What is the purpose of the Signal Strength Display?
Doppler signals of very low strength are not accepted or processed by the instrument. This feature
assists in rejection of environmental noise and vibration. Use the display to evaluate signal strength in
your application. Strong signals will increase in percentage to a maximum of 100% or greater.
Can I change the length of the sensor cable?
Yes. Technological advances in Greyline Doppler design allow cable lengths up to 500 ft (152 m) with
no loss of signal strength. Extended cable (Greyline Option DXC) should be installed in rigid or flexible
conduit for mechanical protection. Use only Greyline shielded coaxial pair (RG174U) cable. Cable
junctions should be made through a terminal block and housed in a watertight metal junction box
(Greyline Option DJB). BNC coaxial connectors (TV cable type) are not recommended for cable
splices.
Does the DFM 5.0 require periodic recalibration?
No. DFM 5.0 calibration does not drift over time. The solid state sensor has no moving parts to wear and
affect calibration. The Doppler flow technique generates an ultrasonic signal proportional to the velocity
of flow. All Greyline timing/counting circuits use crystal-controlled frequency references to eliminate
any drift in the processing circuitry.
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DFM 5.0 Doppler Flow Meter
