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MITS Janus Time Engine
Page 12 of 39
Copyright© Instrumentation Technology Systems 2020
20200929
1.3
IRIG B time code generator
The IRIG B time code generator samples the current time on the fractional second rollover of the
time master and generates both B007 and B127 timecode streams.
1.3.1
An IRIG B127 output buffer
The IRIG B127 AM signal stream is isolated from the output through an audio transformer
having a 600 Ω output impedance. The primary is driven by an independent adjustable gain
(webserver or command-line adjustment) amplifier offering a peak to peak amplitude range of
1-10 Vp-p.
1.3.2
An IRIG B007 output buffer
The IRIG B007 time code output is a buffered and short circuit protected TTL output capable of
driving up to 10 TTL loads for up to 100 meters of 50Ω coax or twisted pair terminated by 50Ω.
A combination of pin sets and a settings command may be used to physically configure this
output to be either single ended or differential pair.
Webserver or command-line settings may invert the polarity of these outputs independently.
1.4
Programmable Frequency Generators
Two programmable frequency generators are synchronized, and phase locked to the time master
such that a leading edge of each TTL clock output aligns within 50 nanoseconds of the fractional
seconds rollover of the time master.
1.4.1
Clock A
The Clock A generator can be set to generate 1 Hz (factory default), 10 Hz, 100, Hz, 1000 Hz, 10
KHz, 100 KHz, 1 MHz and 10 MHz by either the webserver or command-line.
The TTL output is buffered and short circuit protected.
1.4.2
Clock B
The Clock B generator can be set to generate 1 Hz (factory default) to 1000 Hz in 1 Hz steps by
either the webserver or command-line.
The TTL output is buffered and short circuit protected.
2.0
NETWORK TIME SYNCRHONIZATION
The MJTE may be synchronized to network time. Network time is either Network Time
Protocol (NTP) or Precision Time Protocol (PTP). Selection of these is mutually exclusive.
When it is desired to synchronize to either NTP or PTP, the first selection is Network Time
Protocol. There is no fail over capability from PTP to NTP or NTP to PTP. If Network Time
fails one of the other time references (IRIG B12x, B00x, 1PPS or GPS) will be selected if
available.