Car Communications System

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Requirement Spec.

Background: Most people who have a car alarm take a while to respond to it, since they might not hear it or might be far away. Our system will provide a two-way communication system for the owner, e.g., when the alarm goes off the car would notify owner, and owner can access the system remotely. With this system, the vehicle’s owner can respond to an alarm immediately, thus cutting down on the time a thief would have to break into the car. This will be a cost effective solution that is user friendly and efficient.

The Deliverables:

A working prototype of the system. It will take a signal (a pseudo car alarm’s trigger) and work from that for testing purposes.

The following manufacturing related artwork and documentation:
Wiring plan
Bill of materials
A report detailing the manufacturing test plan and associated analysis
Parts list, assembly drawings, and assembly instructions

User’s Manual

System specification, including the design concept, block diagram, functional description of the blocks, a system description, and any analysis done during system design.

Schematic diagrams and circuit descriptions

Special Restrictions:

Our system must be compatible with the vast majority (if not all) of the car alarm systems on the market.

The system must be capable of running off the car’s 12V battery.

The system must be small and not obtrusive to the car’s functions.

Principle of Operation: To install the system, the user must wire it up to the car’s battery and to the existing alarm’s trigger signal. One should be able to place this system anywhere in the car; inside the car under the dash is the recommended location. Once installed, the user will call the system for the first time to do the startup configuration, such as to choose a password, choose a number for the system to call, and so forth. Once this is done, the user will only need to interact with the system if the alarm has been activated or if the user wishes to use the extra features. If the alarm goes off, the user will be called immediately and will be able to respond. To use the other features, the user can simply call the car and, using a touch-tone phone, input the desired options via the number pad.

User Interface: The user interface (to owner) is based on accessing of any phone. To access the system’s functions, the user will just need to call the provided number. The system will be installed in conjunction with an existing car alarm, so the trigger signal from that alarm will be fed into our addition. The user will also have to connect our system to the car’s electrical system so it can access the various electrical functions. Our addition will also need power from the car’s battery, and will have a power input for that.

Input: The system will have several inputs. To get power, the system will feed from the car’s 12 volt battery. In order to realize that the alarm has been tripped, a signal from the already existing car alarm will be used as an input to our system. When that signal goes high, the alarm has been activated. The system will also need to change some of the car’s states, such as headlights, door locks, and so forth. So our system will have signals that will connect directly into the car’s systems. Our system will also need to receive calls via a cellular modem of some sort. To interact with the user, the system will know how to interpret touch tone signals from the phone’s number pad.

Output: In the case that the alarm is triggered, the output of the system will be a phone call to the predefined number stored in the system’s memory. The user, (i.e., owner) can call the system and select one of the following options:

Lock/unlock the doors: If the car has power door locks, the system will be interfaced with the car’s electrical systems and will send a signal through the central locking system to lock and unlock the doors at the user’s request. If the car does not have power door locks, this feature will be unavailable.

Start the engine: Similar to a remote starter, our system will be interfaced with the car’s starter and be able to send a signal to it to start the engine from a call.

Turn on/off the headlights: The system can be programmed to call the user if the headlights have been on for a certain amount of time. The system will be interfaced with all the electrical system, and therefore be able to discern (via a signal) whether the headlights are on or not and toggle their state by changing the signal to high or low.

Activate the car’s horn: Upon user request, the system will send a signal through the car’s electrical system to the car horn to sound the horn.

The User’s Manual: This is an addition to an existing car alarm that will notify a user immediately if the alarm has been triggered, and will accept calls from the user to perform the various tasks listed above. The system has two modes: the car calling the user and the user calling the car. The first mode is autonomous and will not occur unless the car’s alarm is triggered. For the user to use the second mode, the instructions are below:

Call the car via any touch tone phone with the system’s number provided.

The system will then prompt you for a password which will be 8 digits for high security; enter the password using the keypad.

After a correct password is entered, the car will begin to vocally list off the functions that it is capable of:

Press 1 to start the engine.
Press 2 to unlock/lock the car doors (on cars with power locks only)
Press 3 to turn on/off the headlights
Press 4 to enter the system menu

Press 1 to change the primary number
Press 2 to change the secondary number
Press 3 to change the tertiary number
Press 4 to change the system password

Once the user has selected which function he/she wants to perform, the system performs the function on the car and the user is free to hang up.

Acceptance Test: Since there are two modes of operation, each one will have a different testing procedure.

To test if the system notifies the user if the alarm goes off, we will connect a switch (a pseudo car alarm) to the system’s alarm input, which will act as the car alarm’s signal. We will then set the switch high (meaning the alarm is going off) and see if the system calls a predefined telephone number.

To test if the user is able to call the system, we will call the system using our own phones and check to make sure the system responds accordingly. To test the various functions, we will have signals coming from the system (for starting the engine, locking the doors, and turning on the headlights). Those signals will be tested after we call the system and we will make sure that the appropriate signals go high, meaning the system has successfully activated the correct function.

Acceptance Test for User Notification: To fully test this mode of the car, we will pulse the car alarm signal high for various amounts of time and with different levels of current to ensure compatibility with most of the car alarms on the market.

Acceptance Test for User Input: To test if the system is able to receive calls and act correctly on the user’s input, the system will be called from a cell phone and a regular touch tone phone to ensure compatibility. Rigorous testing will ensure that the system acts correctly on the keypad commands received from the user.

Production Cost: The parts we plan to include are a cellular modem that is capable of calling to any phone. A voice system is also needed, as well as a way to interpret the touch tone signals from the keypad. A small amount of storage space will be required to store 3 phone numbers that consist of 10 digits, including area code. A decent car alarm system will cost roughly $100, and our target price for our system will be around $100-$200. We estimate that an initial prototype can be built with less then $500.

Dispute Resolution Mechanism: All disputes will be settled by binding arbitration, with the arbitrator being Professor Moritz, our advisor.