What Is a Data Recorder?
A Data Recorder is a device used to record various physical quantities over a long period of time. The recorded data is analyzed and processed as necessary before being used.
The first type of data recorder is a voice or music recorder. Once called tape recorders, these devices recorded analog signals on magnetic tape. As sound began to be processed digitally, recording media changed from DATs and MDs to memory cards and hard disks. Nevertheless, the fundamentals of Data Recorders remain the same.
Industrial Data Recorders records a wide range of data, including sound and vibration, pressure, temperature/humidity, acceleration, stress, position information, voltage/current, and even digital data on a network.
Instruments that can record multiple physical quantities at the same time and understand how they relate to each other are also commonly used. The number of signals that can be recorded simultaneously is called a channel, and a four- or eight-channel configuration is common.
Some manufacturers refer to Data Recorders as Data Loggers. Strictly speaking, a logger records digital data, but since most recorders today handle digital data, it is safe to assume that the two refer to the same thing.
Uses of Data Recorders
Data Recorders are used to record data output from an observation object via sensors and transducers over a long period of time.
There are various uses for data recorders, but some specific examples are listed below:
- To record the operating status of equipment in a production department. The data to be recorded include temperature, pressure, voltage, current, pressure, and other factors that have a significant impact on the process. These recorded data are used as important information for product quality assurance.
- In the field of sound and vibration, data recorded at a concert hall site may be used for detailed frequency analysis as part of acoustic evaluation.
- As for the use of digital data recording, data flowing over a network is used to investigate the cause of line problems, check the operation of digital equipment, and analyze malfunctions.
- What we call an Event Data Recorder is also a type of Data Recorder. It is mainly used to record traffic accidents and other incidents. Most automobiles on the market today are equipped with an event data recorder in the airbag computer, which records the vehicle speed, magnitude of impact, engine speed, throttle position, and yaw rate at the time of the accident, as well as driving maneuvers such as braking and acceleration. This is a powerful tool for investigating the cause of accidents and taking countermeasures.
- Voice recorders and flight recorders are also used to investigate the cause of aircraft accidents and are also a type of Data Recorder.
Principle of Data Recorder
Data Recorders basically record the voltage applied to the input terminals. Therefore, any physical quantity must be converted to a voltage by a sensor or transducer and then input to the Data Recorder.
Examples of sensors/transducers include microphones for sound, accelerometers for vibration/shock, strainmeters for stress, GPS receivers for location information, current probes for current, etc. Other sensors used include thermometers, hygrometers, pressure sensors, displacement sensors, speed sensors, light sensors, and magnetic field sensors.
Since Data Recorders handle signals from a wide variety of sensors, they are equipped with amplifiers and attenuators to amplify or attenuate the signals to appropriate levels before inputting them into the A/D converters.
The memory device can be an external memory device such as an SD card, an internal hard disk, etc. When data is transferred directly to a PC via a USB interface, the PC itself can be considered the memory device.
In the case of a multi-channel Data Recorder, the input terminals of each channel are connected to an isolation amplifier. Therefore, the input terminals of each channel are isolated from each other.
Each sensor connected to the input terminals does not necessarily have a common potential. Therefore, the moment they are connected to the Data Recorder, a loop current may flow, and in the worst case, the sensors may be damaged. To prevent such accidents, channel-to-channel isolation is essential.