What the receiver must recognize
Time code carries encoded time in an electrical waveform. Successful decoding requires compatible signal format, electrical input and data encoding. A matching connector alone does not establish compatibility. A time-code reader acquires time from that waveform; a generator produces it. These are separate capabilities.
IRIG: pulse-coded time and carrier modulation
IRIG is the Inter-Range Instrumentation Group family of time codes. IRIG-B uses a one-second frame with 100 bit positions carrying time-of-year information, markers and optional additional data. The IRIG letter identifies the code format; it does not by itself specify the electrical waveform or all encoded fields.
- DCLS/unmodulated: DC level-shift pulses carry the code through their pulse widths.
- AM: the code is carried by changes in the amplitude of a carrier. NTP100-TC supports IRIG-B with a 1 kHz AM carrier as well as unmodulated IRIG-B.
Check that the source waveform matches the receiver input. A DCLS input and an AM input are not interchangeable merely because both signals are called IRIG-B. IEEE 1344 extensions can supply year and additional status/offset information; confirm that both ends support the required encoded fields.
SMPTE LTC: time and frame numbering
SMPTE time code is used in film and broadcast systems. Linear/longitudinal time code (LTC) carries hours, minutes, seconds and frame numbers in a serial electrical signal. It also has user bits that can carry additional information such as a date under a supported encoding scheme.
Match the frame rate and drop-frame/non-drop-frame mode. Drop-frame time code skips selected frame numbers to keep numbering aligned with elapsed time at rates such as 29.97 fps; it does not discard video frames. A receiver’s support for 30 fps non-drop-frame does not establish support for 29.97 drop-frame.
Time-of-day decoding alone does not establish the calendar date. Check the supported date encoding, such as Leitch/Masterclock user bits or SMPTE 309M, at both ends.
Compatibility checks for support
- No decode: check for a valid waveform, DCLS versus AM, supported SMPTE frame rate, balanced/unbalanced wiring, signal level and termination for the installed receiver.
- Intermittent decode: inspect the signal at the receiving input and check cable condition, connectors, loading and grounding.
- Stable decode but wrong date/time: compare date/year encoding, UTC/local-time basis and any source or receiver offset. Correct signal amplitude cannot supply a date that the generator is not encoding.
NTDS/TCDS display inputs
NTDS and TCDS displays use NTP, TC or dual controllers. LUX belongs to the NTDS family. Time-code input requires a TC or dual controller; only NTP and dual controllers expose NTP/network options. See the controller reference. Confirm the supported time-code format for the installed display controller.
Related references
For current product datasheets and manuals, visit Masterclock Resources.
Article ID: KB-TC-001
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