(September, 1998; revised 1 October 2001)
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| Definitions | dBFS =
dB relative to Full Scale, i.e. the indicated maximum peak record level
as indicated by the level meter of a digital audio workstation, DAT recorder
or CD recorder. |
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| Recording Levels: |
A 30-second 1-KHz Reference Tone should be recorded at the beginning of each tape or disc (according to the Recording Sequence below) at 12-dB below the chosen peak program level. • NPR recommends that the Reference Tone be recorded at –18-dBFS and that program peaks do not exceed –6-dBFS. • If you choose to record at a level which causes program peaks to approach 0-dBFS, the Reference Tone should be recorded at –12-dBFS. • Automation Cue Tones should be recorded at –5-dB relative to the selected Reference Tone Level, i.e. at –23-dBFS if the NPR-recommended record level is used, and –17-dBFS if a 0–dBFS peak program level is used. Summary:
NB: If program peaks exceed the Reference Tone level by more than 12-dB, the satellite transmission may be distorted or the program submission may be rejected. |
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| Recording Format: | DAT:
Sampling Rate: 48-KHz sample rate is recommended. 44.1KHz tapes will be
accepted.
CD: Format Recordings must conform to "Red Book" (audio CD) standard, with the exception of tonle levels and Track ID's as below. Track IDs: Tracks must include at least 5 SMPTE frames, or 1/6 second between each Track ID and the first audio sample. Stop IDs are not necessary.
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| Automation Tones |
30 second
break (following tone): 25Hz tone recorded on the LEFT channel only. Level: 25-Hz Automation Cue Tones should be recorded at –5-dB relative to the selected Reference Tone Level (see above). Length: Tone length should be 2 seconds not including fade up and fade out time.
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| Recording Sequence |
15 seconds of recorded silence 15 seconds of recorded silence Start ID, with a minimum of 5 SMPTE frames or 1/6 second between ID and first Program audio sample Beginning of program Track 1: 30 seconds of 1kHz reference tone Track 2: 1 second of silence, followed by entire program. (Track 2 Start ID to include a minimum of 5 SMPTE frames between ID and first Program audio sample) |
Additional Comments
Please note that the STC is a switching facility with a limited control of transmitted levels. There are no mixing consoles in the STC.
For optimum audio quality from the satellite system, the dynamic range of a digital recording should be moderately limited, as the STC has no processing equipment between your recording and the satellite. It is therefore essential that the average program level of your recording equal the Program Operating Level indicated by the 1 kHz reference tone.
Only a small percentage of programming transmitted is actually aired by stations directly from the satellite---most programs are recorded to be used at a later time, with many stations still utilizing older analog equipment. Many subtleties will be lost if levels are not sufficient enough to be captured by analog equipment.
Conversely, excessive peak levels that do not appear distorted on a digital recording may be distorted by the satellite system and/or by analog equipment at the broadcast stations.
If you have questions, please contact:
Toby Pirro (tpirro@npr.org) or Paco DeBartolomeo, STC Supervisors at (202) 513-2641, or
Program Submissions
If you have questions, please contact Russ Lehman (rlehman@npr.org) , Audio Engineering Supervisor/Cultural
Operations at (202) 513-2576.