Facsimile Tape

      Facsimile Tape
      Updated 19 Dec 2004

    Here is another facsimile communication Facsimile Tape, means which has great potential value especially for the mobile services in the past. From the standpoint of general information, the following references will prove helpful.

    The first such eqiupment was assembled in 1931 and was put trough a series of test and demonstrations. The apparatus was in three parts, a typewriter rebuilt to print on strip instead of on a page, a scanner, and a recorder; each with the necessary amplifiers, The original scanner operated on the same priciple as the early´ televission devices, using a disc about 4 inches in diameter with a circular row of holes near its periphery.
    This openings were brilliantly illuminated and their image was focussed through a projection lens and prism on the tape. As the disc rotated the light spots followed one another across the 1/2-inch tape at a rate of 30 per second.
    Meanwhile the tape moved forward at a rate to give 60 scanning lines per linear inch. The reflected light from the paper was collected by a phototube, and thus facsimile impulses were obtained and amplified in the usual way.
    The recorder followed the principles already used in the broadcast facsimile receiver, exept for the reduction in scaleof the helix drum. Also, a typewriter ribbon was substituted for the carbon paper. Fair  results were obtained with this apparatus. By using serial motors. and altenators special tests were made at speeds up to 120 inches per minute, which is equal to abot 200 words per minute of typewriting.
    In most of this work both scanner and recorder were driven by synchronous 60-cycle motors. It was apparent at once, however, that much leeway could be allowed in the speed control if a two-turn helix were used.
    This would give two copys of the line of type, one above the other; and as one line drifted off at bottom of the tape the other would come in at the top. Thus there would always be complete readable words in one line or the other.(see below).

    Facsimile tape as a distinct method of communication was employed as early 1901 by denison. See Ranger reference. During the latter part of the third decade and up to 1940 consiridation has been given to facsimile tape by quite a number of workers. In general, this work has divided into two groups, mechanicl and photo-optical scanning. The spiral helix and printer bar combination has been employed in both instances for recording purposes. A rather low ratio of intelligence handling to keying speed has handicapped facsimile tape when compared directly with the Baudot type of time code printer. Nevertheless, as stated previously, definitefields of application are available for facsimile tape. Practically all keying arrangements reported on to date are on-off keying of the r-f or audio subcarriers.

    The two references listed below (Withacker & Collings, and Kleinschmidt) are typical of these methods.

    Ranger (I.R.E. Proc., Vol. 14, No. 2, April, 1926, R. H. Ranger.)

    Withaker & Collings (RCA Institutes Technical Press, “Radio Facsimile”, pp. 284-293, J. N. Whiteaker, F. C. Collings)

    Siemens & Halske (Br. Patent 427,257, Siemens & Halske)

    International Inventions (Br. Patent 380,217, International Inventions)

    Kleinschmidt (U.S. Patent 2,046,328, E. E. Kleinschmidt et al.)

    (C) Marius Rensen


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