PIPE OF QUARTER-MILLION VOICES

A 2-INCH DIAMETER BURIED PIPE WILL SOME DAY CARRY A QUARTER OF A MILLION SIMULTANEOUS TELEPHONE CONVERSATIONS-- ENOUGH CAPACITY TO TRANSMIT, LETTER-BY-LETTER, A FULL 24- VOLUME SET OF ENCYCLOPEDIA IN ONE-TENTH OF A SECOND. THIS HOLLOW PIPE, OR WAVEGUIDE, IS PART OF AN ECONOMICAL NEW COMMUNICATIONS SYSTEM SCHEDULED FOR A 1974 FIELD TRIAL IN NORTHERN NEW JERSEY BY BELL LABS ENGINEERS. AT&T'S LONG LINES DEPARTMENT EXPECT TO INITIATE COMMERCIAL SERVICE USING THE NEW SYSTEM IN THE LATE 1970'S TO HELP MEET EXPECTED GROWTH IN LONG-DISTANCE CALLING, DATA COMMUNICATIONS AND PICTUREPHONE SERVICE DURING THE NEXT DECADE. TO HANDLE THE COMMUNICATIONS LOAD, THE SYSTEM WILL EXPLOIT THE HIGH INFORMATION-CARRYING CAPACITIES OF MILLIMETER WAVES--SO-CALLED BECAUSE THEIR WAVELENGTHS ARE ONLY A FEW MILIMETERS LONG. THESE WAVES LIE BETWEEN MICROWAVES AND INFRARED LIGHT WAVES IN THE FREQUENCY SPECTRUM. SO GREAT IS THEIR INFORMATION-CARRYING POTENTIAL THAT THE WAVE-GUIDE SYSTEM'S FREQUENCY BAND, EXTENDING FROM 40-110 GHZ, WILL HAVE GREATER CAPACITY THAN ALL THE LOWER RADIO FREQUENCIES COMBINED. HERE'S HOW THE NEW SYSTEM WILL HANDLE COMMUNICATIONS TRAFFIC: MILLIMETER WAVES GENERATED BY SOLID-STATE DEVICES WILL CARRY PULSE-CODED INFORMATION THROUGH THE CIRCULAR WAVEGUIDE. USE OF THE PULSE CODE MODULATION TECHNIQUE WILL CONVERT ALL TYPES OF SIGNALS-- VOICE, TV, PICTUREPHONE OR DATA--TO SIMILAR STREAMS OF EASILY TRANSMITTED PULSES. TO MAINTAIN THEIR SIGNAL STRENGTH, THE PULSES WILL BE DETECTED AND REGENERATED BY REPEATERS SPACED AT 20 MILE INTERVALS ON RELATIVELY STRAIGHT ROUTES. THIS COMPARES TO A REPEATER SPACING OF A FEW MILES WITH PRESENT COAXIAL CABLE SYSTEMS. BETWEEN NOW AND THE 1974 FIELD TRIAL, WESTERN ELECTRIC CO. WILL DEVELOP SPECIAL TECHNIQUES FOR MANUFACTURING STRAIGHT LENGTHS OF UNIFORM WAVEGUIDE--NEEDED SINCE ANY IMPERFECTIONS IN WAVEGUIDE ROUNDNESS OR STRAIGHTNESS DECREASE ITS TRANSMISSION EFFICIENCY. /CU/

• Corporate Authors:

  Communications User

  ,    
• Publication Date: 1970-11

Subject/Index Terms

• TRT Terms: Communication systems; Millimeter waves; Pulse code modulation; Waveguides
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00225927
• Record Type: Publication
• Report/Paper Numbers: pp 6-7
• Files: TRIS
• Created Date: Apr 18 1971 12:00AM