US2464667A

US2464667A - Method of transmitting telegraphic signals

Info

Publication number: US2464667A
Application number: US683594A
Authority: US
Inventors: Boosman Herman Bernardl Rudolf; Posthumus Klaas
Original assignee: Hartford National Bank and Trust Co
Current assignee: Hartford National Bank and Trust Co
Priority date: 1943-06-24
Filing date: 1946-07-15
Publication date: 1949-03-15
Anticipated expiration: 1966-03-15
Also published as: FR905770A; DE863074C; BE456800A; GB620497A; NL66620C; CH248117A

Description

H. B. R. BOOSMAN EIAL ,6 7

2 Shets-Sheet 1 JIM W; AMPLIFIER TRANSMITTER FIG.

INVENTORS HERMAN BERNARD RUDOLF BOOSMAN TJISKE DOUMA KLAAS PSZTHUMUS BY 1%,1 A ENT METHOD OF TRANSMITTING TELEGRAPHIC SIGNALS March 15, 1949.

Filed July 15, 1946 JUL March 15, 1949.

Filed July 15, 1946 H. a. R. BOOSMAN EIAL 2,464,667

METHOD OF TRANSMITTING TELEGRAPHIC SIGNALS 2 Sheets-Sheet 2 AMPLIFIER TRANSMITTER FIG , TRANSFER RECEIVER oswcs 6 HERMAN BERNARDYRUDOLF INVENTO S BOOSMAN TJISKE DOUMA KLj AS PiSTHUMU 'Agt m Patented Mar. 15, 1949 METHOD OF TRANSMITTING TELE- GRAPHIC SIGNALS Herman Bernard Rudolf Boosman,

and Klaas Posthumus, Eindhovcn,

Tjlske Douma,

Netherlands,

assignors to Hartford National Bank and Trust Company, Hartford, Conn.,

as trustee Application July 15, 1946, Serial No. 683,59;

In the Netherlands June 24, 1943 Section 1, Public Law 690, August a, 1946 Patent expire! June 24; 19.63

20 Claims. (01. 250-8) This invention relates to a method of transmitting telegraphic signals and also to transmitting and reeciving devices arranged for the transmission and reception respectively of signals emitted by this method.

According to the invention, the mean energy required for the transmission is materially reduced .by transmitting one or more pulses of substantially constant length of time at the beginning and in some cases at the end of each signal to be transmitted, either the pulses at the beginning of several signals or the pulses at the end and the beginning of the same signal having a difiering time nature.

A further advantage of the method according to the invention consists in that the signal hiss ratio occurring in the receiver can be raised considerably over the signal hiss ratio obtainable in the usual transmission of telegraphic signals, the mean transmission energy being otherwise the same.

In order that the invention may be clearly understood and readily carried into effect it will now be described more fully with reference to the accompanying drawing.

The figures of the drawing are as follows:

Fig. 1 is a pattern of the telegraph signals to be transmitted,

Fig. 2 is a schematic diagram of a preferred embodiment of a transmitter for emitting pulses of the type shown in line b of Fig. 1,

Fig. 3 is a pattern illustrating various pulses generated in the transmitter of Fig. 1,

Fig. 4 is a schematic diagram of another preferred embodiment of a transmitter,

Fig. 5 is a schematic diagram of a receiver for the reception of pulses of the type shown in line 41 of Fig. 1, and

Fig. 6 is a schematic diagram of a pulse generator for use in connection with a receiver of the type shown in Fig. 5.

Figure 1 shows a telegraphic signal to be transmitted made up of a dash, a dot and a dash. The energy required for the transmission of the signal is proportional to the cross-hatched surface areas. For enabling the transmission of this energy a transmitter of definite power is required and this power must be such that the mean energy to be transmitted per time unit, or in other words the contents of the cross-hatched surfaces divided by the time T, can be coped with by the transmitter without overloading.

According to the invention, the telegraphic signals as shown in Figure 1a are transmitted by means of pulses of constant length of time, for.

example of the nature shown in Figure 1b, 10 or Id. In the case of the pulse nature shown in Figure 117 two short successive pulsesjare emitted at the beginning of each signal, whereas the end of each signal is denoted by a single pulse. In the case of the pulse nature shown in Figure 1c the beginning of each dash is represented by two pulses, the begimiing of each dot and the end of both dashes and dots. by a single pulse. The

pulse nature shown in Figure 1d essentially corresponds with the nature shown in Figure 1c, the

difference being that the pulses at the end of the telegraphic signals are emitted.

As before, the energy required for the transmission of pulses of the nature shown in the Fi ures 1b, 1c and 1d is decided by the surface area of the pulses. This energy is materially lower than the energy required for the transmission of the signals shown in Figure 1a. The same remark applies to the mean energy. The'use of a transmitter of identical power therefore permits oi the pulses shown in Figures 117, 1c and 1d being emitted with considerably larger amplitudes and with greater steepness. This ensures a more favourable signal hiss ratio on the receiver side than in the case of transmitting the signals shown in Figure 1a, particularly if receivers sensitive to the flank steepness are used.

Figure 2 shows a transmitter device for emitting pulses of the nature shown in Figure 11) by wireless telegraphy. This transmitting device comprises a key I, a device 2 for the conversion of telegraphic signals into pulses of the nature shown in Figure 111, an amplifier 3 and a transmitter 4, in which a carrier wave is so modulated by the amplified pulses that carrier wave pulses are obtained, and in addition an aerial 5 by which the high-frequency oscillations are emitted.

At the beginning of a dash to be transmitted the key I is moved to the left with the result that a condenser 6 becomes charged across a resistance 1 until the starting-up voltage of a gridcontrolled gaseous discharge tube 8 is reached. At this moment the condenser E. is suddenly discharged across the tube 8 with the result that a pulse-like voltage as represented in Figure 3 by the impulse Ill is set up across a resistance 9 in the cathode lead of the tube 8. Concurrently with the charging of the condenser 6 a condenser ll becomes charged across a resistance l2. Due to the fact that the time constant of the charging circuit of the condenser ll exceeds that of the charging circuit of the condenser 6, the start-. ing-up voltage of the grid-controlled gaseous discharge tube It is reached slightly later than the 3 starting-up voltage of the tube 0. The startingup of the tube I3 brings about a sudden discharge of the condenser II with the result that as before a pulse is set up across the resistance said pulse being designated I4 in Figure 3 and occurring slightly later than the pulse I0.

At the end of the dash the key is moved to the right with the result that a condenser I5 becomes charged via a resistance I0 and, as the startingup voltage of a grid-controlled gaseous discharge tube I8 is reached, gets discharged across this tube and sets up a pulse across the output resistance 9. This pulse is designated I1 in Figure 3.

At the beginning of the next signal two pulses I0 and I9 are set up in succession in an identical manner, whereas at the end of the signal a single pulse is obtained.

The pulses obtained in succession across the resistance 8 are caused after amplification by an amplifier sin the transmitter I to modulate a carrier wave.

In the embodiment described, the grid circuits of the tubes 0, I0 and I6 include a common source of bias. If the bias voltages of the tubes 8, I3 and I0 are made singly variable the starting-up voltages can be so adjusted that the pulses generated by the tubes have an identical absolute height.

The device described also permits of settingup pulses of the nature shown in Figure 1d. In this case it is, however, necessary for the key I to be arranged so as to be moved into the lefthand position for setting up dashes, into the righthand position for setting up dots and to occupy an intermediate position of equilibrium in the intervals between the signals.

It is not essential that the tubes 8, I3 and I 6 should be constituted by grid-controlled gaseous discharge tubes. It is directly possible to use standard neon tubes in the circuit described but in this case the starting-up voltage is no longer adJustable. In addition, the value of the voltage pulse across the output resistance is decided approximately by the difierence between the starting-up and the operating voltages of the tubes. In this case, the amplitude of the voltage pulses set up is therefor generally smaller and amplification of the pulses before they are fed to the transmitter will be necessary.

In practice it has been found that in the use of neon tubes a common output resistance 9 in the cathode lead of the tubes does not involve any difficulty. In the use of grid-controlled gaseous discharge tubes it is desirable to employ the circuit arrangement shown in Figure 4. In this case, relative influencing of the tubes 8, I3 and I 8 is avoided by including a separate resistance 2|, 22 and 23 respectively in the cathode lead of each of the tubes and the feeding the voltages set up across these resistances via

decoupling resistances

24, 25 and 26 respectively to a common output resistance 21.

A device for the reception of pulses of the nature shown in Figure 1a is shown in Figure 5, the oscillations received in the aerial I00 being led to a receiver IGI which is arranged in the usual manner and in which after detection pulses of the nature shown in Figure 1b are set up. These pulses are fed, in some cases via'a transfer device I02, later to be more fully described, to a device I03 which serves for the conversion of pulses into telegraphic signals. The telegraphic signals set up in the output circuit of the device I03 are fed to a reproduction device are.

The device I 03 comprises two discharge tubes I05 and I08, the anode circuit of one tube being connected to the grid circuit of the other tube, as in the case oi. the well-known kalirotron circuit arrangement which, as is well-known, has two positions of equilibrium in which either the tube I05 allows the passage of current and the tube I06 is blocked or conversely.

In the oil position the tube I00 allows current to pass and the tube I00 is disrupted. If the pulses received are then fed to the grid oi. the tube I00, as shown in the figure, and this is effected in such manner that the grid of the tube becomes more positive, the circuit continues occupying the said position of equilibrium. In order to ensure that on reception of two associated pulses at the beginning of each signal the circuit passes to the other position of equilibrium, 9. tube I01 is connected in parallel with the tube I00 and has the received pulses fed to it via a resistance I08. In addition, a condenser I I0 shunted by a very high resistance I00 is interconnected between the grid and the cathode of the tube I01. In the of! position, the tube I01 is disrupted by means of a source of bias III. The time constant of the integrating network formed by the elements I00, I09 and H0 is chosen to be such that only after reception of two pulses in quick succession the voltage set up by the pulses across the condenser 0 has increased to such an extent that the negative bias of the tube I01 is balanced at least in part and the tube I01 is rendered conductive. As soon as anode current passes in the tube I01 a voltage drop is set up across a resistance II2, which is included in the grid circuit of the tube I06 and puts this tube out of operation, the tube I05 becoming thus conductive.

At the beginning of the second of two associated pulses a voltage drop is consequently set up across a resistance I I3 in the cathode lead of the tube I05, said voltage drop subsisting until under the influence of the single pulse received at the end of the signal the tube I06 is again rendered conductive so that the tube I05 is disrupted. Thus, telegraphic signals are consequently received across the resistance I I3 and are fed to the reproduction device It.

In order to secure a stable operation of the device I03 it is desirable that the pulses fed to the latter should have identical amplitude at all times. For this purpose, provision is made for a device I02, which is constituted for example by a limiter. Preferably, however, it is constituted by a device for generating pulses which is normally disrupted and is governed by the pulses received.

One form of construction of such a device is shown in Figure 6. The device concerned is constituted by a relaxation generator comprising a condenser H4 which can be charged across a resistance H5 and can be discharged across a relay tube IIG, each time the grid of the tube II6 has fed to it a received pulse. At each dis charge of the condenser a pulse-like voltage can be obtained via a resistance II1 included in the cathode lead.

In order to prevent disturbances which are set up between the pulses-and whose amplitude is of pulses corresponding said mark signals, the

wave radio telegraphy signals of the mark-space type, comprising the steps of converting the mark signals into pulse signals of substantially constant duration and spaced in time corresponding to the duration of said mark signals, the pulse signals corresponding to the initiation of said mark signals being different in number from those corresponding the the termination thereof, transmitting said pulse signals through space, receiving said signals, and converting said pulse signals back to said mark signals thereby reproducing said telegraphy signals.

2. A method of communicating by continuous wave radio telegraphy signals of the mark-space type, comprising the steps of converting the mark signals into pulse signals comprising a pair of pulses corresponding to the initiation or said mark signals and a single pulse corresponding to the termination of said mark signals, transmitting said pulse signals through space, receiving said pulse signals, and converting said received pulse signals back to said mark signals thereby reproducing said telegraphy signals.

3. A method of communicating by continuous wave radio telegraphy signals of the dot-spacedash type, comprising the steps of converting the dot signals into pulse signals comprising a single pulse corresponding to the initiation and termination of said dot signals and converting the dash signals into pulse signals comprising a. pair to the initiation of said dash signal and a single pulse corresponding to the termination of said dash signal, transmitting said pulse signals through space, receiving said pulse signals, and converting said received pulse signals back to said dot-space-dash signals thereby reproducing said telegraphy signals.

4. A method of communicating by continuous wave radio telegraphy signals of the dot-anddash type, comprising the steps of converting the dot signals into pulse signals comprising a single pulse corresponding to the initiation of said dot signals and converting the dash signals into pulse signals comprising a pair of pulses corresponding to the initiation of said dash signals, transmitting said pulse signals through space, receiving said pulse signals, and converting said received pulse signals back to said dot-and-dash signals thereby reproducing said telegraphy signals.

5. Apparatus for communicating by means of continuous wave radio telegraphy signals of themark-space type, comprising a gaseous discharge tube device to convert the mark signals into pulse signals of substantially constant duration and spaced in time corresponding to the duration of pulse signals corresponding to the initiation of said mark signals being different in number from those. corresponding to the termination thereof, means to transmit said pulse signals through space, means to receive said transmitted pulse signals, and a second discharge tube device to convert said pulse signals back to said mark signals thereby to reproduce said telegraphy signals.

6. Apparatus for communicating by means of continuous wave radio telegraphy signals of the mark-space type, comprising a gaseous discharge tube device to convert the mark signals into pulse signals comprising a pair of pulses corresponding to the initiation of the mark signals and a single pulse corresponding to the termination of said mark signals, means to transmit said pulse signals through space, means to receive said transmitted pulse signals, and a second discharge tube device to convert said pulse signals back to said mark signals thereby to reproduce said telegraphy signals.

7. Apparatus for communicating by means of continuous wave radio telegraphy signals of the dot-and-dash type, comprising a gaseous discharge tube device to convert the dot signals into pulse signals comprising a single pulse and to convert the dash signals into pulse signals comprising a pair of pulse signals through space, means to receive said transmitted pulse signals, and a second discharge tube device to convert said pulse signals back to said mark signals thereby to reproduce said telegraphy signals,

8. Apparatus for communicating by means of continuous wave radio telegraphy signals of the dot-and-dash type, comprising a gaseous discharge tube device to convert the dot signals into pulse signals comprising single pulses corresponding to the initiation and termination of said dot signals and to convert the dash signals into pulse signals comprising a pair of pulses corresponding to the initiation of said dash signals and a single pulse corresponding to the termination thereof, means to transmit said pulse signals through space, means to receive said transmitted pulse signals, and a second discharge tube device to convert said pulse signals back to said mark signals thereby to reproduce said telegraphy signals.

9. Apparatus for keying a continuous wave transmitter for radio telegraphy transmission of the mark-space type wherein the initiation and termination of each mark signals is represented by a different number of pulses of substantially constant duration, said duration being short in comparison to the duration of said mark signal, comprising a plurality of capacitors, each of said capacitors having a charging circuit and a discharging circuit, the discharging circuit of at least one of said plurality of capacitors having a time constant difierent from the remainder of said capacitors, means responsive to the initiation of said mark signal simultaneously to charge a given number of said plurality of capacitors, means to discharge said given number of said plurality of capacitors across the discharging circuit thereof, means responsive to the termination of said mark signal to charge a different number of capacitors, means to discharge said different number of capacitors across the discharging circuit thereof, and means to connect the discharging circuits of said capacitors to said transmitter.

10. Apparatus for keying a continuous wave transmitter for radio telegraphy transmission of the mark-space type wherein the initiation and termination of each mark signal is represented respectively by a pair of pulses and a single pulse of substantially constant duration, comprising a first, a second and a third capacitor, each of said capacitors having a charging circuit and a discharging circuit, the discharging circuits of said first and said second capacitors having different time constants, means responsive to the initiation of said mark signal simultaneouslyuto charge said first and said second capacitors} means to discharge said capacitors in succession across the discharging circuits thereof, means responsive to the termination of said mark signal to close the charging circuit of said third capacitor, means to discharge said third capacitor across the discharging circuit thereof,

pulses, means to transmit said and means to connect the discharging circuits of said capacitors to said transmitter.

11. Apparatus for keying a continuous wave transmitter for radio telegraphy transmission of the dot-and-dash type wherein the initiation and termination of each dot signal is represented respectively by a single pulse and the initiation and termination of each dash signal is represented by a pair of pulses and a single pulse of substantially constant duration, comprising a first, a second and a third capacitor, each of said capacitors having a charging circuit and a discharging circuit, the discharging circuits of said first and said second capacitors having difierent time constants, means responsive to the initiation of said dash signal to close the charging circuits of said first and said second capacitors simultaneously to charge said first and said second capacitors, means to discharge said capacitors in succession across the discharging circuits thereof, means responsive to the termination of said dash signal to close the charging circuit of said third capacitor, means responsive to the inititation and termination of said dot si nal to charge said third capacitor, means to discharge said third, capacitor across the discharging circuit thereof, and means to connect the discharging circuits of said capacitors to said transmitter.

12. Apparatus for keying a continuous wave transmitter for radio telegraphy transmission of the dot-and-dash type wherein the initiation of each dot signal is represented respectively by a single pulse and the initiation of each dash signal is represented by a pair of pulses of substantially constant duration, comprising a first, a second and a third capacitor, each of said capacitors having a charging circuit and a discharging circuit, the discharging circuits of said first and said second capacitors having different time constants, means responsive to the initiation of said dash signal to close the charging circults of said first and said second capacitors simultaneously to charge said first and said second capacitors, means to discharge said capacitors in succession across the discharging circuits thereof, means responsive to the initiation of said dot signal to close the charging circuit of said third capacitor, means to discharge said third capacitor across the discharging circuit thereof, and means to connect the discharging circuits of said capacitors to said transmitter.

13. Apparatus for keying a continuous wave transmitter for radio telegraphy transmission of the mark-space type wherein the initiation and termination of each mark signal is represented respectively by a pair of pulses and a single pulse of substantially constant duration, comprising a first, a second, and a third capacitor, each of said capacitors having a charging circuit and a discharging circuit comprising a gaseous discharge transmitter for radio telegraphy transmission of "the mark-space type wherein the initiation and tube and a resistor, the discharging circuits of said first and said second capacitors having different time constants, means responsive to the initiation of said mark signal to close the charging circuits of said first and said second capacitors simultaneously to charge said first and said second capacitors, means comprising the gaseous discharge tubes of the respective discharging circuits to discharge said capacitors in succession across said resistor, means responsive to the termination of said mark signal to close the charging circuit of said third capacitor to charge said capacitor, means comprising the gaseous discharge tube of the respective discharging circuit to distermination of each mark signal is represented respectively by a pair of pulses and a single pulse of substantially constant duration, comprising a first, a. second and a third capacitor, each of said capacitors having a charging circuit and a discharging circuit comprising a grid-controlled gaseous discharge tube and a discharging resistor, the discharging circuits of said first and said second capacitors havin different time constants, means responsive to the initiation of said mark signal to close the charging circuits of said first and said second capacitors simultaneously to charge said first and said" second capacitors. means comprising the respective grid-controlled gaseous discharge tube of said discharging cir-.

cuits to discharge said first and said second capacitors in succession across the discharging resistors of the respective discharging circuits, means responsive to the termination of said mark signal to close the charging circuit of said third capacitor to charge said third capacitor, means comprising the respective grid-controlled gaseous discharge tube to discharge said third capacitor across the discharging resistor of the respective discharge circuit, and means to connect the discharging circuits of said capacitors to said transmitter.

15. Apparatus for keying a continuous Wave transmitter for radio telegraphy transmission of the mark-Space type wherein the initiation and termination of each mark signal is represented respectively by a pair of pulses and a single pulse of substantially constant duration; comprising a first, a second and a third capacitor, each of said capacitors having a charging circuit and a discharging circuit, said discharging circuits comprising a grid-controlled gaseous discharge tube for each of the respective capacitors coupled to a common discharging resistor, the discharging circuits of said first and said second capacitors having difierent time constants, means responsive to the initiation of said mark signal to close the charging circuits of said first and said second capacitors simultaneously to charge said first and said second capacitors, means comprising the respective grid-controlled gaseous discharge tube of said discharging circuits to discharge said first and said second capacitors in succession across said common discharging resistor, means responsive to the termination of said mark signal to close the charging circuit of said third capacitor to charge said third capacitor, means comprising the respective grid-controlled gaseous discharge tube to discharge said third capacitor across said common discharging resistor, and means to connect said discharging resistor to said transmitter.

16. Apparatus for keying a continuous wave transmitter for radio telegraphy transmission of the mark-space type wherein the initiation and termination of each mark signal is represented respectively by a pair of pulses and a single pulse of substantially constant duration, comprising a first, a second and a third capacitor, each of said capacitors having a charging circuit and a discharging circuit comprising a grid-controlled gaseous discharge tube, a coupling resistor and a discharging resistor, the discharging circuits of said first and said second capacitors having diflerent time constants, means responsive to the initiation of said mark signal to close the charging circuits of said first and said second capacitors simultaneously to charge said first and said second capacitors, means comprising the respective grid-controlled gaseous discharge tube of said discharging circuits to discharge said first and said second capacitors in succession across the discharging resistors of the respective discharging circuits, means responsive to the termination of said mark signal to close the charging circuit of said third capacitor to charge said third capacitor, means comprising the respective gridcontrolled gaseous discharge tube to discharge said third capacitor across the discharging resistor of the respective discharge circuit, and I means comprising said coupling resistors to couple said discharging resistors to said transmitter. 1'7. Apparatus for receiving continuous wave radio telegraphy signals of the mark-space typewherein the initiation and termination of each mark signal is represented respectively by a difierent number of pulses of substantially constant duration, comprising a first gaseous discharge tube having an input circuit and an output circuit, a second electron discharge tubehaving an input circuit coupled to the output circuit of said first electron discharge tube and an output circuit coupled to the input circuit of said first electron discharge tube to render said second tube conducting when said first tube is non-conducting and conversely to render said second tubenon-conducting when said first tube is conducting, a. discharging circuit coupled to said first tube and being responsive only to the greater number of said pulses, means to apply said signals to the input circuit of said first tube, and means coupled to the output circuit of said second tube to reproduce said signals.

18. Apparatus for receiving continuous wave radio telegraphy signals of the mark-space type wherein the initiation and termination of each mark signal is represented respectively by a pair of pulses and a single pulse of substantially constant duration, comprising a first electron discharge tube having an input circuit and an output circuit, a second electron discharge tube having an input circuit coupled to the output circuit of said first electron discharge tube and an output circuit coupled to the input circuit of said first electron discharge tube to render said second tube conducting when said first tube is nonconducting and conversely to render said second tube non-conducting when said first tube is conducting, a discharging circuit coupled to said first tube and being responsive only to said pair of pulses, an integrating network coupled to the input circuit of said first tube, means to apply said signals to said integrating network, and means coupled to the output circuit of said second tube to reproduce said signals.

19. Apparatus for receiving continuous wave radio telegraphy signals of the mark-space type wherein the initiation and termination or each mark signal is represented respectively by pairs of pulses and a single pulse of substantially constant duration, comprising a first electron discharge tube having an input circuit and an output circuit, a second electron discharge tube having an input circuit coupled to the output circuit of said first electron discharge tube and an output circuit coupled to the input circuit of said first electron discharge tube to render said second tube conducting when said first tube is nonconducting and conversely to render said second tube non-conducting when said first tube is conducting, a discharging circuit coupled to said first tube and being responsive only to said pairs of pulses, a pulse signal generator coupled to the input circuit of said first tube, means to apply said signals to said pulse signal generator, and means responsive to the output of said second tube to reproduce said signals.

20. Apparatus for receiving continuous wave radio telegraph signals of the mark-space type wherein the initiation and termination of each mark signal is represented respectively by pairs of pulses and a single pulse of substantially constant duration, comprising a first electron discharge tube having an input circuit and an output circuit, a second electron discharge tube having an input circuit coupled to the output circuit of said first electron discharge tube and an output circuit coupled to the input circuit of said first electron discharge tube to render said second tube conducting when said first tube is nonconducting and conversely to render said second tube non-conducting when said first tube is conducting, a discharging circuit coupled to said first tube and being responsive only to said pairs of pulses, a pulse signal generator coupled to the input circuit of said first tube and being responsive only to signals having an amplitude above a predetermined threshold value, means to apply said signals to said pulse signal generator, and means responsive to the output of said second tube to reproduce said signals.

HERMAN BERNARD RUDOLF BOOSMAN. TJISKE DOUMA. miss POSTHUMUB.

REFERENCES crrm) The following references are of record in the file of this patent:

UNITED STATES PATENTS 540,233 Great Britain Oct. 9, 194-1