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Acam Mess-electronic - Solutions in Time
The use of
Time offers fantastic possibilities to solve difficult physical measurement
tasks elegantly.
Nearly all physical units like position, weight,
pressure and temperature can be captured by using time measurement.
Based on digital TDC-Technology (TDC - Time-to-Digital Converter),
acam's products and development services enables the potential of time
measurement from nanseconds down to the pico second range in solutions for
otherwise difficult measurement tasks.
A range of standard solutions,
based on TDC technology is available.
Acam TDCs find applications in
consumer, automotive, industry and scientific applications.
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TDCs were first developed for scientific
purposes using a combination of time-to-analog (TAC) and analog-to-digital
(ADC) converter. The sophisticated design of the TAC made these solutions
inattractive and uneconomic outside the research environment.
Acam has
developed fully digital time-to-digital converters on a single chip.
The high precision of the time measurement - down to 14 ps - in
combination with the large dynamic range (up to 30 Bit) as well as high
stability over temperature and supply voltage makes them feasible for use in
real-world' industrial applications.
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Measuring strain gauges is one of
the big challenges for sensor technology
The Picostrain measuring
principle is breaking new grounds. The ratio of the resistors is ascribed to a
time interval measurement, not to a voltage difference like in Wheatstone
bridges.
The sensor's resistors together with a capacitor act as
low-pass filters. The capacitor, charged to Vcc, is discharged through the
sensor's resistors.
The discharge time to trigger level (selectable) is
precisely measured by a TDC (Time-to-Digital Converter).
By using this
technique the resistors can be measured with a precision in the parts per
billion range.
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The Picoturn sensor is made of a simple coil with a ferrite
core. Together with a resistor this forms an R-L network, the time constant of
which is measured by a TDC.
Placing a vane of a compressor wheel in
front of the coil will change the time constant of the R-L network by the
appearance of eddy currents.
A DSP-unit following the TDC measurement
unit processes the time data and calculates the rotational speed.
The
time measurement is done with very high precision. The resolution is about 125
ps. The time constant of the R-L network can be very small, allowing high
sampling rates in the range of 1 to 3 million samples per second. |
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The Picocap measuring principle
shows a new approach to capacitance measurement. For this purpose the sense
capacitor and a reference capacitor are connected to a resistor, forming a
low-pass filter.
Practically there is no limit for the capacitor value.
Sensors from nearly 0 fF up to tens of nF can be measured. The Picocap devices
also support differential sensors with inside linearisation.
The
capacitors are charged to the supply voltage and then discharged through the
resistor. The discharge time down to an arbitrary trigger level is measured
with ultra-high precision using a TDC (Time-to-Digital Converter). |
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