Building a Broadcast Clock: The Math Behind Radio Station Programming Schedules

By the KAVANA engineering team -- June 2026

The broadcast clock defines what happens in each minute of an hour: news at :00, traffic at :15, music rotation at :02-:12, commercial break at :20-:24. The implementation challenges are different from general scheduling problems.

The Core Constraint: Hard Time Boundaries

A broadcast clock is not a soft deadline system. When the clock says news starts at :00, news starts at :00. Not at :00:03 because the previous track ran long. The system continuously predicts when currently-playing content will finish and pre-loads the next item in advance.

Early finish: Fill content from a duration-indexed pool. A 45-second gap gets a 40-45 second music track.

Late finish: Fade out early (acceptable for music) or accept the late boundary and compensate later in the hour.

Duration Estimation for AI Content

For AI-generated content, duration is estimated using character count with a language-specific model. For Mandarin: approximately 4-5 characters per second at standard broadcast speech rate. For English: word count divided by 2.5.

The estimate is wrong about 15% of the time by more than one second. The system measures actual duration once generation is complete and re-evaluates the schedule.

The Fill Pool

Every station running a broadcast clock needs a fill pool indexed by duration range:

• 5-15 seconds: station IDs, jingles
• 15-30 seconds: short musical passages
• 30-60 seconds: instrumental clips
• 60-180 seconds: full music tracks

The Math of the Full Hour

A standard broadcast hour in China allocates:

• 4-8 minutes of news and information
• 8-12 minutes of advertising
• 2-4 minutes of weather, traffic, and station IDs
• 38-44 minutes of music

The scheduler uses a greedy heuristic to find feasible assignments in under 100ms.

What This Means for AI-Assisted Broadcast

AI-generated segments should be scheduled with a buffer -- not immediately before a hard clock boundary. Schedule AI traffic reports to end at :58:30 and accept a 90-second music fill if they finish early.

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KAVANA provides broadcast clock management as part of our playout software platform. Learn more at kavanafm.com.