WO1986002794A1

WO1986002794A1 - Process for reducing the loading of a transmission circuit by the receiving circuit of several transmission/receiving sets, and a circuit arrangement for realisation of the process

Info

Publication number: WO1986002794A1
Application number: PCT/DE1985/000413
Authority: WO
Inventors: Lothar Blomberg
Original assignee: Brown, Boveri & Cie Aktiengesellschaft
Priority date: 1984-10-31
Filing date: 1985-10-25
Publication date: 1986-05-09
Also published as: EP0199807A1; DE3439789A1; DE3439789C2

Abstract

In a mains-type house-line or house-communication system operating by the dialogue method, the number of connectable transmission/receiving sets should be as large as possible. This can be achieved if the receiving circuit of a transmission/receiving set requires only a small part of the transmission power emitted. According to the invention, in synchronisation with the switching of the transmission from transmission to reception and vice-versa, a switching is effected of the coupling impedance linked with the mains line. This is designed is such a way that a lower-ohm transmission output impedance and a higher-ohm receiving input impedance is produced. The circuit arrangement developed for implementation of the process is so designed that a repeater (Ü1) couples both a transmission circuit (1) and also a reception circuit (2) to the leads of a network. Connected in series with the secondary winding (W2) of the repeater (Ü1) is a controllable switch (T3) which is short-circuited during the transmission mode and thus is low-ohmic, and during the receiving mode is open and thus high-ohmic.

Description

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Method for reducing the load on a transmitting circuit by means of the receiving circuit of a plurality of transmitting / receiving devices and circuit arrangement for carrying out the method

The invention relates to a method in the preamble of claim 1 and a circuit arrangement of the type mentioned in the preamble of claim 3.

In the field of network-connected home automation technology, systems have been used so far in which transmitters on the one hand serve to issue commands and on the other hand receivers serve to record and execute the commands. A more convenient home automation system, however, requires a dialog system in which the receiver reports back that a command received by the transmitter has been carried out and, if necessary, transmits further information about this. In order to implement such a dialog system, a transmitter circuit must be assigned to the receiver and the transmitter must receive a receiver circuit to receive the feedback. This results in two transceivers, which can send or receive information as required. Dialog systems of this type are mandatory for house intercom systems, since the flow of information cannot usually be restricted to one direction.

In order to keep the circuit structure of such transceivers simple, a common converter is used to connect the device to the network. Both the output of the transmitter circuit and the input of the receiver circuit are connected to the secondary winding of this converter. Now the output resistance of the sensor The circuit should be as small as possible, ie the characteristic curve of the voltage output plotted as a function of the load resistance formed by the network should run steeply in the lower range so that the greatest possible transmission power can be delivered to the network. However, the load resistance formed by the network is primarily determined by the number of receivers connected, it having to be taken into account that high-frequency signals are used for transmission, that is, the load behavior of the network at 50 Hz can largely be disregarded. However, since the low impedance of the transmission circuit now remains effective even when the transceiver is switched to reception, the number of receivers that can be connected is severely restricted. Because, of course, the load resistance must not fall below a minimum value, because otherwise the addressing of the .receivers would no longer be guaranteed.

The object of the invention is to provide a method of the type mentioned in the preamble of claim 1, which makes it possible to significantly increase the number of receiving circuits that can be connected to the network. Furthermore, a circuit arrangement for a transceiver is to be designed in such a way that it enables the method to be carried out with little circuit complexity.

This object is achieved by the features characterized in claim 1. Further expedient refinements and developments of the subject matter of the invention are mentioned in the subclaims.

The method according to the invention has the advantage that it can be used both in telecontrol and in telephone systems. It can be assumed that in only one device sends to the spatially limited long-distance transmission circuit of a house or an apartment, while all other devices receive. The signal to be transmitted is fed into the network by a device with a low coupling impedance and can be taken off by a large number of other devices with a high coupling impedance. The number of receiver circuits that can be connected can be significantly increased by the high-impedance receiver input impedance.

While the subscribers of a telephone device ensure that only one subscriber transmits at a time, a further development of the invention provides for a telecontrol device that all transmitters / receivers, with the exception of the control device, are fundamentally switched to receive . Only a command from the control device also enables one of the other devices to send information. In this case, an automatic timer ensures that, after the send command, the affected transceiver automatically switches from sending to receiving in a predetermined time span.

A circuit arrangement for carrying out the method according to the invention has a transformer, the primary winding of which is connected to the network directly or via intermediate elements. During transmission, the secondary winding of the transmitter is acted upon by the output signal of a transmission circuit, and during reception it transmits transmission signals coming from the network to the input of a receiver circuit. A control circuit effects the switching between sending and receiving. According to the invention, a controllable switch is connected in series for the secondary winding of the transformer, which switch is closed and thus in transmission mode low-resistance and open during reception and is therefore high-resistance. With the controllable switch, a switchover of the impedance of the transformer is achieved in a simple manner.

A further development of the invention provides that the secondary winding of the transformer has one end at the output stage of the transmitter circuit and the other end at a parallel circuit formed by the controllable switch on the one hand and the input of the receiver circuit on the other. The position of the controllable switch ensures that not only can the coupling impedance be switched over, but that when the switch is switched to transmission, the input of the receiver is practically at zero potential. The receiver, which is not modulated, therefore does not consume any electricity during the transmission time. '

The output stage of the transmission circuit works with a relatively high supply voltage, so that a low coupling impedance can be achieved by a high transmission ratio of the windings of the transformer. In a further development, the invention provides that a capacitor is inserted between the output stage of the transmission circuit and the parallel circuit, preferably between the secondary winding and the parallel circuit. This blocks the high DC voltage component of the output stage of the transmission circuit compared to the controllable switch.

To utilize new technologies, the control circuit is advantageously implemented by a microprocessor and the controllable switch by a transistor. The collector-emitter path of the Sistor is parallel to the input of the receiver circuit, while the base-emitter path is parallel to a capacitor which forms an integration element with an upstream resistor for the signal coming from the microprocessor. This effectively suppresses voltage peaks which can arise during a rapid switchover between transmit and receive operation. To protect against high interference voltages, which could endanger the transistors, they are protected by a tens diode connected in parallel with their collector-emitter path.

The transformer is expediently designed such that its network-side inductance is equal to or greater than 0.2 mH. At 120 kHz, this results in an impedance of 150 ohms, which should not be undercut if possible, so that the input impedance of the receiving circuit is not too low. The transmission ratio of the transformer should also be at least 1: 5, while the voltage amplitude emitted by the output stage of the transmission circuit should be at least 10 volts.

The increased voltage amplitude for the output stage of the transmission circuit is advantageously generated by doubling the voltage of the output voltage of the power transformer used for the rest of the power supply.

The power consumption of the transceiver can be reduced in that the control circuit also completely or at least partially switches off the power supply to the transmitter circuit when the controllable switch is opened. If you suppress the broadcasting nal, so the output stage of the transmission circuit is not driven and accordingly does not consume any electricity.

An embodiment of the circuit arrangement according to the invention is described in more detail below and explained using a circuit diagram shown in the drawing.

The circuit arrangement shown in the drawing essentially consists of a transmission circuit 1, a reception circuit 2, a coupling circuit 3 and a power supply circuit 4.

The basic ideas of the invention are used in the coupling circuit 32. A transformer U1 has its primary winding W1 connected to lines of the network 5 via a capacitor C3 and thus enables the transmission signals from the transmission circuit 1 to be coupled to the network * or to the primary winding W2. the .Empfangssig¬ signals from the network to the receiving circuit 2. For this purpose, the secondary winding W2 of the transformer U1 is at one end E1 at the output of the transmitting circuit 1 and at the other end E2 via a capacitor .C2 at a parallel circuit through the input F of the receiving circuit 2 on the one hand, and on the other hand is formed by the collector-emitter path of a transistor T3. Parallel to the base-emitter path of the transistor T3 is a capacitor C4, which forms an integration element with a resistor R7, which delays the signals coming from a control circuit A. Interference pulses emanating from the control circuit A, which can arise due to rapid switching between transmission and reception or vice versa, are damped by the integration element R7, C4. The control circuit A formed by a microprocessor ensures that the emitter-collector control path of the transistor T3 is turned on during the transmission phase. As a result, the end E2 of the secondary winding W2 of the transformer U1 lying at the parallel circuit F, T3 is pulled to zero potential, so that a low impedance is produced in the secondary circuit. The translation ratio W1: W2 of the transformer U1 is also selected such that the coupling impedance is as low as possible towards the network.

The receiver circuit 2 also has its input F at zero potential during the transmission phase, that is to say when the transistor T3 is activated. There is therefore no control signal at input F, so that the receiving circuit 2 also consumes practically no current during this time. During the reception phase ^■ Steuer¬ locks circuit A transistor T3. As a result, the primary circuit of the transmitter U1 becomes high-resistance, so that reception takes place with a high coupling impedance.

The transmission circuit 1 operates at a frequency of 120 kHz. The signal present at its input H is generated by a multivibrator and is therefore rectangular. However, the signal to be supplied to the network must be sinusoidal and low-distortion in accordance with the FTZ regulations and have low harmonics.

To pass on the information, telegram blocks T = 1ms are used, which control a transistor T1 via a high-resistance base resistor R1. Due to an inductance L1, the collector current of the transistor T1 has a trapezoidal shape, which is one Corresponding reduction in harmonics. A further reduction in the harmonic content is forced by a resonant circuit-guided transformer U2, so that a clean sinusoidal voltage can already be taken from behind it. The sinusoidal signal is fed to the base of a second transistor T2, which is biased via a voltage divider R4, R5. The bias voltage is generated via the control circuit A, and is selected so that the transistor T2 is blocked during the reception phase. As with the receiving circuit, the transmitting circuit only requires a supply current when it is in operation. This means that the power supply is low and the power supply can be dimensioned weak. Not only is unnecessary power consumption avoided, but the components can also be dimensioned to save space.

So that the transmission circuit 1 can deliver the highest possible power to the transformer U1, its output stage T2 is subjected to a correspondingly high collector voltage. A voltage doubler circuit is used in the power supply 4 to generate them. The voltage doubler circuit constructed from the diodes D4, D5 and the capacitors C8, C9 is connected to the same secondary winding of a mains transformer N, which also serves to supply a voltage regulator SR, which supplies the rest of the circuit with current. The DC voltage component coming from the output stage T2 of the transmission circuit 1 is suppressed behind the secondary winding W2 at its end E2 by a capacitor C2, so that it does not reach the collector of the transistor T3. The transistors T2, T3 are each protected against overvoltages by a tens diode D2, D3 lying parallel to their emitter-collector path. In reception mode, the RF signal coming from the network reaches the transistor T3 with the aid of the transformer U1, which is blocked in this case. From the collector of transistor T3, the signal is applied via capacitor C5 and a high-resistance resistor R8 to the base of a transistor T4, from the output of which it arrives at a resonant circuit-guided transformer U3, which ensures the appropriate selection. For further processing, the signal is taken from the output of a downstream output stage T5.

Claims

1. A method for reducing the load on a transmission circuit whose high-frequency output signal is superimposed on a power line, to which several transmission / reception devices are connected within a spatially limited area, preferably within a house or apartment, which are dependent on the Coded transmission signal perceive certain control and / or transmission tasks and can alternately be switched from transmission to reception mode, characterized in that synchronously with the switching of the transceivers from transmission to reception and vice versa, a switchover of the other Coupling impedance applied to the mains cable, and a low-impedance transmitter output impedance and a higher-impedance receiver input impedance are effective.

2. The method according to claim 1, characterized gekennzeich¬ net that in a telecontrol all transmitters / receivers, except the control device, are basically switched to reception, as long as a command from the control device for transmission is missing and an automatic timer ensures that, after the send command, the affected transceiver switches automatically from send to receive in a predetermined time span.

3. Circuit arrangement for carrying out the method according to claim 1 for a transceiver a transmitter, the primary winding of which is connected directly or via intermediate elements to the network and whose secondary winding is subjected to the output signal of a transmission circuit during transmission operation and transmits transmission signals coming from the network to the reception of a receiver circuit during reception operation and enables switching between transmission and reception is characterized by the fact that a controllable switch (T3) is connected in series with the secondary winding (W2) of the transformer (Ü1), and a control circuit (A) ensures that it is closed during transmission and thus has a low resistance and is open during reception and is therefore high-impedance.

4. Circuit arrangement according to claim 3, characterized in that the secondary winding (W2) of the transmitter (Ü1) with one end (E1> indirectly or directly at the output stage (T2) of the transmission circuit (1) and with its other end ( E2) is due to a parallel connection of the controllable switch (T3) on the one hand and the input (F) of the receiving circuit (2) on the other.

5. Circuit arrangement according to one of claims 3 to 4, characterized in that between the output stage (T2) of the transmission circuit (1) and the parallel circuit (T3, F) preferably between the secondary winding (W2) and the parallel circuit (T3, F), there is a capacitor (C2).

6. Circuit arrangement according to one of claims 3 to 5, characterized in that the control circuit (A) are realized by a microprocessor and the controllable switch (T1) by a transistor, wherein the collector-emitter path to the input (F) of the receiving circuit (2) and the base-emitter path to a capacitor (C4) lie in parallel, and an upstream resistor (R7) with the capacitor (C4 ) for the control signal coming from the microprocessor, an integrator (R7, C4) is formed.

7. Circuit arrangement according to one of claims 3 to 6, characterized in that to the collector-emit ter section of the transistor (T1) and the output stage (T2) of the transmission circuit (1) each have a tens diode (D2, D3) pa¬ parallel is switched.

8. Circuit arrangement according to one of the claims. 3 to 7, characterized in that the transformer (Ü1) is designed so that its network-side inductance is equal to or greater than 0.2 mH (150 ohms at 150 kHz).

9. Circuit arrangement according to one of claims 3 to 8, characterized in that the translation ratio (W1: W2) of the transferring device (Ü1) is greater than 1: 5 and the secondary winding (W2) of the transferring device (Ü1) when transmitting with a voltage amplitude of more than 10 volts is applied.

10. Circuit arrangement according to one of claims 3 to 9, characterized in that the increased collector voltage of the output stage transistor (T2) of the transmitting circuit (1) is effected by doubling the voltage of the output voltage of the mains transformer (N) serving for the remaining power supply.

11. Circuit arrangement according to one of claims 3 to 10, characterized in that the control circuit (A) with the opening of the controllable switch (T1) also completely or at least partially switches off the power supply to the transmission circuit (1).