NO119851B - - Google Patents

Description

Automatic alarm signal receiver.

The present invention relates to an automatic alarm transmitter for certain signals, in particular for the pre-signal of SOS. Devices of this type must, e.g. monitor radio signals regarding distress at sea, to determine whether there is an alarm signal among the received signals. Such an alarm signal ideally consists of 12 characters, each lasting 4 seconds with intermediate pauses each of 1 second. The length of the characters can then be allowed to fluctuate between 3.5 and 6 seconds and the pauses between 0.01 and 1.5 seconds. When three consecutive characters and the intervening pauses meet these conditions, the device must trigger an alarm.

A device is known in which a signal is triggered by an electromagnetic relay being connected to a rectifier tube which, upon the arrival of an SOS pre-signal or a permanent signal with a similar time constant, causes the relay to operate. Below this, a direct current will be interrupted when the pre-signal arrives. With these Morse pulses, the cathode of the rectifier tube is cooled so much that the anode current ceases. The relay arranged in the anode circuit is thereby demagnetized and thereby ends the alarm current circuit. However, this device cannot be tuned so precisely that it in practice only responds to emergency signals, and therefore often gives a false alarm.

A device working with electronic relays has also been proposed, whereby an alarm is triggered when three successive characters have a length from a to b seconds, e.g. 3.5 to 6 seconds and the intermediate pauses have a length of c to d sec., e.g. 0.01 to 1.5 seconds. In this case, an electronic counting device is arranged by which the alarm is triggered. At the device's entrance are two electronic relays with an action delay of d seconds. One of these relays firstly causes a further electronic relay with a delay of e = a — d seconds to react and secondly, when it fails, it causes a pulse to be sent to a blocking stage, which, if it does not is blocked by the relay that has reacted with a one-second delay, this pulse passes on to a zero step which with each pulse erases any correct pulses previously recorded by the counting step, — while the other relay located at the input reacts when a pause lasts longer than d seconds. It then gives a pulse to the zero stage either directly or via the blocking stage. The relay with a delay of e seconds affects, firstly, a further electronic relay with a delay of f = b — a seconds, which relay, when returning, gives a pulse directly or above the blocking stage to the zero stage, and secondly, when it drops out, gives a pulse to the counter stage.

However, this entails the disadvantage that the delay time for the two input relays is strongly dependent on the height of the disturbance level when the disturbance voltage is no longer small in relation to the required useful voltage. The present invention solves the task of avoiding this disadvantage, and also further simplifying the electronic alarm transmitter's structure.

According to the invention, an input stage is provided which only passes on such characters to the following stages whose size is above this input connection's reaction threshold. It controls an electronic relay with an action delay of d seconds, and releases the reaction of a further electronic relay with a reaction delay of e seconds, which is then activated by the relay with a d second delay. When the relay has reacted, it gives a pulse to the counting step with a delay of e seconds. Furthermore, a relay is affected with a delay of f seconds, which relay, when it has reacted in the same way as the relay with a delay of d seconds, causes an extinguishing stage to operate. Likewise, means are arranged which cause the extinguishing stage to only pass on the extinguishing pulses to the counting stage when the relay with the delay of e seconds is in rest position.

With the aid of the embodiment shown in the drawing, the invention is explained in more detail.

Fig. 1 shows a detailed connection diagram and fig. 2 a block diagram.

The device essentially consists of a counting stage 6, 7, which is formed by the pipes Rø 9 and Rø 10 and several electronic relays 2, 3 and 4.

The operation of these relays is explained by relay 4, which has a delay of 2.5 seconds and is formed using the 1.

(on the drawing on the left) system of the double tube Rø 7 (system Rø 7/1) and the double tube Rø 8. In contrast to the known flip-flop connections, the cathodes in the tube Rø 8 do not have the same potential. The cathode in the first system is given a positive bias Uk, which is less than the tube's operating voltage Ub. As a result of the increase in the voltage on the cathode, the tube's first system can be supplied with a control voltage which is either positive or negative in relation to the cathode potential. — Here is an explanation of what is meant by "raising the cathode": The applied control voltages are always positive, i.e. greater than zero. If the cathode is now at zero potential, the positive control voltage is always positive opposite the cathode. At a positive cathode potential (raising the cathode), on the other hand, the positive control voltage can be greater or less than the voltage on the cathode, i.e. it can be positive or negative just opposite the cathode potential. — In the resting state, the control gate of the 1st (left) system of the tube Rø 7 — which is connected in front of the tube Rø 8 — is at the cathode potential, i.e. the tube is open. Its internal resistance forms a bridge over a capacitor C 12 lying in parallel between the resistance W 38 and the zero potential. As a result, there is

the grid of the tube Rø 8 first system by correct adaptation of the resistors W 35 to W 39 a lower voltage in relation to the cathode voltage Uk. The grid therefore has a negative bias, and the tube is blocked. The voltage divider, which consists of the anode resistance W 40 in the first system of the tube Rø 8 and two further resistors W 43 and W 44, and which lies between the operating voltage Ub and the negative bias voltage U , is adapted so that when the first system in the tube Rø 8 is blocked, i.e. ., when no anode current passes through the resistor W 40, the second system of the pipe Rø 8 will inevitably have a grid bias drawn between the resistors W 43 and W 44 and thus be open. In the rest position, the first system of pipe Rø 7 and the second system of pipe Rø 8 are therefore open, and the first system of pipe Rø 8 is blocked.

If the pipe's Rø 7 first system is now blocked, i.e. the relay is to be brought into operation, then the voltage appearing on the capacitor C 12 rises. Corresponding to the time constant of the RC link formed by the resistor network and the capacitor, the voltage on the tube Rø 8's first system grid rises so much that the anode current sets in. Due to the associated larger voltage drop across the resistor W 40 in the voltage divider W 40, W 43 and W 44, the voltage on the grid in the tube Rø 8 other system drops. Thereby, the current passing through the resistors W 41 and W 42 located in the anode current circuit also decreases, while the potential at the connection point for these two resistors and thus on the first grid of the tube Rø 8 rises. This process now continues regardless of the further charging of the capacitor C 12 until the grid current sets in at the first system of the pipe R 8 . Due to the anode current then flowing through the resistance W 40, the negative voltage on the grid in the second system of the tube Rø 8 becomes so great that this is completely blocked. During operation, the first system of pipe Rø 7 and the second system of pipe Rø 8 are therefore blocked, while the first system of pipe Rø 8 is open.

By suitably dimensioning the resistors W 38 and W 39, it is achieved that the changeover from one state to the other takes place relatively quickly. The resulting voltage jumps are differentiated and used as switching pulses. If the first system of the tube Rø 7 is opened again, the capacitor C 12 discharges over this tube's anode-cathode section. As soon as the grid in the first system of the tube Rø 8 becomes negative in relation to the cathode, the tube Rø 8 two systems falls back to its rest position. This return time is short compared to the delay time.

Relays 2 and 3 formed by tubes Rø 3 and Rø 4 and tubes Rø 5 and Rø 6 respectively work in essentially the same way. The function of capacitors C 12 and resistors W 38 to W 44 is taken over by capacitor C 7 and resistors W 16 to W 22 respectively the capacitor C 10 and the resistors W 26 to W 34.

The relay 2 formed by the tubes Rø 3 and Rø 4 with a 1.5 second delay directly opposite the relay 4 certainly shows a property in that a double triode Rø 3 is connected in front of the tube Rø 4 bistable connection. This is necessary because, as will be explained later, this relay checks compliance with the shortest pause duration of 0.1 second. Therefore, the capacitor C 7 must be able to discharge itself very quickly via the pipe's Rø 3 other system.

If the input stage 1 described in the following emits a positive pulse upon the arrival of a character, then this will only reach the grid in the pipe Rø 3 other system via the diode Gr 2 and the capacitor C 5, while it will be prevented from reaching the grid in the first system with the grid shunt resistor W 9 by means of the oppositely polarized diode Gr 1. The previously blocked second system due to the negative grid bias applied across the resistor W 15 is opened, and due to the voltage drop across the resistors W 11 and W 12, the anode voltage drops. This negative voltage surge reaches across the capacitor C 3 to the grid in the first system. This is blocked and the voltage at its anode rises, as there is no longer any voltage drop across the anode resistor W 10. This positive voltage surge reaches across the capacitor C 6 to the grid in the open second system with the grid diversion resistors W 13 and W 14 and prevents an increase in the internal resistance, so the capacitor C 7 can be discharged very quickly. The time constant of the participating RC links is adjusted so that the capacitor C 7 is discharged during this process so that its terminal voltage becomes a fraction of the original one. Now the grid voltage in the pipe's Rø 3 second system has again acquired a negative potential, i.e. the pipe system is again blocked. By a reaction of the input stage 1, a negative pulse reaches across the diode Gr 1 and the capacitor C 4 to the grid in the tube R 3 first system, while it is prevented from reaching the second system by means of the diode Gr 2. The hitherto open system is blocked , the anode voltage rises so that a positive pulse goes over the capacitor C 6 to the grid in the blocked second system and opens this. The interaction between the two systems is the same as before, so that the capacitor C 7 can again be discharged very quickly. The difference when compared with the first case lies only in the fact that the process does not begin at the pipe's Rø 3 second system but at the first. The individual device parts are dimensioned such that the relay switches immediately upon the arrival of a pulse and after a period of 1.5 seconds again returns to the rest position. This is the opposite of what applies to relays 3 and 4.

This relay, which is formed by pipes Rø 5 and Rø 6 and which has a delay of 2 seconds, is controlled by two factors. On the arrival of a character, the pipe's Rø 2 other system is blocked and thus also the pipe's Rø 5 other system. However, the relay only reacts when the tube's Rø 5 first system is also blocked. This happens when relay 2 with pipes Rø 3 and Rø 4 reacts. As it must be prevented that the capacitor C 10 discharges earlier than the capacitor C 7 at the end of the sign — because otherwise, after the counting pulse transmitted over the capacitor C 17, a quenching pulse to the counting stage would immediately follow via the capacitor C 8 and the tube Rø 7/2 — it is arranged a delay link with the resistor W 23 and the capacitor C 9. The grid drain resistors W 22 and W 23 are arranged in the usual way, as are the anode resistors W 24 and W 25. The condition for the relay to react is therefore the arrival of a character and that the relay 2 works.

Input stage 1, consisting of the first system of pipe Rø 1 (Rø 1/1) and pipe Rø 2, works essentially according to the same principle as the relays, but has some peculiarities with regard to dimensioning. It has the task of first reacting when a certain voltage is exceeded and then immediately switching over, and at as close to the same voltage value as possible to fall back to the starting position. The resistance W 3 is therefore smaller than in steps 2, 3 and 4, and the return of the voltage from the anode in the second system by the pipe Rø 2 to the first system takes place directly from the anode and not via a voltage divider. Instead of the two resistors W 41 and W 42 in step 4, only one resistor W 6 is arranged here. The resistors W 2, W 4, W 5, W 7 and W 8 as well as the capacitor C 1 correspond in their operation to the resistors W 39, W 40, W 43, W 44 and the capacitor C 12. However, the capacitor C 1 is significantly smaller so that the delay time of this stage only varies to a few milliseconds. Instead of the resistors W 36 and W 37, only one resistor W 2 is arranged. The grid diversion resistor for the tube Rø 1/1 is denoted by W 1. The capacitor C 2 serves to give the pulses emitted at the envelope steeper flanks. It is the stage's task to first switch over at a specific input voltage and thereby put the following stages into operation. Disturbances from lower voltages are thus kept away, and the delay times of the electronic relays remain constant, regardless of whether a disturbance level of a certain voltage was already present.

The counting stage 6, 7 consisting of the pipes Rø 9 and Rø 10 has the task of notifying the grid in the second system of the pipe Rø l, the so-called trigger step 8, such a voltage after the arrival of 3 successive correct signs that this system is opened. For this purpose, the counter stage is built up of two normal flip-flop connections with resistors W 45 to W 52 and W 55 to W 64. The resistors W 45 and W 47 respectively W 55 and W 57 are together with great accuracy the same size as the resistors W 53 and W 63 respectively, so that the structure's symmetry is not damaged. The arrangement with the two resistors is only made with the intention that from the connection point above the resistors W 46 and W 56, respectively, a voltage of a suitable size can be extracted for controlling the release stage 8. The capacitors C 15, C 18, C 21 and C 23 serve known way to give the pulses steeper flanks. The connection of pipes Rø 9 and Rø 10 to the pipe Rø 7's other system takes place via capacitors C 14, C 19 and diodes Gr 3, Gr 4. With the diodes, it is achieved that only negative pulses reach the stages and that the two stages are not connected with each other over the bars.

The pipe Rø 9 is further controlled via the condenser C 17 by the pipe Rø 6's other system. The capacitor C 11 which is arranged for this system serves to give the switching pulses steeper flanks. The tube Rø 7/2 in step 5 only amplifies positive pulses (thus emits negative pulses) and this only when the tube Rø 6 is in the rest position, because the working point is otherwise too far into the negative area. Stages 6 and 7, respectively the tubes Rø 9 and Rø 10, are further connected to each other via the capacitor C 20. Cathode capacitors are denoted by C 16 and C 22. The operation of the counting stage is as follows: In the resting state, the two tubes Rø 9 and Rø 10 are the first systems blocked, and the other systems open. In the connection points between the resistors W 45 and W 47, respectively W 55 and W 57, there is then a voltage that exceeds the resistors W 46 and W 56 serving to switch off the two flip-flop connections also becomes effective on the grid in the other system of the tube Rø 1 and lies below its cathode potential, so that the release stage 8 is blocked. It is only opened when the first two systems of the pipes Rø 9 and Rø 10 have been opened, as the grid only then has at least cathode potential. C 24 is located at the grid of this tube and causes a slight delay in the release, which is necessary in the later described error case III.

When now, upon the arrival of a correct sign across the capacitor C 17 from the relay's 3 tube Rø 6, a negative counting pulse reaches the tube Rø 9, then the bistable system formed by this tube switches over in a known way, that is, the left system is opened and the right is blocked. Hereby, a positive pulse is given over the capacitor C 20 to the tube Rø 10 which, however, does not influence the bistable system. Now the pipe Rø 9's first system and the pipe Rø 10's second system are now opened, so that the release step still remains blocked. When another negative counting pulse is sent across the capacitor C 17 to the tube Rø 9, the bistable system switches back to its initial position. At the same time, a pulse is again given to tube Rø 10, which this time, however, is negative, so that the bistable system formed by this tube likewise switches over. After the second sign, pipe Rø 9's second system and pipe Rø 10's first system are thus opened. Trigger stage 9 still cannot come into operation. On the arrival of a third correct character, tube Rø 9 switches again, i.e. tube Rø 9's first system is opened again and gives a positive pulse to tube Rø 10, which pulse does not influence this tube. Now both tubes' first systems are opened, so that the grid in the tube's Rø 1 second system achieves cathode potential. The release step 8 then comes into operation.

However, it is not satisfactory if the alarm is only triggered after the arrival of three correct characters; it must also be ensured that in the case of intermediate false characters, or pauses, the counting stage is switched back to the starting position. This task is solved by the fact that on the arrival of a false signal, the pipe's Rø 7 (stage 5) gives another system above the capacitors C 14, C 15 and the rectifiers Gr 3, Gr 4 an extinguishing pulse to both pipes, whereby the pipes Rø 9 and Rø 10 the first two systems are blocked and the counting stage is thereby brought back to the starting position.

The entire device operation will be explained in more detail in connection with the operating cases that are possible.

1. Operating case.

A character is longer than 3.5 and shorter than 6 seconds, the pause is longer than 0.01 and shorter than 1.5 seconds. For simplicity, a character duration of 4 seconds and a pause duration of 1 second are assumed.

At the beginning of the character, the input stage switches with tubes Rø 1/1 and Rø 2

change to a working position as soon as the reaction threshold is exceeded. The resulting voltage jump is differentiated and given as a pulse to relay 2, which immediately switches over and after 1.5 seconds returns to its rest position. The pulse given by this across the capacitor C 8 to the pipe's Rø 7 (stage 5) other system is negative, thus has no effect.

At the same time, the pipe's Rø 5 first system is blocked, while the second system had already been blocked when the input stage switched over. Relay 3 (Rø 5 and Rø 6) switches after 2 seconds. After a further 0.5 seconds, the sign ends, whereby relay 2 switches over and relay 3 returns to its rest position. Hereby, a negative pulse is emitted from the anode in the tube Rø 6's other system across the capacitor C 17 to the tube Rø 9 and switches this.

After a pause of 1 second, the entire process repeats itself, the tube Rø 9 (step 6) returns to the initial position and gives a negative pulse to the bistable coupling 7, whereby the tube Rø 10 switches over. After the arrival of 3 characters, as already described, Rø 1/2 becomes live and triggers the alarm, e.g. over a relay.

2. Failure case I:

A character is longer than 1.5 and shorter than 3.5 seconds.

The process is the same as in case 1 until the pipe R 4 wraps. As the sign ends before tube Rø 6 switches over, the counting step is not affected from there. A positive pulse arising at the end of the symbol at pipe Rø 4 reaches the pipe Rø 7 (switch-off stage 5) other system and is amplified when the pipe Rø 6 (relay 3) is in the output position and connects as a negative pulse the pipes Rø 9 and Rø 10 back to their starting position.

3. Failure case II:

A character is shorter than 1.5 seconds. At the beginning of the character, as already described, a pulse reaches step 2. However, since the character ends before the delay time of 1.5 seconds has elapsed, neither counting nor switching off can take place. Switching off does not take place in this case, to avoid that short disturbance characters within the normal pause between characters would prevent an alarm from being triggered.

4. Failure case III:

A character is longer than 6 seconds. The first sequence is the same as in case 1. After relay 3 (Rø 6) switches, the first system of pipe Rø 7 is blocked, whereby after the delay time of 2.5 seconds has elapsed, pipe Rø 8 switches over (relay 4). At the end of the character, the sequence as under 1 takes place, then as the last step the tube Rø 8 returns to the starting position. The resulting positive pulse reaches across the capacitor C 13 to the tube Rø 7's second system, which acts as extinguishing stage 5, and is amplified when the tube Rø 6 is already back in the rest position. It then switches the pipes Rø 9 and Rø 10 back to the initial position as a negative pulse.

5. Failure case IV:

A pause is shorter than 0.01 seconds. For pauses shorter than 0.01 seconds, the input stage does not return to the initial position. The following character is thus added to the first and gives a character that lasts longer than 6 seconds. The course then takes place as in case 4.

6. Failure case V:

A pause is longer than 1.5 seconds.

In the case of pauses lasting longer than 1.5 seconds, after the preceding characters have ceased, tube Rø 4 returns to its rest position, as its delay time amounts to 1.5 seconds. However, when the input stage is in its rest position, the pipe Rø 5's other system remains open and the pipe Rø 6 is not switched. At the beginning of a new character, the tube Rø 4 switches over; the resulting positive pulse brings the pipes Rø 9 and Rø 10 over Rø 7/2 back to their starting position.

Claims (2)

1. Automatic alarm signal receiver calculated to trigger an alarm device upon receipt of predetermined alarm signals comprising a predetermined number of equal signal elements with a predetermined duration that lies between a and b seconds, and which are separated by intermediate equally long and predetermined pauses of between c and d seconds duration, which receiver is particularly intended for receiving the international SOS pre-signal which consists of 12 signal elements each having a duration of 4 seconds and with intermediate pauses of 1 second each, the receiver comprising an input stage, three of unsymmetrical, bistable electron tube junctions be- standing relays with different reaction delays of d, e = a — d and f = b — a seconds respectively, which relays are controlled depending on the input stage, an electronic counter stage which is controlled by the mentioned relays and triggers the alarm device, when it receives three consecutive signal elements which lie within the above-mentioned limits, and are separated by spaces within the time limits assigned to them, and a feedback stage which is also controlled by the mentioned relays and resets the counting stage to the initial or rest position, when it receives signal elements with intermediate pauses which do not satisfy the above-mentioned conditions, characterized by the fact that the input stage (1) is arranged and regulated in such a way that, firstly, it only reacts when the duration of a break is at least c seconds and then only forwards to the subsequent relays such signal elements that have amplitudes that exceed a predetermined value and thereby causes (2) of the mentioned relays to re agere, whose reaction has a delay of d seconds, and prepares the reaction of the relay (3) which during the reaction has a delay of e seconds, and which is then made to react by the first-mentioned relay after a delay of d seconds (2) with a delay of d seconds, as the latter relay (3), when it returns to its initial or resting position, emits a counting pulse to the counting stage so that all signal elements with a duration from a to b seconds cause a forwarding of the counting stage (6, 7), while the first-mentioned relay (2), when it falls, emits a feedback pulse to the extinguishing stage (5), which is, however, controlled with the help of the aforementioned second relay (3) in such a way that the feedback stage is always blocked, when the other relay (3) has reacted, but is otherwise affected by the pulses emitted from the first-mentioned relay (2) and brings the counting stage (6, 7) back to zero so that upon reception of a signal element with a duration of less than a second, any counted pulses are extinguished and further that the third electronic relay (4) with a reaction delay of f seconds is affected by the second relay (3) and reacts when the duration of a signal element exceeds b seconds and emits , when it falls at the end of the character, a return pulse to the then opened return stage (5) which therefore, in the case of a signal element of more than b seconds' duration, switches the counting stage back to zero and finally that with pauses longer than d seconds, the first electronic relay (2) which fell due to the long pauses, react at the beginning of the next signal element and thereby deliver to the counting stage (6, 7) a feedback pulse above the feedback stage (5). 2. Alarm receiver according to claim 1, characterized in that the counting stage (6, 7) consists of two bistable toggle switches each with two electron tubes (Rø 9, Rø 10) working over a common anode resistance, that the anode resistance (W 50) for the first toggle switch (Rø 9) over a capacitor (C 17) is connected to the anode of the last tube (Rø 6/2) in the electronic relay (3) with a second reaction delay and the anode resistance (W 61) of the second toggle switch (Rø 10) in the counting circuit (6, 7) over a capacitor (C 20) is connected to the anode of the first tube (Rø 9/1) in the first bistable flip-flop (Rø 9), while the grid in the first tube for both flip-flops is connected with the feedback stage ( 5) and that the change of the equilibrium state in the counting stage with a view to forwarding through the influence of the anode resistors (W 51, W 61) occurs with negative counting pulses.