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  • Figure 61-1 Audio systems use both electromagnetic radio waves and sound waves to reproduce sound inside the vehicle.
  • Figure 61-2 The relationship among wavelength, frequency, and amplitude.
  • Figure 61-3 The amplitude changes in AM broadcasting.
  • Figure 61-5 Using upper and lower sidebands allows stereo to be broadcast. The receiver separates the signals to provide left and right channels.
  • Figure 61-6 The five types of antennas used on General Motors vehicles include the slot antenna, fixed mast antenna, rear window defogger grid antenna, a powered mast antenna, and an integrated antenna.
  • Figure 61-8 If all ohmmeter readings are satisfactory, the antenna is good.
  • Figure 61-10 A typical power antenna assembly. Note the braided ground wire used to ensure that the antenna has a good ground plane.
  • Figure 61-11 Between 6 and 7 volts is applied to each speaker terminal, and the audio amplifier then increases the voltage on one terminal and at the same time decreases the voltage on the other terminal causing the speaker cone to move. The moving cone then moves the air, causing sound.
  • Figure 61-12 A typical automotive speaker with two terminals. The polarity of the speakers can be identified by looking at the wiring diagram in the service manual or by using a 1.5 volt battery to check. When the battery positive is applied to the positive terminal of the speaker, the cone will move outward. When the battery leads are reversed, the speaker cone will move inward.
  • Figure 61-13 (a) Two 4 ohm speakers connected in series result in total impedance of 8 ohms. (b) Two 4 ohm speakers connected in parallel result in total impedance of 2 ohms.
  • Figure 61-14 Crossovers are used in audio systems to send high-frequency sounds to the small (tweeter) speakers and lowfrequency sounds to larger (woofer) speakers.
  • Figure 61-15 Two capacitors connected in parallel provide the necessary current flow to power large subwoofer speakers.
  • Chart 61-1 The rating of the capacitor needed to upgrade an audio system is directly related to the wattage of the system.
  • Figure 61-16 A powerline capacitor should be connected through the power wire to the amplifier as shown. When the amplifier requires more electrical power (watts) than the battery can supply, the capacitor will discharge into the amplifier and supply the necessary current for the fraction of a second it is needed by the amplifier. At other times when the capacitor is not needed, it draws current from the battery to keep it charged.
  • Figure 61-17 Voice commands can be used to control many functions, including navigation systems, climate control, telephone, and radio.
  • Figure 61-18 The voice command icon on the steering wheel of a Cadillac.
  • Figure 61-19 Bluetooth earpiece that contains a microphone and speaker unit that is paired to a cellular phone. The telephone has to be within 33 ft (10 m) of the earpiece.
  • Figure 61-20 SDARS uses satellites and repeater stations to broadcast radio.
  • Figure 61-21 An aftermarket XM radio antenna mounted on the rear deck lid. The deck lid acts as the ground plane for the antenna.
  • Figure 61-22 A shark-fin-type factory antenna used for both XM and OnStar.
  • Figure 61-23 A radio choke and/or a capacitor can be installed in the power feed lead to any radio, amplifier, or equalizer.
  • Figure 61-24 Many automobile manufacturers install a coaxial capacitor, like this one, in the power feed wire to the blower motor to eliminate interference caused by the blower motor.
  • Figure 61-25 A “sniffer” can be made from an old antenna lead-in cable by removing about 3 in. of the outer shielding from the end. Plug the lead-in cable into the antenna input of the radio and tune the radio to a weak station. Move the end of the antenna wire around the vehicle dash area. The sniffer is used to locate components that may not be properly shielded or grounded and can cause radio interference through the case (housing) of the radio itself.
  • Chart 61-2 Radio noise can have various causes, and knowing where or when the noise occurs helps pin down the location.

Halderman ch061 lecture Presentation Transcript

  • 1. AUDIO SYSTEM OPERATION AND DIAGNOSIS 61
  • 2. Objectives
    • The student should be able to:
      • Prepare for ASE Electrical/Electronic Systems (A6) certification test content area “H” (Accessories Diagnosis and Repair).
      • Describe how AM and FM radio works.
      • Explain how to test speaker polarity.
      • Explain how to match speaker impedance.
      • Explain how crossovers work.
  • 3. Objectives
    • The student should be able to:
      • Describe how satellite radio works.
      • Explain how Bluetooth systems work.
      • Discuss voice recognition systems.
      • List causes and corrections of radio noise and interference.
  • 4. AUDIO FUNDAMENTALS
  • 5. Audio Fundamentals
    • Introduction
      • Audio systems include
        • Radio (AM, FM, satellite)
        • Antenna systems
        • Speaker systems
  • 6. Audio Fundamentals
    • Introduction
      • Audio systems include
        • Aftermarket enhancement devices that increase sound energy output
        • Diagnosis of audio-related problems
  • 7. Audio Fundamentals
    • Types of Energy
      • Two types of energy affect audio systems
      • Electromagnetic energy or radio waves
        • Antennas capture radio waves and send them to radio or receiver
  • 8. Audio Fundamentals
    • Types of Energy
      • Acoustical energy, usually called sound
        • Radios and receivers amplify radio wave signals
  • 9. Figure 61-1 Audio systems use both electromagnetic radio waves and sound waves to reproduce sound inside the vehicle.
  • 10. Audio Fundamentals
    • Terminology
      • Radio waves travel at speed of light (186,282,000 miles per second)
      • Radio waves are electromagnetic
  • 11. Audio Fundamentals
    • Terminology
      • Measured in two ways: wavelength and frequency
        • Wavelength is time and distance between two high points or two low points
          • Wavelength is measured in meters
  • 12. Audio Fundamentals
    • Terminology
      • Measured in two ways: wavelength and frequency
        • Frequency, also known as radio frequency (RF), is the number of times a waveform repeats itself in a given amount of time
          • Frequency is measured in hertz (Hz)
  • 13. Audio Fundamentals
    • Terminology
      • Measured in two ways: wavelength and frequency
        • Frequency, also known as radio frequency (RF), is the number of times a waveform repeats itself in a given amount of time
          • A signal with 1 Hz frequency is one radio wavelength per second
  • 14. Audio Fundamentals
    • Terminology
      • Radio frequencies
        • Measured in kilohertz (kHz), thousands of wavelengths per second, and megahertz (MHz), millions of wavelengths per second
  • 15. Figure 61-2 The relationship among wavelength, frequency, and amplitude.
  • 16. Audio Fundamentals
    • Terminology
      • Radio frequencies
        • The higher the frequency, the shorter the wavelength
  • 17. Audio Fundamentals
    • Terminology
      • Radio frequencies
        • The lower the frequency, the longer the wavelength
  • 18. Audio Fundamentals
    • Terminology
      • A longer wavelength can travel farther than shorter wavelength
      • Lower frequencies provide better reception at longer distances
        • AM radio frequencies range from 530 to 1,710 kHz
  • 19. Audio Fundamentals
    • Terminology
      • Lower frequencies provide better reception at longer distances
        • FM radio frequencies range from 87.9 to 107.9 MHz
  • 20. Audio Fundamentals
    • Modulation
      • Modulation describes when information is added to a constant frequency
      • Base radio frequency used for RF is carrier wave
  • 21. Audio Fundamentals
    • Modulation
      • A carrier is a radio wave changed to carry information
      • Two types of modulation
        • Amplitude modulation (AM)
  • 22. Audio Fundamentals
    • Modulation
      • Two types of modulation
        • Frequency modulation (FM)
  • 23. Audio Fundamentals
    • Modulation
      • AM waves have amplitude that can be varied, transmitted, and detected
      • Amplitude is the height of the wave as graphed on an oscilloscope
  • 24. Figure 61-3 The amplitude changes in AM broadcasting.
  • 25. Audio Fundamentals
    • Radio Wave Transmission
      • More than one signal can be carried by radio wave
      • Called sideband operation
  • 26. Audio Fundamentals
    • Radio Wave Transmission
      • Sideband frequencies measured in kilohertz
      • Signal above the assigned frequency is the upper sideband
  • 27. Audio Fundamentals
    • Radio Wave Transmission
      • Signal below assigned frequency is the lower sideband
      • The capability allows radio signals to carry stereo broadcasts
      • When signal is decoded by radio, the two signals become right and left channels
  • 28. Figure 61-5 Using upper and lower sidebands allows stereo to be broadcast. The receiver separates the signals to provide left and right channels.
  • 29. Audio Fundamentals
    • Noise
      • Radio waves are form of electromagnetic energy, so other energy can impact them
  • 30. Audio Fundamentals
    • Noise
      • A bolt of lightning generates radio-frequency bandwidths known as radio-frequency interference (RFI)
  • 31. Audio Fundamentals
    • Noise
      • RFI is a type of electromagnetic interference (EMI)
      • RFI interferes with radio transmission
  • 32. Audio Fundamentals
    • AM Characteristics
      • AM radio reception is achieved over long distances because waves bounce off ionosphere
      • AM radio needs a good antenna
  • 33. Audio Fundamentals
    • FM Characteristics
      • FM waves have high RF and short wavelength
      • They travel only a short distance
  • 34. Audio Fundamentals
    • FM Characteristics
      • FM waves travel in straight line from transmitter to receiver
      • FM waves travel through ionosphere; they don’t bounce off of it
    ?
  • 35. Audio Fundamentals
    • Multipath
      • Multipath caused by reflected, refracted, or line of sight signals reaching antenna at different times
      • Radio receives two signals at same frequency
  • 36. Audio Fundamentals
    • Multipath
      • Causes echo effect
      • Flutter, or picket fencing, occurs when part of FM signal is blocked
  • 37. Audio Fundamentals
    • Multipath
      • The blocking causes weakening of signal; only part is received
      • Sound is on-again off-again
  • 38. RADIOS AND RECEIVERS
  • 39. Radios and Receivers
    • Antenna receives radio wave
    • Converts to weak, fluctuating electric current
    • Current travels to radio
  • 40. Radios and Receivers
    • Radio amplifies signal and sends to speakers
    • Speakers convert signal to acoustical energy
    • Radios and receivers have five input/output circuits
  • 41. Radios and Receivers
    • Power
      • Usually a 12 volt feed to keep internal clock alive
  • 42. Radios and Receivers
    • Ground
      • Lowest voltage in circuit
      • Connects indirectly to negative terminal of battery
  • 43. Radios and Receivers
    • Serial data
      • Turns radio on and off
    • Antenna input
  • 44. Radios and Receivers
    • Speaker outputs
      • Wires connect receiver to speakers
  • 45. ANTENNAS
  • 46. Antennas
    • Types of Antennas
      • Radio antennas receive very weak signal, about 25 microvolts AC (0.000025 VAC)
      • Radio amplifier increases signal strength
  • 47. Antennas
    • Types of Antennas
      • Five types of antennas
        • Slot antenna
          • Concealed in roof of some plastic body vehicles
  • 48. Antennas
    • Types of Antennas
      • Five types of antennas
        • Slot antenna
          • Antenna is surrounded by metal on Mylar sheet
  • 49. Antennas
    • Types of Antennas
      • Five types of antennas
        • Rear window defogger grid
          • Uses heating wires to receive signals
  • 50. Antennas
    • Types of Antennas
      • Five types of antennas
        • Rear window defogger grid
          • Special circuitry separates the RF from the DC heater circuit
  • 51. Antennas
    • Types of Antennas
      • Five types of antennas
        • Powered mast
          • Offers best overall performance available
  • 52. Antennas
    • Types of Antennas
      • Five types of antennas
        • Powered mast
          • Vertical rod
  • 53. Antennas
    • Types of Antennas
      • Five types of antennas
        • Integrated antenna
          • Sandwiched in windshield and an appliqué on rear window glass
  • 54. Antennas
    • Types of Antennas
      • Five types of antennas
        • Integrated antenna
          • Antenna in rear window is primary antenna and receives AM and FM
  • 55. Antennas
    • Types of Antennas
      • Five types of antennas
        • Integrated antenna
          • Secondary antenna is located in front windshield
  • 56. Antennas
    • Types of Antennas
      • Five types of antennas
        • Integrated antenna
          • Secondary antenna receives only FM signals
  • 57. Figure 61-6 The five types of antennas used on General Motors vehicles include the slot antenna, fixed mast antenna, rear window defogger grid antenna, a powered mast antenna, and an integrated antenna.
  • 58. ANTENNA DIAGNOSIS
  • 59. Antenna Diagnosis
    • Antenna Height
      • Antenna collects all radio-frequency signals
      • AM radio operates best with as long an antenna as possible
  • 60. Antenna Diagnosis
    • Antenna Height
      • FM reception works best when antenna height is exactly 31 in. (79 cm)
      • A defective antenna
        • Will greatly affect AM radio reception
  • 61. Antenna Diagnosis
    • Antenna Height
      • A defective antenna
        • May affect FM radio reception
    ?
  • 62. Antenna Diagnosis
    • Antenna Testing
      • If antenna or lead-in cable is broken (open)
        • FM reception may be weak
  • 63. Antenna Diagnosis
    • Antenna Testing
      • If antenna or lead-in cable is broken (open)
        • There will be no AM reception
  • 64. Antenna Diagnosis
    • Antenna Testing
      • Ohmmeter should read infinity between center antenna lead and antenna case
      • Case of the antenna must be properly grounded to vehicle body
  • 65. Figure 61-8 If all ohmmeter readings are satisfactory, the antenna is good.
  • 66. Antenna Diagnosis
    • Power Antenna Testing and Service
      • Most antennas use circuit breaker and relay to power reversible, permanent magnet electric motor
  • 67. Antenna Diagnosis
    • Power Antenna Testing and Service
      • Motor moves nylon cord attached to antenna mast
      • Some vehicles have dash-mounted control to regulate antenna height
  • 68. Antenna Diagnosis
    • Power Antenna Testing and Service
      • Many operate automatically when radio is turned on or off
      • Power antenna is usually mounted between outer and inner front fender or in rear quarter panel
  • 69. Antenna Diagnosis
    • Power Antenna Testing and Service
      • Unit contains the motor, a spool for the cord, and upper- and lower-limit switches
      • Power antenna mast tested same as fixed-mast antenna
  • 70. Figure 61-10 A typical power antenna assembly. Note the braided ground wire used to ensure that the antenna has a good ground plane.
  • 71. SPEAKERS
  • 72. Speakers
    • Purpose and Function
      • Purpose of speaker is to reproduce original sound as accurately as possible
  • 73. Speakers
    • Purpose and Function
      • Human ear hears sound from very low frequency of 20 Hz to as high as 20,000 Hz
      • No speaker can reproduce sound over such a wide range
  • 74. Figure 61-11 Between 6 and 7 volts is applied to each speaker terminal, and the audio amplifier then increases the voltage on one terminal and at the same time decreases the voltage on the other terminal causing the speaker cone to move. The moving cone then moves the air, causing sound.
  • 75. Speakers
    • Replacement speakers should be securely mounted and wired for correct polarity
  • 76. Figure 61-12 A typical automotive speaker with two terminals. The polarity of the speakers can be identified by looking at the wiring diagram in the service manual or by using a 1.5 volt battery to check. When the battery positive is applied to the positive terminal of the speaker, the cone will move outward. When the battery leads are reversed, the speaker cone will move inward.
  • 77. Speakers
    • Impedance Matching
      • All speakers used on same radio or amplifier should have same internal coil resistance, called impedance
  • 78. Figure 61-13 (a) Two 4 ohm speakers connected in series result in total impedance of 8 ohms. (b) Two 4 ohm speakers connected in parallel result in total impedance of 2 ohms.
  • 79. Speakers
    • Impedance Matching
      • If two 4 ohm speakers are used on the rear and they are connected parallel, total impedance is 2 ohms
      • R T = 4Ω (impedance of each speaker) = 2 ohms
          • 2 (number of speakers in parallel)
  • 80. Speakers
    • Impedance Matching
      • The front speakers should also represent a 2 ohm load from the radio or amplifier
  • 81. Speakers
    • Impedance Matching
      • Consider this example:
        • Two front speakers: each 2 ohms
  • 82. Speakers
    • Impedance Matching
      • Consider this example:
        • Two rear speakers: each 8 ohms
  • 83. Speakers
    • Impedance Matching
      • Consider this example:
        • Solution: Connect the front speakers in a series (connect the positive of one speaker to the negative of the other) for a total impedance of 4 ohms
          • 2 Ω + 2 Ω = 4 Ω
  • 84. Speakers
    • Impedance Matching
      • Consider this example:
        • Connect the two rear speakers in parallel (positive to positive, negative to negative) for a total impedance of 4 ohms
          • 8 Ω ÷ 2 = 4 Ω
  • 85. Speakers
    • Speaker Wiring
      • Use the largest wire possible for speakers to ensure full power reaches speakers
      • Typical speaker wire is about 22 gauge (0.35 mm 2 )
  • 86. Speakers
    • Speaker Wiring
      • Tests conclude that increasing wire gauge up to 4 gauge (19 mm 2 ) increases sound quality
      • All connections should be soldered
  • 87. Speakers
    • Speaker Wiring
      • CAUTION: Be careful when installing additional audio equipment on a General Motors vehicle system that uses a two-wire speaker connection called a floating ground system. Other systems run only one power (hot) lead to each speaker and ground the other speaker lead to the body of the vehicle.
  • 88. Speakers
    • This system helps prevent interference and static that could occur if these components were connected to a chassis (vehicle) ground. If the components are chassis grounded, there may be a difference in the voltage potential (voltage); this condition is called a group loop.
  • 89. Speakers
    • Speaker Wiring
      • CAUTION: Regardless of radio speaker connections used, never operate any radio without the speakers connected, or the speaker driver section of the radio may be damaged as a result of the open speaker circuit.
  • 90. SPEAKER TYPES
  • 91. Speaker Types
    • Introduction
      • No one speaker can reproduce sound over a wide frequency range
      • Speakers available in three types
  • 92. Speaker Types
    • Introduction
      • Tweeters are for high-frequency ranges.
      • Midrange is for mid-frequency ranges.
      • Woofers and subwoofers are for low-frequency ranges.
  • 93. Speaker Types
    • Tweeter
      • Tweeter is designed to reproduce high-frequency sounds
      • Usually between 4,000 and 20,000 Hz (4 and 20 kHz)
  • 94. Speaker Types
    • Tweeter
      • Very directional—human ear can detect location of speaker while listening to music
  • 95. Speaker Types
    • Tweeter
      • Tweeter should be mounted in vehicle in line of sight to listener
      • Usually mounted on inside door near the top of windshield A pillar
  • 96. Speaker Types
    • Midrange
      • Midrange speaker is best able to reproduce sounds in middle of human hearing range
  • 97. Speaker Types
    • Midrange
      • Usually from 400 to 5,000 Hz
      • Speakers are directional—human ear can locate the source
  • 98. Speaker Types
    • Subwoofer
      • Subwoofer (woofer) produces lowest frequency sounds
      • Usually 125 Hz and lower
  • 99. Speaker Types
    • Subwoofer
      • Midbass speaker may also reproduce frequencies from 100 to 500 Hz
      • Low-frequency sounds are not directional
  • 100. Speaker Types
    • Subwoofer
      • Sounds seem to come from everywhere
      • Location of speakers is not critical
  • 101. Speaker Types
    • Speaker Frequency Response
      • Frequency response is how a speaker responds to a range of frequencies
      • Typical frequency response for midrange speaker is 500 to 4,000 Hz
    ?
  • 102. SOUND LEVELS
  • 103. Sound Levels
    • Decibel Scale
      • Decibel (dB) is a measure of sound power
      • One decibel is the faintest sound human can hear in midband frequencies
  • 104. Sound Levels
    • Decibel Scale
      • The dB scale is logarithmic—a small change in dB reading results in a large change in volume
      • An increase of 10dB in sound pressure equals doubling perceived volume
  • 105. Sound Levels
    • Quiet, faint
      • 30 dB: whisper, quiet library
      • 40 dB: quiet room
    • Moderate
      • 50 dB: moderate range sound
      • 60 dB: normal conversation
    • Loud
      • 70 dB: vacuum cleaner, city traffic
      • 80 dB: busy noisy traffic, vacuum cleaner
  • 106. Sound Levels
    • Extremely loud
      • 90 dB: lawnmower, shop tools
      • 100 dB: chain saw, air drill
    • Hearing loss possible
      • 110 dB: loud rock music
  • 107. CROSSOVERS
  • 108. Crossovers
    • Definition
      • Crossover separates frequency of a sound and sends a certain frequency range to another speaker
      • Two types of crossovers: passive and active
  • 109. Crossovers
    • Passive Crossover
      • A passive crossover does not use external power source
      • It uses a coil and capacitor to block certain frequencies
  • 110. Crossovers
    • Passive Crossover
      • Frequencies a speaker can handle are let through
      • A passive crossover that passes low frequency sound is a low-pass filter
      • A passive crossover that passes high frequency sound is a high-pass filter
  • 111. Crossovers
    • Active Crossover
      • An active crossover uses an external power source to produce superior performance
      • Sometimes called an electronic crossover or a crossover network
  • 112. Crossovers
    • Active Crossover
      • Much more expensive than passive crossovers
      • Two amplifiers needed to fully benefit from active crossover
  • 113. Crossovers
    • Active Crossover
      • One amplifier is for midrange and high range frequencies
      • One amplifier is for subwoofers
  • 114. Figure 61-14 Crossovers are used in audio systems to send high-frequency sounds to the small (tweeter) speakers and lowfrequency sounds to larger (woofer) speakers.
  • 115. AFTERMARKET SOUND SYSTEM UPGRADE
  • 116. Aftermarket Sound System Upgrade
    • Power and Ground Upgrades
      • Upgrades can include
        • Separate battery for audio system
  • 117. Aftermarket Sound System Upgrade
    • Power and Ground Upgrades
      • Upgrades can include
        • Inline fuse near battery to protect wiring and components
  • 118. Aftermarket Sound System Upgrade
    • Power and Ground Upgrades
      • Upgrades can include
        • Wiring properly sized to amperage draw of system and length of wire
  • 119. Aftermarket Sound System Upgrade
    • Power and Ground Upgrades
      • Upgrades can include
        • Ground wires at least the same gauge as the power side wiring
  • 120. Aftermarket Sound System Upgrade
    • Powerline Capacitor
      • Powerline capacitor (stiffening capacitor) refers to large capacitor of 0.25 farad
  • 121. Aftermarket Sound System Upgrade
    • Powerline Capacitor
      • Connects to an amplifier power wire
      • Provides electrical reserve energy needed by amplifier to provide deep bass notes
  • 122. Figure 61-15 Two capacitors connected in parallel provide the necessary current flow to power large subwoofer speakers.
  • 123. Aftermarket Sound System Upgrade
    • Powerline Capacitor
      • Battery power is often slow to respond
      • When amplifier attempts to draw large amount of current, capacitor will stabilize voltage level
  • 124. Aftermarket Sound System Upgrade
    • Powerline Capacitor
      • Rule of thumb: connect capacitor with capacity of 1 farad for each 1,000 watts amplifier power
  • 125. Chart 61-1 The rating of the capacitor needed to upgrade an audio system is directly related to the wattage of the system.
  • 126. Aftermarket Sound System Upgrade
    • Capacitor Installation
      • Powerline capacitor connects to power leads between inline fuse and amplifier
    ?
  • 127. Figure 61-16 A powerline capacitor should be connected through the power wire to the amplifier as shown. When the amplifier requires more electrical power (watts) than the battery can supply, the capacitor will discharge into the amplifier and supply the necessary current for the fraction of a second it is needed by the amplifier. At other times when the capacitor is not needed, it draws current from the battery to keep it charged.
  • 128. Aftermarket Sound System Upgrade
    • Capacitor Installation
      • If connected to circuit without precharging, capacitor can blow inline fuse
      • Precharge capacitor by following these steps:
        • STEP 1: Connect the negative terminal of capacitor to good chassis ground.
  • 129. Aftermarket Sound System Upgrade
    • Capacitor Installation
      • Precharge capacitor by following these steps:
        • STEP 2: Insert automotive 12 V light bulb between positive terminal of capacitor and positive terminal of battery.
          • Light will light as capacitor is being charged and go out when capacitor is charged
  • 130. Aftermarket Sound System Upgrade
    • Capacitor Installation
      • Precharge capacitor by following these steps:
        • STEP 3: Disconnect light from capacitor.
          • Connect the power lead to the capacitor
  • 131. VOICE RECOGNITION
  • 132. Voice Recognition
    • Parts and Operation
      • Voice recognition allows driver to perform tasks by using voice commands
      • Voice recognition can be used for these functions
      • Navigation system operation
  • 133. Figure 61-17 Voice commands can be used to control many functions, including navigation systems, climate control, telephone, and radio.
  • 134. Voice Recognition
    • Parts and Operation
      • Sound system operation
      • Climate control system operation
  • 135. Figure 61-18 The voice command icon on the steering wheel of a Cadillac.
  • 136. Voice Recognition
    • Parts and Operation
      • Telephone dialing and related functions
      • Microphone usually placed in driver’s side sun visor or overhead console in center
  • 137. Voice Recognition
    • Diagnosis and Service
      • For problem with voice recognition system, follow these steps:
        • Verify customer complaint.
          • Check owner manual or service information for proper voice commands
  • 138. Voice Recognition
    • Diagnosis and Service
      • For problem with voice recognition system, follow these steps:
        • Check whether aftermarket accessories may be interfering or were converted for components used with voice recognition system.
  • 139. Voice Recognition
    • Diagnosis and Service
      • For problem with voice recognition system, follow these steps:
        • Check for stored diagnostic trouble codes using a scan tool.
        • Follow recommended troubleshooting procedures.
  • 140. BLUETOOTH
  • 141. Bluetooth
    • Operation
      • Bluetooth is standard for short-range communications
      • Range is 33 ft (10m)
      • Operates in ISM band between 2.4000 and 2.4835 MHz
  • 142. Bluetooth
    • Operation
      • Works on two levels
        • Provides physical communication using low power
  • 143. Bluetooth
    • Operation
      • Works on two levels
        • Suitable for use with small handheld or portable devices, such as ear-mounted speaker/microphone
  • 144. Bluetooth
    • Operation
      • Works on two levels
        • Provides standard protocol for how data is sent and received
  • 145. Bluetooth
    • Operation
      • Bluetooth is wireless, low cost, and automatic
      • Bluetooth allows use of hands-free telephone
  • 146. Bluetooth
    • Operation
      • Bluetooth telephone equipped vehicle has these components
        • Bluetooth receiver built into navigation or sound system
  • 147. Bluetooth
    • Operation
      • Bluetooth telephone equipped vehicle has these components
        • Microphone allowing driver to use voice commands and have phone conversations
  • 148. Bluetooth
    • Operation
      • Many cell phones are equipped with Bluetooth
      • Caller may use ear-mounted microphone and speaker
  • 149. Figure 61-19 Bluetooth earpiece that contains a microphone and speaker unit that is paired to a cellular phone. The telephone has to be within 33 ft (10 m) of the earpiece.
  • 150. SATELLITE RADIO
  • 151. Satellite Radio
    • Parts and Operation
      • Satellite radio, or Satellite Digital Audio Radio Services (SDARS), is fee-based system using satellites to broadcast high-quality radio
      • SDARS broadcasts on the S-band of 2.1320 to 2.345 GHz
    ? ?
  • 152. Satellite Radio
    • Sirius/XM Radio
      • Sirius/XM radio is standard or optional on most vehicles
      • XM radio uses two satellites in geosynchronous orbit
  • 153. Satellite Radio
    • Sirius/XM Radio
      • Sirius and XM radio combined in 2008 and share some programming
      • The two types of satellite radios use different protocols so they require different radios
  • 154. Satellite Radio
    • Sirius/XM Radio
      • Combination radio is available
  • 155. Satellite Radio
    • Reception
      • Reception can be affected by tall buildings and mountains
      • To ensure consistent reception, SDARS providers do the following:
        • Include a buffer circuit in the radio that stores several seconds of broadcasts to provide service when traveling
  • 156. Satellite Radio
    • Reception
      • To ensure consistent reception, SDARS providers do the following:
        • Provide land-based repeater stations in most cities
  • 157. Figure 61-20 SDARS uses satellites and repeater stations to broadcast radio.
  • 158. Satellite Radio
    • Antenna
      • Antenna must receive signals from satellite and repeater stations
  • 159. Figure 61-21 An aftermarket XM radio antenna mounted on the rear deck lid. The deck lid acts as the ground plane for the antenna.
  • 160. Figure 61-22 A shark-fin-type factory antenna used for both XM and OnStar.
  • 161. Satellite Radio
    • Diagnosis and Service
      • First, verify customer complaint
      • Check that monthly service fee has been paid
  • 162. Satellite Radio
    • Diagnosis and Service
      • Check antenna for damage or faults from lead-in wire
      • Antennas must be installed on metal surface for proper ground
  • 163. Satellite Radio
    • Diagnosis and Service
      • Check service information for exact tests and procedures
      • Check these websites for additional information
        • www.xmradio.com
        • www.sirius.com
        • www.siriusxm.com
    ?
  • 164. RADIO INTERFERENCE
  • 165. Radio Interference
    • Definition
      • Radio interference caused by variations in voltage in powerline or picked up by antenna
  • 166. Radio Interference
    • Definition
      • A whine that increases in frequency with engine speed is an alternator whine
      • Alternator whine can be eliminated by installing radio choke or filter capacitor wire to radio
  • 167. Figure 61-23 A radio choke and/or a capacitor can be installed in the power feed lead to any radio, amplifier, or equalizer.
  • 168. Radio Interference
    • Capacitor Usage
      • Ignition noise is raspy sound that varies with engine speed
      • Noise is usually eliminated by installation of capacitor on positive side of ignition coil
  • 169. Radio Interference
    • Capacitor Usage
      • Connect capacitor to power feed wire on radio or amplifier, or both
      • Ground capacitor
  • 170. Radio Interference
    • Capacitor Usage
      • Use 470 μ F, 50 volt electrolytic capacitor
      • Special coaxial capacitor can also be used in the powerline
  • 171. Figure 61-24 Many automobile manufacturers install a coaxial capacitor, like this one, in the power feed wire to the blower motor to eliminate interference caused by the blower motor.
  • 172. Radio Interference
    • Radio Choke
      • A radio choke is a coil of wire that can be used to reduce or eliminate radio interference
      • Installed in the power feed wire to the radio equipment
  • 173. Radio Interference
    • Radio Choke
      • Make certain all units containing a coil have a capacitor or diode attached to the power-side wire
  • 174. Radio Interference
    • Braided Ground Wire
      • Braided ground wire is usually specified when electrical noise is a concern
      • Radio-frequency signals travel on surface of a conductor rather than through the core
  • 175. Radio Interference
    • Braided Ground Wire
      • Overlapped wires of braided ground strap short out any radio-frequency signals traveling on surface
  • 176. Radio Interference
    • Audio Noise Summary
      • Radio noise can be broadcast or caused by noise (voltage variations) in the power circuit of radio
      • Most radio interference comes from installation of amplifier, power booster, equalizer, or other radio accessory
  • 177. Radio Interference
    • Audio Noise Summary
      • Major cause of interference is variation in voltage through ground circuit wires
  • 178. Radio Interference
    • Audio Noise Summary
      • Make sure all ground connections are clean and tight
      • Placing capacitor in the ground circuit may be beneficial
  • 179. Radio Interference
    • Audio Noise Summary
      • CAUTION: Amplifiers sold to boost the range or power of an antenna often increase the level of interference and radio noise to a level that disturbs the driver.
  • 180. Radio Interference
    • Audio Noise Summary
      • Capacitor and/or radio chokes are most commonly used components
      • Two or more capacitors can be connected in parallel to increase capacity of original capacitor
  • 181. Radio Interference
    • Audio Noise Summary
      • Sniffer can be used to locate source of interference
      • Sniffer is length of antenna wire with a few inches of insulation removed from end
  • 182. Radio Interference
    • Audio Noise Summary
      • Sniffer is attached to antenna input terminal
      • Radio is turned on and set to weak station
  • 183. Radio Interference
    • Audio Noise Summary
      • End of sniffer is moved around areas of dash to locate source of interference
      • Radio noise will increase as sniffer comes to electromagnetic leakage
  • 184. Figure 61-25 A “sniffer” can be made from an old antenna lead-in cable by removing about 3 in. of the outer shielding from the end. Plug the lead-in cable into the antenna input of the radio and tune the radio to a weak station. Move the end of the antenna wire around the vehicle dash area. The sniffer is used to locate components that may not be properly shielded or grounded and can cause radio interference through the case (housing) of the radio itself.
  • 185. Chart 61-2 Radio noise can have various causes, and knowing where or when the noise occurs helps pin down the location.
  • 186. FREQUENTLY ASKED QUESTION
    • What Does a “Capture” Problem Mean?
      • A capture problem affects only FM reception and means that the receiver is playing more than one station if two stations are broadcasting at the same frequency. Most radios capture the stronger signal and block the weaker signal.
    ? BACK TO PRESENTATION
    • However, if the stronger signal is weakened due to being blocked by buildings or mountains, the weaker signal will then be used. When this occurs, it will sound as if the radio is changing stations by itself. This is not a fault with the radio, but simply a rare occurrence with FM radio.
  • 187. FREQUENTLY ASKED QUESTION
    • What Is a Ground Plane?
      • Antennas designed to pick up the electromagnetic energy that is broadcast through the air to the transmitting antenna are usually one-half wavelength high, and the other half of the wavelength is the ground plane. This one-half wavelength in the ground plane is literally underground.
    ? BACK TO PRESENTATION
    • For ideal reception, the receiving antenna should also be the same as the wavelength of the signal. Because this length is not practical, a design compromise uses the length of the antenna as one-fourth of the wavelength; in addition, the body of the vehicle itself is one-fourth of the wavelength. The body of the vehicle, therefore, becomes the ground plane.
    • Any faulty condition in the ground plane circuit will cause the ground plane to lose effectiveness, such as:
      • Loose or corroded battery cable terminals
      • Acid buildup on battery cables
      • Engine grounds with high resistance
      • Loss of antenna or audio system grounds
      • Defective alternator, causing an AC ripple exceeding
        • 50 mV (0.050 V)
      • Figure 61-7 The ground plane is actually one-half of the antenna.
  • 188. TECH TIP
    • The Hole in the Fender Cover Trick
      • A common repair is to replace the mast of a power antenna. To help prevent the possibility of causing damage to the body or paint of the vehicle, cut a hole in a fender cover and place it over the antenna.
    BACK TO PRESENTATION
    • If a wrench or tool slips during the removal or installation process, the body of the vehicle will be protected.
      • Figure 61-9 Cutting a small hole in a fender cover helps to protect the vehicle when replacing or servicing an antenna.
  • 189. TECH TIP
    • Skin Effect
      • When a high-frequency signal (AC voltage) is transmitted through a wire, the majority of it travels on the outside surface of the wire. This characteristic is called skin effect. The higher the frequency, the closer to the outer surface the signal moves.
    BACK TO PRESENTATION
    • To increase audio system output, most experts recommend the use of wire that has many strands of very fine wire to increase the surface area or the skin area of the conductor. Therefore, most aftermarket speaker wire is stranded with many small diameter copper strands.
  • 190. WARNING
    • Hearing loss is possible if exposed to loud sounds. According to noise experts (audiologists), hearing protection should be used whenever the following occurs.
    BACK TO PRESENTATION
    • You must raise your voice to be heard by others next to you.
    • You cannot hear someone else speaking who is less than 3 ft (1 m) away.
    • You are operating power equipment, such as a lawnmower.
  • 191. FREQUENTLY ASKED QUESTION
    • What Is a Bass Blocker?
      • A bass blocker is a capacitor and coil assembly that effectively blocks low frequencies. A bass blocker is normally used to block low frequencies being sent to the smaller front speakers. Using a bass blocker allows the smaller front speakers to more efficiently reproduce the midrange and high-range frequency sounds.
    ? BACK TO PRESENTATION
  • 192. FREQUENTLY ASKED QUESTION
    • What Do the Amplifier Specifications Mean?
      • RMS power
        • RMS means root-mean-square and is the rating that indicates how much power the amplifier is capable of producing continuously.
    ? BACK TO PRESENTATION
    • RMS power at 2 ohms
      • This specification in watts indicates how much power the amplifier delivers into a 2 ohm speaker load. This 2 ohm load is achieved by wiring two 4 ohm speakers in parallel or by using 2 ohm speakers.
    • Peak power
      • Peak power is the maximum wattage an amplifier can deliver in a short burst during a musical peak.
    • THD
      • Total harmonic distortion (THD) represents the amount of change of the signal as it is being amplified. The lower the number, the better the amplifier (e.g., a 0.01% rating is better than a 0.07% rating).
    • Signal-to-noise
      • This specification is measured in ratio decibels (dB) and compares the strength of the signal with the level of the background noise (hiss). A higher volume indicates less background noise (e.g., a 105 dB rating is better than a 100 dB rating).
  • 193. FREQUENTLY ASKED QUESTION
    • Where Did Bluetooth Get Its Name?
      • The early adopters of the standard used the term Bluetooth, and they named it for Harold Bluetooth, the king of Denmark in the late 900s. The king was able to unite Denmark and part of Norway into a single kingdom.
    ? BACK TO PRESENTATION
  • 194. FREQUENTLY ASKED QUESTION
    • Can Two Bluetooth Telephones Be Used in a Vehicle?
      • Usually. In order to use two telephones, the second phone needs to be given a name. When both telephones enter the vehicle, check which one is recognized.
    ? BACK TO PRESENTATION
    • Say “phone status” and the system will tell you to which telephone the system is responding. If it is not the one you want, simply say, “next phone” and it will move to the other one.
  • 195. FREQUENTLY ASKED QUESTION
    • What Does ESN Mean?
      • ESN means electronic serial number. This is necessary information to know when reviewing satellite radio subscriptions. Each radio has its own unique ESN, often found on a label at the back or bottom of the unit. It is also often shown on scan tools or test equipment designed to help diagnose faults in the units.
    ? BACK TO PRESENTATION
  • 196. TECH TIP
    • The Separate Battery Trick
      • Whenever diagnosing sound system interference, try running separate 14 gauge wire(s) from the sound system power lead and ground to a separate battery outside of the vehicle. If the noise is still heard, the interference is not due to an alternator diode or other source in the wiring of the vehicle.
    BACK TO PRESENTATION
  • 197. REAL WORLD FIX
    • Lightning Damage
      • A radio failed to work in a vehicle that was outside during a thunderstorm. The technician checked the fuses and verified that power was reaching the radio. Then the technician noticed the antenna. It had been struck by lightning.
    BACK TO PRESENTATION
    • Obviously, the high voltage from the lightning strike traveled to the radio receiver and damaged the circuits. Both the radio and the antenna were replaced to correct the problem.
      • Figure 61-26 The tip of this antenna was struck by lightning.
  • 198. REAL WORLD FIX
    • The General Motors Security Radio Problem
      • A customer replaced the battery in a General Motors vehicle and now the radio display shows “LOC.” This means that the radio is locked and there is a customer code stored in the radio.
      • Other displays and their meaning include:
    • “ InOP”
      • This display indicates that too many incorrect codes have been entered and the radio must be kept powered for one hour and the ignition turned on before any more attempts can be made.
    • “ SEC”
      • This display means there is a customer’s code stored and the radio is unlocked, secured, and operable.
    • “ ---”
      • This means there is no customer code stored and the radio is unlocked.
    • “ REP”
      • This means the customer’s code has been entered once and the radio now is asking that the code be repeated to verify it was entered correctly the first time.
    BACK TO PRESENTATION
    • To unlock the radio, the technician used the following steps (the code number being used is 4321).
    • STEP 1: Press the “HR” (hour) button: “000” is displayed.
    • STEP 2: Set the first two digits using the hour button: “4300” is displayed.
    • STEP 3: Set the last two digits of the code using the “MIN” (minutes) button: “4321” is displayed.
    • STEP 4: Press the AM-FM button to enter the code. The radio is unlocked and the clock displays “1:00.”
    • Thankfully, the owner had the security code. If the owner had lost the code, the technician would have to secure a scrambled factory backup code from the radio and then call a toll-free number to obtain another code for the customer. The code will only be given to authorized dealers or repair facilities.