The communications frequency study was made to facilitate spectrum planning by FAA Frequency Management personnel. The study relates communications intelligibility to frequency channel spacing, bandwidth, modulation type, and signal-to-interference ratio. The overall approach was to conduct talker/listener intelligibility tests, voice communications equipment tests, and digital communications equipment tests. The test procedure subjected the Speech Communications Index Meter (SCIM) simulated speech signals, the Air Traffic Control (ATC) messages, and the Modified Rhyme Tests (MRTs) to specific levels of interference. The SCIM signal was first applied to the SCIM analyzer for computation and display of articulation index (AI). The ATC messages and MRTs were then recorded at the configuration which produced these discrete values of AIs. These recordings were subsequently used to perform subjective intelligibility testing. Talker/listener intelligibility tests were conducted to determine the particular values of AI required for communications links within the ATC system using both ATC and MRT vocabularies. Voice and digital communications tests were conducted to obtain data pertaining to channel assignments for various configurations of conventional and proposed operational modes.

  • Corporate Authors:

    National Aviation Facilities Experimental Center

    Federal Aviation Administration
    Atlantic City, NJ  United States  08405
  • Authors:
    • O'Brien, P J
    • BUSCH, A C
  • Publication Date: 1969-3

Media Info

  • Pagination: 64 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00146815
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: FAA-RD-68-59 Final Rpt., NA-69-21
  • Files: NTIS, TRIS, USDOT
  • Created Date: Feb 16 1977 12:00AM