The Scanner and Sub-Scanners consists of a collection of thousands of instruments designed to gather information about the environment outside a TARDIS. Chief among these is the visual signal, which is displayed on the Scanner Screen found in any of the Control Rooms. In most cases the image translator can enhance the available light so that even in darkness a colour image can be produced. If the capsule is surrounded by total darkness the scanner can be switched to infra-red or a traditional searchlight can be activated. The visual signal has a maximum magnification of 200 power. It can even be pre-set to visually locate specific items, but the operator should be aware that the Visual Orientation Circuits can be confused by heavy fog. The Scanner can also be refocused with some difficulty, to show the interior of various rooms within the TARDIS. A TARDIS memory bank automatically records audio and visual images presented on the Scanner.
Other sensors built into the Scanner (but on a separate circuit from the visual signal) include audio circuits (to relay sound), a gravity dilation meter, seismic sensor, warp oscilloscope, movement detectors, magnetic field sensors, magnetic compass, metal detectors, radiation detectors, transmat beam detectors, absence detectors, a hyperspatial-mass sensor, thermal search circuit, infra-red sensors, low-light sensors, terrain mappers, and an altimeter. The radiation detectors can be adjusted to measure the radiation count for an entire planet. There is a space radar that can detect ships in orbit of the current planet. Active Sensors use detector beams and have a range of about 100 miles.
When some types of 5-dimensional Scanning Modes are enabled, the Time Rotor will rotate within the Column, presenting the operator with and approximation of the ship's current space-time coordinates. The passive Time-Line Flux Adjuster detects some types of temporal anomalies and has a range of about 60 million light-years (though it must be told what to look for and where to search).
The TARDIS Scanner is keyed to its operator's brain pattern and can track his biodata movements over at least a mile or two. Some operators have preprogrammed a switch that will instantly display the location of their symbiotically linked Time Lord. The Scanner can also be reconfigured to focus on other psionic resonances.
It is standard operating procedure to check the display dials for oxygen, atmospheric pressure, temperature, and radiation before leaving the ship. The Atmosphere Monitoring Subsystem's Atmosphere Analysers can help identify a G-Type environment (aka Gallifrey-like) and is hooked to a dial that will indicate if the air quality will be fatal to humanoids after a few hours of exposure. There is a display light on the console that warns the crew if the outside environment is dangerous. The TARDIS has a Seismic Scanner that predicts local volcanic stability over short periods of time. The materialization indicator light will continue to flash and and buzz if the capsule has arrived on a moving vessel. Some of the sensors trigger alarms that alert the crew, such as if a TARDIS is shifted into Warp Drive, or when the doors are opened and the exterior environment is extremely hostile. Some forms of danger can be detected up to 20,000,000 light years away.
The Scanner's Image Translator (see picture), located in the Master Control Console, interprets the absolute positive value of the coordinates to create the visual image. The scanner has an interstitial beam synthesizer that is essential to its operation. Data collected by the Scanner (especially the visual signal) is usually displayed in 3D on the full-colour Scanner Screen, which is usually located on the wall of the Control Room. Most screens offer full colour but some are only capable of black and white. Different types of scans can be made to appear on the scanner depending on which band the operator selects. Band 6 is good for observing neutron stars.[/ttv] The scanner can collect data from aerial scans and use it to update pre-existing maps in the data banks. It can even create symbolic displays to represent 4-dimensional phenomenon such as time loops. This screen can also be used to display data from the Control Console.[/ttv] Images and data presented on the Scanner Screen can be manipulated with a light pen. Many versions of the Scanner Screen have shutters that close when the scanner has been deactivated.
There are other, less popular, ways to view information from the Scanner. An entire wall of the Control Room can be converted into a massive screen. A Trans-Temporal Projector can create a hologram-like image with accompanying sound that allows the operator and the console to appear (from the operator's point of view) to be surrounded by the outside environment.
Shortly after de-materialization and right before re-materialization the Scanner Screen can show an image of the appropriate planet. If the Scanner is used while travelling in the Space-Time Vortex, a 3D representation of the Vortex Wormhole will appear on the screen. A red tint is often used for travelling forwards in time and a blue tint usually indicates travel into the relative past. Many people find seeing all of reality spinning by to be a disturbing experience. For this reason the scanner screen is often deactivated during vortex travel.
If the Scanner hasn't been used in a long time the image will be vague and hazy as the system warms up. Strong exterior magnetic fields can interfere with the Scanner by disrupting the flow of Artron Energy. If a TARDIS is transported into Exo-Space (E-Space) it will require a local Image Translator to properly interpret the new negative coordinates. Without it the Scanner will only show positive coordinate images from Normal Space (N-Space). The Scanner is calibrated according to continuous constant time. If there is no flow of time outside a TARDIS then the Scanner Screen will show only gibberish. If the TARDIS is severely damaged the self-repair circuits might require so much power that the Scanner will not operate. Any faults in the interstitial beam synthesiser which prevent the scanner's operation. Some parts of the Scanner Mechanism, such as circuit board K17, can only be replaced by leaving the TARDIS and accessing the scanner from outside the ship.
The following color code is used:
- Black: For information from the TV Series, including Dimensions in Time, and 1996 TV Movie.
- Blue: For information from the Novels and Audios including Target, Virgin, BCC, and Big Finish.
- Green: For information from 'licensed' reference sources such as the Technical Manual, Doctor Who Magazine, and the Role Playing Games.
- Red: For information from unofficial sources -The Faction Paradox series, behind the scenes interviews, author's speculation, and popular fan belief.
The TARDIS Technical Index is copyright Will B Swift.