Chris Scott & Associates - www.scott-inc.com 
 PUBLIC RADIO NETWORK AUTOMATION
 Sub second break adjustment - The circuit interfaces to automation systems accepting a "closure "" for time synchronization
Public radio stations have had mixed success using timed break triggers with NPR feeds.  NPR is unique among radio networks in that  many programs are fed without cue tones or other break-start signals. Instead, NPR producers use scheduled time posts", which flank the cutaway breaks. Theoretically, these one second pauses would be simple to target with a carefully timed automatic insertion, given the time synchronization accuracy available. In practice however, several factors conspire to cause transitions to occur during network announcer speech, resulting in "up cut" or truncated audio. One of these factors is the lack of sub-second timing adjustability. Due to satellite transmission and encoding / decoding delays, network feeds often suffer from non integer second latencies. This pulse delay circuit can relocate a network (SOSS) or GPS derived top-of-the-hour time sync closure to another, slightly later time, and provide a mechanism for fine-tuning the center of pause cutaway to avoid clipping or up cutting the network feed.  Pulse delay circuit for sub-second timing adjustment :  

The TIMESYNC allows you to tweak your radio automation PC time to network time with .1 second granularity rather than integer seconds.
  The TIMESYNC board  

The Microchip 16C711/JW is a self-contained microcontroller using a 4 MHz ceramic resonator as its clock frequency timebase, producing a precisely repeatable pulse delay. All inputs and outputs are optically isolated, and an internal watchdog timer and brownout reset make it very reliable. The delay is programmed by setting the dipswitch with an eight-bit binary number of tenth-seconds.  

Specifications: 

  • One opto-isolated input triggers on leading edge
  • Three opto-isolated open collector outputs
  • 0 - 25.5 second pulse delay
  • Dip switch selectable delay - 100 millisecond increment
  • Requires 9 - 15 vdc, unregulated.
  • LEDs indicate input, output, and status

FIRMWARE for Microchip's 16C711 microcontroller - requires hardware programmer download (2K) Intel HEX file

Note: As a free service to non-profit automated stations who do not own a PIC programmer, chips will be programmed for those who furnish 1) an erased 16C711/JW chip ($10 from Digi-Key) and 2) A suitable self-addressed, stamped envelope for return. Buy two; the spare is cheap. Email for details.

The TIMESYNC schematic
Chris Scott & Associates 
P.O. Box 52 
Bowling Green, KY 42102 

Phone: (270) 781-5301 
 

Fax: (270) 781-1232 

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