Carrier Current Telephony and Telegraphy

Colpitts, E. H.; Blackwell, O. B.

doi:10.1109/t-aiee.1921.5060708

Cited by 58 publications

(1 citation statement)

References 12 publications

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“…The "single-sideband, suppressed-carrier" type of telephone transmission, invented by John R. Carson,22 has long been used in the Bell System in carrier systems on wire circuits. 23 Since the advantages of single sideband in radio transmission have been described by Hartley,24 and in the radio transmitter by Heising," we shall only briefly review the benefits arising from its use.…”

Section: S' = S-gimentioning

confidence: 99%

The Receiving System for Long-Wave Trans-Atlantic Radio Telephony

1928

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Transmission considerations and practical limitationsindicate that in the lower frequency range, frequencies near 60 kc are best suited for transatlantic radio-telephone transmission. A radio receiving location in Maine gives a signal-to-noise ratio improvement over a New York location equivalent to increasing the power of the British transmitter about 50 times.Various types of receiving antennas are briefly discussed. The waveantenna is selected as being most suitable for long-wave radio telephony. The various factors affecting wave-antenna performance and methods for measuring the physical constants of wave-antennas are discussed in detail. Highfrequency ground conductivities determined from wave-antenna measurements are given. Combination of several antennas to form arrays is found to be a desirable means of decreasing interference. The use of a wave-antenna array in Maine decreases the received noise power by an additional 400 times. If the receiving were to be accomplished near New York using a loop antenna, we would have to increase the power of the British transmitting station 20,000 times to obtain the same signal-to-noise ratio. Comparisons of calculated and observed directional diagrams of wave-antennas and wave-antenna arrays are presented and discussed.The transmission considerations governing the design of a radio receiver for commercial telephone reception are outlined.Mathematical discussions of the wave-antenna, antenna arrays, qua-sitilt angle, and probability of simultaneous occurrence of telegraph interference are given in the appendices. E AARLY in October, 1915, engineers of the Bell System stationed in Paris heard the words "good-night Shreeve" which had been transmitted from Arlington. That date then marks the inception of transatlantic radio-telephone receiving. The progress which has been made in the radio-telephone receiving art since these first experiments is demonstrated by contrasting the homodyne receiver and the non-directional antenna then used with the present commercial receiving system employing double-demodulation of single side-band signals and an extensive array of wave-antennas forming a highly directional

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Section: S' = S-gimentioning

confidence: 99%

The Receiving System for Long-Wave Trans-Atlantic Radio Telephony

1928

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Mutual Inductance in Wave Filters with an Introduction on Filter Design

Johnson¹,

Shea²

1925

Bell System Technical Journal

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Carrier Systems on Long Distance Telephone Lines¹

Affel¹,

Demarest²,

Green³

1928

Bell System Technical Journal

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Synopsis: Two previous papers before the American Institute of Electrical Engineers discussed the activities of the Bell System in the development of multiplex telephone and telegraph systems using carrier current methods. The present paper describes developments which have resulted in improvements in the carrier telephone art during the past few years. A new, so‐called type “C” system is described in detail, together with suitable repeaters and pilot channel apparatus for insuring the stability of operation; the line problems are considered and typical installations pictured. The growth of the application of carrier telephone systems and their increasingly important part in providing long distance telephone service on open‐wire lines are shown.

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Carrier Current Telephony and Telegraphy

Cited by 58 publications

References 12 publications

The Receiving System for Long-Wave Trans-Atlantic Radio Telephony

The Receiving System for Long-Wave Trans-Atlantic Radio Telephony

Mutual Inductance in Wave Filters with an Introduction on Filter Design

Carrier Systems on Long Distance Telephone Lines¹

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Carrier Current Telephony and Telegraphy

Cited by 58 publications

References 12 publications

The Receiving System for Long-Wave Trans-Atlantic Radio Telephony

The Receiving System for Long-Wave Trans-Atlantic Radio Telephony

Mutual Inductance in Wave Filters with an Introduction on Filter Design

Carrier Systems on Long Distance Telephone Lines1

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Carrier Systems on Long Distance Telephone Lines¹