Title of Invention

''AN IMPROVED MULTI-CHANNEL/LINGUAL, MULTI-MODE WIRELESS AUDIO TRANSMITTER AND RECEIVER SYSTEM''

Abstract

The present invention provides for An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system consists of a wireless audio transmitter and a receiver with headphones wherein the transmitter is capable of transmitting audio (voice, music or combination thereof) stored in digital form in different languages by using either infrared carrier or radio frequency carrier to the receiver. The transmitter under the present invention is placed near the object or exhibit, transmits digital audio or coded audio stored in it about the object. The transmitter is capable of using a radio frequency or an infrared carrier. It provides for indoor as well as outdoor use. The receiver has both the modes of reception indoor as well as outdoor. It is useful and works as an alternative to human guides as well as text for information placed near the object in places of public interest such as art galleries, exhibitions, museums etc.

Full Text

FIELD OF INVENTION An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system consists of a wireless audio transmitter and a receiver with headphones wherein the transmitter is capable of transmitting audio (voice, music or combination thereof) stored in digital form in different languages by using either infrared carrier or radio frequency carrier to the receiver. The device is entirely solid state and there are no moving parts in the system rendering it inherently more reliable. The device is capable of being used as an alternative to human guides as well as texts of information placed near the objects in various places of public interests such as Art galleries, exhibitions, museums etc. a visitor to such a place is provided the headphones and receiver capable of selecting the language visitor wishes with the help of frequency selection. The transmitter placed near the object or exhibit transmits digital audio or a number coded in audio stored in it about the object which is received by the visitor who has his or her eyes on to the object and is able to observe salient features thereof and several visitors enjoy one or different objects at the same time without disturbing fellow visitors. The system is also to the benefit of those with sight impairments or those who do not have their reading glasses while visiting the object/exhibit. The transmitter is capable of using either a radio frequency or an infrared carrier as may be required. In places where exhibits are too close-by, nearby radio frequency transmitters may interfere with each other. Therefore, more directional infrared (IR) beams are preferable under such circumstances. However, if the transmitter is to be installed in a large monument then it is advisable to use radio frequency. But, there may be locations where both indoor and outdoor exhibits are present (for example,forts with their own museums). In such cases, it is highly desirable that user should not be burdened with two receivers (one for outdoor use and another for indoor use). The present system provides for a combination of both the modes of reception in one receiver permitting the user to move seamlessly between indoor and outdoor locations and use the same receiver to hear the description. Not only this the system provides for multi-mode receiver capable of automatically switching from RF to IR or vice-versa as may be required by the movement of the visitor to indoor and outdoor locations. The system has built-in battery. In the event of AC main failure, the battery takeover and the audio transmission continues without any interruption. The system is weather-proof and can be deployed in outdoor locations as well. PRIOR ART The known and conventional systems are able to receive audio signals modulated either on radio-frequency or infrared carrier. However, IR and RF transmissions have their own limitations. The present system combines the two technologies to create a new audio reception device, which can be deployed in a variety of locations (indoor and outdoors). Commentary system under US Patent 5854844 uses electromagnetic induction. The user has to bring a reception coil very close to the transmitter antenna. It is not suitable in multi-user situation. Wireless Receiver under US Patent No.5218641 uses IR and allows receiving signals in near line of sight or in small cone around transmitting diodes. It is not suitable for outdoor deployment. Wireless Optical Communication system under US Patent No. 4882770 can use IR or RF but does not have digital audio stored in solid-state memory and automatic transmitter on/off as per the requirement. Electronic Tour Guide under US Patent No. 4163123 and Multi channel System with Information Systems under US Patent No.58996215 use infrared only and therefore, cannot be used outdoors. US Patent No.4457019 uses RF only, therefore, indoor use with smaller exhibits is very difficult. US Patent No.5850610 uses RF only, therefore, it cannot be used in the situations when exhibits are close by. FRANCE Patent No.2661032 uses IR and CD combination. CD unlike solid state memory, has the problem of track jumping if used as a mobile audio replay device. Also it cannot be used outdoors. Thus the known/prior art has its limitations which are addressed by the present invention. SUMMARY OF THE INVENTION The present invention therefore addresses all the limitations of the prior art and provides for the system which has two parts, viz. 1. Audio player with audio stored in digital format in a solid state memory and wireless transmitter (IR or RF); and 2. Wireless Audio receiver (IR & RF) with headphones with or without audio stored in digital format. The transmitter transmits audio on two channels to provide bilingual commentary. The player stores audio in digital form. The player converts this digital audio into analog and transmits the same over a wireless link. The transmitted audio is received by the wireless audio receiver and played back over a pair of headphones or a speaker. The visitor can select the channels (therefore the language) by means of a switch provided on the receiver. THE TRANSMITTER (Ref Fig. A) Points (1) and (2) are two digital memory banks of the transmitter, each capable of storing the digitized audio for certain specified duration and each meant to store audio in one language. Thus the two memory banks may have audio in two languages. Point (3) is the controller which sends addresses to each of these banks, to access a certain sample (one byte or more) of digitized audio from each bank. These samples then become available at output of each of the memory banks. Points (4) and (5) are digital to analog converters for converting the digitized audio samples of the two banks into analog system The analog signals pass through the reconstruction filters at points (6) and (7) that smoothen the analog waveform. Thereafter the said smoothened analog waveforms are used to modulate two carrier waves of frequency f1 and f2 Hz. Two FM modulators/Oscillators at points (10) and (11) perform the modulation. The resulting modulated waves are then added by an adder at point (12). The power of added signal is then amplified by power amplifier at point (13). The amplified signal is then sent to a transmission sub-system at point (14) for transmission. Thus a signal carrying two channels of audio information (Language A and B is transmitted simultaneously over the wireless link. In case of indoor installation the transmission subsection at point (14) is an array of infrared emitting diodes. In case of outdoor installations this transmission subsection is an antenna. The transmitter also has a battery (42), a battery charger (43) and a timer (44). This timer allows or disallows flow of power to rest of the circuitry, depending upon time of the day. This is to avoid unnecessary transmission during the period when museum or monument under consideration is closed to the public. THE AUDIO RECEIVER (Ref Fig.B) Audio receiver has two sections namely IR and RF. The IR section of the audio receiver at point (15) consists of an array of infrared sensitive photo-diodes. The RF section of the audio receiver consists of an antenna at point (40). The modulated IR signal transmitted by the transmitter is received by the photo-diode array at point (15) and converted into equivalent electrical signal. In RF section the modulated RF signal transmitted by the transmitter is received by the antenna at point (40). The modulated IF and RF signals are band-pass filtered at points (16) and (28) respectively to eliminate noise from the signals. The filtered signals are then amplified by an amplifier at points (17) and (29) respectively for IR and RF signals. The amplified signals are then mixed by mixers at points (18) and (30) with one of the two frequencies coming from a local oscillators at points 20 and 32 respectively. The frequency selection is done by the user by means of a switch at point (27) or (31) as per the choice of language. As a result of mixing and subsequent amplification by amplifiers at points (19) and (33) and band-pass filtration at points (21) and (34) an intermediate frequency (IF) is generated which is equal to the difference between local oscillator frequency and the frequency of the incoming signal. This frequency modulated is then amplified with the help of amplifiers at points (22) and (35) and passed through a limiting amplifier at points (23) and (36). Then the frequency modulated signal is demodulated using a quadrature detector at points (24) and (38). As a result of this demodulation, the original audio signal is recovered. The outputs from the limiting amplifiers (23) and (36) are applied to Receiver Controller (37). Based on the relative strengths of these signals, this controller selects either Audio Signal-IR or Audio Signal-RF via Audio Selection unit (39). The selected audio signal is then amplified (25) and played back over a pair of headphones or speaker (26). In case the audio is stored in the receiver then the transmitter transmits the exhibit number in audio. This number is received by the receiver. The receiver then uses this number to fetch the appropriate audio segment from its own memory (41) and play the same over its headphone or speaker. The receiver decodes these numbers using an audio tone-to-number decoder (45). The Receiver behaviour under various signal conditions is as follows: 1. When both IR and RF signals strengths are below a threshold, none of the signals is demodulated and therefore, no audio output is made available at the speakers. 2. When RF signal strength is below the threshold while IR signal strength is above the threshold, the FM carrier carried over IR is demodulated to recover the audio signal. This signal is then played back over the speakers. 3. When RF signal strength is above the threshold while IR signal strength is below the threshold then RF signal is demodulated to recover the audio signal. This signal is then played back over the speakers. 4. When both the signals strengths are above the threshold then this is the case of interfering signals. In this case, no audio will be made available on the speakers. The receiver has a reception mode override switch (41). This is to counter the problem of receiver switching into IR mode due to strong IR due to sunlight etc. This switch can be used to ensure that only RF portion of the receiver remains active even through there is strong spurious IR signal at that location. STATEMENT OF INVENTION: An apparatus for transmission and reception of multi channel audio, a wireless transmitter, an audio player, a wireless audio receiver (15) (40), headphones (26), carrier waves, modulators/oscillators (10) & (11), characterised in that; the number of simultaneous users in a given transmission zone is not restricted by the number of carrier frequencies available and practically unlimited by doing a broadcast of the audio signal to all receivers in the zone or by storing the audio in each of the receivers The providesaudio commentary in more than one language. WE CLAIM: 1. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system comprising a wireless transmitter, an audio player, a wireless audio receiver (15) (40), headphones (26), carrier waves, modulators/oscillators (10) & (11), characterised in that; the number of simultaneous users in a given transmission zone is not restricted by the number of carrier frequencies available and practically unlimited by doing a broadcast of the audio signal to all receivers in the zone or by storing the audio in each of the receivers and it provides audio commentary in more than one language. 2. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 1, wherein the carrier waves used for transmission are IR/RF. 3. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 2, wherein the wireless transmitter consists of two digital memory units, storing data in digital form in different language. 4. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 1, wherein the transmission subsection used in the said wireless transmitter is an array of infrared emitting diodes for indoor installation whereas for outdoor installation the transmission subsection is an antenna. 5. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 1, wherein the transmitter consists of a battery, a battery charger, a timer. 6. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 1, wherein the audio player consists audio in digital form, converts this stored audio into analog, transmits it over a wireless link. 7. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 1, wherein the audio receiver has two sections namely IR Section consisting of an array of IR sensitive photo diodes and RF Section comprising of an antenna. 8. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 1, wherein the headphones play the audio signal selected by receiver controller. 9. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 4, wherein wireless audio transmitter transmits the number of receiver. 10.An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 7, wherein wireless audio receiver receive the said number, transmitted by the transmitter. 11. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 7, wherein wireless audio receiver store the audio within itself in digital/in analog form. 12. An improved multi-channel/lingual, multi-mode wireless audio transmitter and receiver system as claimed in Claim 11, wherein the wireless audio receiver plays the audio corresponding to the number received. 13.An apparatus for transmission and reception of multi channel audio, substantially as herein described with reference to the description and as illustrated in the accompanying drawings.

Documents:

1225-del-2001-abstract.pdf

1225-del-2001-claims.pdf

1225-del-2001-correspondence-others.pdf

1225-del-2001-correspondence-po.pdf

1225-del-2001-description (complete).pdf

1225-del-2001-drawings.pdf

1225-del-2001-form-1.pdf

1225-del-2001-form-13.pdf

1225-del-2001-form-19.pdf

1225-del-2001-form-2.pdf

1225-del-2001-form-3.pdf

1225-del-2001-form-5.pdf

1225-del-2001-petition-138.pdf