US2594071A - Code signal transmission system - Google Patents

Description

April 1952 c. REVERCHON 2,594,071

CODE SIGNAL TRANSMISSIONSYSTEM Filed Oct. 1, 1949 2 SHEET$-SHEET l K0 rq 5 2 a 1:1 w ij/\\\ :1 .Q m I? :2 4 :1

i a $1 Q Q W m wclw April 1952 c. REVERCHON CODE SIGNAL TRANSMISSION SYSTEM 2 SHEETS- SHEET 2 Filed Oct. 1, 1949 N W6 :M c 6 mm Ev 5 YE w a WR rn E M b I: U a w nw/ 5 L C rU m. 29 mum "5m m b 5 5 n. a a W m L. 4 Wu 0 1 1M5 "Mm v M M nm6 wa Patented Apr. 22, 1952 OFFICE CODE SIGNAL TRANSMISSION SYSTEM Claude Reverchon, Lons-le-Saunier, France Application October 1, 1949, Serial No. 119,122 In France June 14, .1949

9 Claims. (Cl. 178-49) This invention relates to code signal trans- I mission, and includes both an improved method of sending telegraphic code, such as Morse code, signals, and apparatus for carrying said method into effect, both the improved method and apparatus being generally applicable for use in connection with telegraphy, radio telegraphy, and similar electric transmission systems.

It is a general object of my invention to provide a method of sending code signals in a novel and improved manner which simplifies the work of the keying operator.

Another object is to provide such a method, and related means, for sending electric code signals composed of dots and dashes in which the number of key-actuations to send any given signal of the code is greatly reduced as compared to the conventional method and means used in sending such signal.

In attaining the above and further objects of my invention, I provide a method of sending code signals of the type made up of shorter signals or dots and longer signals or dashes, said method comprising for each code signal combination to be transmitted, automatically sending a uniform sequence of said dots equivalent in total duration to the overall length of said code signal to be transmitted, and each time a dash is to occur in said code signal, generating a signal having a length and timing such as to overlap the end of a dot and the start of the next dot in said uniform sequence, whereby said combined signals will cooperate to produce the desired code signal to be transmitted. The dot signals form ing the uniform sequence may be termed the dot pattern signals, while the further signals bridging the dots of the pattern to cause them to merge into a dash may be termed the bridge signals.

While the dot pattern'signals are-according to my invention emitted automatically upon actuation of a first key so as to last all the while said first key remains depressed, preferably the bridge signals are also adapted to be emitted in uniform sequence upon and throughout depression of a second key, the frequency rate of said intermediate signals being equal to or slightly greater than one half that of the pattern signals.

An improved sending device according to my invention may comprise a first key-actuated means adapted upon depression of the key to generate a uniform sequence or pattern of dots, a second key-actuated means adapted upon depression of its related key to generate a bridge signal adapted to overlap the end of a dot and the start of the next dot in said pattern, and

means to deliver the mixed pattern and bridge signals to a common output. The said second key-actuated means may be such as to produce a uniform sequence of said bridge signals at a rate equal to or slightly greater than one half that of said pattern. Furthermore, the device may and preferably does include means for timing said bridge signals in such relation with said pattern dots as to produce automatically the desired overlapping relationship therebetween.

The invention will now be described in fuller detail with reference to some specific embodiments thereof, given by way of indication rather than limitation, and in connection with the accompanying diagrammatic drawings, in which:

Figure 1 is an explanatory diagram showing the manner in which the pattern signals and the bridge signals cooperate to produce a dash signal of a code signal combination.

Figure 2 is a wiring diagram of a sender device embodying my invention.

Figure 3 is a wiring diagram relating to a modified embodiment.

Figure 4 is a somewhat diagrammatic overhead view of the key assembly.

Figures 5a, 5b and 5c are further explanatory diagrams of the operation of my improved method of signal code transmission.

As stated, my method essentially consists of automatically generating a uniform sequence or pattern of dots throughout the whole duration of the code signal to be transmitted. This pattern is in itself suillcient to produce the dots" in said code signal and to time the gaps or blanks between consecutive dots and/or dashes therein. To produce a dash at a requisite point of the code signal, an accessory or bridge signal is used. As shown in Fig. l, the emission of each bridge signal such as 2 is made to commence during the production of a. pattern dot I and terminates during the production of the next following dot in the pattern. Since the pattern signals and the bridge signals are, as mentioned hereinabove, mixed together in a common output circuit, the

resulting output signal 3 is equal in duration to two consecutive dots plus the gap or blank therebetween and may thus serve as a dash in the code combination used. I

' Preferably, the bridge signals are generated automatically in a uniform sequence, the: rate of ;frequency of which should be about twice as slow as that of the pattern dots, in order to allow of producing more than one consecutive dash in a resulting code signal to be transmitted.

The production of pattern dots and that of bridge signals is controlled by means of separate keys, so that it is possible selectively to produce the pattern by itself, or simultaneously the pat tern. with the necessary bridge signals.

Various automatic systems constructed on known lines may be used to produce both the pattern and the bridge signals. Thus oscillators of various types, or clockwork mechanisms made to actuate electric contacts, may be used. One satisfactory embodiment, about to be described, comprises the use of a parallel combination of oscillatory circuits of a type well-known in the art of electric signal transmission. As shown in Fig. 2, two relays 8 and 9 of the conventional telegraphic type are provided, each relay comprising an electromagnet winding I0, II with a soft iron core 8, 9' adapted to actuate'a related set of contacts 4, 5. The relay 8 which is to generate the pattern signals comprises a reversing set of contacts l9 and a set of operating contacts 4. The relay 9 which is to generate the bridge signals has associated with it rest contacts 23 and operating contacts 5. Each of the relay coils I0, I I is connected in series in an individual circuit, both circuits in parallel being supplied from a common source of direct current I4. In each circuit there is interposed a key I2, I3, and the keys are independently operable to actuate either relay at will.

To generate the dot pattern or uniform sequence of dots, the operator depresses the pattern key I2. Current then flows through the pattern circuit from source l4, through the closed contacts of reverser switch I9, pattern key I2, resistance I5, and'condenser I6, charging the latter. The potential across I1 and I8 gradually increases; The value of resistance I is so predetermined that the voltage between H and I8 can reach a value high enough to energize pattern relay 8. The armature 8' of this relay then attracts the movable elements both of the reversing contacts I9 and of the operating contacts 4, thus breaking the pattern circuit between I9 and I2, and at the same time closing the contacts 4. The condenser I6 discharges freely through the winding I0, and the voltage across its electrodes gradually drops off until it reaches a value low enough to de-energize the relay 8, the armature 8' of which releases the movable elements both of I9 and 4, so that both these sets of contacts are restored to its initial jposition. The above-described cycle will be repeated as long as the key I2 is held down by the operator.

In this way it will be seen that the contacts 4 are alternatively opened and closed, and this is effective to produce the desired pattern of dots at the, output terminals 6 and I.

In idle condition of the circuit, with the key I2 open or raised, a resistance 20 shunting the key I2 is such as to allow a small flow of current through the winding II], this idle current being.

well below the minimum value necessary to energize therelay 8. Thispre-existi'ng current flow makes it'possible to reduce somewhat the time elapsing between the instant the key I2 is depressed and that at which the current reaches its full value operative to energize the relay.

Now to describe the production of the so-called bridgesignals, the exemplary device shown includes, as already stated, circuit mea'n's' 'for automatically producing a sequence of "such bridge'signals, and generally'similar to 'the circuit means described above for the production of the dot pattern signals. However, the fbridge" relay used, rather than actuating a reverser switch I9, is made to actuate a simple pair of rest contacts 23. Bridge signals are only generated upon concurrent depression of both keys I2 and I3, so as to first cause the production of one or more dots. During the production of each dot, the reverser I9 connects the source M with a terminal of the bridge key I3. If this key is depressed, the full voltage of the source will appear across condenser 2!, for a length of time which does not exceed the duration of a dot. The charge of the condenser 2! may therefore increase during a length of time not longer than the duration of a dot. To enable the condenser to build up a sufficiently high charge across its electrodes during such a comparatively short period of time, the by-pass resistor 24 is so predetermined as to allow at all times an idle current of comparatively high magnitude to flow through the winding II. It will thus be seen that the value of resistor 24 determines the greater or lesser degree of overlap of a bridgesignal over the dot preceding it.

The capacity of condenser 2| should be so selected that the natural oscillatory frequency of the bridge relay will be slightly greater than one half the oscillatory frequency of the pattern relay, in order to insure satisfactory timing between both sets of signals, the said timing being due to the action of reverser I9, as described.

The bridge signals are thus generated across the contacts 5. Since both sets of contacts 4 and 5 are, as shown, connected in parallel across the common output 6, I, it will be seen that the combined pattern and bridge signals will appear across this common output in the form of the desired Morse or similar code signal combinations. r

In operating an improved sender constructed as described above, it is sometimes found that there is a tendency for the pattern dots to slur together, and this tendency is the more marked as the speed of keying operation is slower, with the duration of the dots longer than that of the intermediate gaps. To obviate this defect, I may shunt the pattern relay coil I0 with a suitably predetermined resistor 25, as shown in the modifled circuit diagram of Fig. 3. When a resistor such as 25 is used, it of course becomes necessary correspondingly to reduce the value of resistor I5. However, the correct value of the resistance 25 to be shunted across the winding 8 depends the form of a variable resistor, or, better yet, a'

series combination of a fixed with an adjustable resistor. The latter then serves as a compensator means, so that it further serves to compensate for any variations, with time, of the circuit constants from their initial value.

The modification shown in Fig. 3 includes a further improvement over the embodiment of Fig. 2, in that it contains means for varying the rate of frequency of the automatic bridge signals, a highly desirable feature. This means comprises an adjustable resistor P inserted in series with the bridge winding II.

Fig. 4 schematically shows in overhead plan view one practical embodiment of the keying assembly of an improved sender according to my invention. As shown the keying assembly comprises a fiat insulating mounting base 3!) on which spectively. The left-hand key assembly, 3|, 43, as shown in the drawing, may form the pattern key [2, while the right-hand key assembly 32, 44 comprises the bridge key 53. Preferably, the pattern key I2 is arranged for actuation with the thumb, and the bridge key l3 for actuation with the forefinger, oi the operators right hand. The pivotal stroke of each key is inwardly limited by its cooperating contact terminal element, 39, 4%,

while outwardly there is provided a stop 4!, 42 against which the associated key is urged by the action of a related spring 31', 33. One pair of terminals is provided by the above-mentioned contact elements 39, 40, while the opposite pair of terminals, connected with the key strips 3!, 32. is shown at 35, 35.

The operation of my improved method of signal code transmission will now be described in greater detail with reference to the explanatory diagrams of Figs. 5a, 5b and 50, as practised by way of example with the apparatus illustrated in either of Figs. 2 or 3, and in Fig. 4.

In the initial or idle condition of the transmitter set, both sets of contacts 4 and 5 are open, and the keys l2 and I3 are held raised by their biassing springs 31, 38 (Fig. 4). We shall first consider the operation in the case where a continuous sequence of dots is transmitted. By depressing the key [2, the operator causes a sequence of energizations of the armature 8 of relay 8. Each of these energized periods of the armature causes it to attract and close the contacts 4 for a period of time equivalent to a dot. Between two consecutive ones of its energized or attractive conditions the armature is de-energized for the same period of time, allowing the com tacts 4 to open. The output terminals 6 and l with which the contacts 4 are connected, are therefore alternately in open-circuit and in short-circuited condition.

Fig. 5a illustrates in diagrammatic form the pattern of signals thus made available across the terminals 6, 7. Each heavy line (or black) represents the duration of a short-circuit across 6 and '3. Two such successive blacks are separated by a blank which represents the time during which the terminals 6 and l are in open circuit.

To generate a sequence of bridging signals, the

operator depresses both the keys l2 and I3. The relays 8 and 9 are then both caused to oscillate in a manner simi1ar to that described above in connection with the relay =8. But as the oscillating rate or frequency of relay 9 is twice as slow as that of the relay 3, it follows that the blacks and blanks generated by the contacts 5 are twice as long as those generated by the contacts 4.

To produce a sequence of dashes, it is merely necessary to combine the outputs of both circuits, i. e. the dots and bridging signals, in a common load circuit. Accordingly, the contacts 4 and 5 are both connected to a common pair of output terminals 6 and l.

The production of a series of dashes is illustrated in Fig. 5b. The uppermost line of blacks and blanks represents the sequential conditions of the contacts 4, the intermediate line those of the contacts 5, while the lowermost line represents the resulting conditions obtaining in the load E-'|' under the combined effect or both outputs. It will be seen that the resulting blacks or short-circuited periods of 66 are each equivalent in extent to the combined duration of two successive dots as provided by the pattern circuit.

Owing to the synchronization provided by the reverser switch IS, a bridging signal can only set in during the production of a dot and can only terminate during the production of the next following dot. Consequently, from the onset of the first dot to the end of the next dot, the successive phases of the combination output cycle are as follows:

4 closed, 5 open,

t closed, 5 closed, 4 open, 5 closed,

4 closed, 5 closed, 4 closed, 5 open,

4 open, 5 open.

This operating cycle is repeated for each successive dash to be transmitted. It will be seen that the production of a dash requires the production of two dots (i. e. a pair of dots) and one bridge signal. From the start to the end of each pair of dots, the output terminals are constantly shorted, either by the contacts 4, or by the contacts 5, or by both 4 and '5. The time interval between two successive dashes is obviously the same as that separating two successive pairs of dots. The net result is that dashes are produced each equal in duration to three dots, and separated by time intervals equal in duration to one dot. This conforms to the requirements of the Morse code.

We shall now discuss the transmission of signals not exclusively formed by dots or dashes, but rather by a combination of both. Whatever the particular signal to be transmitted, the operator should first depress the key l2 to initiate the signal, and keep this key depressed until the end of the signal (this in order to produce the pattern). Moreover, where the signal to be transmitted includes one or more dashes, the operator must depress the key is each time that the said one or more dashes are to occur, and keep that key depressed for a suitable interval of time. To take an example in the Morse code, the letter Y (dash-dot-dash-dash) is obtained as follows (see Fig. 5c). The operator depresses both key i2 and I3. Then, after the beginning of the first bridge signal and before the onset of the third dot, he rel-eases the key l3 for a short time so as to arrest the operation of the bridging oscillator. Then the key i3 is again closed during the time interval separating the third from the fourth dot. Then there only remains to wait for the end of the signal, whereupon both keys are released together.

It will of course be understood that many variations may be made in and from the specific cir cuit arrangements and constructional details illustrated and described without exceeding the scope of the invention, as defined in the ensuing claims.

Thus the condensers It and 2| may be provided adjustable, thereby providing further means for varying the rate of operation. Auxiliary operative contacts may be mounted on the relays and connected with output terminals other than 6 and I.

What I claim is:

1. In a sender for transmitting code groups of dots and dashes, means for generating a first uniform sequence of dot signals, means for generating a second uniform sequence of bridging signals at a rate of frequency substantially one half that of said first dot sequence, mean for synchronizing the output of said second generating means with the output of said first generating means,

means for preventing said second generating means from initiating its operationexcept during the production of one of said dot signals, and common output means for both said dot and said bridging signals.

2. In a sender for transmitting code groups of dots and dashes, means including a first key and an oscillating relay circuit adapted upon continued depression of said first key to generate a first uniform sequence of dot signals, means including a second key and a second oscillating relay circuit adapted upon continued depression of said second key to generate a second uniform sequence of bridging signals at a rate of frequency substantially one half that of said first dot sequence, means for preventing said second relay circuit from responding to the depression of said second key to effectively commence generating its said sequence of bridging signals except during the production of one of said dot signals by said first relay circuit, and common output means for combining both said dot and said bridging signals.

3. Sender system as in claim 2 wherein said response-preventing means comprises a switch actuated by said first relay means.

4. First keying means actuatable to generate a first continued sequence of dot signals, second keying means actuata'ble to generate a second continued sequence of bridging signals at one half the rate of said dots, switch means controlled by said first keying means for preventing the initiation of said bridging signal sequence by said second means except during the generation of a dot by said first means, and common output means for combining both signal sequences.

5. In a signal transmission system, a first relay including an armature and an oscillatory circuit winding and a first key in series therewith, a second relay including an armature and an oscillatory circuit winding and a second key in series therewith, a D.-C. supply for both said relays, a pair of output contacts for said first relay and a pair of output contacts for said second relay, each armature when energized being operative to close the related output contacts, a further set of contact means associated with each relay and actuated by the related armature upon energization thereof to cut ofi the D.-C. supply from the related circuit and de-energize said related relay, whereby continued depression of either key will cause the related armature to be sequentially energized and de-energized to generate a uniform sequence of signals across the related pair of output contacts, means synchronizing the outputs of both circuits, the said further set of contact means associated with said first relay being adapted when, and only when, actuated by its relay, to connect said second circuit with said supply, and common output terminals connected in parallel across said first and said second output terminals.

6. The system claimed in claim 5 wherein the respective oscillatory circuit constants of said first and said second relay are so selected and correlated that the output rate of said signal sequence is twice as slow in said second as in said first circuit. 7

7. The system claimed in claim 6 wherein said further set of contact means associated with said first relay comprises a set of reversing contacts adapted when not actuated to connect only said first, and when actuated to connect only said sec ond key with said supply source.

8. The system claimed in claim '7 which further comprises a by-pass resistor shunting said first key to provide a small current flow through said first relay in the non-depressed position of said first key.

9. The system claimed in claim 8 which further comprises a by-pass resistor shunting theseries combination of said second key with said reverser switch to produce through said second relay in the non-depressed condition of said second key 2. current flow which is high though not high enough to operate said second relay.

CLAUDE REVERCHON.

No references cited.

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