Novatech Bitronics M87X Series, Manual

Page: 89 / 184

ML0021 August 15, 2018
73
Copyright 2018 Bitronics, LLC
Converter, part number M870-MODIRIGBCV, is necessary when connecting an IRIG-B
signal of Amplitude Modulated format to one of the serial ports, P2, P3, or P4, on the
M87x.
5.7.2c Carrier/Resolution
There are six IRIG Carrier/Resolutions:
0 - No Carrier/Index Count Interval
1 - 100 Hz/10 ms
2 - 1 kHz/1 ms
3 - 10 kHz/0.1 ms
4 - 100 kHz/10 μ s
5 - 1 MHz/1 μ s
Since the M87x does not support the Sine Wave Amplitude Modulated Format
Designation, only the No Carrier/Index Count IRIG Carrier/Resolution is applicable, when
connected to an IRIG-B master using Pulse Width Coded Format. The M87x Modulated
IRIG-B Converter serves as the signal demodulator, essentially converting from sine wave
modulated into pulse width coded format.
5.7.2d Coded Expressions
There are four IRIG Coded Expressions:
0 - BCD, CF, SBS
1 - BCD, CF
2 - BCD
3 - BCD, SBS
The M87x only uses the BCD portion of the expression and as a result can accept any of
the standard IRIG Coded Expressions.
5.7.3 M87x IRIG-B Implementation
The M87x receives the IRIG-B serial pulse code via the serial ports on the Host CPU
module (Section 3.1.1). The IRIG-B signal is decoded by the Host CPU module, and the
resulting IRIG time is compared to the M87x’s time. The M87x processes the time errors
and corrects its local time to coincide with the IRIG time.
5.7.3a M87x IRIG-B Receiver
As previously mentioned, the M87x receives the IRIG-B signal via the standard serial ports
located on the Host CPU’s front panel (Section 3.1.1). Port P2, P3, or P4 can be
configured to accept IRIG-B. The ports can be configured via the 70 Series Configurator
software utility.
5.7.3b M87x IRIG-B Decoder
The M87x IRIG Decoder parses the bit stream from the IRIG Receiver into registers that
represent the number of days, minutes, and seconds since the beginning of the present