off the mirror and heads in the opposite direction, creating a directed beam of light—a spotlight—rather than an omnidirectional source. Unit 4, Chapter 13, Lesson 13: Space Operations

  33. CommunicationBasic Principles—Gain (cont’d) • In this way, most of the light energy is concentrated into a smaller area, resulting in a brightness in one direction that is much, much greater than it was when the bulb gave off light in all directions. • This “gained” extra power density by using the parabolic mirror illustrates the basic principle of an antenna. • Spacecraft often rely on specially designed “dish” antennas to let us focus the energy on a particular point of interest such as a receiving antenna. • Ground stations usually use another directional (dish) antenna to better receive the signal, as well as transmit commands back to the spacecraft. Unit 4, Chapter 13, Lesson 13: Space Operations

  34. Satellite Control Networks • The Spaceflight Tracking and Data Network (STDN) mostly tracks and relays data for the Space Shuttle and other near-Earth missions. • STDN includes ground-based antennas at White Sands, New Mexico. • Space-based portions use the Tracking and Data Relay Satellites (TDRS) in geostationary orbits. Unit 4, Chapter 13, Lesson 13: Space Operations

  35. Satellite Control Networks (cont’d) Tracking and Data Relay Satellite’s (TDRS) Second Terminal Unit 4, Chapter 13, Lesson 13: Space Operations

  36. Satellite Control Networks (cont’d) • The deep-space tracking network (DSN) • Includes very large antennas (more than 70 meters in diameter). • Tracks and enables operators to receive data from interplanetary missions. Deep Space Network (DSN) Unit 4, Chapter 13, Lesson 13: Space Operations

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