Filter
Top Products
Reference Manual
00809-0100-4444, Rev AC
Section 7: Digital Signal Processing
January 2015
129
Digital Signal Processing
Section 7 Digital Signal Processing
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 129
Safety messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 129
Process noise profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 130
High process noise diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 130
Optimizing flow reading in noisy applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 131
Explanation of signal processing algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 134
7.1 Introduction
Magmeters are used in applications that can create noisy flow readings. The Rosemount
8732EM has the capability to deal with difficult applications that have previously manifested
themselves in a noisy output signal. In addition to selecting a higher coil drive frequency (37 Hz
vs. 5 Hz) to isolate the flow signal from the process noise, the 8732EM microprocessor has
digital signal processing that is capable of rejecting the noise specific to the application. This
section explains the different types of process noise, provides instructions for optimizing the
flow reading in noisy applications, and provides a detailed description of the digital signal
processing functionality.
7.2 Safety messages
Instructions and procedures in this section may require special precautions to ensure the safety
of the personnel performing the operations. Read the following safety messages before
performing any operation described in this section.
Explosions could result in death or serious injury.
Verify the operating atmosphere of the sensor and transmitter is consistent with the
appropriate hazardous locations certifications.
Do not remove the transmitter cover in explosive atmospheres when the circuit is live.
Before connecting a HART-based communicator in an explosive atmosphere, make
sure the instruments in the loop are installed in accordance with intrinsically safe or
non-incendive field wiring practices.
Both transmitter covers must be fully engaged to meet explosion-proof requirements.