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- VW Tiguan 2.0 DBGC 2018, VW Touran 1.6 BSE 2008
Глоссарий автомобильных электрических сигналов
| Amplitude: The voltage level of a signal above or below zero volts. The signal in the example at left has an amplitude of 2V. |
Analog Signal: An electrical signal whose amplitude can be measured at an infinite number of positions along the waveform. | |
Digital Signal: An electrical signal with an instantaneous change in amplitude (called a pulse) from low to high and high to low. Since the change in state is instantaneous, the amplitude can only be measured in two positions, high or low. The pulse shown at left is a positive pulse, because the normal state of the waveform is low and the pulse goes high. However, with a negative pulse, the normal state of the waveform is high and the pulse goes low. | |
Sine Wave: An analog signal where the current reverses direction at regular intervals, also called alternating current (AC). In automotive applications, sine waves are produced by either the alternator (unrectified) or inductive sensors (such as the RPM sensor). | |
Square Wave: A digital signal that continuously alternates between on and off. A true square wave is on and off for an equal length of time. A variation of the square wave is the rectangular wave, which is on and off for an unequal length of time, but is usually still called a square wave. | |
Period: The time required for a signal to complete one cycle. It can be measured in seconds (s), milliseconds (ms) or microseconds (μs). | |
Frequency: The number of times a signal repeats in one second (cycles per second), measured in Hertz (Hz). The example at left has a frequency of 3Hz. The frequency of a signal can be fixed or variable. Any sensor that measures a rotating component (such as the camshaft position sensor) generates a variable frequency signal. | |
Pulse Width: The time that a signal remains on during one period. It can be measured in seconds (s), milliseconds (ms) or microseconds (μs). Pulse width is similar to duty cycle, except duty cycle is measured in percent (%) instead of time, see duty cycle. | |
Duty Cycle: The percentage (%) of time a signal remains on during one period. Duty cycle is similar to pulse width, except pulse width is measured in time instead of percent, see pulse width. Duty cycle is calculated by dividing the pulse width (s, ms or μs) by the period (s, ms or μs), and then multiplying the result by 100. For example, a signal with a 50 ms pulse width and a 100 ms period has a 50% duty cycle. | |
Pulse Width Modulation (PWM): A signal that varies the pulse width of a signal. It is also called variable duty cycle. | |
Waveform: The graphic representation of an electrical signal as displayed on an oscilloscope screen. While waveform is the preferred name, it is also called a trace or a pattern. | |
Leading Edge: When viewing a waveform, the change in vertical height at the beginning of the signal. It is also called the rising edge or positive edge. | |
Trailing Edge: When viewing a waveform, the decrease in vertical height at the end of a signal. It is also called the falling edge or negative edge. | |
Networked Signals: A signal that consists of a sequence of coded pulses (sequence of event signals) used to broadcast data between a network of control modules. The CAN and LIN busses use networked signals. | |
Sawtooth Wave: A signal in which the amplitude instantaneously rises and then ramps down, giving the appearance of a sawtooth. Sawtooth signals are used in the hood switch circuit in late model Volkswagens. |
Note: The following lists provide general information on sensors, actuators and their signals. They are not
intended to account for every sensor and actuator in the vehicle, and applications include, but are not limited
to, those listed.
Analyzing Automotive Electrical Signals
Three factors affect automotive signals:
Amplitude
Frequency
Sequence of Events
Amplitude: On/Off, analog, pulse width modulated and duty cycle signals are characterized by the rate
of change in amplitude or the time the signal remains in the high or low state. When used in sensor
applications, the amplitude or pulse width (duty cycle) of a signal is varied to supply data to a control
module. Thermistors, potentiometers, Hall switches and pressure sensors are commonly used in this
way.
Frequency: Square and sine wave signals are examples of signals that are characterized by changes in
frequency (the number of times they repeat themselves per second). In sensor applications, Hall and
inductive sensors are used to provide rotational data such as RPM, CMP and wheel speed sensors.
Sequence of Events: Sequence of event signals are characterized by a series of pulses that can be
compared to messages sent by Morse code. By altering the sequence of the pulses, an almost infinite
number of coded messages can be quickly and accurately transmitted between different control modules.
Networked signals that are used by the CAN and LIN buses are examples of sequence of event signals.
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