EP0230173B1 - Remote presence-monitoring device for a moving object, an animal or a human being within a close proximity - Google Patents

Abstract

A device for the remote surveyance of a moving object, an animal or a human being comprises, on the object, the animal or the human being monitored, a portable transmitter (1) including an RF oscillator (6) and means (8, 9) for chopping the output RF carrier from the oscillator (6) into a train of amplitude modulated signals forming a coded signal of identification of the transmitter holder, and also comprises a remote receiver housed into a portable casing (2). In order to facilitate the localization of the transmitter holder or carrier, the receiver comprises only a whip antenna (5) which is manually orientable in all directions and the receiver circuit comprises a decoder (28) at the input of which is applied the received coded signal, means (30, 31, 33) producing a sound signal are connected at the output of the decoder and means (32, 39-43) producing a variable light signal are connected to the output of the decoder (28) to give a visual indication varying as a function of the direction and the distance of the transmitter (1).

Description

The present invention relates to a device for remote monitoring of the presence, in a close area, of a mobile object, an animal or a human being.

We know that domestic animals tend to run away quite often, far enough from their usual place of stay. This results in fairly long and often fruitless searches for the owners of these animals.

In addition, the same problem arises with regard to the surveillance of children likely to be abducted, or of vehicles likely to be stolen.

Devices are already known providing such remote monitoring. One of these devices, which is described in US Pat. No. 4,528,566, comprises a transmitter carried by the person or animal to be monitored, this transmitter comprising an HF oscillator, the carrier of which is cut to the rhythm of a coded signal uniquely identifying the carrier of the transmitter. The Hf signal thus produced is applied to a transmitting antenna to be received remotely by a receiving antenna system connected to a direction-finding receiver. In this known device, the antenna system comprises, on the one hand, a whip antenna connected directly to the input of an HF amplifier and, on the other hand, an antenna in a half-wave resonant loop, orientable around a vertical axis for the azimuth scanning, which is also connected to the input of the HF amplifier via a half-wave delay line. The receiver also comprises a mixer receiving the amplified HF signal and the output signal of a local oscillator, and a low frequency amplifier feeding a loudspeaker.

Such a known device has several drawbacks which make it easy to use. In fact, it is relatively heavy and bulky, it requires that its housing be placed in a vertical position so that the rotating loop antenna can perform its azimuth scanning and it only makes it possible to perform an approximate localization by sound. bearer the notam transmitter without making it possible to appreciate the distance at which it is. Furthermore, it does not make it possible to carry out a clear discrimination between the signals transmitted by several carriers being in the monitored area because all the HF signals produced simultaneously by the respective transmitters of the various carriers, with the same carrier, could be received. simultaneously by the receiver, being superimposed and no longer generating, therefore, an easily recognizable low frequency signal.

The present invention aims to solve this problem of surveillance by very convenient means of use which make it possible to easily locate a mobile object, an animal or a determined human being among a set of these and to locate the direction with precision. which is then the object, animal or human being monitored, among others, as well as its distance.

To this end, this device for remote monitoring of a mobile object, an animal or a human being, comprising, on the object, the animal or human being monitored, a portable transmitter comprising an oscillator HF, means for cutting the HF carrier of the oscillator output into a train of amplitude modulated signals forming a coded signal identifying the carrier of the transmitter, and an antenna transmitting the coded signal, and a remote receiver housed in a portable housing and comprising a receiving antenna for receiving the coded signal received from the transmitter and means for producing a signal making it possible to identify the direction in which the carrier of the transmitter is located, is characterized in that the receiver only has a whip antenna which can be manually oriented in all directions and the receiver circuit includes a decoder at the input of which the received coded signal is applied, means producing a sound signal connected to the decoder output so as to be put into service only when the received coded signal is recognized as being valid by the decoder and means producing a variable light signal connected to the decoder output to give a variable visual indication depending on the direction and distance from the transmitter.

An embodiment of the present invention will be described below, by way of non-limiting example, with reference to the appended drawing in which:

Figure 1 is a diagram illustrating the principle of a remote monitoring device according to the invention.

Figure 2 is a block diagram of the monitoring device.

Figure 3 is an electrical diagram of an embodiment of the transmitter.

Figure 4 is an electrical diagram of an embodiment of the receiver.

The monitoring device according to the invention, the principle of which is illustrated in FIG. 1, comprises a transmitter assembly 1 carried by a mobile object, a human being or an animal, and a direction finder located at a distance from the previous one. The transmitter 1 can be worn in any suitable way, for example by being housed in a collar 3 worn by the animal, or in a bracelet. The transmitter 1 comprises an antenna 4 transmitting a coded signal identifying the object, the person or the animal carrying the transmitter. This coded signal consists of a VHF signal, for example of frequency 72 MHz, amplitude modulated by a digital coding signal, this coded signal characterizing the carrier of the transmitter 1.

The direction-finding receiver is contained in a casing 2 of molded plastic, having a shape which can be easily held by hand. This receiver comprises a single "whip" antenna 5 making it possible to receive the signal coming from the transmitter 1. The receiver makes it possible, from the strength of the received signal, to locate the direction and the distance of the carrier from the transmitter 1 ,

As can be seen in FIG. 2, the transmitter 1 comprises a VHF oscillator 6 transmitting a VHF carrier at a frequency of 72 MHz for example. This signal can be in broken from time to time, in order to increase the autonomy of feeding. The output of the oscillator 6 is connected to a final amplifier stage 7, the output of which is connected to the transmitting antenna 4. Furthermore, the transmitter 1 contains a sequencer circuit 8 connected to an encoder 9. The sequencer 8 applies to the encoder 9 a niche signal consisting of alternating rectangular voltage pulses of duration of 7 seconds each, for example, which are separated by intervals, also of 7 seconds, in which the voltage is zero. The encoder 9 delivers at its output a word of several bits I, for example nine bits, which uniquely identifies the carrier of the transmitter 1. This identification signal I is applied to the final amplifier stage 7.

If we refer to Figure 3, we see that this figure shows the electrical diagram of a form of execution of the transmitter. This transmitter includes a stabilized power supply 10 which is connected by a switch 11 to the two poles of a battery 12. This stabilized power supply supplies all the components of the transmitter with a DC voltage of + 5V. Consequently, as soon as the switch 11 is closed, the sequencer 8 is put into service, its operating period being determined by a resistor bridge 13, 14 and the associated capacitor 15. Furthermore, the VHF oscillator 6 is of the quartz type 17 and it includes a transistor 18. The collector of this transistor 18 is connected to the base of another transistor 19 constituting an intermediate amplifier stage and the emitter of this latter transistor. is in turn connected to the base of a transistor 21 forming part of the final amplifier stage 7. The emitters of the two transistors 19 and 21 are connected to the collector of a transistor 22 whose base is connected to the output of the encoder 9. Between the antenna 4 and the transistor 21 of the final amplifier stage is interposed a filter network 22 guaranteeing the purity of the signal transmitted.

The goniometric receiver comprises, inside the box 2 (FIG. 2), an HF amplifier 24 at the input of which the signals picked up by the antenna 5 are applied, and whose output is connected to an input of a mixer 25. Another input of this mixer is connected to a local oscillator 26 whose frequency is slightly different from that of the carrier of the signal emitted by the transmitter 1. This frequency of the local oscillator can be for example 71.545 MHz. The output signal from the mixer 25 is applied to a low-frequency amplifier 27, the output of which is connected to a decoder 28. The receiver also comprises an amplifier 29, the input of which is connected to an output of the mixer 25, and a sequencer 31 the input of which is connected to the output of the decoder 28. The amplifier 29 and the sequencer 31 are connected to a field indicator 32 while another output of the sequencer 31 is connected to a circuit 33 for controlling an alarm sound or buzzer 30. The field indicator 32 is a drive circuit of seven light-emitting diodes (LEDs) 37,38,39,40,41,42,43 which appear on one side of the housing 2, as can be see in FIG. 1. Preferably these light-emitting diodes are distributed at an angle, the two red diodes 37.38 being the most spaced apart being followed by two yellow diodes 39.40 then two green diodes 41.42, the last green diode 43 being located e at the vertex of the angle. All the components of the receiver are connected to a stabilized power supply 34 which is connected to a battery 35 by a start switch 36 and which delivers at its output a DC voltage of + 5V for the supply of the various circuits.

The various circuits of the receiver 2 appear on the detailed electrical diagram of FIG. 4 which corresponds to a non-limiting embodiment.

• 1) Le signal modulé comporte un code différent de celui prédéterminé sur lequel a été réglé le décodeur 28. Ce décodeur 28 reste alors inerte et l'indicateur de champ 32 reste à zéro car il est alors mis en court-circuit par un transistor 44 relié à une sortie du décodeur 28, bien que cet indicateur de champ reçoive le signal de sortie du mélangeur 25, après amplification par l'amplificateur 29 (du type LM 358). Dans ce cas le buzzer 30 n'est pas excité, aucun signal sonore n'est émis, et seul l'allumage des deux diodes électroluminescentes rouges 37,38 indique que l'appareil est en service, mais sans avoir toutefois localisé le porteur de l'émetteur 1.
• 2) Le signal modulé appliqué à l'entrée du décodeur 28 comporte un code correspondant à celui qui a été prédéterminé. Dans ce cas le décodeur 28 change d'état à sa sortie et il libère le séquenceur 31. Ce séquenceur 31 émet, à sa sortie qui est reliée au circuit 33 de commande du buzzer 30, un signal périodique si bien que toutes les 200 millisecondes, par exemple, le buzzer 30 est mis en service. Par ailleurs le transistor 44 est bloqué si bien que l'indicateur de champ 32 n'est plus mis en court-circuit. Cet indicateur de champ peut traiter alors le signal analogique présent à son entrée et qui provient du mélangeur 25, à travers l'amplificateur 29. Cet indicateur de champ commande l'allumage sélectif des diodes électroluminescentes 39 à 43 pour permettre de repérer, à partir de l'allumage de ces diodes, la direction dans laquelle se trouve le porteur de l'émetteur et sa distance. Si toutes les diodes 39 à 43 sont allumées et le buzzer 30 fonctionne, ceci veut dire que l'antenne 5 est orientée dans la bonne direction et que l'émetteur 1 est très proche. Si la diode verte 43 du sommet de l'angle est seule éteinte et le buzzer fonctionne, la direction d'orientation de l'antenne 5 est assez bonne mais l'émetteur est éloigné à environ 200-400 mètres. Lorsque les trois diodes vertes 41,42,43, sont éteintes, les diodes jaunes 39,40 étant allumées, et le buzzer fonctionne, ceci signifie que la direction de l'antenne 5 est assez bonne mais que l'émetteur se trouve à une distance comprise entre 500 et 1000 mètres. L'allumage sélectif des diodes électroluminescentes 39-43 est ainsi fonction de l'amplitude du signal appliqué à l'entrée de l'indicateur de champ 32, lequel n'est toujours rendu actif que si le signal codé reçu est reconnu valide par le décodeur 28.

The operation of the receiver 2 is as follows: as soon as the switch 36 is closed, all the circuits are energized, which is indicated by the lighting of the two red light-emitting diodes 37, 38 connected to the output "8" of the field indicator 32 which is of the 237 BG type. The local oscillator 26 is also put into operation and as soon as a 72MHz frequency signal appears on the antenna 5, all of the mixer circuits and intermediate frequency ensures the shaping of the low frequency modulation. This modulated signal is applied, after being amplified by the low frequency amplifier 27, to the input of the decoder 28 which may be of the MC145028 type from the company MOTOROLA. Two cases are then possible:

• 1) The modulated signal comprises a code different from the predetermined one on which the decoder 28 has been set. This decoder 28 then remains inert and the field indicator 32 remains at zero because it is then short-circuited by a transistor 44 connected to an output of the decoder 28, although this field indicator receives the output signal from the mixer 25, after amplification by the amplifier 29 (of the LM 358 type). In this case the buzzer 30 is not excited, no sound signal is emitted, and only the lighting of the two red light-emitting diodes 37,38 indicates that the device is in service, but without having however located the carrier. the transmitter 1.
• 2) The modulated signal applied to the input of the decoder 28 includes a code corresponding to that which has been predetermined. In this case the decoder 28 changes state at its output and it releases the sequencer 31. This sequencer 31 emits, at its output which is connected to the circuit 33 for controlling the buzzer 30, a periodic signal so that every 200 milliseconds , for example, buzzer 30 is put into operation. Furthermore, the transistor 44 is blocked so that the field indicator 32 is no longer short-circuited. This field indicator can then process the analog signal present at its input and which comes from the mixer 25, through the amplifier 29. This field indicator controls the selective lighting of the light-emitting diodes 39 to 43 to make it possible to identify, from from the lighting of these diodes, the direction in which the carrier of the transmitter is located and its distance. If all the diodes 39 to 43 are lit and the buzzer 30 is working, this means that the antenna 5 is oriented in the right direction and that the transmitter 1 is very close. If only the green diode 43 at the top of the angle is off and the buzzer is working, the orientation direction of the antenna 5 is fairly good but the transmitter is distant at around 200-400 meters. When the three green diodes 41,42,43 are off, the yellow diodes 39,40 being on, and the buzzer is working, this means that the direction of the antenna 5 is quite good but that the transmitter is at a distance distance between 500 and 1000 meters. The selective lighting of the light-emitting diodes 39-43 is thus a function of the amplitude of the signal applied to the input of the field indicator 32, which is always made active only if the coded signal received is recognized as valid by the decoder 28.

If the red diodes 37 and 38 are only lit and the buzzer 30 is working, this means that the modulated signal received contains a valid code and it is possible to find the direction of the transmitter 1, by moving the antenna 5, by based on the lighting of diodes 39-43.

It is naturally possible to envisage various variant embodiments of the receiver 2. In particular, it is possible to use a single integrated circuit grouping together the HF amplifier 24, the mixer 25, the local oscillator 26 and the low frequency amplifier 27.

The LED indicator can be replaced by a liquid crystal display which is more precise and more economical in energy consumption.

One can integrate in the same circuit the decoder 28, the sequencer 31, the visualization control and the routine indications (state of the batteries, course to be held etc ...).

It is also possible, according to an alternative embodiment, to add to the transmitter 1 a receiver ensuring permanent communication between the mobile (transmitter) and the monitoring receiver. This radio link then allows the automatic triggering of the transmitter 1 according to a programmed perimeter, and the determination of the distance and the direction separating the two elements, this various information being indicated in clear on the surveillance receiver.

In the case where the transmitter 1 is carried by a human being, this transmitter can be provided with a direct call button, by momentary action, while the receiver is then in permanent standby. The action on the call button triggers the receiver, the transmitter 1 taking its configuration of sequenced transmissions and the search procedure remaining the same as previously.

For more collective uses (in the case of windsurfers or mountain rescue for example) and to make the intervention possible more efficient and above all faster, we can provide for the selection of a single channel which corresponds to two separate words at transmission and in the same way at discrimination in receiver 2 of these signals.

Although the device according to the invention has been described in a particular application for monitoring a living being, it goes without saying that it can be used for any other purpose, in particular for monitoring any mobile object that can to be stolen. It can be used in particular for remote monitoring of vehicles such as trucks, motorcycles etc ... or of boats, in ports, to prevent theft of these.

Claims (5)

1. Device for the remote surveyance of a moving object, an animal or a human being, comprising, on the object, the animal or the human being monitored, a portable transmitter (1) comprising an RF oscillator (6), means (8, 9) for chopping the output RF carrier from the oscillator (6) into a train of amplitude modulated signals forming a coded signal of identification of the holder of the transmitter, and an antenna (4) transmitting the coded signal, and a remote receiver housed in a portable casing (2) and comprising a receiver antenna (5) for picking up the coded signal received coming from the transmitter (1) and means for producing a signal for locating the direction in which the holder of the transmitter (1) is located, characterized in that the receiver comprises only one whip antenna (5) manually orientable in all directions and the receiver circuit comprises a decoder (28) at the input of which is applied the coded signal received, means (30, 31, 33) producing a sound signal connected at the output of the decoder (28) so as to be put into operation only when the coded signal received is recognized as being valid by the decoder (28) and means (32, 39-43) producing a variable light signal connected to the output of the decoder (28) to give a visual indication varying as a function of the direction and the distance of the transmitter (1).
2. Device according to Claim 1, characterized in that the output of the decoder (28) is connected to a sequencer (31) connected to a circuit (33) for controlling a sound alarm or buzzer energized periodically.
3. Device according to either one of the preceding Claims, characterized in that the receiver comprises a field indicator (32) constituted by a driving circuit of electroluminescent diodes (37-43) of different colours of which the selective lighting is a function of the amplitude of the signal applied to the input of the field indicator (32) which is connected, through an amplifier (29), to an output of an intermediate frequency mixer circuit (25) which is connected between an RF amplifier (24) and a low frequency amplifier (27) and which is connected to a local oscillator (26).
4. Device according to Claim 3, characterized in that the field indicator (32) is connected to a switch transistor (44) connected to the output of the decoder (28) so as to short-circuit and place out of operation the field indicator (32) when the code of the signal received is not recognized as valid by the decoder (28).
5. Device according to either one of Claims 3 and 4, characterized in that the electroluminescent diodes (37-43) appear on a face of the casing (2) and these electroluminescent diodes are distributed, forming an angle, two red diodes (37, 38) being the most remote, followed by two yellow diodes (39, 40) then by two green diodes (41, 42), the last green diode (43) being located at the apex of the angle, all the yellow and green diodes (39-43) being lit only when the antenna (5) is oriented in the right direction and when the transmitter (1) is very near.

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