AU2003262406B2 - Audio signal processing apparatus - Google Patents

Description

WO 03/090388 PCT/NZ03/00069 AUDIO SIGNAL PROCESSING APPARATUS TECHNICAL FIELD This invention relates to audio signal processing and transmitting devices and systems. More particularly, but not exclusively, the present invention relates to a frequency modulated stereo transmitter and audio signal processing apparatus adapted to be interfaced to a computer to enable audio signals to be processed and transmitted to an FM stereo receiver.

BACKGROUND ART Audio music in recent years has involved the use of various digitally encoded audio formats such as mini computer disc, computer disc and compressed MP3 files. The term "MP3" is a type of format ("codec") for compressing and decompressing data designed specifically for audio. It allows you to compress large audio files into much smaller ones, store them on your computer's hard drive (or other storage device), and then later "decompress" or play them back. However, to achieve this process a personal computer is generally used to decompress and decode digital files and play such files. For many users this may mean being restricted to being in the vicinity of a personal computer that can carry out this process.

It is an object of the invention to provide an audio signal processing system and apparatus which overcomes at least some of the abovementioned problems, or at least to provide the public with a useful choice.

SUMMARY OF THE INVENTION According to a broad aspect of the invention there is provided an audio signal processing apparatus, the apparatus including a microprocessor means having a storage means adapted to receive an input digital audio signal from an external entertainment device and to feed the digital audio signal to a digital processing means, the digital processing means being configured and arranged to convert the inputted digital audio signal to an analog audio signal and feed the output analog audio signal to an encoding means, the encoding means for encoding the analog audio signal into a frequency modulated baseband signal that is then modulated onto a synthesised WO 03/090388 PCT/NZ03/00069 2 radio carrier wave at a predetermined frequency, and wherein the output analog audio signal is transmittable to a suitable receiver means.

Preferably the memory means is an electrically erasable programmable read only memory.

Desirably the memory means is a flash memory in the form of a flash memory card.

Advantageously the flash memory card is replaceable.

Desirably the predetermined frequency of the radio carrier wave is substantially between and 110MHz.

Preferably the entertainment device is a personal computer adapted to process and play mono or stereo music. Desirably the digital audio signals are received via a universal serial bus from the entertainment device.

Preferably the encoding means is a stereo multiplex encoder. Desirably the analog audio signal is encoded to a frequency modulated stereo baseband signal.

Advantageously the microprocessor means is programmed to set the preferences and such preferences are stored in the memory means.

Preferably the apparatus further includes analog input means to allow, in use, an external codec format MP3 player to communicate with the apparatus to enable an output audio signal to be played.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be illustrated, by way of example only, with reference to the accompanying drawing in which: Figure 1: Shows a schematic diagram of the audio signal processing apparatus according to a preferred embodiment of the invention.

WO 03/090388 PCT/NZ03/00069 3 DETAILED DESCRIPTION OF THE DRAWINGS Referring to figure 1, an audio signal processing system and apparatus, generally referred to as 1, according to a preferred embodiment of the invention, is illustrated.

The audio signal processing apparatus 1 is configured and arranged to provide a portable apparatus for remote listening of mono or stereo music, audio and the like from digital and analog entertainment devices to enable, for example, music MP3's to be remotely played by utilising the FM stereo transmission band between substantially about 75MHz to 110MHz.

The audio signal processing apparatus 1 includes a microprocessor means 3 having a storage means 2. The storage means 2 is in the form of a memory means preferably including an electrically erasable programmable read only memory ("EEPROM"). The storage means 2 can alternatively or additionally include a flash memory in the form of a releasably attachable flash memory card. Any other known and suitable storage means may be used in the invention.

The microprocessor means 3 can be suitably programmed and adapted to receive a digital audio signal from an external entertainment device from a stereo music source and/or from an analog source from a computer means 4. The computer means 4 may optionally be a personal computer adapted to interface with the apparatus 1 of the invention. The digital audio signal may, for example, be from a compressed MP3 file that is suitably decompressed and restored and then fed via a computer interface means in the form of a USB interface cable 5 to the microprocessor means 3.

The apparatus 1 may be powered by a suitable external power source fed from the computer means 4 via the interface means 5, or by a separate suitable direct current power supply via power input 10 from an external power supply such as, for example, a vehicle cigarette lighter adapter socket or the like. In such a case, a transformer means for stepping down or regulating voltage to a required voltage level is incorporated in the apparatus 1. It is seen that the power input 10 may be used when an external power source is required when the computer means 4 is not connected to the device 1.

If no such power source or power supply is available, advantageously the apparatus 1 desirably includes a rechargeable power supply 12. The power supply 12 is preferably any suitable DC WO 03/090388 PCT/NZ03/00069 4 voltage power supply, and is desirably a rechargeable battery or batteries. The apparatus 1 includes a transformer means incorporated in the power supply means or the power supply 12 to regulate the power supply as required. It will be appreciated that various mains AC power supplies and car vehicle power DC supplies exist in a number of different countries, and versions of the apparatus 1 will be adapted to accommodate such power supplies available when an internal battery pack is not relied on.

The microprocessor means 3 feeds the digital audio signal to a digital processing means 6 in the form of a digital signal processor to form an analog audio signal. The digital signal processor 6 preferably includes integrated audio features, and at least one digital to analog converter.

Preferably the digital signal processor 6 is configured and arranged with two high speed digital to analog converters. The digital signal processor 6 desirably includes tone and volume controls.

The output analog audio signal from the digital signal processor 6 is fed into an encoding means desirably in the form of a stereo multiplex encoder 7. The encoder 7 encodes the analog audio signal into a suitable FM standard stereo baseband signal that is fed to a transmitting means 8.

The transmitting means 8 modulates the baseband signal onto a phase locked loop synthesised radio carrier wave for transmission. The frequency of the carrier wave can be desirably preprogrammed or set at power up from stored user preferences in the EEPROM 2 of the microprocessor means 3.

The output signal from the transmitter means can be received by a suitable receiver means 9.

The receiver means 9 may be an FM stereo receiver, and more desirably can include a standard radio walkmanTM, or a home or portable/car entertainment unit. The preferred FM stereo transmission band is preferably between substantially about 75 MHz and 110 MHz.

The user preferences can be set by the computer means 4 via the USB interface means Preferably a suitable Compact Disc containing a suitable driver is loaded via the computer 4 to allow a user to select a suitable FM channel, and other preferences such as tone and volume control settings. These settings are stored in the EEPROM 2. The apparatus 1 may be adapted to allow analog left and right audio signals to be received at the input end of the encoding means 7 for transmission to the FM receiver 9.

WO 03/090388 PCT/NZ03/00069 The audio processing apparatus 1 desirably functions to process and transmit a suitable audio signal to a remote FM stereo receiver 9. This is advantageous as the apparatus 1 can provide a wireless link in FM Stereo or mono for the purpose of remote extending the use of various personal digital and analog entertainment devices, so that various audio sources, including digital audio MP3 music, can be played on a home or portable entertainment system without wires by utilising a suitable FM frequency channel within a selected FM Stereo transmission band, typically between about 75 MHz to 110 MHz.

The apparatus 1 is configured and arranged so that the computer means 4 and associated power supply is not required after the initial set up preferences are selected and stored in the EEPROM 2. A separate stereo analog source can be used via analog input means in the form of external analog inputs 11. These inputs are used to receive left and right stereo analog signals into the encoder 7. In this arrangement it will be appreciated that the microprocessor 3 can still be used to set the desired FM channel and operational preferences for the device 1.

In a MP3 playing mode, the analog inputs 11 allow devices, such as a portable MP3 player and the like (not shown), that are provided with analog outputs, to be used in conjunction with the apparatus 1. The apparatus 1 is configured to allow a user to select MP3's to be played on a home entertainment or stereo system, or in a vehicle stereo system. It will be appreciated that in this mode the apparatus 1 is configured and arranged such that the digital to analog converters in the digital signal processor 6 are by-passed, as required.

It is further envisaged that the apparatus 1 can be used in conjunction with a personal computer 4 to play digital audio music such as MP3's by playing such music on the personal computer and having the system 1 process and transmit such music to a portable FM receiver 9 such as a walkmanTM without the need for an infra red transmitter on the personal computer 4. Such an apparatus 1 of the invention may advantageously operate through office partitions and standard thin internal walls of many buildings.

The apparatus 1 is preferably encased in a suitable and resilient housing 13 adapted to allow various inputs, and outputs as required, to be accessible. The housing 13 is desirably made of any plastics material, and is made of a moulded plastics material adapted to a shape for easy handling and management.

WO 03/090388 PCT/NZ03/00069 6 Wherein the aforegoing reference has been made to integers or components having known equivalents, then such equivalents are herein incorporated as if individually set forth.

Accordingly, it will be appreciated that changes may be made to the above described embodiments of the invention without departing from thdie principles taught herein.

Additional advantages of the present invention will become apparent for those skilled in the art after considering the principles in particular form as discussed and illustrated. Thus, it will be understood that the invention as described is not intended to be restrictive in any way, and is intended to be illustrative. Many other embodiments will be apparent to those skill in the art upon reviewing the above description, and therefore the invention is not intended to be limited to the particular embodiments described or illustrated, but is intended to cover all alterations or modifications which are within the scope of the invention and the appended claims.

Claims (12)

1. An audio signal processing apparatus, the apparatus including a microprocessor means (P adapted to receive an input digital audio signal from an external entertainment device and to feed the digital audio signal to a digital processing means, the digital processing means being configured and arranged to convert the inputted digital audio signal to an analog audio signal and feed the output analog audio signal to an encoding means, the encoding means for encoding the analog audio signal into a frequency modulated baseband signal that is then modulated onto a synthesised radio carrier wave at a predetermined frequency, and wherein the output analog audio signal is transmittable to a suitable receiver means, and wherein the microprocessor means includes a memory means for storing user preferences including the predetermined frequency modulated output carrier signal.

2. An apparatus according to claim 1 wherein the memory means is an electrically erasable programmable read only memory, and wherein the user preferences include tone and volume settings.

3. An apparatus according to claim 1 wherein the memory means is a flash memory.

4. An apparatus according to claim 3 wherein the flash memory is a releasably attachable flash memory card.

An apparatus according to claim 1 wherein the predetermined frequency of the radio carrier wave is substantially between 75MHz and 110MHz.

6. An apparatus according to claim 1 wherein the entertainment device is a personal computer adapted to process and play mono or stereo music.

7. An apparatus according to claim 1 wherein the digital audio signals are received via a universal serial bus from the entertainment device.

8. An apparatus according to claim 1 wherein the encoding means is a stereo multiplex encoder. 7 AMENDED SHEET lirs &UA6 PCT/NZ2003/0000 6 9 Received 09 August 2004

9. An apparatus according to claim 1 wherein the analog audio signal is encoded to a frequency modulated stereo baseband signal.

10. An apparatus according to claim 1 wherein the microprocessor means receives an input digital audio signal from the external entertainment device via a universal serial bus connector and associated cable means.

11. An apparatus according to claim 1 further including analog input means to allow, in use, an external codec format MP3 player to communicate with the apparatus to enable an output audio signal to be played.

12. An audio signal processing apparatus substantially as herein described with reference to figure 1. 8 AlNDED SHEET Iir~p