Appendix A: Technical Reference
Principles of Operation
SITRANS LR 460 is a long range FMCW (Frequency Modulated Continuous Wave) radar transmitter. Radar level measurement uses the time of flight principle to determine distance to a material surface.
FMCW radar transmits a continuous wave. The frequency of the wave is constantly increasing: this is known as the sweep. By the time the first part of the wave has been reflected off the target and returned to the device, the part of the wave that is just being emitted is at a higher frequency. The difference in frequency between the transmitted and received signals is proportional to time of flight.
Electromagnetic wave propagation is virtually unaffected by temperature or pressure changes, or by changes in the vapor or dust levels inside a vessel.
SITRANS LR 460 consists of an enclosed electronic component coupled to an antenna and process connection. The electronic component generates an electromagnetic signal from 24.2 GHz to 25.2 GHz that is directed to the antenna.
The signal is emitted from the antenna, and the reflected echoes are digitally converted to an echo profile. The profile is analyzed to determine the distance from the material surface to the reference point on the instrument. This distance is used as a basis for the display of material level and output.
Measurement Response
The measurement response (response rate) limits the maximum rate at which the display and output respond to changes in the measurement. Once the real process fill/ empty rate (m/s) is established, a response rate can be selected that is slightly higher than the application rate. The response rate automatically adjusts the filters that affect the output response rate.
There are three preset options: slow, medium, and fast.
Related |
| Response | LOE Timer | Fill Rate | Empty Rate | |
Parameters |
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| Rate | (minutes) | ||
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| 1 | * | slow | 100 | 0.1 m/minute | 0.1 m/minute |
Values | 2 |
| medium | 10 | 1 m/minute | 1 m/minute |
3 |
| fast | 1 | 10 m/minute | 10 m/minute | |
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| |||||
If none of the preset options is satisfactory, the filters can be adjusted individually.
A: Technical Reference
7ML19985JM01 | SITRANS LR 460 – INSTRUCTION MANUAL | Page |
