GB2242090A

GB2242090A - A communication system

Info

Publication number: GB2242090A
Application number: GB9003217A
Authority: GB
Inventors: Christopher Brook Taylor
Original assignee: S V O Ltd
Current assignee: S V O Ltd
Priority date: 1990-02-13
Filing date: 1990-02-13
Publication date: 1991-09-18
Also published as: GB9003217D0

Abstract

The communication system comprises transmitter means 14 including an accousto-electric transducer 16 for converting a voice signal into an electrical signal and means 17 to 20 responsive to said electrical signal for emitting a light signal representative of said voice signal to remote receiver means. Alternatively or additionally the communication system comprises receiver means 15 for receiving a light signal from remote transmitter means and for converting the light signal into an audio signal. The transmitter/receiver means may be provided in or on an article of headgear, such as a crash helmet 12, and the remote receiver/transmitter may be a two way radio fitted to a motor cycle. This allows a rider to communicate with the two way radio without the need for an umbilical cable between the rider and the radio. <IMAGE>

Description

A Communication System This invention relates to a comunication system, particularly, but not exclusively, to a communication system for transmitting voice signals over short distances, in environments that have a high ambient noise level, where spurious radio signals could be a disadvantage and/or where there is a high level of radio signals that could affect radio wave transmission, and where cables are undesirable.

One such environment is on a motor cycle. Yet there is a requirement for some motor cycle riders, e.g.

police riders, to communicate with a two way radio fitted to the motor cycle. At present, this is done by providing an umbilical cable between the helmet of the rider and a two way radio fitted to the motor cycle.

This is inconvenient, undesirable and indeed even hazardous.

According to one aspect of the present invention there is provided a communication system comprising transmitter means including an accoustoelectric transducer for converting a voice signal into an electrical signal and means responsive to said electrical signal for emitting a light signal representative of said voice signal to remote receiver means, the communication system alternatively or additionally including receiver means for receiving a light signal from remote transmitter means and for converting the light signal into an audio signal.

Preferably, the communication system comprises both said transmitter means and said receiver means.

Preferably, the transmitter and/or receiver means is/are provided in or on an article of headgear, more preferably in the form of a helmet, and typically in the form of a crash helmet.

If the communication system comprises transmitter means, the means responsive to said electrical signal preferably comprises amplifier means, modulating means and light emitting means, and in this case the modulating means advantageously comprises a square wave generator and means for frequency modulating a square wave produced by the square wave generator in response to the electrical signal produced by the accousto-electric transducer.

If the communication system comprises receiver means, the receiver means preferably comprises means for converting a modulated light signal into an electrical signal, amplifier means, demodulating means and an electro-accoustic transducer.

Advantageously, the communication system also comprises remote transmitter means for emitting a light signal representative of an audio signal and/or remote receiver means for receiving a light signal from a transmitter means and for converting said light signal into an electrical or audio signal.

Preferably, the transmitter/receiver means is for transmitting/receiving an infra-red light signal.

According to another aspect of the invention, there is provided an article of headgear provided with a communcation system comprising transmitter means including an accousto-electric transducer for converting a voice signal into an electrical signal and means responsive to said electrical signal for emitting an infra-red light signal representative of said voice signal to remote receiving means, and receiver means for receiving an infra-red light signal from remote transmitter means and for converting the infra-red light signal into an audio signal.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a motor cycle and rider equipped with one embodiment of a communication system according to the present invention, Figure 2 is a block circuit diagram of a transmitter of the communication system of Figure 1, Figure 3 is a block circuit of a receiver of the communication system of Figure l.

Referring firstly to Figure 1, there is shown therein a motor cycle 10 and a rider 11. The rider is wearing a crash helmet 12 and the motor cycle 1 is equipped with a two way radio 13. The rider 11 is in communication with the radio 13 via an infra-red link including a transmitter 14 and a receiver 15 both of which are incorporated in the helmet 12.

The transmitter 14, which is shown in Figure 2, comprises an accousto-electrical transducer in the form of a piezo-electric microphone 16, an amplifier 17 for amplifying the electrical signal produced by the microphone 16, a modulator 18, a further amplifier 19 for amplifying the modulated signal, and a light emitting diode (L.E.D.) 20. It is advantageous to use a square wave as the carrier signal because light emitting diodes have a better output at a certain current and voltage, and this is best maintained with a square wave rather than a sinusoidal or triangular wave form. The modulator 18 thus includes a square wave generator and the square wave thus generated is frequency modulated by the input signal from the amplifier 17, in preference to amplitude modulation by the input signal for the reason given for preferring a square wave as the carrier signal.The amplifier 19 is provided to give an appropriate signal strength to operate the light emitting diode 20 to its maximum efficiency.

The light signal produced by the light emitting diode 20 is received by an infra-red receiver (not shown) and fed to the two way radio 13.

The receiver 15 provided in the helmet 12 receives signals from the two way radio by way of an infra-red transmitter (not shown) similar to transmitter 14 but without a microphone 16.

The receiver 15 comprises a photodiode 21 which converts the light signal into an electrical signal , a high gain pre-amplifier 22, a demodulator 23, a filter 24, an audio amplifier 25 and head set 26.

The photodiode 21 is a high speed PIN photodiode, with high photosensitivity, housed in a black infra-red transmissive moulding to reduce ambient light interference.

The photodiode 21 acts as a low gain push pull amplifier and provides two signals to the pre-amplifier 22. The pre-amplifier 22 incorporates matching circuits which compare the two signals from the photodiode 21 and which serve to filter out any noise that is common to the two signals so as to limit any interference that may be introduced into the wires connecting the photodiode 21 to the amplifier 22. The pre-amplifier 22 also incorporates gyrator circuits which are used to filter out most ambient light frequencies.

The demodulator 23 takes the form of a comparitor filter network and the output of the demodulator 23 is again filtered by filter 24 to provide an acceptable audio value and then amplified by amplifier 25 to drive one or more piezoelectric speakers in head set 26.

The communication system described above avoids the need for an umbilical cable between the helmet 12 and the two way radio 13 and is therefore more convenient and less hazardous than existing systems.

It is important that the component parts of the transmitter 14 and receiver 15 should be as small as practically possible because of the limited space available in the helmet. Also it is important to keep the weight of the helmet as low as possible. It is therefore desirable to use c-mos components and high capacity nickel cadmium batteries in the helmet.

The invention is not limited to the particular application described above. It could, for example, be adapted to provide one or two way communication between a motor cycle rider and a pillion passenger. In that case, the rider could have a transmitter and/or receiver in the rear of his/her helmet and the passenger could have a receiver and/or transmitter in the front of his/her helmet. The invention could also be adapted to provide communication between a rally driver and his navigator, or could be used in other environments where it is required to transmit voice signals over short distances, typically up to about 30 metres.

Claims

C=MS

1. A communication system comprising transmitter means including an accousto-electric transducer for converting a voice signal into an electrical signal and means responsive to said electrical signal for emitting a light signal representative of said voice signal to remote receiver means, the communication system alternatively or additionally including receiver means for receiving a light signal from remote transmitter means and for converting the light signal into an audio signal.

2. A communication system as claimed in claim 1, wherein the communication system comprises both said transmitter means and said receiver means.

3. A communication system as claimed in claim 1 or claim 2, wherein the transmitter andtor receiver means is/are provided in or on an article of headgear.

4. A communication system as claimed in claim 3, wherein the article of headgear is in the form of a helmet.

5. A communication system as claimed in any one of the preceding claims and comprising said transmitter means, wherein the means responsive to said electrical signal comprises amplifier means, modulating means and light emitting means.

6. A communication system as claimed in claim 5, wherein the modulating means comprises a square wave generator and means for frequency modulating a square wave produced by the square wave generator in response to the electrical signal produced by the accoustoelectric transducer.

7. A communication system as claimed in any one of the preceding claims and comprising the receiver means, wherein the receiver means comprises means for converting a modulated light signal into an electrical signal, amplifier means, demodulating means and an electro-accoustic transducer.

8. A communication system as claimed in any one of the preceding claims, further comprising remote transmitter means for emitting a light signal representative of an audio signal and/or remote receiver means for receiving a light signal from a transmitter means and for converting said light signal into an electrical or audio signal.

9. A communication system as claimed in any one of the preceding claims, wherein the transmitter/receiver means is for transmitting/receiving an infra-red light signal.

10. A communication system substantially as hereinbefore described with reference to the accompanying drawings.

11. An article of headgear provided with a communication system comprising transmitter means including an accousto-electric transducer for converting a voice signal into an electrical signal and means responsive to said electrical signal for emitting an infra-red light signal representative of said voice signal to remote receiving means, and receiver means for receiving an infra-red light signal from remote transmitter means and for converting the infra-red light signal into an audio signal.