Patent GB-736048-A (GB)
Title: Instrument for the measurement of speed errors in teleprinter machines or the like
IPC: H04L12/26
Filed: 1953-04-20
Abstract: 736,048. Testing-apparatus for code telegraphy. SIEMENS & HALSKE AKT.-GES April 20, 1953 [April 19, 1952; April 23, 1952], No. 10826/53. Class 40 (3). A device for checking the speed of teleprinter transmitters comprises means to extract the start signals from a series of teleprinter signals sent in maximum sequence (preferably the " Here is " transmission) and apply them to either a relay frequency-measuring bridge, as in Fig. 1, or to a summation device which effectively times the duration of a predetermined number of said signals, as in Fig. 2. In each case a polarized receiving relay ER changes over its contact er on receipt of a start signal and thereby applies a pulse from condenser C1 to the winding I of a polarized ralay ST. Contact st is thus changed over and relay HR releases. Contact hr<SP>1</SP>1 connects condenser C2 from charging resistor R2 to the inductor L1 and sets up oscillations in the circuit L1, C2 which is tuned to about 4 c/s. such that a half-cycle will occupy 120 milliseconds and bridge 6 elements at the normal speed of 50 bands. The arrangement is such that the first half-cycle maintains relay ST in its changedover condition and the next half-cycle causes it to revert, re-energizing relay HR. Thus relay HR releases only for each start signal received. In the embodiment of Fig. 1 contacts hr<SP>11</SP> pulse-charge condenser C3 which is arranged in one arm of a bridge having a measuring instrument J connected in its diagonal. To avoid initial heavy surges being applied to instrument J the contacts WR<SP>11</SP> of an eighteen-position selector relay WR, which is pulsed by contacts hr<SP>111</SP>, serve to render the instrument circuit functional only at the fourth signal and disconnect it at the eighteenth. The instrument J gives its maximum reading after about ten-twelve signals and holds it for about six-eight signals (i.e. one second), and may be calibrated directly in percentage speed error. In the embodiment of Fig. 2 a continuous indication is provided by a pointer (Fig. 3, not shown) which is coupled to a steadily running clock movement U for a period of eighteen telegraph signals and is then held in the position attained. Contacts a<SP>111</SP> are in the operated condition when the first start signal causes HR to release. As relay A is slugged the contacts hr<SP>1</SP>2 energize relay K from a local battery OB. Contacts hr<SP>111</SP> pulse the selector relay WR as before and relay K is held operated over contacts WR<SP>1</SP> for the duration of eighteen signals. The armature of relay K (Fig. 3, not shown) closes a clutch between the pointer and drive-shaft of movement U and thus the amount of rotation of the pointer is an indication of the teleprinter speed. Before each operation the pointer is reset by pressing the key T, whereupon relay K is held operated over contacts T<SP>11</SP> until the pointer reaches its predetermined start position at which contacts nK are mechanically opened to de-energize K. Movement U is driven from the usual 1000 c/s. supply by frequency dividing in the two stages R÷ 1  and R÷ 2  to operate relay R at 50 c/s. Contacts r energize movement U from the local battery OB by a condenser divider C27, C28, and its drive shaft is arranged to rotate at about 1 revolution per second so that the pointer will travel about 2¢ revolutions at a teleprinter speed of 50 bands.