U10C034 MSO User’s Manual v1.4 June 2008
41
This test checks for high voltage levels on the Tip and Ring pins. Hazardous
potential is based on two terminal T-G and R-G AC voltage and two terminal T-G
and R-G DC voltage. The system shall provide a fail indication if the T-G or R-G
AC voltage is greater than 50 volts RMS or the T-G or R-G DC voltage is greater
than 135 volts. This is accomplished by putting the SLIC into the high impedance
disconnected mode. The tip and ring sense inputs are then read to see if a
hazardous potential voltage is present. This test fails if the voltages are greater
than the thresholds stated meaning that a hazardous voltage has been detected.
Foreign Electromotive Force Test (FEMF)
This test checks for high voltage levels on the Tip and Ring pins. FEMF is based
on two terminal T-G and R-G AC voltage and two terminal T-G and R-G DC
voltage. The system shall provide a fail indication if the T-G or R-G AC voltage is
greater than 10 volts or the T-G or R-G DC voltage is greater than 6 volts. This is
accomplished by using the results from the previous hazardous potential test.
This test fails if the voltages are greater than the thresholds stated.
Notes:
In this test, if the T-G or R-G DC voltage is greater than 6 volts, this test will be
failed in normal way, but due to the hardware design, there has tolerance
detected by our SW.
Receiver Off hook Test (ROH)
This test determines if the telephone receiver is in the off hook state. A receiver
off hook is identified by sequentially generating two AC voltages across Tip and
Ring, one at approximately 10 Vrms and one at approximately 5 Vrms. The tip
and ring voltages are measured at each voltage setting to look for a non-linear
relationship. If the second set of voltage readings is less than 85% of the
intended value the test fails. This test differentiates between an off hook
condition and a simple resistive fault.
Tip to Ring Resistive Faults Test
This test checks for resistive faults which are DC resistance faults across Tip and
Ring. The test provides a fail indication if the measured resistance is less than
150 K Ohms.
Tip to Ground Resistive Faults Test
This test checks for resistive faults which are DC resistance faults across Tip and
Ground. The test provides a fail indication if the measured resistance is less than
150 K Ohms.
Ring to Ground Resistive Faults Test
This test checks for resistive faults which are DC resistance faults across Ring
and Ground. The test provides a fail indication if the measured resistance is less
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