Model: MC-1-M (2U)
Doc. Ref. no. : - m05/om/101
Issue no. 14
Page 71 of 103
User’s Manual
IRIG-B DCLS time codes (IRIG-B 00x) and IRIG-B AM time codes (IRIG-B 12x) are always generated
simultaneously. Using telnet if we configure the IRIG-B output for IEEE 1344 protocol than both IRIG-
B00x and IRIG-B12x gives IEEE 1344 protocol CF bits output. Similarly, we can configure IRIG-B output
for UTC time/ Local time effect of configuration will be on both IRIG-B 00x and IRIG-B 12x.To configure
IRIG-B please refer Telnet Appendix.
•
Configuration of IRIG-B time code using any other Ethernet port except
Ethernet port NTP1will not reflect on IRIG-B output port.
•
All the IRIG-B time code will have same configuration as shown in Telnet
menu of Ethernet port NTP1.
11.2.2.7
Connecting IRIG-B Time Code:
GPS Master Clock model MC-1-M time code outputs are designed to handle multiple loads. The output
terminals of IRIG-B time code are BNC type. Input devices have different type of IRIG-B time code input
connectors. Co-axial cables can be connected directly from model MC-1-M to end device. To adapt
twisted pair cabling with model MC-1-M, use BNC Breakout or other similar adapter.
NOTE: In case of shielded twisted pair cabling do not connect shielding of cable to model MC-1-M,
ground it at the receiver end.
Following factors come into effect by transmitting time code to multiple/single devices over long distance,
1) Resistive loss in cabling
2) Electromagnetic interference
3) Propagation delay
4) Input impedance of end device
1) Resistive loss in cabling: -Resistive loss in cabling affects the available output voltage at the input
device. Wire has a certain resistivity associated with it that is determined by its metallic composition,
and resistance determined by the diameter and length.
2) Electromagnetic interference: -Electromagnetic interference (EMI) includes a variety of sources of
interfering signals, ranging from dc and low-frequency (50 or 60 Hz) all the way up through the RF
(Radio Frequency) and microwave region. All of these signals have the potential to interfere in one
way or another with the accurate and reliable distribution of timing signals.
3) Propagation Delay: -Electromagnetic waves travel at the speed of light (C) in free space/vacuum
and a fraction of that speed through cabling which cause delay in IRIG-B Time code output.
4) Input impedance of end device: -By connecting, multiple devices to GPS Master Clock MC-1-M
results in decrease of drive voltage due to increase in load current. In many cases, model MC-1-M
time code output are “fanned out” to a no of devices. The exact no of possible load can be determine
from input impedance of each connected devices. To know input impedance of connected devices
please refer specific device manual.
