MULTI AV SYSTEM : System Description

Multi AV system means that the following systems are integrated.

FUNCTION NAME
Navigation system function
Audio function
DVD playback function
Hands-free phone function
USB connection function
Voice recognition function
Touch panel function
Rear view monitor function
Vehicle information function
Intelligent key interlocking function
Auto Light Adjustment System

COMMUNICATION SIGNAL

• AV control unit function by transmitting/receiving data one by one with each unit (slave unit) that configures them completely as a master unit by connecting between units that configure MULTI AV system with two AV communication lines (H, L).
• Two AV communication lines (H, L) adopt a twisted pair line that is resistant to noise.
• The AV control unit is connected by CAN communication, and it receives data signal from ECM and combination meter. It computes and displays fuel economy information value with the obtained information.
• The AV control unit is connected with display unit and serial communication, and it transmits the required signal of display and display control and receives the response signal from display unit.
• The AV control unit has a vehicle setting function and transmits/receives vehicle setting state data to/from BCM via CAN communication.
• The AV control unit receives a steering angle signal from the steering angle sensor via CAN communication and controls an expected course line during rear view monitor operation.
• The AV control unit transmits an ECO pedal reaction force setting signal (STANDARD/SOFT/OFF) to ECM that is necessary for ECO mode setting.
• The AV control unit transmits ON/OFF signals of DCA (distance control system), LDP (lane deviation prevention support system) and BSI (blind spot intervention) necessary for drive support system settings.

NAVIGATION SYSTEM FUNCTION

Description

• The AV control unit controls navigation function while GPS tuner has built-in map data, GYRO (angle speed sensor), on the HDD (Hard Disk Drive).
• The AV control unit inputs operation signal with communication signal, through display unit (touch panel) and multifunction switch and steering switch.
• Guide sound is output to front speaker through BOSE amp. from AV control unit when operating navigation system.
• A vehicle position is calculated with the GYRO (angle speed sensor), vehicle sensor, signal from GPS satellite and map data stored on HDD (Hard Disk Drive), and transmits the map image signal (RGB image, RGB area, RGB image synchronizing) to the display.

Position Detection Principle

The navigation system periodically calculates the current vehicle position according to the following three types of signals.

• Travel distance of the vehicle as determined by the vehicle speed sensor
• Vehicle turning angle determined by the gyroscope (angular speed sensor)
• The travel direction of the vehicle determined by the GPS antenna (GPS information)

The current position of the vehicle is then identified by comparing the calculated vehicle position with map data, which is stored in the HDD (Hard Disk Drive) (map-matching), and indicated on the screen with a current location mark. More accurate data is used by comparing position detection results from GPS to the map-matching.

The current position is calculated by detecting the travel distance from the previous calculation point, and its direction change.

• Travel distance

  The travel distance is generated from the vehicle speed sensor input signal. The automatic distance correction function is adopted for preventing a miss-detection of the travel distance because of tire wear etc.

• Travel direction

  The gyroscope (angular velocity sensor) and GPS antenna (GPS information) generate the change of the travel direction. Both have advantages and disadvantages as per the following descriptions.

  Fig 2: Vehicle Positioning Diagram

  Courtesy of NISSAN MOTOR CO., U.S.A.
  ADVANTAGES AND DISADVANTAGES OF GYROSCOPE AND GPS ANTENNA
  
  

  Type	Advantage	Disadvantage
  Gyroscope (angular velocity sensor)	The turning angle is precisely detected.	Errors are accumulated when driving a long distance without stopping.
  GPS antenna (GPS information)	The travel direction (North/South/East/West) is detected.	The travel direction is not precisely detected when driving slowly.

Input signals are prioritized in each situation. However, this order of priority may change in accordance with more detailed travel conditions so that the travel direction is detected more accurately.

Map-matching

Map-matching repositions the vehicle on the road map when a new location is judged to be more accurate. This is done by comparing the current vehicle position (calculated by the normal position detection method) from the map data stored in the HDD (Hard Disk Drive).

There is a possibility that the vehicle position may not be corrected in the following case, and when vehicle is driven over a certain distance or time in which GPS information is hard to receive. Correct manually the current location mark on the screen.

• In map-matching, several alternative routes are prepared and prioritized in addition to the road judged as currently driving on. Therefore, due to errors in the distance and/or direction, an incorrect road may be prioritized, and the current location mark may be repositioned to the incorrect road.

  If two roads are running in parallel, they are of the same priority. Therefore, the current location mark may appear on either of them alternately, depending on maneuvering of the steering wheel and configuration of the road, etc.

  Fig 4: Identifying Vehicle Route On Map Display

  Courtesy of NISSAN MOTOR CO., U.S.A.
• Map-matching does not function correctly when road on which the vehicle is driving is new, etc. and not recorded in the map data. Also, map-matching does not function correctly when road pattern stored in the map data and the actual road pattern are different due to repair, etc.

  Therefore, the map-matching function judges other road as a currently driving road if the road is not in the map, and displays the current location mark on it. Later, the current location mark may be repositioned to the road if the correct road is detected.

• Effective range for comparing the vehicle position and travel direction calculated by the distance and direction with the road data is limited. Therefore, correction by map-matching is not possible when there is an excessive gap between current vehicle position and the position on the map.
  Fig 5: Identifying Vehicle Route On Map Display For Newly Constructed Road

  Courtesy of NISSAN MOTOR CO., U.S.A.

GPS (Global Positioning System)

GPS (Global Positioning System) is developed for and is controlled by the US Department of Defense. The system utilizes GPS satellites (NAVSTAR), transmitting out radio waves while flying on an orbit around the earth at an altitude of approximately 21,000 km (13,049 mile).

The receiver calculates the travel position in three dimensions (latitude/longitude/altitude) according to the time lag of the radio waves that four or more GPS satellites transmit (three-dimensional positioning). The GPS receiver calculates the travel position in two dimensions (latitude/longitude) with the previous altitude data if the GPS receiver receives only three radio waves (two-dimensional positioning). GPS position correction is not performed while stopping the vehicle.

Accuracy of the GPS will deteriorate under the following conditions:

• In two-dimensional positioning, GPS accuracy will deteriorate when altitude of the vehicle position changes.
• The position of GPS satellite affects GPS detection precision. The position detection may not be precisely performed.
• The position detection is not performed if GPS receiver does not receive radio waves from GPS satellites. (Inside a tunnel, parking in a building, under an elevated highway etc.) GPS receiver may not receive radio waves from GPS satellites if any object is placed on the GPS antenna.
  NOTE:

  • The detection result has an error of approximately 10 m (32.81 ft) even with a high-precision three dimensional positioning.
  • There may be cases when the accuracy is lowered and radio waves are stopped intentionally because the GPS satellite signal is controlled by the US trace control center.

AUDIO FUNCTION

Description

• The audio function is adoption of the following system, and it is equipped with the following functions.
  AUDIO FUNCTION REFERENCE CHART
  
  

  FUNCTION	SYSTEM
  	BOSE® Studio Surround® Sound System (16 speaker models)	BOSE Stereo Sound System (10 speaker models)
  AM/FM radio	X	X
  Satellite radio	X	X
  CD/DVD	X	X
  Bluetooth™ audio	X	X
  Music Box (Hard Disk Drive)	X	X
  Active noise control system	X	X
  AudioPilot® 2 Noise Compensation Technology	X	X
  BOSE® Centerpoint® 2	X
  X: Applicable

• The adoption of the AudioPilot® 2 Noise Compensation Technology enables the correction of frequency bands which tend to be masked by driving noise.
• The BOSE Stereo Sound System features 8-channel amplifier and ten high-performance 3-way speakers integrated into the front doors. Furthermore, the 6x9-inch woofers mounted in the front doors provide deep bass sound.
• With the adoption of 14EQch digital amplifier and 16 speakers, BOSE® Studio Surround® Sound System provides smooth and natural sound over the range from bass to treble through the optimum placement of speakers for each seat and the control of amplifier.
• BOSE® Studio Surround® Sound System is adoption of BOSE® Centerpoint® 2 enables sound effects with a sense of realism even to playback sound of two-channel audio.
• The table below shows speakers mounted to each system.
  SPEAKERS INFORMATION
  
  

  SPEAKER		SYSTEM
  		BOSE® Studio Surround® Sound System (16 speaker models)	BOSE Stereo Sound System (10 speaker models)
  Front door 3 Way speaker	Front door woofer	X	X
  	Front door squawker	X	X
  	Tweeter	X	X
  Rear door speaker		X	X
  Rear woofer		X	X
  Center speaker		X	X
  Satellite speaker		X
  Seat speaker		X
  X: Applicable

Operating Signal

Audio system operation can be performed with multifunction switch, preset switch, steering switch, touch panel function or voice recognition function.

• Operating signal is transmitted to AV control unit with AV communication when it is operated by multifunction switch or preset switch. The disk ejection operating signal is performed by hardwire.
• Operating signal is transmitted to AV control unit with steering switch signal when it is operated by steering switch.

Screen Display

Switching of display is performed with serial communication between display unit and AV control unit. Operation status of audio is indicated at display unit.

AM/FM Radio Mode

• AM/FM radio tuner is built into AV control unit.
• Sound signals (AM/FM radio) are received via window antenna.
• AM/FM main antenna signal is amplified via antenna amp. and FM sub antenna signal is transmitted to AV control unit.
• AV control unit outputs sound signal is input to BOSE amp., and BOSE amp. outputs to each speaker.

Satellite Radio Mode

• Satellite radio tuner is built into AV control unit.
• Sound signal (satellite radio) is received by satellite radio antenna and is transmitted to AV control unit. AV control unit outputs sound signal to BOSE amp. The signal is also outputted from BOSE amp. to each speaker.

CD Mode

• CD function is built into AV control unit.
• AV control unit outputs sound signal to BOSE amp., and BOSE amp. outputs the signal to each speaker during playback.

Bluetooth™ Audio Mode

• Bluetooth™ audio function is built into AV control unit.
• Bluetooth™ audio can play music data in the portable audio by means of Bluetooth™ communications between the portable audio and the AV control unit.
• AV control unit outputs sound signal to BOSE amp., and BOSE amp. outputs to each speaker.

Music Box Mode

• Music CD data is stored on HDD that is built into AV control unit, and it can be played.
• AV control unit outputs music (sound signal) that is stored on HDD to BOSE amp., and BOSE amp. outputs to each speaker.

AudioPilot® 2 Noise Compensation Technology

• AudioPilot® 2 continuously corrects audio signals to compensate for background noise.
• AudioPilot® 2 noise compensation technology is a sound improving system that picks up by a front microphone any noises or the sound of music coming into the vehicle, and that uses the BOSE amp. to revise the frequency feature of music in real time in response to the frequency feature of the noise while driving and listening to music.
  Fig 7: Audiopilot® 2 Noise Compensation Technology Diagram

  Courtesy of NISSAN MOTOR CO., U.S.A.

*: DSP stands for Digital Signal Processor and enables digital processing of sound signals. DSP features precise signal processing and calculation with the digital technology on a small scale that analog methods find it difficult to process and calculate.

BOSE® Centerpoint® 2 (BOSE® Studio Surround® Sound System)

• BOSE® Centerpoint® 2 provides a surround-sound effect, based on a stereo sound source, such as CD or MP3.
• The BOSE amp. receives a BOSE® Centerpoint® 2 ON signal during a stereophonic sound playback and divides the sound among five channels to add a sense of simulated surround playback sound.

Active Noise Control System

• The active noise control system incorporates the BOSE Engine Harmonic Cancellation (EHC) technology.
• The active noise control system outputs an antiphase sound from the speakers (front door speaker, rear door speaker and rear woofer) against unpleasant engine booming noise (2nd and/or 3rd engine rev at 700 - 5000 RPM) and reduces sound pressure level by the interference with engine booming noise. (VQ37VHR models)
• The active noise control system outputs an antiphase sound from the speakers (front door speaker, rear door speaker and rear woofer) against unpleasant engine booming noise (4th engine rev at Idle speed - 2500 RPM) and reduces sound pressure level by the interference with engine booming noise. (VK56VD models)
• The BOSE amp. receives an engine speed signal from ECM and receives microphone signals from the front and rear microphone.
• The BOSE amp. receives a door state signal. The active noise control system does not operate with any door open.
• Based on signals detected by the front and rear microphones, the BOSE amp. generates an antiphase sound (microphone signal) weakening interior engine booming noise in real time according to a unique algorithm^*1 by a DSP^*2 built in the BOSE amp. Then, the BOSE amp. mixes the antiphase sound with a sound signal received from the AV control unit to transmit the mixed sound signal to each speaker.
  NOTE: *1: Algorithm means a fixed procedure to solve a question.
  *2: DSP stands for Digital Signal Processor and enables digital processing of sound signals. DSP features precise signal processing and calculation with the digital technology on a small scale that analog methods find it difficult to process and calculate.
  Fig 8: Active Noise Control System Signals Diagram

  Courtesy of NISSAN MOTOR CO., U.S.A.

DVD PLAYBACK FUNCTION

• DVD is played by inserting DVD into the AV control unit.
• DVD image signals are transmitted to the display unit and DVD sound signals are transmitted to each speaker via BOSE amp.

HANDS-FREE PHONE FUNCTION

• AV control unit includes hands-free phone function.
• Hands-free communication can be operated by connecting using Bluetooth™ communication with cellular phone.
• Operation is performed by steering switch, and operating condition is indicated on display unit.
• Guide sound that is heard during operation is input from AV control unit to BOSE amp., and is output from front speaker and center speaker.

When A Call Is Originated

Spoken voice sound output from the microphone (microphone signal) is input to AV control unit. AV control unit outputs to cellular phone with Bluetooth™ communication as a TEL voice signal. Voice sound is then heard at the other party.

When Receiving A Call

Voice sound is input to own cellular phone from the other party. TEL voice signal is output to door speaker, and the signal is input to BOSE amp. via AV control unit by establishing Bluetooth™ communication from cellular phone.

USB CONNECTION FUNCTION

• Connecting iPod® or USB memory allows the driver to play iPod® music files or USB memory-stored music files, video data, and image viewer data.
• Sound signals of music files stored in iPod® or USB memory is transmitted from the USB connector to the AV control unit. The AV control unit transmits the sound signals to the woofer and each speaker via BOSE amp.
• Video signals and image viewer file signals are transmitted from the USB connector to the AV control unit.

  The data and files are displayed on the front display unit screen.

• iPod® is recharged when connected to USB connector.
• Only files that meet the following conditions will be played.
  FILES REFERENCE CHART
  
  

  	Music file	Video file	Image viewer file
  File format	"MP3", "WMA", "AAC", "M4A"	"DivX", "MPEG4 (ASF)"	"JPEG"
  File extension	".mp3", ".wma", ".aac", ".m4a"	".divx", ".afs", ".avi"	".jpg", ".jpeg"
  Maximum file size	2 GB	2 GB	2 MB

  NOTE:

  • iPod® is a trademark of Apple inc., registered in the U.S. and other countries.
  • Image signals cannot be received from iPod®.
  • Use the enclosed USB harness when connecting iPod® to USB connector.

VOICE RECOGNITION FUNCTION

• Each operation of multi AV system can be performed by inputting sound to microphone.
• Start of sound recognition system can be performed by steering switch.

TOUCH PANEL SYSTEM

Each operation of multi AV system can be performed by directly touching a display.

REAR VIEW MONITOR FUNCTION

• The AV control unit supplies power to the rear view camera when receiving a reverse signal.
• The rear view camera transmits camera images to the display unit when power is supplied from the AV control unit.
• The AV control unit transmits a warning message, fixed guide lines, and predictive course lines to the display unit by RGB digital image signal. Rear view monitor images are displayed by combining the RGB digital image signal and the camera image signals from the rear view camera.
• Predictive course lines are controlled by a steering angle sensor signal received the AV control unit via CAN communication.

VEHICLE INFORMATION FUNCTION

Status of audio, climate control system, fuel economy, maintenance and navigation etc. are displayed.

INTELLIGENT KEY INTERLOCKING FUNCTION

The AV control unit recognizes a door-unlocked state of intelligent key according to an intelligent key recognition signal transmitted from BCM and saves two different types of audio settings and navigation settings.

Settings saved in the AV control unit

• Map display
• Route guidance
• Locator
• Route search
• Sound quality
• Radio preset
• Language

AUTO LIGHT ADJUSTMENT SYSTEM

When the light switch is in the 1st or 2nd position, the dimming of the display is judged according to a dimming signal transmitted from BCM to the AV control unit. Display illuminance is independent of vehicle exterior illuminance detected by the auto light detecting sensor even when the light switch is in 1st or 2nd position.