Navigation System Description - Overview
Overview
The navigation system is a highly-sophisticated, hybrid locating system that uses satellites and a map database to show where you are and to help guide you to a desired destination.
The navigation system receives signals from the global positioning system (GPS), a network of 24 satellites in orbit around the earth. By receiving signals from several of these satellites, the navigation system can determine the latitude, longitude, and elevation of the vehicle. In addition, signals from the system's yaw rate sensor and the PCM (vehicle speed pulse) enable the system to keep track of the vehicle's direction and speed of travel.
This hybrid system has advantages over a system that is either entirely self-contained or one that relies totally on the GPS. For example, the self-contained portion of the system can keep track of vehicle position even when satellite signals cannot be received. When the navigation system is on, the GPS can keep track of the vehicle position even when the vehicle is transported by ferry.
The navigation system applies all location, direction, and speed information to maps and calculates a route to the destination entered. As you drive to that destination, the system provides both visual and audio guidance.
This navigation system also has voice recognition that allows voice control of most of the navigation functions. The TALK and BACK buttons on the steering wheel activate the voice control. The voice control also allows control of the audio and climate functions.
The illumination signal (headlights on) is used by the audio-navigation unit to automatically switch the display between Night and Day brightness modes. When the gauge control module brightness control is set to full brightness, the navigation system stays in the day mode, even with the headlights on.
The GA-Net II communication bus passes information back and forth between the multi-information display unit, the tuner unit, the HandsFreeLink control unit, the XM receiver, and the audio-navigation unit. The information passed on this bus is audio settings directed by the audio-navigation unit.
HDD Navigation System
The Accord uses a hard disc drive (HDD). The HDD system improves route calculation and POI searching time, as well as these additional functions:
- Ripping music to the HDD with on-board CD database (CDDB) information provided by Gracenote.
- Customers can save their personal pictures to the HDD and use the images as wallpaper when they are not using the navigation system.
- See the Owner's Manual or the Navigation System Manual for more information.
There are two software programs that run on the audio-navigation system:
- Navigation system software - This software comes pre-loaded on the HDD and runs the navigation system. It can be updated with the update disc.
- Map software - This is commonly referred to as update navigation DVD that customers can order to update their map info, POI DB, and CDDB information. This also comes pre-loaded on the HDD, but the customer can choose to update it yearly.
When you order a reman HDD, the latest navigation system software is loaded on the HDD, along with the latest Map software that the customer had installed on their HDD.
The Gracenote CDDB is updated quarterly.
The HDD shuts down to protect itself from damage, if the audio-navigation unit internal temperature is 183 °F (84 °C) or higher.
Warning of extreme temperatures in the audio-navigation unit is displayed on the navigation screen as an error message.
USB Adapter
The USB module is built into the audio-navigation unit. Customers can load images (which can be used as wallpaper), music, and the CDDB. Not all USB devices and devices functions work with the USB adapter. Please see the Owner's Manual for more information.
Multi-View Rear Camera System
Overview
The multi-view rear camera system is a functionality that provides three different view images of the rearview camera to the multi-information display unit, and can be changed by user operation. The guiding lines are different according to the view mode difference. The rearview camera is connected directly to the audio-navigation unit.
- Normal View Mode
The display shows the basic view.
- Wide View Mode
The display shows wider visibility than the normal view, which helps the driver confirm any objects approaching from right and left.
- Top Down View Mode
The display shows the view from the top angle of the vehicle, which helps the driver confirm the distance from any object behind.
When the vehicle is in R, the rearview camera image automatically appears on the center display. You can change the display while the vehicle is in R by pressing the interface dial.
INTERFACE DIAL:
- The rearview camera image changes between the wide view, the normal view, and the top down view in this order by pressing ENTER.
- You can change the rearview camera image brightness by rotating the interface dial. The brightness adjustment is not affected by the screen brightness adjustment in Setup.
BACK button:
Pressing and holding the CANCEL button for three seconds turns the guide lines on and off.
Basic Control
When the audio-navigation unit detects the BACK LT signal (when the vehicle is in R) for at least 0.5 seconds, the center display turns on the rearview camera. The center display delays for the 0.5 seconds to prevent changing the screen image too frequently because of incorrect shift lever selection.
Changing Camera Views
When the rearview camera image is displayed, pressing the interface dial sends a signal from the audio-navigation unit to the rearview camera using the CAMERA BIT0 and CAMERA BIT1 signal lines to change the rearview camera view.
| Wide | Normal | Top Down | |
|---|---|---|---|
| CAMERA BIT 0 Signal | OFF (0 V) | ON (8 V) | OFF (0 V) |
| CAMERA BIT 1 Signal | OFF (0 V) | OFF (0 V) | ON (8 V) |
View Mode Memorization
Any time the audio-navigation unit loses power (battery disconnected, navigation unit disconnected, etc.) the rearview camera defaults to the normal angle view. The rearview camera will also default to this angle if you had the top down angle selected when you turned the vehicle to the OFF (LOCK) mode. If you change the rearview camera to the wide view, the rearview camera will remember this view when you turn the vehicle to the ON mode.
Navigation Function
The navigation system is composed of the audio-navigation unit, the PCM (vehicle speed pulse), the gauge control module, the GPS antenna, the multi-information display unit, the navigation switch panel, the HandsFreeLink control unit, the rearview camera, and the roof antenna (RBDS-TMC).
Function Diagram
GA-Net Bus Configuration
The GA-Net bus passes control commands throughout audio, navigation, mult-information display unit, tuner unit, XM receiver, and HFL components. Because the entire bus is interconnected between components, an open or short in the GA-Net bus harness may cause any or all of these functions to become inoperative.
Vehicle Speed Pulse
The vehicle speed pulse is sent by the PCM. The PCM receives a signal from the output shaft (countershaft) speed sensor, then processes the signal and transmits it to the speedometer and other systems.
Yaw Rate Sensor
The yaw rate sensor (located in the audio-navigation unit) detects the direction change (angular speed) of the vehicle. The sensor is an oscillation gyro built into the audio-navigation unit.
Sensor Element Structure
The sensor element is shaped like a tuning fork, and it consists of the piezoelectric parts, the metal block, and the support pin. There are four piezoelectric parts: one to drive the oscillators, one to monitor and maintain the oscillation at a regular frequency, and two to detect angular velocity. The two oscillators, which have a 90-degree twist in the center, are connected at the bottom by the metal block and supported by the support pin. A detection piezoelectric part is attached to the top of each oscillator. The driving piezoelectric part is attached to the bottom of one oscillator, and the monitoring piezoelectric part is attached to the bottom of the other oscillator.
Oscillation Gyro Principles
The piezoelectric parts have electric/mechanical transfer characteristics. They bend vertically when voltage is applied to both sides of the parts, and voltage is generated between both sides of the piezoelectric parts when they are bent by an external force. The oscillation gyro functions by utilizing this characteristic of the piezoelectric parts and Coriolis force. (Coriolis force deflects moving objects as a result of the earth's rotation.) In the oscillation gyro, this force moves the sensor element when angular velocity is applied.
Operation
1. The driving piezoelectric part oscillates the oscillator by repeatedly bending and returning when an AC voltage of 6 kHz is applied to the part. The monitoring-side oscillator resonates because it is connected to the driving-side oscillator by the metal block.
2. The monitoring piezoelectric part bends in proportion to the oscillation and outputs voltage (the monitor signal). The navigation unit control circuit controls the drive signal to stabilize the monitor signal.
3. When the vehicle is stopped, the detecting piezoelectric parts oscillate right and left with the oscillators, but no signal is output because the parts are not bent (no angular force).
4. When the vehicle turns to the right, the sensor element moves in a circular motion with the right oscillator bending forward and the left oscillator bending rearward. The amount of forward/rearward bend varies according to the angular velocity of the vehicle.
5. The detecting piezoelectric parts output voltage (the yaw rate signal) according to the amount of bend. The amount of vehicle direction change is determined by measuring this voltage.
Global Positioning System (GPS)
The global positioning system (GPS) enables the navigation system to determine the current position of the vehicle by using the signals transmitted from the satellites in orbit around the earth. The satellites transmit the satellite identification signal, orbit information, transmission time signal, and other information. When the GPS receiver receives a signal from four or more satellites simultaneously, it calculates the current position of the vehicle based on the distance to each satellite and the satellite's position in its respective orbit.
Position Detection Image with GPS Satellite
Precision of GPS
The precision of the GPS varies according to the number of satellites from which signals are received and the view of the sky. The accuracy is indicated by the color of the GPS icon shown on the display.
| GPS Icon Color | Number of Satellites | Condition | Description |
|---|---|---|---|
| No GPS icon shown | None | Faulty reception | The GPS cannot be utilized due to a faulty GPS receiver, open in the wire, or other fault or interference. |
| 2 or less | Impossible to detect vehicle position | GPS function is normal. The satellite signals received by the GPS are too few to detect the vehicle position. | |
| White GPS icon shown | 3 | Vehicle position detectable in 2 dimensions | The longitude and latitude of the vehicle position can be detected (less precise than detection in three dimensions). |
| Green GPS icon shown | 4 or more | Vehicle position detectable in 3 dimensions (elevation displayed) | The longitude, latitude and the altitude of the vehicle position can be detected (more precise than detection in two dimensions). |
GPS Antenna
The GPS antenna amplifies and transmits the signals received from the satellites to the GPS receiver.
GPS Receiver and Clock
The GPS receiver is built into the audio-navigation unit. It calculates the vehicle position by receiving the signal from the GPS antenna. The current time, vehicle position and signal reception condition is transmitted from the GPS receiver to the audio-navigation unit to adjust vehicle position and the clock in the multi-information display unit.
Radio Data System-Traffic Message Channel (RBDS-TMC)/Radio Broadcast Data System -Traffic Message Channel (RBDS-TMC)
The Radio Broadcast Data System -Traffic Message Channel (RBDS-TMC) is a broadcast for delivering traffic and travel information to the driver. The RBDS-TMC data is typically coded using the 57 kHz ±3 kHz subcarrier on FM broadcast.
The RBDS-TMC system uses a decoder in the audio-navigation unit to decode the traffic information data. It is integrated directly into a navigation system.
The traffic information is displayed with the navigation route guidance. It is used to avoid traffic jams and accidents (see the Navigation System Manual for more information).
Audio-Navigation Unit Functions
The audio-navigation unit calculates the vehicle position and guides you to the destination. The unit performs map matching correction, GPS correction, and distance tuning. It also controls the menu functions and the HDD, and interprets voice commands. With control of all these items, the audio-navigation unit makes the navigation picture signal, then it transmits the signal to the multi-information display unit.
Calculation of Vehicle Position
The audio-navigation unit calculates the vehicle position (the driving direction and the current position) by receiving the directional change signals from the yaw rate sensor and the travel distance signals from vehicle speed pulse (VSP) of the PCM.
Map Matching Tuning
The map matching tuning is accomplished by indicating the vehicle position on the roads on the map. The map data transmitted from the HDD is checked against the vehicle position data, and the vehicle position is indicated on the nearest road. Map matching tuning does not occur when the vehicle travels on a road not shown on the map, or when the vehicle position is far away from a road on the map.
GPS Tuning
The GPS tuning is accomplished by indicating the vehicle position as the GPS's vehicle position. The audio-navigation unit compares its calculated vehicle position data with the GPS vehicle position data. If there is large difference between the two, the indicated vehicle position is adjusted to the GPS vehicle position.
Distance Tuning
The distance tuning reduces the difference between the travel distance signal from the VSP and the distance data on the map. The audio-navigation unit compares its calculated vehicle position data with the GPS vehicle position data. The audio-navigation unit then decreases the tuning value when the vehicle position is always ahead of the GPS vehicle position, and it increases the tuning value when the vehicle position is always behind the GPS vehicle position.
Audio Guidance
The audio-navigation unit transmits audio driving instructions before entering an intersection or passing a junction. The audio instructions come through the stereo amplifier to the front speaker.
Muting Signal Logic
The audio muting logic is orchestrated by the audio-navigation unit. The audio-navigation unit determines what audio source has priority to use the speakers.
The priority of the audio sources is as follows:
HFL has the highest priority, followed by navigation, and finally the radio/CD-DVD player. The priority is passed by HFL to the audio-navigation unit by GA-Net.
The audio-navigation unit temporarily disables the voice control buttons, but allows guidance to be heard. In addition, the audio-navigation unit suppresses the output from the audio system, the tuner unit, the XM receiver, the HandsFreeLink control unit (Bluetooth audio), or other audio accessories.
When the navigation system sends out a voice route guidance command, the front speaker (s) sound is reduced, and the navigation voice is heard in the front speaker (s).
When the navigation voice control system is in use, all of the speakers are muted, and the navigation voice prompts are heard from the front speaker (s).
Solar Angle
The climate control unit uses the sun's angle, along with the sunlight sensor to control the driver/passenger A/C air flow.
Off Road Tracking (bread-crumbs)
Off road tracking dots that can be followed on the map to retrace your route back to a mapped (digitized) road.
Clock and Time Zone
The clock set up allows you to set daylight savings time, auto time zone and time adjustment.
Control Interface
Multi-information Display Unit
The multi-information display unit uses a liquid crystal display (LCD). The LCD is an 8 inch diagonal, thin film transistor (TFT), strip type with 384, 000 pixels. The color film and fluorescent light are laid out on the back of the liquid crystal film.
Audio-Navigation Unit
The audio-navigation unit includes the 5.8 inch touch screen that is used to input audio commands.
Navigation Switch Panel
- The navigation hard buttons and the interface dial are used to input navigation commands.
- The display mode button switches the display between Day mode, Night mode, and off.NOTE: When you activate this button, the display auto dimming is turned off.
- The AUDIO button displays the audio system information.
TALK Button
Activates the voice control system in the audio-navigation unit to accept voice commands.
HANG-UP/BACK Button
Returns the display to the previous screen (similar function as the CANCEL button), or is used to end a call.
PICK-UP Button
This button is used to answer incoming calls or to make outgoing calls. You can also go directly to the Cellular Phone screen by pressing this button.
HFL-Navigation Voice Control Switch
The navigation voice control switch is combined with the HFL switch. navigation TALK/BACK commands are sent to the audio-navigation unit via the HandsFreeLink control unit.
Front HFL-Navigation-ANC Microphone
Receives voice commands and transmits them to the audio-navigation unit or the HandsFreeLink control unit. The microphone unit consist of two microphones. One microphone is combined with the front active noise cancellation microphone. The microphones detects the driver's voice and passenger's voice separately.