Patent GB-618234-A (GB)
Title: Code-controlled apparatus
IPC: H04L15/26
Filed: 1945-07-31
Abstract: 618,234. Type-printing telegraphy; light, utilizing. WINTER, A. C. July 31, 1945, No. 19612. Convention date, Dec. 28, 1943. [Class 40 (iii)] [Also in Group XXXVII] Code-controlled apparatus operating to a code of the kind in which the intelligence conveyed is determined by the lengths of the code-signal elements, and possibly also by their sequence (e.g. the Morse code), comprises means for measuring the time-lengths of received codesignal elements, means for measuring the timelengths of received code spaces, adjustable regulator means for establishing a value which the code space measuring means cannot exceed, means for comparing a measured code-signal element with a measured code space and result-producing means controlled by the result of the comparison. Distribution and differentiation of code signals. Receipt of any code-signal (dot or dash) energizes a receive relay 135 (Figs. 1 and 3, which depict the apparatus following the receipt of the letter R (dot, dash, dot), but before printing has taken place) and applies battery to stepping magnets 137f, 138f to step a space-switch 138 to its first operative contact 1, and prepare a code-switch 137 to step when its magnet 137f is released at the next space received. Relay 136 is energized by contact 135c and connects anode battery to a code diode CD which then charges the first code condenser 1CC (selected by the code switch 137). Receipt of the following space signal releases the receive relay 135, thus stepping the code switch 137 to its contact 2 ready for the next code-signal, and releasing relay 136 to energize a space diode SD which charges the first space condenser 1SC (selected by the space switch 138). The charging rates of the code and space condensers are controlled by diode filament rheostats 401, 402 respectively, arranged so that the code condensers 1CC ... 4CC have twice the time constant of the space condensers 1SC ... 4SC, so that in a given time a dot will produce a charge of, say, X volts, a space 2X volts, and a dash 3X volts. The potential on the code and space condensers is applied as additional grid bias to triodes 1CV ... 4CV and 1SV ... 4SV respectively. Consequent unbalance of their anode currents causes either the associated dot magnet 405 or dash magnet 404 to close and a corresponding one of permutation magnets 1PR1 ... 4PR1 or 1PR2 ... 4PR2 of a switching device to record a dot or dash. Subsequent code signals and spaces cause permutation switches 420, 421 to prepare a unique path from the power supply to one of a plurality of printing magnets 411. Manual regulator. A regulator voltage (2X volts) is supplied via a rheostat 406 to oppose the grid bias voltage of space-regulating triodes 1SR ... 4SR and so keep limit relays 400 normally closed. The space-condenser charges are also applied as grid bias and when the potential of any space condenser approaches the regulator voltage the associated limit switch 400 releases and prevents further charging of that condenser. In this way the charge on a space condenser due to the space following a final code signal of a letter is not larger than that due to a space following any other code-signal. Printing and spacing. Receipt of the first code-signal of a character operates a self-locking relay 410 and each subsequent short code-space therefore charges a letter condenser LC via its letter diode LD, but each following code signal applies battery via contact 136d to the grid of a letter thyratron LT to fire it and so discharge the letter condenser- LC. Receipt of a longer letter space allows the letter condenser LC potential to approach the regulator voltage, and at the grid of a letter triode. LV these voltages nullify each other and the grid bias battery LG stops anode current flowing and releases the letter relay LR. At its contact 409f the printing circuit prepared above is completed and a character is printed, and a release magnet 430 (Fig. 3) is operated to allow spring-controlled switches 137, 138 to return to contacts 1 and 0 respectively. At contact 409e the grid bias battery 425 is short-circuited and the space thyratrons 1ST .... 4ST and code thyratrons 1CT ... 4CT fire and allow the space and code condensers 1SC ... 4SC and 1CC ... 4CC to discharge. At contact 409d a grid bias battery 435 is short-circuited, the letter thyratron LT fires and the letter condenser LC discharges. At contact 409i the holding circuit for relay 410 is broken. The apparatus is thus returned to normal ready to receive another character. A word condenser WC is similarly employed to operate a spacebar SB by means of a magnet 418. Discharge of the word condenser WC via its thyratron WT does not take place when a letter is printed, but only whenever a code-signal is received and contact 136d places battery via rheostat 437 on the grid of the word thyratron WT. The printing and spacing magnets 411, 418 may operate keys of a normal typewriter of the tape-printing type and preferably electrically actuated. Automatic regulator. In order to adjust the above apparatus to different transmission speeds, manual adjustment of the regulator rheostat 406 must be made. The following automatic device obviates this necessity, and may be connected to the above apparatus at points J, L, M, N (Figs. 1, 3, 15) and brought into circuit by manual switches 440, 441 (Figs. 1, 3). So far as the regulator (Fig. 15) is concerned, the first received code signal is effective only to step an auxiliary step-switch 138-1 to its only operative contact 1. The following codespace steps auxiliary switch 137-1 to its only operative contact 2 and via switch 138-1 and diode SMD charges a space-measuring condenser SMC, and also via an alternator-switch- 300-2 changes regulator and word-regulator condensers RC, WRC respectively, both at the same rate. The second received code-signal changes holding condenser SHC1 (or SHC2 as determined by switch 300-1). As this charge approaches that of the space-measuring condenser SMC, the two charges nullify each other at the grid of valve SHV1 or SHV2 and leave the grid controlled solely by the bias battery 257c or 258c. Thus, limit relay 257 or 258 opens and removes the charging current from condenser SHC1 or SHC2. Similarly, the voltage on the regulator condenser RC and on word-regulator condenser WRC is limited by that on SHC1 or SHC2 according to the position of alternator - switch 300 which moves on receipt of a second space. The voltage on the regulator condenser RC is therefore dependent on the length of the first space in the preceding letter-group, and is applied via point L (Fig. 1) and switch 440 as the regulator voltage for the system. The value of this regulator voltage is unchanged by the reception of the letters E or T which have no second code-signal. When a letter has been printed, switch 409 (Figs. 1, 3) short-circuits via point M the bias batteries of space-measuring and regulator thyratrons SMT, RT and discharges their condensers SMC, RC. The space-holding condenser SHC1 or SHC2 is discharged through thyratron SHT1 or SHT2 when the alternator switch 300-3 moves on. The word-regulator condenser is discharged on the receipt of the next code-signal. Instead of thyratrons, diodes may be used to discharge the various condensers (Fig. 13, not shown). In a modification (Fig. 18), the permutation switches 420, 421 are replaced by three-position switches 550. Each dot or dash received is sequentially routed by auxiliary switch 137-2 to a coil 552A of one of these switches 550, which comprise two coils 552, 552A (Fig. 19). Coil 552A is effective to pull the armature 550a to the dot contact 550c against a weak spring 551a when any code signal is received. If a dash is received, a triode 1CV operates a dash relay 404 to energize coil 552 and moves the armature 550a to the dash contact 550d against a strong short spring 551b. The first permutation switch 550 has only a dot and a dash position, since it need never record a non-signal condition. A further modification (Fig. 14, not shown) replaces the mechanical stepswitches 137, 138 by an electrical distributer comprising a series of relays. The receive relay 135 may be replaced by a photo-electric cell in order that " blinker " transmission may be responded to. Specifications 618,225 and 618,235 are referred to.