Multi Information Display (MID) Audio System: Notes

As stated the low line audio system is based around the Multi Information Display unit. The system comprises:

• MID unit
• Cassette unit, mini disc unit or CD unit
• CD auto changer (optional)
• Radio unit
• Telephone (optional)
• Digital signal processor (DSP-optional)
• Speakers
• Amplifier (optional).

All the low line systems use the MID unit as a control panel for the whole system. The MID is located in the center of the fascia. The MID unit incorporates a two line LCD display with controls that allow the user to control the radio, cassette player, CD player/auto changer, trip computer, telephone and amplifier (DSP). Depending upon the customers selection of options the MID has four different front panels to allow for control of the different options. These are as follows:

• DSP and Phone
• Phone No DSP
• DSP No Phone
• No DSP No Phone.
  Fig 1: Identifying Multi Information Display (MID) Audio System

  Courtesy of LAND ROVER NORTH AMERICA, INC.

Six rocker buttons are located below the MID. Each rocker button has a pressure point on the left and the right. There are effectively 12 switching levels for this button unit. Arranged to the right next to the display are the buttons for the selection of AUDIO, DSP, TELEPHONE, CLOCK and BC (on-board computer). The AUDIO button has one pressure point each on the left and right. In the case of versions with DSP, the left pressure point is assigned to AUDIO and the right to DSP. The buttons for TELEPHONE with the handset symbol and BC with the CLOCK are laid out as rocker buttons. To the left next to the display is a rocker button for the search and scan functions. The button for the manual search function is inserted in the center of this rocker button. A rotary increment sensor is used to control AUDIO and the hands-free speaking feature of the telephone volume, as well as the ON / OFF switch for the AUDIO system. This is carried out by means of an increment sensor with an integrated push switch. The rotary controller has 36 incremental steps of 10° each.

The MID lighting is controlled by a photo-transistor sensor. The brightness of the lighting can also be influenced manually by the instrument lighting dimmer. When the vehicle lighting is switched off, the display brightness is governed exclusively via the sensor, this gives a daytime minimum brightness of 60 % of the control range is defined. When the instrument dimmer is switched on, the controlling range from the daytime minimum brightness onward is expanded by the dimension of the dimmer position. The dimmer position is taken from the "dimming" message. With "light off" the LED function indications are activated at the maximum level and with "light on" with the value of the day/night threshold, irrespective of the photo-transistor.

Control signals for the MID are sent along the I-bus.