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selected Port must be configured for IRIG-B via the 70 Series Configurator software utility.
To connect the IRIG-B master to a Port (Figure 3, pg. 22):
- Connect the IRIG-B signal to terminals 2 and 4.
- Connect the IRIG-B signal common to terminal 6.
- Terminal 5 provides a connection to earth ground via a 100Ω resistor for
shielding.
5.7.11 Modulated IRIG-B
The M87x may be used with Modulated IRIG-B systems, provided that the external
Modulated IRIG-B adapter is used (P/N M870-MODIRIGBCV)
5.7.12 Setup Instructions for Use of the M87x Modulated IRIG-B Converter (Sine
Wave, Amplitude Modulated, IRIG-B master)
The M87x Modulated IRIG-B Converter is a demodulating adapter used with the M87x
Host module for connection from an IRIG-B master that uses an amplitude-modulated sine
wave, and meets one of the input formats specified below. The setup required in order to
use the M87x Modulated IRIG-B Converter is described by the following information, which
includes the Converter specifications:
Input impedance:
Input Format :
IRIG-B120, B123,
1kHz modulated sine wave, amplitude 3Vpp – 10Vpp,
modulation ratio 3:1
Power:
Time skew:
Use:
Plug Converter into M87x serial port (P2, P3, or P4).
Fasten Converter to the M87x by tightening 2 hold down screws.
The recommended torque rating is 2.2 In-Lbs, 0.25 N-m.
Connect BNC to clock source.
Configuration:
On the "Port Assignment" page (previously "serial port" tab) set the
appropriate port to IRIG-B.
On the IRIG-B page set the Absolute Time Offset to 620 μsec. (This
offset value includes the 600 μsec time skew attributed to the
converter). The number used for the Absolute Time Offset may need
to be increased, depending on time skew contributed by clock source
and cable lengths. The remaining items on the IRIG-B page can
initially be left at the default values. If there are problems with
acquiring synchronization with the IRIG-B source, turning on the
debug messages may help in diagnosing the problem. (Refer to
section 3.1.1a; Debug messages are turned on when service port P1
is running in logging mode). Depending on the installation it may be
necessary to relax some of the qualifying parameters to achieve
ML0021
>10KΩ
Supplied by M87x serial port
600 μsec.
August 15, 2018
78
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Troubleshooting
