CH615304A5 - Method for remotely controlling the switching-on and -off of load objects in a power system by means of remote control signals radiated at radio frequency, and device for carrying out the method - Google Patents

Description

The present invention relates to a method for remote control of the switching on and off of load objects on or from a power supply system on the basis of radio-frequency remote control signals and to a device for carrying out the method.

Remote control methods are already known from ripple control technology, according to which remote control commands are preferably superimposed as sound-frequency signals on a power network and are received by any number of remote control receivers connected to this power network. Such remote control commands are usually coded on the transmit side and decoded on the receive side and then executed by a switching element assigned to the remote control receiver and the load object to be remote controlled.

In the known ripple control systems, there is only very little attenuation of the signal level between the transmitter and the individual receivers, with only slight level differences occurring at the various connection points of the remote control receivers, for example in a ratio of 1: 2. In view of the high interference level of the power network used as a transmission channel, however, very considerable powers are required for the remote control signals. Power of around 10-50 kW per transmitter is usually required, and in many cases it proves necessary to have to feed the remote control signals simultaneously at several points in the power grid.

A disadvantage of this known system is therefore the high outlay on the transmission side. This is especially true if a spatially extended area has to be covered. The present invention is therefore based on the object of avoiding these disadvantages and of creating a remote control system which allows a large number of remote control receivers to be reached in a large area with little or no effort on the transmitter side and, moreover, the receiver-side effort within the scope of known at

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to keep the remote control receiver connected to the power grid.

The present invention relates to a method for remote control of the switching on and off of load objects in a power network by means of radio-frequency remote control signals, which is characterized in that the remote control signals are added on the transmission side as extraordinary modulation of the ordinary modulation of a radio frequency transmitter intended for another task, whereby for the extraordinary modulation and the ordinary modulation different modulation parameters are used and that on the receiving side the components of the received signal generated by the extraordinary modulation are separated from the ordinary modulation on the basis of their different modulation parameters and after their evaluation as a control signal a switching element for the connection or disconnection of a load object to the or from the power grid.

The invention also relates to a device for carrying out the method mentioned.

The invention is explained below, for example, with reference to the drawing. Show:

Fig. 1 is a block diagram of an embodiment of a remote control receiver;

Fig. 2 is a circuit diagram of a high frequency part;

Fig. 3 is a circuit diagram of a low frequency filter.

The same reference symbols are used in all figures for corresponding parts.

In contrast to the known ripple control systems, where tone-frequency signals of a power line or the associated mains voltage are superimposed, the present invention uses modulated high-frequency signals which are emitted by a transmitter intended for another task. This completely eliminates the very considerable effort required for the transmitters in known ripple control systems. The exploitation of a radio frequency transmitter intended for another task, for example a radio transmitter intended for normal radio programs for the additional task of remote control of the switching on and off of load objects to or from a power grid is now not readily possible, rather the special conditions of the orderly transmitter to be transmitted ordinary modulation, d. H. of the radio program are duly taken into account. For example, it would not be permissible that the simultaneous transmission of remote control commands would also be heard by the receivers of the ordinary modulation, i.e. the speech and music modulation of the radio transmitter, and likewise sound frequencies that may occur in the ordinary modulation must not have any disruptive influence on the remote control commands to be transmitted , that is, to exert extraordinary modulation.

The decoupling of extraordinary and ordinary modulation can now be achieved by using different modulation parameters. For example, in the case of a radio transmitter working for the ordinary modulation (radio program) with amplitude modulation, the remote control commands could be transmitted as extraordinary modulation by, preferably slight, frequency or phase modulation. A sufficiently small frequency or phase shift would not lead to a low-frequency interference signal corresponding to the remote control commands in normal amplitude modulation broadcast receivers.

However, it is also possible to use different frequency ranges for the difference of the modulation parameters for the ordinary and extraordinary modulation with less effort on the transmission side, but both modulations with the same type of modulation, for example

To transmit amplitude modulation.

In the former case, the reception of the ordinary modulation, i.e. H. of the radio program, normal amplitude modulation radio receivers are provided or

5 continue to be used, whereas for receiving the remote control commands, i. H. Frequency modulation receivers or phase modulation receivers would have to be provided for the evaluation of the additionally transmitted extraordinary modulation. Such frequency modulation or phase modulation lo receivers are characterized in that, in a manner known per se, they have a frequency-selective input part, an amplitude limiter connected downstream of this and a frequency or frequency limiter connected downstream of this. Have phase discriminator. The aforementioned discriminator emits at its output a tone-frequency pulse sequence corresponding to the remote control command entered on the transmission side, which can be decoded in a manner well known from ripple control technology and converted into a control signal for the switching element to be controlled remotely.

A disadvantage of this solution described above is, of course, that the transmitter intended for another task, for example the amplitude-modulated radio transmitter, has to be modified by circuitry interventions in such a way that, in addition to amplitude modulation, it also for simul-taneous frequency or phase modulation for the extraordinary modulation, d. H. the remote control commands.

Although this measure of changing the circuitry of an existing transmitter does not pose any particular difficulties for the person skilled in the art, it should nevertheless be borne in mind that such interventions are generally undesirable. As a rule, the radio stations and the high-voltage networks are assigned to different companies or institutions.

Since radio transmitters, as mentioned, are generally not operated by the same body as the power grid, it is usually not permitted to carry out circuit and operational interventions in a transmitter system in order to enable this change in the type of modulation desired for remote control transmission. On the other hand, consent to the use of the transmitter intended for another task for the transmission of the extraordinary modulation (remote control commands) is easier to achieve if, on the one hand, no circuit-like intervention in the transmitter system has to be carried out, and on the other hand, the simultaneous transmission of Remote control commands caused no interference with the radio transmission.

In contrast to the previously described first case, the same modulation type, namely amplitude modulation, is therefore provided for both the ordinary modulation (radio program) and the extraordinary modulation (remote control command) according to the second case now to be described. It is therefore sufficient if both signals are simultaneously fed to the modulation input of the existing transmitter, which is present anyway. Of course, different modulation parameters must also be used in this second case in order to ensure the decoupling of ordinary and extraordinary modulation.

The normal modulation (radio program) of a 60 amplitude-modulated radio transmitter encompasses approximately the low-frequency range of 100-5000 Hz, but at most approximately 30-10,000 Hz.Frequencies above this range are usually already strongly suppressed on the transmission side for reasons of reduction of interference from neighboring transmitters. It is therefore hardly feasible for the remote control commands provided here, ie the extraordinary modulation, to use frequencies above the audio frequency range occupied by the radio transmission. Against that

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Frequencies below the frequency range intended for radio transmission can be considered. Frequencies below approximately 30 Hz are practically non-existent in the normal modulation of a radio transmitter, and frequencies in the range of approximately 10-20 Hz can therefore be provided for extraordinary modulation, for example for remote control purposes.

However, it should be noted that such low frequencies can usually only be processed with a reduced amplitude in conventional modulation amplifiers of radio transmitters. It is therefore advantageous not only to choose the extraordinary modulation differently in terms of its frequency range from the ordinary modulation, but also in terms of its degree of modulation.

While the ordinary modulation in amplitude modulation broadcast transmitters is now operated with a maximum degree of modulation of approximately 95%, according to the present exemplary embodiment, a greatly reduced degree of modulation of, for example, only approximately 5% is provided for the extraordinary modulation. This ensures that the modulation part of the radio transmitter is in no way overridden by the remote control commands, which are strictly outside the frequency range of the radio modulation. Because of this, as a result of intermodulation, the extraordinary modulation could cause interference in the reception of the radio program.

There are therefore no particular difficulties with the choice of the modulation parameters for the extraordinary modulation on the transmission side. On the other hand, special precautions must be taken for the receiving side in order to reliably recover the additional, ie. H. to ensure extraordinary modulation, which corresponds to the remote control commands to be transmitted.

The structure of a remote control receiver will now be described, which is suitable from high-frequency received signals, which have both an ordinary modulation (radio program) and an extraordinary modulation (remote control command), which recover the remote control commands corresponding to the extraordinary modulation.

The following parameters are assumed here: existing radio transmitter for amplitude modulation for the radio program to be transmitted with an audio frequency range of a maximum of 50-10,000 Hz,

maximum degree of modulation for proper modulation (radio program) 95%,

additional extraordinary amplitude modulation in the frequency range below 30 Hz with a reduced degree of modulation of 5%,

Carrier frequency of the radio transmitter in the so-called medium wave range, d. H. between 520 kHz and 1560 kHz,

Remote control commands as coded commands in the form of pulse sequences of an audio frequency of 15 Hz are fed to the modulation input of the radio transmitter.

Fig. 1 shows a block diagram of an embodiment of such a remote control receiver. The remote control receiver as a whole is labeled 1. The remote control receiver 1 is followed by a switching element 2, for example a toggle relay, for remote switching on or off of a load object 3, for example a hot water tank, to a power supply network 4. The remote control receiver 1 itself is also connected to the power supply network 4 and has a power supply part, not shown to supply the various electronic components of the remote control receiver with power in a manner known per se.

The remote control receiver 1 contains, for example, a ferrite antenna known per se as part of an input circuit which is tuned to the high-frequency vibrations to be received. The remote control receiver 1 can also have an antenna connection 5. The remote control receiver 1 can be connected to an additional antenna 6 via the connection 5. A coupling to the power grid 4 could also be considered as an additional antenna 6, for example. However, it should be noted here that the radio-frequency signals are freely transmitted on the transmission side and are not directly impressed on the high-voltage current as in ripple control technology. Despite the possible use of the power line as an additional antenna, the present case is a high-frequency signal transmission in accordance with the radiation and not a line-based signal transmission.

A receiving part 7 of the remote control receiver is preferably implemented in a superposition circuit (superhete rodyn) known per se with an auxiliary oscillator 8. The receiving part 7 has, for example, LC circles and / or piezoelectric filters or the like as selection means. However, it should be noted that due to the very low frequency range for the extraordinary modulation, the corresponding sidebands are so close to the carrier frequency that a high-frequency or intermediate-frequency separation of them from the ordinary modulation is practically impossible.

Accordingly, on the output side of a known demodulator contained in the receiving part 7, both a DC component corresponding to the carrier-frequency signal and a mixture of low-frequency signals appear, originating from both the ordinary and the extraordinary modulation. With sufficiently small up or. intermediate frequency bandwidth of the receiving part 7, however, it is entirely possible to at least partially suppress at least a part, mainly the higher frequencies, of the ordinary modulation.

In a manner known per se, the DC voltage component mentioned can be used for automatic gain control of the high-frequency part 7.

The receiving part 7 is designed in such a way that it outputs the aforementioned mixture of low-frequency signals at its output 9 in addition to the DC voltage component mentioned, but only the DC voltage component at its further output 10. This DC voltage component is a measure of the received signal strength at the demodulator.

The signal mixture present at output 9 is fed to an input 11 of a low-frequency filter 12, in which the remote control commands transmitted as extraordinary modulation are separated or recovered by low-frequency selection means.

The low-frequency filter 12 has the task of using the supplied signal mixture to produce the tone-frequency pulse sequences corresponding to the extraordinary modulation of the transmission signal, i. H. the coded remote control commands to recover. For this purpose, it can be equipped with appropriate low-frequency filter circuits, which can be designed, for example, in the form of active RC filters. The low-frequency filter 12 preferably contains at least one high-pass filter for suppressing the DC voltage component and a low-pass filter, preferably of a higher order, for suppressing the low-frequency signal components originating from the ordinary modulation.

At its output 13, the low-frequency filter 12 emits a low-frequency pulse sequence corresponding to the remote control command whenever a remote control command is supplied as an extraordinary modulation to the transmission signal of the radio transmitter.

This low-frequency pulse sequence is

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Aisle 13 is fed to an input 14 of a rectifier 15, preferably a full-wave rectifier, in order to obtain a DC voltage pulse pulse gap sequence corresponding to the original remote control command, which sequence is output by the rectifier 15 at its output 16. 5

As such, a type of direct current pulse sequence obtained in this way, which corresponds to a remote control command, could be fed to a decoder in a manner known from ripple control technology in order, if the decoded remote control command is found correctly, to switch device 2 assigned to remote control receiver 1 and load object 3 to control. For reasons of transmission security, however, it is advantageous to carry the DC voltage pulse sequence mentioned from the output 16 of the rectifier 15 to an input 17 of a level comparator 18. The level comparator 18 represents a threshold value level, the response level of which is continuously adjusted by feeding the DC voltage component available at the output 10 of the receiving part 7 to an input 19 of the level comparator 18 to the received signal strength determined at the receiving location. The level comparator 18 is dimensioned 2o in such a way that it only allows the pulse comparator 18 to run through those pulse sequences which have or achieve a degree of modulation of approximately 5%.

This measure prevents the DC voltage pulse sequence recovered from the extraordinary modulation from being impaired by interference signals of low frequency.

At its output 19a, it outputs a pulse sequence which has been found to be good by the level comparator 18 to an input 20 of a decoder 21 known from ripple control technology. 30th

If a received pulse sequence is found to be good by the decoder 21, it outputs a control signal at its output 22 for the control of the switching element 2 connected downstream for switching on or off the load object 3 assigned to the remote control receiver 1 to and from the 35 power line 4 .

2 shows a circuit diagram of an exemplary embodiment of a high-frequency part 7. An input circuit 23 tuned to the frequency to be received is formed by a ferrite antenna 24 and a capacitor 25. The input circuit 23 is transformer-connected to a mixer stage 26. The mixing stage 26 is also supplied with the oscillator signal generated by the oscillator 8, which is shifted by the intermediate frequency with respect to the frequency to be received.

For reasons of long-term stability, it is advantageous to use a piezoelectric element 27 for stabilizing the oscillator frequency. Such elements are priced today. available which are below the price of an LC circuit and are therefore economically viable. so

The mixing stage 26 is coupled to an intermediate frequency amplifier 29 via a band filter 28 which is tuned to the intermediate frequency. The intermediate frequency amplifier 25 is followed by an output circuit 30 tuned to the intermediate frequency, followed by a demodulator 31. 55

A diode 33 connected to a secondary winding 32 of the output circuit 30 supplies to the output 9 of the high-frequency part 7 both a DC component corresponding to the strength of the carrier frequency and a mixture of low-frequency signals. These low-frequency 6o signals originate from both the ordinary and the extraordinary modulation.

A further diode 34 generates a DC voltage corresponding to the strength of the carrier frequency for the automatic gain control, which is amplified in a control voltage amplifier 35 and fed to both the intermediate frequency amplifier 29 and the mixing stage 26.

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This automatically acting gain control achieves a size of both the DC voltage component and the low-frequency signals that is only relatively little dependent on the differences in the strength of the received signal. After all, if the received signal is very weak, both the size of the DC voltage component and the low-frequency signals are expected to decrease noticeably.

While the mixture of DC voltage component and the various low-frequency signals appears at output 9, only the DC voltage component is fed to output 10 via a low-pass element 36.

3 shows a circuit diagram for an exemplary embodiment of a low-frequency filter 12. As mentioned earlier, the task of the low-frequency filter is to convert the low frequency recovered by demodulation to that of extraordinary modulation, i. H. recover the component corresponding to the remote control commands. Since the frequency spacing between the sidebands of the high-frequency signal, which corresponds to the extraordinary modulation to the carrier frequency, is relatively very small, for example, is only 15 Hz with respect to a few 100 kHz carrier frequency, the extraordinary modulation is separated on the receiving side with the aid of a suitable low-frequency filter . The pass band of this low-frequency filter is approximately between 10 and 20 Hz in the present case, so that the frequency of the tone frequency pulse sequence of 15 Hz corresponding to the remote control pulses is let through by the filter even with relatively fast keying.

The low-frequency filter has an attenuation of around 20 db per decade against the low frequencies, whereas the transmission curve drops from around 20 Hz upwards with around 80 db per decade.

This characteristic can be realized, for example, with a structure according to FIG. 3.

The input 11 of the low-frequency filter 12 is followed by a first-order low-pass 37, this is followed by an isolation amplifier 38. The isolation amplifier 38 is followed by a first-order high and low-pass filter 39, followed by a further isolation amplifier 40, which is followed by a second-order low-pass filter, the output of which is connected to the output 13 of the low-frequency filter 12.

In the present exemplary embodiment of the low-frequency filter 12, the various filter stages are implemented with the aid of operational amplifiers. Since such operational amplifiers have a so-called offset voltage and this is not readily stable, in particular is changed by temperature influences, it is advisable to compensate the offset voltage of stages 39 and 40 in the manner shown in FIG. 3 by means of stages 41 and 40 bridging amplifier low pass 42. Since low and high passes of the type mentioned above are known per se from the literature, in a given case it is only a question of the exact dimensioning of the same. This can be left to the person skilled in the art, so that further information is unnecessary here. However, the mandatory condition for the low-pass filter is that its passband characteristic has an attenuation of at least 40 dB per decade in the range between the highest frequency used for the extraordinary modulation and the lowest frequency used for the ordinary modulation. The low-frequency filter 12 must therefore be characterized overall by a higher-order low-pass filter in the range mentioned.

It is of course also possible to use the extraordinary modulation, i. H. to transmit the control commands in the manner of frequency shift keying (frequency shift). This type of modulation can be assumed to be known per se, so that further information is unnecessary here. In such a case, the low-frequency filter 12 would have to be on the receiving side

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615304 g should be designed accordingly. For example, it would be possible to perform other tasks for certain radio frequency transmitters.

radiated for the recovery of a remote control command points towards the known ripple control systems

the pulse sequence two the following advantages matched to the two nominal frequencies:

agreed to provide active RC filters or N-path filters. Would the frequency shift keying of the extraordinary modulation 5 1. Elimination of the effort on the transmission side;

in a manner known per se on the transmission side to the network frequency 2. Spatially very long range;

bound, this could also be a trigger on the receiving side. 3. Very high transmission security;

clock generators for the N-path filter using the 4. The application of different modulation parameters

Mains frequency. See also Swiss Patent No. ter for extraordinary and ordinary modulation

540 608 and 566 086. i o of the transmitter in question allows a relatively simple

The present invention, according to which remote control signals and inexpensive structure of the receivers in question

for the switching on or off of load objects in a Starkger, which is considerable in view of their large number

Power grid as an extraordinary modulation is one of economic importance.

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3 sheets of drawings

Claims (13)

615304 PATENT CLAIMS 1. A method for remote control of the switching on and off of load objects in a power supply network by means of radio-frequency remote control signals, characterized in that the remote control signals are added on the transmission side as extraordinary modulation of the ordinary modulation of a high-frequency transmitter intended for another task, whereby for the extraordinary modulation and Ordinary modulation different modulation parameters are used and that on the receiving side the components of the received signal generated by the extraordinary modulation are separated from the ordinary modulation on the basis of their different modulation parameters and, after their evaluation as control signals, are fed to a switching element for connecting or disconnecting a load object to or from the power grid will. 2. Apparatus for carrying out the method according to claim 1, characterized on the one hand by a modulatable high-frequency transmitter, at the modulation input of which, in addition to the modulation signals for the orderly modulation of the transmission signal, also modulation signals which correspond to remote control commands are supplied for the extraordinary modulation of the transmission signal, the extraordinary modulation has different modulation parameters compared to ordinary modulation and, on the other hand, has at least one remote control receiver which is tuned to the frequency of the transmission signal of the high-frequency transmitter and which is designed such that it responds only to the modulation parameters of the extraordinary modulation. 3. The method according to claim 1, characterized in that as modulation parameters for the ordinary modulation amplitude modulation and for the extraordinary modulation frequency or. Phase modulation is applied. 4. The method according to claim 1, characterized in that amplitude modulation is used for both the ordinary and the extraordinary modulation, but that for the extraordinary modulation an outside the frequency range of the ordinary lying frequency range is used. 5. The method according to claim 4, characterized in that a degree of modulation is selected for the extraordinary modulation, which is smaller than the maximum degree of modulation of the ordinary modulation. 6. The method according to claim 5, characterized in that the degree of modulation of the extraordinary modulation is monitored and evaluated at the receiving end and only those demodulated signals are supplied to their evaluation which correspond to a predetermined degree of modulation. 7. The method according to claim 3, characterized in that the reception side of the selectively selected and amplified received signal is limited in its amplitude and is fed to a frequency or phase discriminator, after which the output signal of the discriminator is decoded. 8. The method according to claim 1, characterized in that for the extraordinary modulation frequency shift keying is applied in a frequency range lying outside the frequency range of the ordinary modulation. 9. The device according to claim 2, characterized in that the remote control receiver is designed for the reception of frequency modulation or phase modulation signals, a selective, amplifying receiving part, an amplitude limiter connected downstream, a frequency or phase discriminator connected downstream and a decoder connected downstream , the output of which is connected to a switching element (2) for switching a load object on and off to or from a power grid. 10. The device according to claim 2, characterized in that the remote control receiver has a selective, amplifying high-frequency part (7), a downstream low-frequency filter (12), a downstream rectifier (15) and a downstream level comparator (18) for evaluating the degree of modulation which is followed by a decoder (21), the output of which is connected to a switching element (2) for switching a load object (3) on and off to or from a power grid (4) (Fig. 1, Fig. 2) . 11. The device according to claim 10, characterized in that the low-frequency filter (12) has a pass band below the frequency range of the ordinary modulation and has a low-pass filter of at least second order (Fig. 3). 12. The device according to claim 11, characterized in that in the low-frequency filter (12) at least two stages are compensated for by a bridging amplifier low-pass filter with respect to their off-set voltages. ■ 13. Device according to claim 2, characterized in that the remote control receiver is designed for the demodulation of frequency-shift-keyed remote control signals. H. Device according to claim 13, characterized in that filters are provided in the manner of N-path filters, the pass frequency is controlled depending on the network frequency.