DE2528854A1 - INTERCOM SYSTEM - Google Patents

Description

Pafenfanwalf Dipl. - Ing.JÖRGEN ROST

8 monks 80 9 7 lim!

Pienzenauerstr. 2, Tel. 988800 "

STOC PriO'jUZION. £ S.p.A. Homa, Italy

Vi / echselsp Rech traffic system

The invention relates to a two-way communication system, wherein The various devices in the system are all connected in parallel to a two-wire telephone line.

The term "intercom" means a device which allows the user to have a conversation without lifting a handset, with a small one Microphone for recording the voice and a small loudspeaker can be used to play back the incoming call.

The use of an intercom is as a telephone preferred if short and temporary connections are always established between two or more participants that belong to the same work area.

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The station set of an intercom system can be a To be the "main apparatus" is an apparatus that works with everyone the system subscriber can be brought into connection, with a number of auxiliary devices being provided, only with the Main set are connectable. In this case, the interconnection of the various devices is made with the aid of a Star-shaped network, with the main apparatus in the middle of the star is arranged.

Alternatively, the vs / echsel speech communication system may have a number from main apparatus. In this case, the interconnection of the various apparatuses is made by means of a Chain circle, whereby each apparatus is connected to all apparatus of the circuit circuit.

In known intercom systems, there is a two-wire line for each station set for transmitting the voice together with two or more additional wires for signaling and intended for switching from the receiver to the transmitter.

From the above it follows that a number of wires is equal to or greater than four for each subscriber with either master set in the case of a star-shaped circle or in the case of a lattice

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circle must be connected. For example, if ten participants are included, at least forty wires must be included connected to each device.

furthermore, almost all currently available systems are from the Simplex type, i.e. it will only connect in one seal at a time, and as a result, manual switching from transmitter to receiver is required. This way becomes the main advantage of the intercom system considerably reduced, that is the advantage for the speaker, that he has both hands free.

There are also voice communications systems for duplex connection available - ie simultaneous connection in opposite directions - but their use has been severely limited due to various disadvantages wii example

a. is the number of connecting lines to each set at least six;

b. the loudspeaker must be at a distance from the microphone be arranged to limit the Larsen effect, the usually only slightly reduced with the result of either a bad reception or

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a bad transmission;

c. the need for a central switching and reinforcement unit to connect the devices to each other.

Intercom systems are also known of the simplex type, no connection lines are used, but ordinary light circuits for voice transmission can be used in accordance with carrier wave principles to avoid the need for inter-station cabling. Its use is very limited because it only means two participants can be connected to each other.

Taking into account the fact that often a voice communication system is installed in a group when it is already in operation, i.e. when the offices are already occupied and work, laying a bundle of cables is a problem. Furthermore, there is a similar problem when after the System installation a main unit must be moved from one room to another.

Taking into account the disadvantage of having to be carried out by hand Switching from receiver to transmitter with the simplex speech sets and the complexity and low effectiveness

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sameness of the duplex voice communication systems is according to the invention a cross-talk kit has been developed that offers the following advantages:

a. all the apparatus of the system are through only one pair of telephones connected, i.e. by a line that consists of only two wires, with the system devices connected in parallel the pair are connected, which is called the "collective" line is called j

b. the apparatus connection is of the type of a quasi-duplex system, i.e. a manual switching from receiver to transmitter is not necessary during each Howling effect is impossible because each apparatus from the receiver to the transmitter is automatic and reciprocally from the same The voice of the speaking participant is switched;

c. the identification number of an apparatus is the apparatus self assigned and set at the moment when the set is installed, and consequently the number of a set does not change when unplugged of the system is moved to another.

These results are achieved by running on the pair of phones two signals of different frequencies are sent, i.e. an ultrasonic frequency, which the signal to control

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of the called set promotes, and a tone frequency which transmits the tone signal for the purpose of connecting to this set.

'The invention is explained in more detail below using an exemplary embodiment with reference to the accompanying drawing:

In the drawing show:

1 shows, in perspective, a transceiver with the system according to the invention,

2a shows the apparatus according to FIG. 1 seen from the rear,

Fig. 2b the apparatus of Fig. 1 seen from the front,

FIG. 2c is a side view of the apparatus according to FIG. 1,

FIG. 2d shows a plan view of the apparatus according to FIG. 1,

Fig. 3 shows the electrical circuit of the apparatus of Fig. 1 in a block diagram

Fig. 4 is a detailed diagram of the speech-hearing logic

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Circuit (block 19 in Fig. 3) in the electrical circuit of the apparatus of Fig. 1,

Fig. 5 is a circuit diagram of the memory circuit (block 11 in Fig. 3) in the electrical circuit of the apparatus of Fig. 1,

6 shows a circuit diagram of the signaling circuit (block 12 in Fig. 3) the electrical circuit of the apparatus of Fig. 1.

With reference to Figures 1 and 2, the apparatus of the invention System on the formation of a key device to be arranged on a table. In particular, can it can be arranged on a telephone set.

The apparatus comprises a decimal keyboard 1 which has 12 keys to form the number of the set to be called on a decimal basis, plus a control current key R and a cancel key, a visual display 2 on which the digits of the number formed on the keyboard 1 appear; a "busy" warning light 3 a volume control for the received sound; a transmission warning lamp 5 for indicating that the associated apparatus sends, a microphone 6 for picking up the voice of the speaking

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Participant, a loudspeaker 7 for playing back the incoming call, a cord 8 with a plug for connecting of the apparatus to the network system and a socket 9 for connecting the apparatus to the collecting line to which all apparatus are connected.

Referring to FIG. 3 which is a block diagram of FIG electrical circuit of the devices - all identical - shows included in the two-way communication system according to the invention includes the electrical circuit

a. a power supply 1o which is connected to the network system by means of a cord 8 for supplying the energy necessary for the electronic circuitry of the apparatus is required,

b. a paging and identification circuit (blocks 11-15) comprising: a memory circuit (block 11) of conventional ones electronic components with integrated circuits for storing the keypad from the participant 1 number formed in binary code, an ultrasonic signaling circuit (block 12) for feeding the line 9 via a Filter 21 with the pulses corresponding to the called number and one for repeating the pulses every 20 ms Decryption circuit (block 13) for transmitting the

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called number for advertisements 2; a circuit for identifying the pulses and call alerts (31ock 14), this circuit is preset by means of an appropriate permanent connector at the moment when the apparatus is installed and is used to identify the incoming impulses and to transmit the call warning to the loudspeaker, an inoperative circuit (block 15) for turning off the apparatus when it is calling or calling if the line is busy with pulses that do not affect the set, and

c. a conversation circuit (block i6-2o) with a microphone amplifier 16 of conventional type for amplifying the audio signals picked up by the microphone 6, with a transmission gate 17 for blanking the audio signal from the amplifier 16, a reception gate circuit 18 for blanking the signals from the line 9, a speech-hearing logic circuit 19 for controlling the transmission and receiving gate circuits 17, 18 in order to sample the signals from the microphone 6 and the line 9, an amplifier 2o of the loudspeaker, which is switched off or connected to the line 9 through the receiving gate circuit 18 is connected depending on instructions from the gate circuit 19, and with a filter between the gate circuit 19 and the line 9.

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The blocks 13-18 and 20, 21 are conventional integrated components that are or are available on the market Circuits of known design and are therefore not described.

The circuits related to blocks 11, 12, 19 are newer Training, the features of which fall within the essence of the invention.

Block 11 - Memory Circuit (Fig. 5). The purpose of this block is to receive the information from the keypad 1 related to the called number, it can comprise either one alone or tens and ones which are stored during the entire call to the signaling circuit 12 with the information of the number of pulses which is to be transmitted, and to feed the decoder 13 with d <jr information for lighting up ei sr called number on the display 2.

Such information is held within memory until the clear key on keyboard 1 is pressed. Since only two signals can continue to emanate from the keyboard for signaling purposes; that is one for the tens and one for the ones, a third jerkon of a key of the number segment of the keyboard has no sequence.

Dor Spoicherblock 11 comprises an encoder 21o, which consists of a

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There is a decimal binary converter of known construction. Of the Input of the encoder 21 ο receives the signals from the ten keys 1 - O of the keyboard via lines 2oo - 2o9.

The outputs of the encoder 21 o are connected to a pawl-type memory unit which is known. The outputs of this memory are connected to a second memory unit 214 of the same type and to blocks 12 and 13 via lines 262, 264, 266 and 268. The four outputs of this second memory are also connected to blocks 12 and 13 via lines 27o _f 272, 274 and 276 and to a NOri gate 218. In block 11 there is included a flip-flop circuit 22o which is connected to both memories via two operational inputs, each memory being arranged to allow the information to pass from the first to the second memory.

The flip-flop circuit 22o has an input 282 for an alternating signal from the output 222 of the encoder 21 ο provided via a timing circuit that has a capacitor 224 and a resistor 226 comprises. Another input 294, which is the reset input of the flip-flop circuit 22o, is available with the output of a NOFJ gate 218 in connection. The block 11 also includes two NOT gates 228, 23o, which as Inverter working. Both inputs to gate 228 are connected in parallel with output 222 of encoder 21 ο,

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while its output with one of the operating inputs 28o of the second memory 214, which is the memory for the tens. Both entrances to the gate 23o are connected in parallel with the output of gate 218, while its output is connected to one of the operating inputs (236) of the first memory 212 via a timing circuit is. The output of the NOK gate 218 is with both i ^ ückstelle inputs 24o, 242 connected in parallel to both memories via a diode 238, the inputs of which are in turn connected to the Delete key C of keyboard 1 via line 216 in connection stand.

The block 11 can be made from the following components manufactured by "Fairchild":

Integrated circuits 931o and 2oo2 for encoder 21o; Integrated circuit 93o8 with pawl function for the memory units 212, 214;

Integrated circuit 9o15 for the arrangement, consisting from gates 218, 228, 23o, with two NOR gates and one EMERGENCY gate can be used;

Integrated circuit 9o24 for flip-flop circuit 22o.

Operation of block 11 (Fig. 5).

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By pressing the key that corresponds to the first digit of the number to be called, one of the circuits of the encoder 21 ο is closed. This encoder, which is connected to a <zr \ zehr · keys on the keyboard via lines 2oa-2o9, has four main outputs 244, 246, 248, 25o, which corresponds to the binary code BCu (1-2-4-8), and provided with an auxiliary output 222, ^ hen one of the encoder circuits is closed by a key, the called number appears on a decimal basis as four-bit information at the above four main outputs, the decimal number being changed to a binary number.

Accordingly, the auxiliary output will be of logic level Change O to logic level 1.

The four signals in 3CQ code (1-2-4-8), which all together represent the called number in binary notation, are hereinafter referred to by the international expression "word". The "fort" appearing at the output of the encoder is supplied, for example, to the memory 212 which comprises a ratchet type integrated circuit. The function of this circuit is to store a few bit words that reach its input and to transfer the location to the four output terminals 254, 256,

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258, 26o, provided äaB 236 and 252 are both the two Hilfsexngänge at logic level O. . If so dio key is pressed, which corresponds to the first digit of the number to be called "is the" / place which directing the paragraph ONTs ^, - ο via the encoder 21 - to the input of the memory appear 212 and dta both t £ inputs 236 and are at their logic level 0, the same is / location is stored directly.

The saved word will then be transmitted, but it will not stored by tens memory 214, the / hit is connected to the output of the internal memory 212 because the tens memory is blocked because its control input is at level 1.

When the pressed button is released, it opens the previously closed circuit, and the auxiliary output 222 of the encoder 21 ο will change from level 1 to level O, and as a result, a negative pulse is sent to the Input 282 of flip-flop circuit 22o appear which causes the flip-flep outputs Q - and Q + to diverge from the Change level O to level 1 and vice versa, the outputs with control outputs 252 and 278 of the memories 212 and 21 β correspondingly are connected. At the same time, the signature

—1 5—

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signal output 222 through the inverting circuit 228 that the input 28o of the memory 212 writhing Level 1 changes.

The situation will now be as follows. The first digit pressed on the keyboard is displayed in the £ iner memory 212 stored in BCD code, and this Storage is prevented from receiving additional »Vorte, because the control input 252 is at the level 1, while the tens memory 214, which is connected to it, can not store the output word from the memory 212 because it is blocked because the control input 28o is to Level 1 has changed.

This occurs when a number from just Einarn is called. On the other hand, if a number is to be called, the one out If there are tens and ones, an additional key is pressed. In the latter case, the first digit should be on the tens, while the second relates to the ones. The behavior of the logic circuit in this Case will be as follows.

When a second key is pressed, a second word is used appear at the output of the encoder 21 ο, which, however, cannot be stored during this moment,

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because the memory 212 is blocked as the control input is at level 1.

At the same time, the auxiliary output 222 will be at level 0 change to level 1 and cause via gate 228 that the level of the input 28o dos memory 214 on Level 1 changes.

The control inputs 278 and 28o of the tens memory 214 will then both be at level 0, and the same memory can thus be the output word from the Hiner memory 212 received. The same word then becomes the output of the Memory 214 transmitted. Any word other than O to the Outputs of gate 214 will be the output of gate 218, which is connected to it, change from level 1 to level O.

The same with input 284 of the flip-flop circuit connected output will reset it, i.e. it will Output - Q - back to O and change output Q + to 1.

The tens memory 214 is switched off again because the control input 278 is changed from 0 to 1, and at the same time the output Q - of the flip-flop circuit 22o has changed the control input 252 of the memory 212 from 1 to 0 and the memory 212 is controlled to store the second word from the

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Output of the coding device 21 ο to be received.

Because the mentioned level O is also present at the input of gate 218 at gate 23o, the output of this gate is changed from level O to Pagel 1, which - via the timing circuit 234, 232 - after a short time, but long enough to allow the second ./ort from encoder 21 o to reach memory 212, reach control input 236 of memory 212 and change it to level 1, thereby disabling memory 212 from receiving other words.

After the above two operations, the two words which correspond to the ones and tens of the numbers to be called - or only correspond to the ones if a number of ones is to be called - appear at the output of the memories 212 and 2.14.

Block 12 - signaling circuit.

The purpose of this circuit is to generate selective signals using pulses. Zr is effective both for transmitting call signals and for detecting an incoming call. The block 12 comprises the following elements:

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1 .-,. 'Square wave oscillator 3o2 _r which is connected to a frequency divider (: 16) 3o4 and to a flip-flop circuit 3o8 via line 31o. The divider 3o4 is connected to a flip-flop circuit 3o6, which in turn is connected to the flip-flop circuit 3o8. The output 314 of the latter circuit is connected to the base of a transistor 318 via a resistor 316, the d-ΐΓ emitter of the transistor being grounded, while the collector is connected to an oscillator, v / whichever c- brain side 32o of a transformer 321, so that a parallel capacitor 322 and a .Widerstand 324 also comprises parallel with dor Primärseitc, wherein said resistor works as a damper. The other ends of the elements 32 o _t 322, 324 are connected to a source of +12 volts.

The secondary of transformer 321 consists of two identical halves. In the middle of these halves, a Uioden bridge 326 is inserted with one end connected to the block and the other end grounded. The secondary ends are connected to the block 21 and each of them to a transistor (332 _f 334) through a resistor (328, 33o), one of the transistors being of PNP construction and the other of NPN construction. The emitter

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of these transistors are connected to one another, while the collector of the PNP transistor is grounded and the collector of the NPN transistor is connected to the input of a monestable multivibrator 336 and via a resistor 338 to a source of + 5 volts. With the monostable multivibrator 336 is a timing circuit is connected comprising a capacitor and a 34o 'Viderstand 342 Oer output 344 of the monostable multivibrator 336 is connected to a pulse counter 346 of known type. The output of the counter 346 is connected to a first input of a comparator 348, likewise of known construction, the second input of which is connected to the memories of the block 11. The output of the comparator 348 is connected to the reset input 35o of the divider (: 16) 3o4. The reset input 352 of the counter 346 is also connected to a pulse shaper 354 which is connected to the mains via a resistor 356 and capacitor 358 and to ground via a voltage limiting diode 36o.

The block 12 can be composed of the following components be:

Integrated circuit 9o16 from Fairchild for the oscillator 3o2 and for the divisor 3o4 (: 16);

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Circuit T 7476 from SGS for the flip-flop circuits 3o6 and 3o8;

Circuit 7486 from SGS for comparator 348; Fairchild circuit 931o for pulse counter 346; Circuits BC 319 and BC 322 from Fairchild for the Transistors 332 and 334;

Circuit T 118 from SGS for the monostable multivibrator

Fairchild circuit BC 319 for transistor 318; Fairchild FDH 9oo diode for diode bridge 326; Diode BZX 83 from Sescosem for the voltage limiting diode 36o.

Operation of the signaling circuit (block 12).

Whenever a word appears at the output of memory 11, the signaling circuit begins to operate to the To signal the device, the number of which is formed on the keypad.

The 15o KHz pulses from the 3o2 square wave generator 'are fed to the divider (: 16) 3o4, the flip-flop circuits 3o6 and 3o8 and the monostable multivibrator 336,

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w & l work together to create impulse groups of eight each To generate impulses. These are the signaling impulses.

üa square pulse not suitable on a two-wire line are transmitted, they have to be modified in sinusoidal pulses. For this purpose the square-wave pulses fed to the base of transistor 318, whose collector with a resonance circuit is connected, which is tuned to 15o KHz, so that the pulse groups in trains of sinusoidal ./eilen changed and the line 9 supplied v / ground.

.Venn the line 9 connected to a detection circuit is, every train of the sinusoidal '..Ve 11 on in a 2n pulse reshaped. This circuit includes transistors 322 and 334 and the monostable multivibrator 336.

The trains of the sinusoidal './all reach the bases of the Transistors 332 and 334, which transform them into pulse groups and feed them to the monostable multivibrator 336.

The first incoming pulse triggers the monostable multivibrator 336 at the level O at its output 344 for the entire Duration of eight pulses.

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The signal thus obtained becomes the input of a payer 346 brought 'which the immediate counting of the impulses out dom monostable multivibrator 336. If the number of incoming pulses is equal to that at the output of the memory 221, 214 (block 11) and consequently at the input Yes comparator 348 is a cut-off voltage for the divider 3o4 at the output 362 dos comparators appear, shown with dom input 35o of the tailor is connected. This voltage will continue to generate pulse groups after the last pulse counted to stop.

After a period of 2o ms - on the basis of the N:; tzfrequenz provides a circuit which includes the above operations are repeated the pulse shaper 354 umfaSt, the counter 346 back soda3.

The transistors 332 and 334 and the monostable multivibrator 336 comprehensive detection circuit functions as a pulse corrector for the incoming pulses from the Line 9.

Block 19: speech-listening logic circuit (Fig. 4).

As mentioned above, this is the purpose of this circuit

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in that the transmission gate 17 and the input gate 18 on or off to enable the device to transmit or to be connected for recording depending on the incoming signals or correspondingly on the outgoing signals.

Furthermore, after producing a transmission or inbound connection of any incoming or outgoing signal do not change the state of the gates until the primary signal is present is.

The third and final function of block 19 is to add time constants for switching off and controlling the gates ensure that the transmission circuit, which comprises blocks 16 and 17, never has the receiving circuit switched on can find which comprises the blocks 18, 2o.

In practice, shutdown times are in the order of magnitude of 10 microseconds and switching times on the order of magnitude of 100 microseconds.

The speech-listening logic circuit (block 19) comprises

a. a first trigger circuit 4oo ^ consisting of one Capacitor 4o1, which is connected to a transistor 4o3 and with the irlrde is connected via a resistor 4o5, is

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The emitter of the transistor 4o3 grounded, a monostable multivibrator 4o9, which is assigned to a timing circuit which comprises a resistor 411 and a capacitor 413, the input of the multivibrator 4o9 with the collector of the transistor 4o3 and with a source of positive voltage via a resistor 4o7 connected is. D-ar output 4o8 of multivibrator 4o9 is connected to input 415 of a NAND gate circuit 417;

b. a second trigger circuit 42o similar to the above comprising: a capacitor 421 connected to the base of the transistor 432, the emitter of which is connected to ground and the collector to a positive voltage through a resistor 425 and to the input of a monostable multivibrator 427 is connected.

The base of the transistor 423 is connected to the same positive voltage through two resistors 429 and 431 in series and to ground through a resistor 431 and a diode 433. The monostable multivibrator 427 is connected to a timing circuit which comprises the resistor 432 and the capacitor 434;

a NAND gate 417, the input of which is connected to the output

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of the monostable t4ultivibrator 427 is connected. ^ s be emphasized that the outputs 4o3 and 426 of the multivibrator 4o9, 427 always have a reversed polarity with respect to each other to have to each other; a transistor 447, the base of which with the output 443 of the gate 417 via a .viderstand 445 is connected, the Zmitter is earthed, and the collector rests with a positive voltage across one another. ”'Resistance 449 and the block 17 in connection; a MAND gate circuit 46o, which works as an inverter and its two inputs 454 and 455 are connected in parallel to gate 417. The exit of the gate 46o stands with the Jarnlamp3 5 over a jider

related 5;

a transistor 459 whose base is connected to the output 456 of the gate 40O via a '..' esistance 457, while the £ rnitter is grounded and the collector is engaged with the block 17 and with _-iner wellspring positive voltage via a resistor 461 in connection.

The following elements can be used to roll block 16 be used:

Fairchild circuit BC 319 for transistors 403, 423, 447, 459;

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Circuit T 118 from SG3 for the monostable multivibrators 4öS / and 427;

ocircuit 74oo from Fairchild for the NAND gate circuits 417 and 46o.

Operation:

The microphone signal amplified by block 16 reaches transistor 4o3 via capacitor 4o1. This transistor has ksins permanent base bias and consequently only those signals whose amplitude is greater than the characteristic base - emitter voltage - that is the minimum voltage of the transistor - make the transistor conductive. In the present case, such a voltage is 0.6 volts. The transistor 4o3 thus functions as Pegaldiskriminator so da3 dio noise signals is less than o, 6 volts to the non-conducting state is not vorändern the transistor, while the nutzvollen signals as o, change gröf3or 6 volts dan transistor in its conducting state. As a result, the terminal 41 o of the monostable multivibrator 4o9f which is connected to the transistor 4o3 _{f is changed} from a positive level - logic level 1 - to a level close to O - logic Pagal Ö -, whereby the multivibrator is triggered and consequently its output 4o3 from level O

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'change to level 1 and stay at that level throughout Duration of the microphone signal at the base of transistor 4o3 will remain. The trigger time of the monostable multivibrator 4o9 is determined by the resistor 41 o and the capacitor 413.

The same also occurs for signals from the amplifier 2o of the loudspeaker 7 which reach the transistor 423 via the capacitor 421. Unlike the transistor 403, the transistor 423 has a threshold value, reduced to 0.1 volts with the aid of a voltage divider consisting of the diode 433 and the resistor 429, and this is done because the noise signals picked up by the loudspeaker 7 are reduced -Longer than the dtt2 recorded by the microphone.

The output 426 of the multivibrator 427 is reversed Voltage with respect to output 408 of the non-stable multivibrator 4o9, so that the behavior of multivibrator 427 is reciprocal with respect to d <is multivibrator 4o9, i.e. its output will be at level O all the time during

which a signal at the base of transistor 423 is present. The output 4o8 of the multivibrator 4o9 and the Output 426 of multivibrator 427 are led to inputs 415 and 435 of NAND gate 417. In order to improve

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stünunissc are the logical functions of the NiATJD gate 417 summarized in the following table.

Logical- Pagel

£ inance 1 Outputs ΰ C. 1 O O 1 1 1 1 1 O

The output 443 of door 417 is connected to an amplification transistor 447 from which block 17 is controlled, and inputs 454 and 455 are connected to an inverting gate circuit 416, the output 456 of which controls block 18 via a Vjjrstäir.aJngstransistor 459.

The following operating conditions can occur.

1. £ s is no signal neither at block 16 nor ora block 2o available. In this case the input 415 is dcis fJAND— Gate 417 at logic level O, while it input 415 d ^ s of the same gate is at level 1. Dor exit 443

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djs Torjs 417 will then be at dom level 1. The transistor 447 will then be conductive and its output 463 will be at level 0 so that the transmission gate (block 17) connected to it will be conductive. The output 443 of the gate Ί17 is also connected to the inputs 454 and 455 dvs gate 46o, which has its output at level O due to its inverting function, via transistor 459, which is connected to it, \ j \ r: romit blocked, and output 405 will be at the logic level 1, so that the gate of block 13 is also blocked, so that in the absence of signals at blocks 16 and 20, the pulse catch is switched on, ie. Each signal on the line 9 can reach the loudspeaker 7 via the filter 21, gate 18 and amplifier 2o.

2. Presence of incoming signals. Uiose signals will be present at block 2o. Every signal from block 2o, when it reaches output 426 of monostable multivibrator 427 via capacitor 421 and transistor 423, will change its output from level 1 to level u.

The inputs 415 and 435 of gate 417 are both at level 0 soin. 'as shown in the table above, the

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The output of gate 417 should again be at logic level 1, unc. the conditions described under 1 remain unchanged stay.

3. Presence of incoming signals and at the same time of .jignalon at block 15. Oi-: situation of transistor 423 and dr; iultivibrators 427 verbl3ibt unchanged uie oign-jle au block 16 reach the multivibrator 4o9 via dc-n capacitor 4o1 4o3 and the transistor so that dor output of the multivibrator 4o3 4o9 front level above sea level to 1 changed. The lingings 415 and 435 of port 417 will then be at levels 1 and 0, respectively, and as shown in the table above, the situation of ports 17 and 13 does not change; consequently the gate 17 will largely not be conductive, and any signal at the microphone 6 will never reach the line V until an incoming signal is available.

4. No incoming signal and signals at block 16.

As has been discussed under 1, the output 435 of the gate 417 is at level 1, while the signals' O3r Z input 415 of the gate 417 present at the block 15 changes from level u to level 1. Both £ ingunge of gate 417 would now be at i-egel 1, and as shown in the table, the condition

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of the exit of the gate 417 will change to F ^v . -gal G.

As a result, the transistor 447 is blocked, and so in output 463 is at shelf 1, so that the gate 17, which is connected to it, is changed to its conductive state, while the transistor 459 is also conductive and s ^ in output am Level is 0 so that the port 18 associated therewith is changed to its non-conductive state.

Transmission control is established on dios3, so that the signals from microphone 6 can reach filter 21 and then line 9 via amplifier 16 and gate 17, while no signal from line 9 can reach loudspeaker 7 because the gate 18 is not conductive. Until a signal is present at block 16, no signal can therefore reach block 2o and reach gate 417 via transistor 423 and multivibrator 427 and change its state. V / ecause the output 456 of the gate 46o is at level 1, and because it is connected to dor -bertragungswarnlampo 5, lstztera be illuminated and thus indicate da3 transmits illustrates apparatus.

General operation.

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The subscriber who wants to call another subscriber, after he has made sure with the help of the warning lamp 3 that the line is not busy, forms the I-Juimur to be called on the keyboard 1; by pressing the keys on the keyboard 1 v / ird the go called number is stored in memory 11 in binary code (see description of block 11, which is the memory circuit); the memory 11 carries the ones stored in binary code Number of the display 2 of the called set and at the same time the same number to the signaling circuit 12; the signaling circuit 12 feeds the line 9 with a number of pulses in the ultrasonic frequency corresponding to called number; these pulses are returned every 2o ms, this cycle being from the 5o HZ frequency of the network is created from which the apparatus is fed; the pulses fed to line 9 are then used by all apparatus received with a number from two to ninety-nine connected to the line; cause these impulses in the line via the locking circuit 15 that the warning lamps 3 of all telephones light up, so that all telephones are warned that the line is busy and all subscribers at the same time with the exception of the caller, are prevented from calling; a signaling tone is emitted from the loudspeaker 7 of the apparatus sent, the decoder 13 is set to by the

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related identification circuit 14 to receive the number of pulses sent by the calling set; d-jr subscriber of the receiving apparatus is thus informed, da3 the call is intended to dsr line for him; he then switches on his device by pressing key A on keyboard 1; the connection between the two stations is thus established, while all other apparatuses are switched off until the conversation starts; de * "called subscriber can now answer the calling subscriber by speaking into the microphone 6;

as long as a signal is present at the microphone ό of a. apparatus, remains illuminated by an electronic circuit aie Jarnlarnpe 5, which at the same time the loudspeaker 7 on operation h :. -ic .r ':; that is during öor time when one of the two participants speaks into the microphone 6 and the loudspeaker of the other participant is switched on to receive, while the microphone 6 of the other participant remains switched off as long as the arste participant speaks; when the first participant finishes speaking, both microphones are switched off while both loudspeakers 7 are switched on; The first of the two participants to speak again causes the repetition of the

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above becchri .bonc-n gearbox; the cljin f'.ikrofon 6 ctufge-ηοατιηοηα voice is pre-amplified by the amplifier 16 and the line ? fed through the gate 17 to the kilter 24; dia Sjlbo -timme v / i rd simultaneously dom logic circuit 19 train: leads, v / r = jlch the Srnpf angstorschaltung 13 in its conductive state changes, whereby dc-r amplifier 2o is turned off, ■ ict associated with dom speaker; if Kaina dignalo am I - '. ikrofort 6 Zind present, v / ill c ac wb -_- rtragungstorschaltung 17, Joe from the logical Jchaltunc 1!': is controlled ', non-conductive, and at the same time um.-U " angatorschGltung 13 conductive, thereby dur amplifier 2o of the loudspeaker 7 connected to the line 9 via the filter 21 v / ill; \ - / hen a voice signal on the line 9 is present, it can reach the speaker 7, a part of the öignales which reaches the loudspeaker, the logic circuit (block 19 ) will block so that in your view, even if someone speaks into the microphone 6, the gate 17 will not be conductive; 18 v in its conducting state / ith the lighting of the Jarnlarnpj cause and show the speaking participants that his voice reaches the listening party; the "ünde dor Entertainment, the calling party prints the C key dor keyboard 1, and as a result, the storage deleted dis Irnpulsübermittlung gesto ppt, the indicator 2 was deleted, the warning lamp 3 for the power line

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is switched off on all devices; from this moment all telephones are on again to make a call ready.

Zs has been described, for example, a preferred embodiment according to the invention. However, the person skilled in the art can make changes and variants. For example, the number of transmission receivers can be greater than two to ninety-nine, as is the case with the embodiment described. The blocks 11, 12 and 19 can also be composed of other components than those described.

Numerous changes and modifications can be made However, without departing from the essence of the invention.

Claims -36-

509882/0808

Claims (9)

Claims / 1 J l / echselsprechverkehrsystem with a large number of receiving gene machines, each provided with a keyboard, a microphone and a loudspeaker for the purpose of connection between two of the apparatuses, characterized in that all system apparatuses are identical and are connected in parallel to a two-wire telephone line that each apparatus has a coding and storage device for storing the number formed on the keyboard in binary code, an ultrasonic signaling device for feeding the line with ultrasonic pulses which correspond to the number to be called and bring them back into circulation, a decoder for these pulses , a speech-hearing logic device which is connected to the line and to the microphone and loudspeaker of the related apparatus, the logic device responding to auditory signals from both the microphone and the line, but not to ultrasonic signals, to create a transmission gate circuit and a receive gate circuit to control and has a device to perform the following functions: in the absence of signals from the microphone and in the simultaneous absence of audio signals from the line, a receiving gate circuit is made conductive and the transmission gate circuit is made non-conductive; in the presence of 509882/0808 tional Aue the hi k ro fön and v in the absence of Signaion from CIOR line / ith the wbertragungstorschcltung leitsnä and not made dia Znpfangstorschaltung conductively _t so long "via the signals from d ^ m microphone are present, thus v / i ade rum di - -b rtragungstorschaltung non-conductive and dio £ raofangstorschaltung is rendered conductive, so that Z ₁ when two of Systerrtteilnehrrter interconnected voice only a two participants aor to familiarize time from the line transferred v / ill, the ultrasonic signals do not interfere with the conversation . 2. System according to claim 1, characterized in that? Each set also has a warning lamp for "busy" that a display for the called number is provided, which is connected to the encoder and the keyboard, since two additional keys in addition to the number keys to form the murmur to be called are provided, namely one for clearing the memory, clearing the display and disconnecting the .Varr.lar-.ipe of the busy line on all devices in the system and allowing a button to switch on the device to a connection. 3. System according to claim 2 _t, characterized in that the Codi> r and storage device a decimal - binary converter, -38- 509882/0808 which is connected to the keyboard, a first memory unit for storing the number formed by the ση of the keyboard, a second memory unit for storing tens of the same number, both memories being connected to the ultrasonic pulse generator and the dom decoder are, a flip-flop circuit, which is connected to the two memories via an NCü gate circuit, two NÜT gate circuits with inverting functions, from then on one is connected to the first memory via a zoom circuit and the other to the second memory, and a diode inserted between the output of the HON gate and the delete key, whereby the information from the keyboard to the coding and memory circuit is retained in the -! - • ..sliders until the delete key is pressed and to the transmit pulse generator for sequentially along the line, and is transmitted to the decoder to display is called number to ö3r Anzeigo. 4. System according to claim 1, characterized in that dio Ultrasonic signaling device comprises a leak wave oscillator, which is assigned to a timer circuit is, which is connected to a power supply, a divider (: 16), which is connected to the oscillator is a first flip-flop connected to the oscillator -39- 509832/0303 t lop circuit, a second flip-flop circuit connected to the first flip-flop circuit, a first transistor, the base of which is connected to the first flip-flop circuit via a first resistor, with an oscillating circuit connected to the collector of the first transistor and comprising the secondary of a transformer and a first capacitor, an NPN transistor and a PNP transistor, the emitters of which are connected to one another and the bases are each connected to the corresponding inde of the secondary of the transformer; a monostable multivibrator, which is connected to the collector of the NPN transistor and a source of positive voltage via a second transistor, a timer circuit associated with this multivibrator, a pulse counter connected to this multivibrator, a comparator, which is connected to the pulse counter and to the coding and storage device and is connected to the divider (: 16) and comprises a pulse shaper which is connected to the counter and to the line via a third resistor and a second capacitor. 5. System according to claim 1, characterized in that the Speech-hearing logic device a first trigger switching -4ο- 509882/0808 - 4ο - kr ^ is composed of a second transistor, whose Base with the transmission gate circuit via a capacitor and is connected to an amplifier of the microphone; a monostable multivibrator that works with the collector doc second transistor and with a source positive voltage is connected and includes a timer circuit, the a'jrn monostable multivibrator is assigned to a second trigger circuit similar to the above, but where the * capacitor is analogous to the capacitor of the first Triggers connected to the loudspeaker and to the receiving gate via dom amplifier of the loudspeaker, a first NANü gate circuit, whose inputs are connected to the outputs of the two monostable multivibrators of the two trigger circuits are connected, a second ΝΛΝϋ gate circuit, whose inputs are connected in parallel to the output of the first NAND gate and the output to the display is connected via a resistor and comprises a second transistor, the base of which is connected to the output of the first NAND gate circuit and with the inputs of the second NANü gate circuit are connected, the collector to a source of positive voltage and to the transmission gate circuit connected is. 6. System according to claim 1, characterized in that the daf3 Alternating wave impulses have a frequency of 15o KHz -41- 509882/0808 7. System according to claim 1, characterized in that each apparatus has substantially the shape of a parallelepiped and can be used as a base for ordinary telephone a ^^ arat di; non. 3. A method for establishing a connection between a number of Zrnpfangs - 'Jindecpparaten that are ullo identical and gerchetzt parallel cn a two-wire telephone line, characterized in that da3 of the calling device on the line with the help of ultrasonic signal-n the coded number are transmitted to the set to be called, the signals causing a display to show the called number on all sets, and a key on a keyboard of the called set is pressed and a conversation between the calling set and the called set is started by means of tone frequency signals , which are transmitted from line represents. 9. Method for establishing a connection between a number of transceiver devices, which are all identical and are connected in parallel to a two-wire telephone line, these devices having a microphone and a loudspeaker, one Zmpfangstorschaltung and an ^O ondetorschaltung are equipped marked characterized -42- 509882/0808 characterized as 3, the audio signal from the line and from the "iikrofon to control gates are been used and thus the speaker with öar line connect and disconnect at the same time the microphone it, v / hen no signal for the" -iikrofon still signals au ^ d ^ r line are available, as "the microphone is connected to the line and at the same d ~ r speaker gcitrannt thereof when dara from microphone and koine signala from represent line signals are vorhancian, and since this- situation is maintained as long wi- ? are vorhandan from dom microphone 2 signal, and "then ö ^ r speaker does with dor line V'jrbundan and rtikrofan it. 509882/0808 Blank page