JPH09501280A - Integrated video and audio signal distribution system for commercial aircraft and other vehicles. - Google Patents

Abstract

(57) Summary Passenger entertainment systems using improved digital audio signal distribution systems and methods for commercial aircraft and other vehicles. A plurality of digital audio signal sources (12) are provided which generate a plurality of compressed digital audio signals. The compressed digital audio signal is provided to a multiplexer (14) which time domain multiplexes such signals to produce a single composite digital audio data signal. The composite digital audio data signal is sent to a demultiplexer (18) capable of selecting a desired channel from the composite digital audio data signal. The selected channel is sent to a decompression circuit (20) where it is decompressed to produce a decompressed digital output signal. The decompressed digital output signal is then sent to a digital-to-analog converter (22) where it is converted to an analog audio signal. The analog audio signal is sent to the audio transducer (24).

Description

DETAILED DESCRIPTION OF THE INVENTION Integrated Video and Audio Signal Distribution System for Commercial Aircraft and Other Vehicles This patent is a continuation of SN (US patent application): 08 / 066,302, filed May 20, 1993. . Field of the invention The field of the invention is on-board entertainment systems for large commercial aircraft and other passenger vehicles. Recently, considerable attention has been given to the design and implementation of cabin entertainment and communication systems for use in large commercial aircraft. Examples of such systems are disclosed in the following patents: US Pat. No. 3,795,771 entitled "Passenger Entertainment / Passenger Service and Self-Test Systems";"Wireless Audio Passenger Entertainment Systems (WAPES)" U.S. Pat. No. 4,428,078; U.S. Pat. No. 4,774,514 entitled "Method and Apparatus for Performing Passenger- and Crew-Related Functions in an Aircraft";"Aircraft including Central Control System for Crew Call Lights and Passenger Reading Lights U.S. Pat. No. 4,835,604 entitled "Service Systems"; U.S. Pat. • US Patent No. 5,123,015 entitled "Chain Multiplexer". As shown in FIG. 1, a conventional (ie, prior art) passenger entertainment system 1 disclosed in the aforementioned patent generally has the following means: a plurality of audio signal sources 2 (eg, compact disc player and audio). Tape player); a plurality of analog-to-digital (A / D) converters 3 for converting analog signals generated by an audio signal source into a digital format; multiplexer 4 for time domain multiplexing (combining) the converted digital signals; Signal distribution network 5 for sending to a plurality of remote locations; at least one demultiplexer 6 for demultiplexing a composite signal and selecting one or more channels from the composite signal; a plurality of digitals for converting the selected channels into an analog format・ Analog (D / A) converter 7; Converts analog signals into sound waves A plurality of audio transducer 8 for conversion; a. As will be readily appreciated by those skilled in the art, while conventional compact disc players can provide digital signal outputs, these digital signal outputs are not easily used in conventional passenger entertainment systems. Can not. One of the main reasons for this is that compact disc players generally include their own internal oscillators, so that when multiple conventional compact disc players are utilized, their digital outputs are out of sync. Therefore, it becomes considerably difficult to combine a plurality of digital outputs. Another major reason why the digital output of conventional compact disc players is not utilized is that conventional compact disc players provide a digital signal output of 16-bit sample size and 44 kHz sampling rate. This makes it difficult to distribute multiple channels (e.g., 50 or more) through the audio signal distribution network without exceeding the desired power consumption level and generating a significant bit error rate. For example, if a conventional compact disc player output with 16-bit sample size and 44 kHz sampling rate must be utilized in a 72-channel system, transfer rates in excess of 50 megabits per second are required. However, conventional systems capable of achieving transfer rates of 50 megabits per second require significantly more power than is desirable in aircraft environments. Moreover, such systems require complex circuitry, generate a large amount of heat, and occupy more space than is desirable in the aircraft environment. Also, as will be readily appreciated by those skilled in the art, increasing data transfer rate will also increase cable attenuation and distortion. Such increases in cable attenuation and distortion make transmission considerably more difficult, especially increasing the bit error rate. As a means of reducing the data transfer rate and, consequently, greatly eliminating the complexity of data transmission, conventional passenger entertainment systems utilize the analog output signal S1 provided by a conventional compact disc player 2, The digital (A / D) converter 3 is used to convert the analog output signal S1 into a digital format. In this scheme, the sample size and sampling rate of the converted signal can be selected so that the transfer rate required to distribute the multiple channels can be minimized. This method gives the desired transfer rate, but at the cost of audio fidelity and sound quality. More specifically, the sample size and sampling rate of the converted signal is reduced, which reduces the resolution of the digital representation of the original analog audio signal and causes significant signal degradation due to quantization errors. This signal degradation effectively limits the range over which the sample size and sampling rate can be reduced. Also, as will be readily appreciated by those skilled in the art, in an aircraft environment, considerable background noise is introduced into the system when the signal is distributed in analog format. In addition, the most common type of noise in an aircraft environment is that produced by aircraft power distribution systems, which has a frequency of approximately 400 Hz. In the following, this type of noise is referred to as "400 Hz background noise". This 400 Hz background noise makes it difficult for an aircraft to convert an analog audio source signal to a digital format without including significant background noise in the resulting digital signal, unless an adequate shield is utilized. However, as mentioned above, in order to achieve a satisfactory data transfer rate and a satisfactory power consumption level, the analog output signal of the conventional compact disc player is used, and the analog output signal is converted into a digital signal with a sufficiently low sample size and sampling rate. The need to convert to a format seems to be generally accepted by manufacturers of traditional passenger entertainment systems. For this reason, the presence of significant amounts of quantization noise, 400 Hz background noise, signal crosstalk, etc., is always inherent in all conventional passenger entertainment and audio distribution systems. Summary of the invention The present invention is directed to an improved passenger entertainment system that employs improved audio signal distribution systems and methods for commercial aircraft and other vehicles. By adopting the system and method of the present invention, a high channel capacity and low power consumption are obtained and maintained substantially unaffected by quantization noise, background noise, crosstalk, etc. Here, preferably, a passenger entertainment system according to the present invention comprises a plurality of "true" digital signal sources (eg a plurality of dedicated compact disc players capable of providing a compressed digital audio signal output), a multiplexer. , Signal distribution circuitry, at least one demultiplexer, one decompression circuit, at least one digital-to-analog converter and at least one audio transducer. The digital audio signal source receives the clock and the enable signal from the multiplexer and, in response, supplies a plurality of compressed digital audio signals to the multiplexer. The multiplexer multiplexes the digital audio source signal to generate a composite digital audio signal and sends the composite digital audio signal to the distribution network. The distribution network sends the digital composite signal to at least one remote location where the demultiplexer is located. The demultiplexer selects one or more desired channels (or signals) from the composite signal and supplies the selected channels to the decompression circuit. Each decompression circuit decompresses the incoming channel and supplies each of the resulting decompressed digital audio signals to a digital-to-analog converter. Each digital audio converter converts the incoming decompressed digital audio signal into an analog audio signal, which is then fed to an audio transducer located, for example, in the passenger headset. Finally, each audio transducer produces a sound wave in response to the sent analog audio signal. As will be readily appreciated by those skilled in the art, a passenger entertainment system in accordance with the present invention converts transmitted digital audio data into a compressed digital format until the data reaches a remote seat position. Since it is maintained, it is completely unaffected by quantization noise, background noise, crosstalk, etc. In contrast, traditional passenger entertainment systems that require all audio data to be provided in analog format and then converted to digital format have an inherent tendency to pick up 400 Hz background noise, which is a significant signal. Deteriorate. In particular, any signal present in analog format in the noisy environment of a commercial aircraft is subject to distortion and degradation due to 400 Hz background noise. If the audio source signal is placed in an analog format where it may be distorted as described above before it is converted to digital format, any signal obtained after analog-to-digital conversion is not the original audio signal, but distorted audio. Will represent a signal. For this reason, users of conventional passenger entertainment systems must be equipped with considerable shielding or significant decontamination (noise reduction) circuits on the input and output signal lines. Without such equipment, the transmitted audio signal must accept the presence of considerable noise. Finally, as will be readily appreciated by those skilled in the art, a digital signal source capable of providing a compressed digital audio signal to the signal distribution network via a multiplexer is used to provide such signal at a later time. The decompression method allows the passenger entertainment system of the present invention to achieve much better signal reproduction conditions than can be achieved utilizing the characteristics of the A / D conversion methods of the prior systems. In particular, prior art systems (including those disclosed in the aforementioned patents) convert analog audio signals provided by conventional compact disc players into digital signals, eg 8-bit size and 20-30 kHz sampling rate. Signal fidelity or quality is significantly sacrificed when converting to a digital signal. In contrast, there is signal degradation when a 16-bit sample size and 37.8 kHz sample size digital signal is compressed according to the present invention to produce a digital signal with the same sampling rate as the 4-bit sample size. However, it is very small. In other words, the digital signal compression rate is close to reducing the amount of data sent through the signal distribution circuit at a ratio of 4 to 1 without causing noticeable deterioration of sound quality. Preferably, the passenger entertainment system of the present invention is, in addition to the digital audio signal distribution system described above, a plurality of analog video signal sources, a plurality of analog audio signal sources, a passenger addressing system, and a plurality of overhead video projectors. , Multiple in-seat video displays, and modular signal distribution circuitry capable of transmitting all audio and video signals to multiple remote seat locations via a single coaxial cable. Such examples are described in detail below in the section entitled "Detailed Description." As will be apparent from the above description, it is an object of the present invention to improve passenger entertainment systems using improved digital audio signal distribution systems and methods for use in commercial aircraft and other vehicles. It is another object of the present invention to improve passenger entertainment systems using improved integrated video and audio signal distribution systems for use in commercial aircraft and other vehicles. It is yet another object of the present invention to present a passenger entertainment system capable of distributing integrated video and compressed digital audio signals via a single coaxial cable. It is yet another object of the present invention to provide a method for efficiently transmitting digital signal compression factors over digital signal distribution circuitry such as those used in commercial aircraft and other vehicles. Brief description of the drawings FIG. 1 is a block diagram illustrating the basic components of a conventional audio signal distribution system commonly used in commercial aircraft and other vehicles. FIG. 2 is a block diagram illustrating the basic components that make up an improved audio signal distribution system in accordance with the present invention. FIG. 3 is a block diagram illustrating the components that make up the preferred embodiment of the improved passenger entertainment system in accordance with the present invention. FIG. 4 is a block diagram illustrating the components that make up a video modulation unit (VMU) according to a preferred embodiment of the present invention. FIG. 4 (a) is a circuit diagram of a tapping unit according to a preferred embodiment of the present invention. FIG. 5 is a block diagram illustrating the circuitry of a video system control unit (VSCU) according to the preferred embodiment of the present invention. FIG. 6 is a block diagram illustrating the circuitry that constitutes a passenger entertainment system controller (PESC) according to a preferred embodiment of the present invention. FIG. 7 is a block diagram of a circuit forming an area distribution box (ADB) according to a preferred embodiment of the present invention. FIG. 7 (a) is a format diagram of a message sent via the DATA1 bus according to the preferred embodiment of the present invention. FIG. 7 (b) is a diagram showing how relays arranged in seat electronics boxes (SEBs) in an addressing scheme are used according to an embodiment of the present invention. FIG. 8 is a block diagram of a circuit constituting a floor isolation box (FDB) according to a preferred embodiment of the present invention. FIG. 9 is a block diagram of a circuit constituting a seat electronics box (SEB) according to a preferred embodiment of the present invention. FIG. 10 is a block diagram illustrating the functional blocks that make up an integrated video audio system (IVAS) gate array according to a preferred embodiment of the present invention. FIG. 11 is a frame format diagram according to a preferred embodiment of the present invention. 12 (a) and 12 (b) are timing diagrams of sync signals and range filter coefficients in a frame format according to a preferred embodiment of the present invention. 13 (a) and 13 (b) are preferred IVAS gate array diagrams between input data, coaxial transmission cable data, and output data. Detailed description To emphasize various embodiments and innovative aspects of the present invention, a plurality of sub-items are provided in the following description. Further, where a particular structure appears in several drawings, that structure is designated using the same reference numeral in each drawing. Digital audio signal distribution system Referring to the drawings, FIG. 2 is a block diagram illustrating the basic components of a digital audio signal distribution system 10 according to one embodiment of the present invention. As shown, the digital audio signal distribution system 10 includes a plurality of "true" digital signal sources 12, a multiplexer 14, a signal distribution network 16, a plurality of demultiplexers 18, a plurality of decompression circuits 20, and a plurality of decompression circuits 20. It has a digital-analog converter 22 and a plurality of audio transducers 24. Each digital audio signal source 12 is, for example, a compact disc player, model No. manufactured and sold by Matsushita Electric Industrial Co., Ltd. of Osaka, Japan. RD-AX7091 can be included. Further, preferably each digital audio signal source 12 receives multiple clocks and enable signals from multiplexer 14 and is responsive to such signals to provide compressed digital audio with a 4-bit sample size and a 37.8 kHz sampling rate. Can generate signal output. More specifically, before being stored on a compact disc (or other digital media), digital audio data is converted from 16-bit format to 4-bit Compact Disc Interactive (CD) by adaptive delta pulse code modulation (ADPCM). -I) Compressed to level B format. ADPM compression and the CD-I Level B format are known in the related art and will not be described in detail here. Here, each of the six digital signal sources 12 preferably supplies eight channels (4 stereo or 8 mono) of compressed digital audio data to the multiplexer 14. The compressed digital audio channels are received from digital audio signal source 12 and the compressed digital audio signals received by multiplexer 14 are multiplexed (combined) in the time domain to form a single composite audio signal. Here, preferably, the transfer rate of the composite audio signal is 19.3536 MHz. Multiplexer 14 sends the composite audio signal to signal distribution circuitry 16, which sends the composite audio signal to a plurality of remote locations, such as passenger seats. One or more demultiplexers 18 are located at remote locations. Each demultiplexer 18 under control of a digital passenger control unit (DPCU) 134 (shown in FIG. 3) selects one or more desired channels from the composite signal and decompresses each selected channel with a decompression circuit 20. Supply to. Each decompression circuit 20 decompresses the channel (signal) sent thereto and supplies the expanded digital signal to the digital-analog (D / A) converter 22 as a result. Each of the digital-to-analog converters 22 converts the signal sent thereto into an analog audio signal, which is sent to the audio transducer 24. Finally, each audio transducer converts the analog audio signal sent to it into sound waves. As described above, since the passenger entertainment system 10 according to the present invention performs the digital-analog conversion only once for each selected channel, it is completely unaffected by background noise, crosstalk, etc. Also, the one-time digital-to-analog signal conversion performed by the system 10 in accordance with the present invention is necessary to convert the selected decompressed digital audio signal into a form usable by the audio transducer. In addition, the "real" digital audio signal source 12 that provides compressed digital audio signals to the signal distribution network 16 via the multiplexer 14 and later decompresses these signals is utilized by the passenger entertainment system of the present invention. Ment system 10 can achieve much better resolution than is achievable using the properties of prior art A / D conversion methods. More specifically, when the prior art system converts an analog audio signal provided by a conventional compact disc player into a digital signal, for example, a digital signal with an 8-bit sample size and a 20-30 KHz sampling rate, the signal resolution (Playback fidelity or sound quality) is considerably sacrificed. In contrast, digital audio signals with a 16-bit sample size and a 37.8kHz sampling rate are compressed, resulting in signal degradation, for example, when producing a digital signal with the same sampling rate as 4 bits, but with very little It is a degree. In short, the digital signal compression rate reduces the amount of data sent through the signal distribution circuit at a ratio of about 4 to 1 without causing noticeable deterioration of sound quality. Overview of passenger entertainment system With reference to FIG. 3, a preferred embodiment of a passenger entertainment system 100 according to a preferred embodiment of the present invention comprises a plurality of true digital audio signal sources 102, a plurality of video signal sources 104, one or more analog audio signals. It may include a mix of audio, video and control signal sources including a source 106, a cabin management terminal 108 and a cabin intercommunication data system (CIDS) 110. Such audio, video and control signal sources 102-110 are interconnected to each other and through multiple audio / video signal distribution systems, as well as multiple remote audio headsets 114, in-seat video monitors 116 and overhead video monitors 118. It is connected to the. The composite audio / video signal distribution system has the following components: Video System Control Unit (VSCU) 120; Passenger Entertainment System Controller (PESC) 122; Video Modulation Unit (VMU) 124; Multiple Area Distribution Boxes (ADBs). 126; Multiple floor isolation boxes (FDBs) 128; Multiple seat electronics boxes (SEBs) 130; Multiple tapping units (TUs) 132; Multiple passenger control units (DPCUs), Multiple in-seat video cassette players (IVCPs) 136; a plurality of video cassette player controllers (VCPCs) 138. Many of the above signal sources 102-110 and signal distribution system components 120-138 are described in more detail below. However, the following general description may be helpful in providing a thorough understanding of the structure and function of the improved passenger entertainment system 100 in accordance with the present invention. As mentioned above in the section entitled "Digital Audio Signal Distribution System", it is preferred here that each of the plurality of digital audio signal sources is a compact disc player manufactured and sold by Matsushita Electric Industrial Co., Ltd. of Osaka, Japan. Model No. Includes RD-AX7091. It is also desirable that each of the digital audio signal sources 102 be capable of providing a compressed digital audio signal output of 4 bit sample size with 8 channels (4 stereo or 8 mono) and a 37.8 kHz sampling rate. Furthermore, according to a preferred embodiment of the present invention, it is possible to generate a digital output signal having eight channels in the Compact Disc Interaction (CDI) Level B format and also to provide the supplied control signals (ie clock and enable signals). Allows any compact disc player (CDP), digital audio tape player (DAT) or other digital audio signal source 102 that can be synchronized to the frame format used by the system. Each of the compressed digital audio signals generated by digital audio signal source 102 is sent to a separate input (not shown) of video system control unit (VSCU) 120. The structure and function of the video system control unit 120 is described in detail in the section entitled "Structure and Function of VSCU" below. However, at this point, a multiplexer (not shown) located within the video system control unit 120 multiplexes the compressed digital audio signal sent to it in the time domain to produce a composite pulse code modulation (PCM) data signal. It must be understood to occur. The composite PCM data signal is then sent to a filter / combiner 312 (shown in FIG. 5) for combining with the composite RF video signal received from the video modulation unit (VMU) 124 and the resulting composite PCM / RF video signal. Is sent to the Passenger Entertainment System Controller (PESC) 122. Here preferably, the passenger entertainment system controller (PESC) 122 performs a second multiplexing operation that adds an additional 24 entertainment channels and 6 passenger address channels to the composite PC M / RF video signal. . More particularly, the Passenger Entertainment System Controller (PESC) 122 separates the composite PCM data / RF video signal into separate PCM data and RF video components. An additional data channel is added to the PCM data part of the separated signal, then the PCM data and RF video parts of the composite signal are recombined and transmitted further. The composite PCM / RF video signal is then sent from the passenger entertainment system controller (PESC) 122 to a plurality of area distribution boxes (ADBs) 126. Area distribution boxes (ADBs) 126 are arranged in a daisy chain shape, where preferably up to eight area distribution boxes are provided along the daisy chain. However, as will be readily appreciated by those skilled in the art, depending on the type of coaxial cable (not shown) used to connect, for example, area distribution boxes (ADBs) 126, additional Can be equipped with 126 area distribution boxes. Each area distribution box 126 taps off (provides branch lines) to a small portion of the composite PCM / RF video signal. The tapped composite PCM / RF video signal is then amplified and split into tapped composite PC M / RF video signals for distribution to multiple floor isolation boxes (FDBs) 128. It will be appreciated that each floor isolation box (FDB) 128 is provided with a separate signal. Each floor isolation box (FDB) 128 acts as a signal splitter utilized by the two daisy chains of seat electronics boxes (SEBs) 130. Here, preferably, each floor barrier box 128 supports up to 30 seat electronics boxes (SEBs) 130 with up to 15 seat electronics boxes (SEBs) 130 arranged in a particular daisy chain. However, it will also be appreciated that the number and specific configuration of seat electronics boxes (SEBs) 130 may vary from system to system. Each seat electronics (SEB) 130 has a directional tap 702, a band-splitting filter 704, a demultiplexer 706, a decompression circuit 708, a plurality of videos depending on the function (audio or video) provided at a given passenger seat position. Processing circuits 714 and 716 (all shown in FIG. 9) may be included. The directional tap 702 taps off into a small portion of the composite PCM / RF video signal used in the seat electronics box (SEB) 130, and this composite PCM / RF video signal is next seated electronics box in a given daisy chain. It functions to convey to (SEB) 130 with a small amount of loss. Band-split filter 704 separates the tapped composite PCM / RF video signal into its separate PCM data and RF video components. The RF video component is sent to each tuner 714 of the video processing circuit, and the PCM data signal is sent to the demultiplexer (IVAS gate array) 706 via the linear analog amplifier 706 and the amplitude comparator 732. The demultiplexer 706, under the control of multiple digital passenger control units (DPCUs) 134, selects one or more desired channels from the composite PCM data signal and decompresses the circuit 708 (ADPCM gate array shown in FIG. 9). ) Send each selected channel to. Further, each decompression circuit 708 decompresses the channel sent thereto, and supplies the decompressed digital audio signal to the pair of digital-analog (D / A) converters 710. The digital / analog converter 710 converts the expanded digital audio signal into an analog signal. The resulting analog audio signal is amplified by amplifier 712 and sent to, for example, a transducer (not shown) located in passenger headphones 114. The RF video portion of the split signal is sent to a plurality of video processing circuits via signal splitter 734. Each of these circuits has a tuner 714 and a tuner control circuit 716 (all shown in FIG. 9). The signal splitter 734 functions to isolate the individual tuners 714 from each other and the tuner control circuit 716 is controlled via a micro processing unit (MPU) 718 and one of a plurality of digital passenger control units (DPCU) 134. . Each tuner 714 is controlled by an associated video control circuit 716 which receives a control signal from the microprocessing unit 718 so that each tuner 714 can select the desired video channel from the composite RF video signal. After the particular video channel is selected, the video processing circuitry sends this channel to the seat display unit (SDU) for display. In-seat video cassette player (IVCPs) 136 is controlled by a video cassette player controller (VCPC) and becomes an additional source of video signals for display by seat display units (SDUs) 116. Here, the in-seat video cassette player (IVCPs) 136 is preferably a part No. manufactured and sold by Matsushita Electric Industrial Co., Ltd. in Osaka, Japan. Can have RD-AV1203. In-seat video cassette players (IVCPs) 136 are controlled in a conventional manner by video cassette player controllers (VCPCs) 138, and when operational, provide analog audio and video signals passed through the seat electronics box (SEB), Provides a seat display unit (SDU) 116 and a passenger headset (not shown). Structure and function of VMU 4, the video modulation unit (VMU) 124 preferably receives the plurality of analog video signals generated by the video signal source 104 at separate balanced input ports 202. Each of the analog video signals sent to the video modulation unit (VMU) 124 is supplied to an amplitude modulator 204 arranged in the video modulation unit 124, and the amplitude modulator 204 is supplied to each of the video signals supplied at the selected carrier frequency. To modulate. Amplitude modulation is well known in the prior art and will not be described in detail here. However, the supplied video signals are preferably modulated here with a selective carrier frequency of 235 MHz to 300 MHz. In addition, each modulator 204 is electronically coupled to and controlled by a Micro Processing Unit (MPU) 205. The microprocessing unit (MPU) 205 is a means for changing the operating parameters of the modulation unit 204, and therefore a means for programmatically selecting the desired carrier frequency. More specifically, the Micro Processing Unit (MPU) 205 is located within the Video System Control Unit (VSCU) 120 via the RS-232 interface 207 (shown in FIG. 5) Central Processing Unit (CPU). Communicating with 316, the microprocessor 205 sets the carrier frequency in response to the signal received from the video system control unit (VSCU) 120. Here, preferably, each carrier frequency (135 MHz to 300 MHz) is set to a default value, or else another value is indicated. The default frequencies for this preferred embodiment are shown in Table 1. However, it should be noted that the frequencies mentioned here preferably only comprise the carrier frequencies and are not intended to limit the scope of the invention to the particular frequencies mentioned. Further, as mentioned above, it is desirable to be able to program the carrier frequency utilized by the passenger entertainment system 100 of the present invention, eg, if interference occurs at a particular frequency, then stored in the memory of the cabin management terminal 108. You can change this frequency by entering a new carrier frequency in the database. Also, the carrier frequency 204 of a particular modulator 204 can be changed if a particular video input signal is not available (ie, if a particular video source 104 becomes inoperable). For example, if a particular video recording is broadcast on channel 1 and the video source 104 sending to channel 1 becomes inoperable, the video recording can be played back by another video source 104 and the modulator coupled to this source is as described above. , The signal sent here can be modulated up to 151.25 MHz (channel 1 carrier frequency). After modulation, each video signal is sent to another input 206 of one of the plurality of primary combiner circuits 20 8. Each primary combiner circuit 208 combines the three video input signals and shapes the composite video signal, each resulting composite signal being fed to one input of a secondary combiner circuit 210. The signal generated by the secondary combiner circuit 210 is referred to herein as the composite RF video signal. Before being distributed throughout the passenger entertainment system 100, the composite RF video signal is passed through a low pass filter 212, amplified by an amplifier 214 and split by a four way splitter 216. Thus, preferably here, the composite RF video signal is provided to four separate output terminals 218 of the video modulation unit (VMU) 124. Referring to FIG. 3, the video modulation unit (VMU) 124 is connected to a plurality of tapping units (TUs) 132, and the tapping unit (TUs) is connected to a plurality of video projectors or video monitors 118. Each tapping unit (TU) 132 is, for example, a TU model No. manufactured and sold by Matsushita Electric Industrial Co., Ltd. in Osaka, Japan. RD-AA5 101 can be included. In addition, each tapping unit 132 can have a video tuner (shown in FIG. 4 (a)) that selects the desired channel from the composite RF video signal, so that each tapping unit 132 (all displays the same channel). It can drive up to three separate video monitors or projectors 118. The tapping unit 132 receives the composite RF video signal from the video modulation unit 124, but the tapping unit 132 is controlled by the central processing unit (CPU) 316 (shown in FIG. 5) located in the video system control unit (VSCU) 120. To be done. More specifically, a central processing unit (CPU) 316, located within the video system control unit (VSCU) 120, controls the channel selection by the tapping unit 132 and the functions of the video monitor or projector 118. Structure and function of tapping unit Further, referring to FIG. 4A, each tapping unit 132 has a directional tap 220, a tuner 222, a tuner control unit (224) and three video signal amplifiers 226. The directional tuff 222 taps off a small portion of the composite RF video signal generated by the video modulation unit 124 and causes a slight loss of the remaining portion of the composite RF video signal to the next tapping unit 132 along a given daisy chain. Function to send by. Tuner control circuit 224 is coupled to central processing unit 316 located within video system control unit (VSCU) 120 and controls tuner 222 in response to signals received therefrom. The tuner 222, in response to the signal received from the tuner control circuit 224, selects the desired channel for viewing the video monitor 118 and sends the selected channel to the amplifier 226. VSCU structure and function 5, the video system control unit (VSCU) 120 of the present invention preferably provides central control functions for the audio and video portions of the passenger entertainment system 100 according to the present invention. . Further, the video system control unit (VSCU) 120 receives the database and program selection information from the cabin management terminal (CMT) 108, and based on this information, the video signal source 104, the digital audio signal source 102, the video modulation unit (V MU). 124, A control signal is given to a plurality of tapping units (TUs) 132. In addition to providing central control functions for the passenger entertainment system 100 in accordance with the preferred form of the present invention, the video system control unit (VSC U) 120 provides all video source audio signals and digital signals generated by the video signal source 104. It receives and multiplexes all compressed digital audio signals provided by audio signal source 102. The signal generated upon completion of the multiplexing operation performed by the video system control unit (VSCU) 120 is referred to herein as the composite PCM data signal. The video system control unit (VSCU) 120 includes a passenger entertainment system controller (PESC) 122, multiple area distribution boxes (ADBs) 126, multiple floor isolation boxes (FDBs) 128 and multiple seat electronics boxes (SEBs) 13. The composite PCM data signal is distributed to a plurality of remote locations via 0. The video system control unit (VSCU) 120 is preferably a mix of compact digital disc players (CDPs) 102 to 48 compressed digital audio channels (8 channels per player) and a video cassette player 104. Up to 48 analog audio channels (4 channels per player) and analog audio playback device 106 (12 channels per player) can be received up to a total of 72 channels. More specifically, the video system control unit (VSCU) 120 is configured to support 3 blocks of input channels, each having 24 channels, so that a particular block of input channels is of only one type. It can have channels (ie compressed digital audio channels or analog audio channels). Therefore, preferably, the video system control unit corresponds to 24 analog audio channels and 48 compressed digital audio channels or 48 analog audio channels and 24 compressed digital audio channels, up to a total of 72 channels. Can be configured. The analog audio channels received from the audio playback device 106 and the video source 104 are converted to a digital format with a 16-bit sample size using an analog digital converter 302, and the resulting digital signal is then adaptively delta pulse code modulated. Compressed to a 4-bit sample size format. Here, preferably the analog-to-digital conversion process is carried out by one of up to 48 MASH (Multistage Noise Shaping) analog-to-digital converters 302 (24 per analog audio board 301). Each MASH analog-to-digital converter 302 receives a single analog input signal, converts this signal to a digital format, and converts the resulting digital signal to another converted digital signal (ie, another MASH analog-to-digital converter 302). Signal) from a single digital output signal having two channels. The MHSH transform is well known in the prior art and will not be described in detail here. Furthermore, the MASH converter is preferably a NASH DAC chip part No. sold by Matsushita Electric Industrial Co., Ltd. in Osaka, Japan. You can have MH646A. After the MASH analog-to-digital signal conversion process is complete, the resulting digital signals, each with two channels, are sent to separate input terminals 304 of a plurality of ADPCM gate arrays 302. Here preferably three ADPCM gate arrays 306 are utilized, each of which is connected to eight separate MASH analog to digital converters 306. The four digital signals, each with two channels, are received by each AD PCM gate array 306, compressed by adaptive delta pulse code modulation, and then multiplexed to form a single compressed digital output signal with eight channels. The resulting three compressed digital output signals are then sent from the ADPCM gate array 306 to separate inputs 308 of an integrated video audio system (IVAS) gate array 310. Further, an integrated video audio system (IVAS) gate array 310 combines the compressed digital audio signal generated by the digital audio signal source 102 with the compressed digital output signal generated by the ADPCM gate array 310 to form a composite PCM data signal. The function of IVAS gate array 306 is described in detail below. However, in this regard, the integrated video and audio system (IVAS) gate array 310 receives the compressed digital audio signal received from the digital audio signal source 102 and the ADPCM gate array 310, multiplexes the converted and compressed signals in the time domain. It is well understood that a composite pulse code modulation (PCM) gate signal is formed. The integrated video audio system (IVAS) gate array 310 then sends the composite PCM data signal to the filter / combiner 312, which combines it with the composite RF video signal provided by the video modulation unit (VMU) 124. . The filter (not shown) of the filter / combiner 312 reduces the amplitude of the composite PCM data signal and changes the resulting waveform to a modulated radio frequency (RF) to produce an analog waveform similar in frequency and other characteristics. ) Shape into a signal. In this way, the composite PCM data signal is a linear analog signal that is placed in passive signal processing components (ie, directional taps, splitters, etc.) as well as area distribution boxes (ADBs) 126 and floor isolation boxes (FDBs) 128. Converted to a form that can be passed through an amplifier A combiner (not shown) of filter / combiner 312 combines the filtered composite PCM data signal with the composite RF video signal to form a composite PCM / RF video signal. The resulting composite PCM / RF video signal is then sent to the Passenger Entertainment System Controller (PESC) 122 for further processing and ultimately distribution to remote seating locations. As further shown in FIG. 5, here preferably the video system control unit (VSCU) 120 can have nine subsystem boards including: two analog signal conversion boards. 301; 1 central processing unit (CPU) board 303; 1 ARINC interface board 305; 1 local area network (LAN) board 307; 1 digital audio board 309; 1 tuner board 311; ( One power board (not shown); one motherboard 313. For convenience, dashed lines are used here to show what circuit components are on a given subsystem board. Each audio signal conversion board 301 has 24 audio signal input ports 302, 24 MASH analog-to-digital converters 314, and 3 ADPCM gate arrays 306. The audio signal input port 314 receives analog audio signals from the plurality of video sources 104 and the audio playback device 106 and then sends these signals to the MASH Aronag-to-digital converter 302. Each of the MASH analog-to-digital converters 302 converts a single incoming analog audio signal into a digital audio signal and the resulting pair of digital audio signals are multiplexed to provide 2 channels and a 16-bit sample size and 37.8 kHz sampling rate. A single digital audio signal having is formed. Then, each of the converted audio signals having two channels is sent to one input terminal 304 of three ADPCM gate arrays 306. In the ADPCM gate array 306, this signal is compressed and combined with the other three converted audio signals to form a compressed digital output signal having 8 channels. Each of the three ADPCM gate arrays 306 produces a separate compressed digital output signal, and then each of the three compressed digital output signals is sent to a digital audio board 309, where an integrated video audio system (IVAS) gate is provided. Array 310 is located. Integrated Video Audio System (IVAS) gate array 310 located on digital audio board 309 receives the compressed digital audio signals from digital audio signal source 102 and ADPCM gate array 306, multiplexes these signals, and outputs the composite PCM data described above. Form a signal. The composite PCM data signal is then provided to the motherboard's filter / combiner 312. The integrated video audio system (IVAS) gate array 310 of the digital audio board 309 also functions as a channel selector or demultiplexer, as described in more detail below. More specifically, an integrated video and audio system (IVAS) gate array 310 is available for selecting preview audio channels for listening at the cabin management terminal 108. In this mode, in response to the control signal generated by the central processing unit (CPU) 316, the integrated video and audio system (IVAS) gate array 310 allows the desired audio channel (1 mono or 2 stereo) from the composite PCM data signal. Select. The selected audio channel with compressed digital audio data is sent to the ADOCM gate array 318, decompressed to 16-bit format, and then a pair of MASH digital-to-analog converters 320 (MASH sold by Matsushita Electric Industrial Co., Ltd. in Osaka, Japan). It is sent to the DAC chip model No. MN6475A), demultiplexed (demultiplexed), and converted to analog format. The resulting analog preview channel is then sent to the gain control circuit 322 and finally to the cabin management terminal 108 for listening, for example, by an audio transducer located on a stereo headset (not shown). The tuner board has a tuner control circuit 324 and a tuner circuit 326. The tuner circuit 326 receives the composite RF video signal generated by the video modulation unit (VMU) 124 and is responsive to the control signal generated by the central processing unit 316 to select a preview video channel from the composite RF video signal. More specifically, tuner control 324 receives control signals from central processing unit (CPU) 316 and, in response, adjusts tuner 326 operating parameters and selects the desired RF video channel. As can be seen from Table 1, the carrier frequency of the channel to be previewed is preferably set to 139.25 MHz or 295.25 MHz, so that the tuner 326 also uses 139.25 MHz or 295.25 MHz as the preview carrier frequency. Set to select. Finally, the selected RF video channel is demodulated by the tuner 236 and sent to the cabin management terminal 108 for viewing. In this way, the channels can be previewed before being distributed throughout the passenger entertainment system 100. On the other hand, if it is desired to monitor only the video channel, then the carrier channel for this video channel can be selected by the tuner 326 in the manner described above and the monitored channel is sent to the cabin management terminal 108 for viewing. CPU board is a central processing unit 316 (preferably a type 68000 series microprocessor manufactured by Motorola, Inc. of Phoenix, Ariz.), A crystal control oscillator 328 with a crystal frequency of 19.66MHz, a frequency divider circuit 330, multiple memories. It has a component 332 and a microprocessor monitoring circuit 334. Central processing unit 316 performs multiple functions including initialization, subsystem control, and subsystem communication management. The chip initialization is executed by writing a program command in a peripheral chip that controls the operation mode of the chip. As part of performing the initialization function, the central processing unit 316 must receive a system configuration database from the cabin management terminal (CMT) 108. Communication between the central processing unit (CPU) 316 and other peripheral devices (or subsystems) is performed as follows. A central processing unit (CPU) 316 communicates with a cabin management terminal (CMT) via a local area network (LAN) 319 for configuration information and execution commands used to control video system functions. The central processing unit (CPU) 316 controls the frequency of the modulator 204 located there and activates the microprocessor 2 of the video modulation unit (VMU) 124 via the RS-232 interface 338 to activate the diagnostic function. Communicate with 05. The central processing unit (CPU) 316 communicates with the cabin intercommunication data system (CIDS) 110 via one of the ARINC-429 interfaces 336. A central processing unit (CPU) 316 controls the selected video signal source 104 via an RS-232 interface 338 which corresponds to the selected video signal source 104. More specifically, the central processing unit (CPU) 316 receives a command from the cabin management terminal (CMT) 108 to control a particular function of the video signal source 104 and the RS-232 corresponding to this video signal source 104. It communicates with the appropriate video signal source 104 via interface 338 to execute this command. Communication between central processing unit (CPU) 316 and digital audio signal source 102 is performed in a similar manner. Finally, communication between the central processing unit (CPU) 316 and the video display units (VDUs) 118 and tapping units (TUs) 132 is carried out via the RS-485 interface 340. A memory component 332 coupled to the central processing unit 316 is a pair of RAM memory for data storage (128 KX 8 each), a pair of EPROMs for program storage (512 K X 8 each), embedded test equipment (BITE). It has a pair of EEPROMs (64K x 8 each) for storage of information, configuration data and downloadable databases. The microprocessor supervisory circuit 334 has a reset line (not shown) of the central processing unit 316, the main function of the supervisory circuit 334 is to ensure continuous system performance. More specifically, if central processing unit 316 is caught in an infinite loop, supervisory circuit 334 detects this condition and resets central processing unit 316. In addition, the monitoring unit 334 can detect potential power interruptions and power failures. In this way, when a power interruption or anomaly is detected, the monitoring circuit 334 sends a signal to the central processing unit 316 so that the central processing unit 316 starts the shutdown process in sequence, that is, backs up critical data. can do. The ARINC interface board 305 has 4 ARINC-429 ports 336, 19 RS-2 32 ports 338 and 3 RS-23 2 ports 338. RS-232 port 338 provides communication between central processing unit 316 and digital audio signal source 102, video source 104 and video modulation unit (VMU) 124. RS-485 port 340 communicates between central processing unit 316 and tapping units (TUs) 132, and ARINC-429 port 336 communicates between central processing unit 316 and Cabin Intercommunication Data System (CIDS) 110. Structure and function of PESC Referring now to FIG. 6, where preferably the passenger entertainment system controller (PESC) 122 has two analog signal conversion boards 401 and 403, a motherboard 405, a CPU board 407, a local area network (LAN). It has a board 409, a power board (not shown) and an ARINC interface board 411. As with the video system controller unit (VSCU) 120, dashed lines are used to indicate which circuit components are located on which board. The first analog signal conversion board 401 has the same components as the audio signal conversion board 301 arranged in the video system control unit (VSCU) 120. More specifically, the first analog signal conversion board 301 has 24 audio signal input ports 402, 24 analog to digital MASH converters 404, and 3 ASPCM gate arrays 406. The audio signal input port 402 receives an analog audio signal from a plurality of audio playback devices 106 and then sends this signal to a MASH analog-to-digital converter 404. The MASH analog-to-digital converter 404 converts each input analog audio signal into a digital format and the resulting digital signal pair is multiplexed into a single digital audio signal with 2 channels and 16-bit sample size and 37.8 kHz sampling rate. A signal is formed. Each of the converted audio signals is then sent to the input terminals 408 of the three ADPCM gate arrays 406. This signal is now compressed and combined with the other three converted signals to form an 8-channel compressed digital output signal. Each of the three ADPCM gate arrays 406 produces a separate compressed digital output signal, and then each of the three compressed digital output signals is sent to the second analog signal conversion board 403. An integrated video and audio system (IVAS) gate array 410 is located on this board 403. The second analog signal conversion board 403 has several components located on the first analog signal conversion board 401 and integrated video and audio system (IVAS) gate array 410. In addition, the second analog signal conversion board has 10 audio signal input ports 412 (a) to (f) and 414, 6 MASH analog / digital converters 416, 1 ADPCM gate array 416, integrated video audio system. (IVAS) having a gate array 410. Here, it is preferable that the voice signal input ports 412 and 414 of the second analog signal conversion board 403 of the passenger entertainment system controller (PESC) 122 have four voice operation switches (VOX) and passenger addresses (PA). There is an audio channel and 6 other PA audio channels. However, at any given time, only 6 PA audio channels are sent to the MASH analog-to-digital converter 416. More specifically, the voice operated switching (VOX) circuit 420 detects the presence or absence of an audio signal at the VOX PA input terminal 414, between the VOX PA input 414 and the first four PA audio channels 412 (a-d). The control signal is supplied to the 4-channel (2: 1) multiplexer 421 which is selected by. Each channel of the multiplexer 421 is controlled by a separate VOX circuit 420, so when the VOX circuit 42 0 detects an audio signal at its input, the signal is sent to the multiplexer 421 and the PA audio input 412 is fed to the VOX PA audio input 414. Prompt multiplexer 421 to replace The analog-to-digital MASH converter 416 and ADPCM gate array 418 function as described above, so these functions will not be described in detail here. The main function of the IVAS Gate Array 410 of the Passenger Entertainment System Controller (PESC) 122 is to add additional audio, control and passenger address signals to the composite PCM / RF video signal. More specifically, the IVAS gate array 410 time-domain multiplexes the PCM data portion of the composite PCM / RF video signal, the compressed signal received from the ADPCM gate arrays 406 and 418 and the CPMS / PSS data message received from the microprocessor 430. Therefore, the compressed signal and the CPMS / PPS data signal sent from the ADPC M gate arrays 406 and 418 are added to the composite PCM data signal. The resulting "perfect" composite PCM data signal is then sent to a filter / combiner 422 for combining with the RF video signal, and the "perfect" composite PCM / RF video signal from the RF combiner 422 into multiple area distribution boxes (ADBs). Sent to 124. It can be seen that the filter / combiner 422 of the passenger entertainment system controller 122 functions similarly to the filter / combiner 312 located within the video system control unit 120. A separator 424 located on the Motherboard 405 of the Passenger Entertainment System Controller (PESC) 122 separates the composite PCM / RF video signals sent by the Video System Control Unit (VSCU) 120, and the Integrated Video Audio System (IVAS). The gate array 410 supplies the PCM data portion of this signal. Separator 424 performs a frequency-based separation function, so all frequency components below about 50 MHz are sent to PCM audio board 403, and all frequency components above about 100 MHz are sent to RF video board 405. . The RF video portion of the separated signal is provided to filter / combiner 422 by separator 424 for recomposition with the PCM data signal. The CPU board 407 of the passenger entertainment system controller (PESC) 122 has the same circuitry as the CPU board 303 located in the video system controller unit (VSCU) 120. More specifically, the CPU board 407 includes a microprocessor 430, a monitoring circuit 432, an oscillator 434, a frequency divider 436, and a plurality of memories 438. Such components function in a similar manner to the components of the CPU board 303 of the video system control unit (VSCU) 120. However, these components are configured to correspond to the functionality of the passenger entertainment system controller (PESC) 122 described above. Structure and function of ADB Referring now to FIG. 7, each area distribution box (ADB) 126 preferably serves as a zone controller for distributing power, audio, video and service data to a plurality of floor isolation boxes (PDBs) 128. Play a role. The area distribution boxes (ADBs) 124 are arranged in a daisy chain configuration in which a maximum of eight area distribution boxes (ADBs) 124 are arranged in each daisy chain. However, it will be readily appreciated by those skilled in the art that the number of area distribution boxes (ADBs) 126 may be varied as described above. The interconnections between the Area Distribution Boxes (ADBs) 126 are made using a single coaxial cable and up to two twisted pair DATA buses (DA TA1 and DATA2 buses). The main function of each area distribution box (ADB) 126 is to tap off a small part of the composite PCM / Rf video signal, and to combine it with the next area distribution box (ADB) 126 in a given daisy chain. Sending the rest of the video signal with little signal loss. An Area Distribution Box (ADB) then amplifies and separates the tapped portion of the composite PCM / RF video signal for further distribution within the passenger entertainment system 100. More specifically, the composite PCM / RF video signal sent to each of the area distribution boxes (ADBs) 126 is added to the first directional tap 502, and this tap 502 is set by the receiving area distribution boxes (ADB) 126. For use, tap off a small portion of the signal and send the rest of the signal to the next area distribution box (ADB) 126 located in the daisy chain (if there is another ADB). The tap output of the directional tap 502 is then sent to a band separation filter 504 which separates the tapped PCM / RF video signal into PCM data and RF video portions, respectively. Each portion of the tapped PCM / RF video signal is then sent to an amplifier 506 or 508 where the signal is amplified, and each amplified signal is then sent to a combiner 510 for resynthesis. The recombined PCM / RF video signal is then sent to a series of bidirectional splitters 513, 514 and 516 which split the PCM / RF video signal to form four PCM / RF video output signals. Finally, the PCM / RF video output signal is sent to separate floor isolation boxes (FDBs) 128. Area distribution boxes (ADBs) 126 also have multiple control functions and perform address allocation protocols. More specifically, control data, configuration information, database information and other messages are downloaded from the Passenger Entertainment System Controller (PESC) 122 to Area Distribution Boxes (ADBs) 126 via the DATA 1 bus. . The RS-485 port 520 serves as an interface between the DATA1 bus and the area distribution box (ADB) 126, and the RS-485 port 520 supplies the data received from the DATA1 bus to the communication controller 522. Upon receipt of the message, the communication controller 522 first acknowledges receipt of the received message and then decides whether to store the message downline (store and process message data) or send. This decision is made by comparing the address information contained in the message with the address of the area distribution box (ADB) 126 determined by the discrete address input 524 to the specific area distribution box (ADB) 126 ... . An example of the message format is shown in Figure 7 (a), with Start Flag 750, Destination Seat Electronics Box (SEB) Number 752, PCU / SDU Code 754, Destination Area Distribution Box (ADB) Number 756, Destination Floor Block Box (FDB). ) Number 758, destination column address 59, source seat electronics box address 760 and PCU / SDU code 761, multiple data / control bytes 762, checksum code 764, two cyclic redundancy check bytes 766 and 768, message end flag Has 770. Furthermore, preferably the communication protocol here comprises a command response protocol which is centrally controlled by the area distribution box (ADB) 126. More specifically, each area distribution box (ADB) 126 initializes all addresses of the seat electronics boxes (SEB s) connected to it before initiating normal communication, and the seat electronics boxes (SEBs) are initialized. ) Must be started. Here, the communication protocol used by the area distribution boxes (ADBs) 126 and the seat electronics boxes (SEBs) 130 will be described. The polling of the seat electronics boxes (SEBs) 130 is executed by the area distribution boxes (ADBs) 126, in order, by address. Here preferably two types of poles are utilized: active pole (APOLL) and inactive pole (IPOLL). These pole types correspond to the "activity states" of seat electronics boxes (SEBs) 130. The seat electronics box (SEB) 130 is active when the area distribution box (ADB) 126 causes the box 130 to participate in normal link communication, while the active seat electronics box (SEB) 130 is addressed to it. It can only be sent after receiving an APOLL message. The Active Seat Electronics Box (SEB) 130 can respond with several types of messages, including: Acknowledgment (ACK), Byte Result (BRES), Active State (ASTA), PSS data. The seat electronics box (SEB) 130 powers up in inactive mode and can only become active when it receives a command from the area distribution box (ADB) 126. The seat electronics box (SEB) 130 is normally inactive if it is not allowed to participate in link communications. Further, the non-active seat electronics box (SEB) 130 can only send in response to an IPOLL message addressed to it from the area distribution box (ADB) 126. After receiving such a message, the seat electronics box (S EB) 130 can only respond with an inactive state (ISTA) or a byte result (BRES). Here again, referring to FIG. 7 (b), the following process is used to allocate seat electronics boxes (SE Bs) 130 addresses in each column. The addressing process can be initiated by the Passenger Entertainment System Controller (PESC) 122 or Area Distribution Box (ADB) 126 sending a Programming Mode (PMODE) command to the Seat Electronics Box (SEB) 130. When the seat electronics box (SEB) 130 receives, the PMODE command opens the normally closed communication relay 736. This scheme allows communication between a single pair of predefined area distribution boxes (ADB) 126 and seat electronics boxes (SEBs) 130. Moreover, only the seat electronics boxes (SEBs) directly adjacent to the floor block boxes (FDB) 128 can communicate with the associated area distribution boxes (ADBs) 126 as soon as the PMODE command is distributed via the DATA 1 bus. . Further, as shown in FIG. 7 (b), the line of DATA1 bus connecting a predetermined area distribution box (ADB) 126 to a pair of seat electronics box (SEB) daisy chains 738 and 740 is a floor block box. Within (FDB) 128 they are reciprocal. In addition, seat electronics boxes (SEBs) 130 are constructed so that the inverse data cannot be correctly interpreted. Thus, when the Area Distribution Box (ADB) 126 communicates with one of a pair of Seat Electronics Box (SEB) columns (or daisy chains) 738, the box 126 can send a non-reversed message. However, if this data distribution box (ADB) 126 communicates with another column 740, then this box 126 must send a reverse message over the DATA1 bus. In this way, a given area distribution box (ADB) 126 can communicate with a single seat electronics box (SEB) when assigning addresses. Once a given seat electronics box (SEB) 130 has been addressed, the area distribution box (ADB) 126 activates this seat electronics box (SEB) 130 and closes its relay, so the area distribution box (ADB) Communication occurs between the next seat electronics box (ADB) 130, which is addressed to 126. This process continues until all functioning seat electronics boxes (SEBs) 130 have been addressed and activated. In addition, by addressing seat electronics boxes (SEBs) 130 in this manner, inactive seat electronics boxes (SEBs) 130 are identified and flagged for inoperative seat electronics boxes (SEBs) 130 for repair. be able to. If all seat electronics boxes (SEBs) 130 or correctly seated or defective seat electronics boxes (SEBs) 130 are not identified, the link status is'normal 'and the area distribution box (ADB) 1 26 to the passenger electronics system controller ( PESC) 122. If an error is detected while addressing the seat electronics boxes (SEBs) 130, the area distribution box (ADB) 126 disables the transmitter (not shown) and enters an inactive state, A command to close relay 736 is sent to this seat electronics box (SEB) 130 to finish programming the defective seat electronics box (SEB) 130. Once the "normal" mode is confirmed, the communication protocol between the Area Distribution Boxes (ADBs) 126 and Seat Electronics Boxes (SEBs) 130 proceeds as follows. Seat electronics boxes (SEBs) 130 are in turn polled by area distribution boxes (ADB) 126 and are not allowed to send information unless polled. When polled, seat electronics boxes (SEBs) 130 can send various responses, but at least status messages are always sent. More specifically, when a message is sent to the seat electronics box (SEB) 130, the seat electronics box (SEB) 130 always responds with at least an ACK or NAK message. FDB structure and functions Referring now to FIG. 8, preferably each floor isolation box (PDB) 128 has one PCM / RF video signal splitter and two digital data signal splitters 604 and 606. The PCM / RF video signal splitter 602 receives the composite PCM / RF video signal from the area distribution box (ADB) 126, splits this signal, and divides each of the resulting split PCM / RF video signals into a separate seat electronics box (SEB). ) Send to 130. Digital data signal splitters 604 and 606 split the DATA1 and DATA2 signals and function in a similar manner. However, after division, one polarity of the resulting divided DATA1 signal is reversed. SEB structure and function Referring to FIG. 9, each seat electronics box (SEB) 130 has a signal input board 701, an audio signal processing board 703, a video signal processing board 715, and a microcontroller unit (MCU) board 707. The input board 701 includes a passive circuit that connects each seat electronics box (SEB) 130 to a floor block box (FDB) 128 or another seat electronics box (SEB) 130 (ie, the next SEB in a daisy chain). The composite PCM / RF video signal sent to each of the seat electronics boxes (SEBs) 130 is added to the directional tap 702 that taps off a small portion of the signal used by the receiving seat electronics boxes (SEBs) 130 and (other SEBs). Send the rest of the signal to the next seat electronics box (SEB) 130 located in the daisy chain (if any). The tap output of the directional tap 702 is filtered by a band splitting filter 704 before being subsequently distributed within the seat electronics box (SEB) 130. More specifically, band split filter 704 comprises a high pass filter and a low pass filter (not shown). The RF video portion of the composite signal is sent through a high pass filter and the PCM portion of the composite signal is sent through a low pass filter. After filtering, the PCM portion of the composite signal is sent to audio board 703 and the RF video portion of the composite signal is sent to video board 705. Upon arrival at audio board 703, the PCM portion of the composite signal is sent to analog amplifier 730, amplitude comparator 732, and added to one input of integrated video audio system (IVAS) gate array 706. The IVAS gate array 706 functions as a decoder and can select a desired PCM data channel from the composite PCM data signal. After one or more channels have been selected by IVAS gate array 706, the channels are sent to ADCM gate array 708 for decompression. After decompression, the selected channel is sent to a pair of MASH digital-to-analog (D / A) converters 710. Here, the channels are separated, converted into analog audio signals, and sent to the headphone amplifier 712. As a particularly innovative aspect of the present invention, the IVAS gate array 706 of a given seat electronics box (SEB) 130 can be instructed to select a nonexistent channel from the composite PCM data signal, thereby allowing the ADPC M gate. Can provide “zero channel” output to array 708. The zero channel output is an output channel that contains a constant value, so it does not change amplitude when converted to analog format. Therefore, when the zero channel is converted to analog format and sent to the audio transducer, no audio is generated. Further, when the zero channel output is processed by the ADPCM gate array 708, MASH digital-to-analog converter 710, and headphone amplifier 712 as described above, an analog audio signal whose amplitude does not change is generated (not shown). This signal can be sent to a noise canceling headset. Noise canceling headsets are available to the passengers wearing them to eliminate virtually all flight noise, cabin noise, etc. One of the compressed digital audio channels can be used as the zero channel in another embodiment. However, it is preferred here to be able to provide the maximum number of audio channels that can be heard by the passengers, and the provision of a separate zero channel will reduce the number of channels available for this purpose. In another revolutionary aspect, the invention allows the passenger to select a video channel for viewing and always send the previously selected audio channel to this passenger's headset when the video channel is not accompanied by an audio channel. The passenger electronics system 100 can be configured. More specifically, the seat electronics box (SEB) is used so that the audio channel is switched on only when the passenger directly or implicitly selects a new audio channel using the Digital Passenger Control Unit (DPCU) 134. 130 IVAS gate arrays 706 can be configured or programmed. The RF video portion of the composite signal is sent from board split filter 704 to video board 705. More specifically, the RF video portion of the composite signal is sent to signal splitter 734 and then to one of up to three video signal tuners 714. Each of the tuners 714 is controlled by the tuner control circuit 716. It can be seen that the signal splitter 734 separates the video tuners 714 from each other. As described above, the tuner control circuit 716 is controlled via one of the micro processing unit (MPU) 718 and the plurality of digital passenger control units (DPCUs) 134. Each of the video tuner control circuits 716 is in turn coupled to a single video tuner 714, which allows tuner 714 to select a desired video channel from the composite RF video signal. After a particular video channel is selected, the video processing circuitry sends this channel to the seat display unit (SDU) for display. Microcontroller unit (MCD) board 707 has a microcontroller 718, an RS-485 port 720 for communication with the DATA1 bus, an address assignment relay 721, and a DPCU interface 722 for communication with digital passenger control units (DPCUs) 134. Microcontroller 718 sends and receives communication data on DATA1 bus via RS-485 port 720, sequentially communicates with digital passenger control units (DPCUs) 134 via DPCU interface 722, and seat electronics box via internal bus 724. Controls the internal operation of (SEB) 130 (ie, channel selection by IVAS gate array 706 and video processing circuit 714). Here, the microcontroller 718 preferably includes an 8-bit controller having 512 bytes of static RAM and an internal analog-to-digital converter (not shown). As a particularly innovative aspect of the present invention, the microcontroller 718 of one seat electronics box (SEB) 130 communicates with the microcontroller 718 of another seat electronics box (SEB) 130 via the DATA1 bus. Can be configured. As a result, the Digital Passenger Control Unit (DPCU) 13 4 located in the first seat position sends the video channel selection data from the first seat electronics box (SEB) used by that seat position one row forward of the first seat position. The second seat electronics box (SEB) 130 utilized by the other seat positions can be supplied. In this way, the seat display unit (SDU) mounted on the back of the front seat receives the selected video signal from the second seat electronics box (SEB) 310 and provides an additional communication link between the two seats. Not equipped, it can be controlled using the Digital Passenger Control Unit (DPCU) 134 located in the rear seat. Structure and function of IVAS gate array The structure and function of the integrated video and audio system (IVAS) gate arrays 310, 410 and 706 will be described with reference to FIGS. However, the structure of the integrated video audio system (IVAS) gate arrays 310, 410 and 706 does not change throughout the passenger entertainment system 100, and only the functions of the integrated video audio system (IVAS) gate arrays 310, 410 and 706 are maintained. You have to understand that it changes. In addition, the integrated video and audio system (IVAS) gate arrays 310, 410 and 706 have a single chip that functions in different ways depending on their location within the passenger entertainment system 100. Thus, the same IVAS gate array chip is preferably used here for any of the video system control unit (VSCU) 120, passenger entertainment system controller (P ESC) or seat electronics box (SEBs) 130. it can. However, the functionality of the chip changes depending on the location where it is placed. As can be seen by first referring to FIG. 10, each IVAS gate array 310, 410 or 706 has multiple prescalers 802, a test voice generator 804, a Manchester decoder 80 6, an audio formatter 808, an audio buffer 810, a timing control logic 810. It has nine functional blocks including 812, communication controller 814, PSS / CPMS buffer 816, and Manchester decoder 818. Prescaler 802 has a portion of a phase locked loop circuit (not shown) that divides the frequencies of the signals sent to the input (not shown) by programmable factors. The phase-locked loop circuit has a phase detector, a filter circuit, and a voltage control oscillator (VCO) (none shown), each dehice is located outside the I VAS gate array, and the prescaler 802 is an IVAS gate array. It is located inside. Each phase locked loop produces a clock phase locked to the PCM data signal. The clock frequency is a programmable multiplier or divisor of the clock derived from the bit rate (that is, the data trust rate), which is used by the ADPCM gate arrays 306, 318, 406, 418 and 708, and MASH analog digital digital and digital. -Supplied to the analog converters 302, 320, 404, 416 and 710. In this scheme, synchronization is maintained throughout the passenger electronics system 100 based on a frame transfer rate of 37.8 KHz. The Manchester decoder 806 receives the clock and serial audio data in Manchester code from the baseband receive interface 820. The Manchester decoder 806 decodes the received serial audio data with NRZ (non-zero return) and detects a unique data pattern used for system synchronization. Upon locating the sync signal, a pulse is generated by Manchester decoder 806 and sent to timing control logic block 812. Further, the NRZ serial audio data is sent from the Manchester decoder 806 to the audio buffer 810, the Manchester encoder 818, and the CPMS buffer 816. A test audio generator 804 having a shift register, counter, and control logic (not shown) is used to test signal distribution within the passenger entertainment system 100. More specifically, the test audio generator 804 produces a square wave of programmable frequency, which is located within the passenger entertainment system control (PESC) 122 (not shown). Can be fed to one input of the digital converter. The MASH analog-to-digital converter converts the square wave into digital format and sends this converted digital signal to the ADPCM gate array 410, as described above. The ADPCM gate array 410 compresses the converted digital signal and provides the resulting compressed signal to one input of the IVAS gate array 410, where the signal is multiplexed with the compressed PCM data signal to provide the entire passenger entertainment system 100. Will be distributed to. A test audio detection circuit (not shown) located in the seat electronics boxes (SEBs) 130 detects the presence of test audio in the PCM data signal and detects the presence of test audio in the passenger entertainment system controller (PESC). Tell 12 2. The audio formatter 808 has nine 32-bit audio sample shift registers (one shift register per eight audio input channels) and one 64-bit RF sample shift register (none of which are shown). The primary function of audio formatter 808 is to insert the bitstream data received from compressed digital audio signal source 102 and ADPCM gate arrays 306, 406 and 418 into a composite PCM data signal. More specifically, the audio formatter 808, under the control of the timing control logic block 812, inserts audio, range and filter data into the composite PCM data signal in the frame format shown in FIG. A fixed relationship is provided between each input port of the audio formatter 808 and the time slot into which audio and control data is inserted. As shown in FIG. 11, each frame 902 of the composite PCM data signal has the following: 8 sync bits 904, 64 Cabin Passenger Management System (CPMS) data bits 90 6; 32 range filter coefficients (R / F) bit 908; 6 channels with 24 bits of passenger address (PA) audio 9 10; 24 channels with 96 bits of passenger entertainment system controller (PESC) audio 912; video system controller unit (VSCU) digital audio 24 channels with 96 bits of 914; Video system controller unit (VSCU) 24 channels with 96 bits of digital audio 916; Video system controller unit (VSCU) 24 channels with 96 bits of optional digital or analog audio 918. The term "analog" as used in the preceding sentence indicates that the unique signal is initially generated by an analog audio source. Therefore, a maximum of 512 bits per frame 902 is preferably provided here. However, it should be noted that the frame format varies considerably depending on the number data type sent through the signal distribution network and the number of bits per data type. Furthermore, it is also desirable that the frame format of the IVAS gate array can be changed programmatically so that it can be changed as needed for a given passenger entertainment system or aircraft environment. Now, referring to FIGS. 12 (a) and 12 (b), and also to Table 2, as those skilled in the art will readily understand, the digital data is a CD-I using adaptive delta pulse code modulation. When compressed to Level B format, data is not only compressed from 16-bit format to 4-bit format. An additional range filter coefficient of 90 8 is added to the data. Thus, these coefficients become an important component of the composite PCM data signal, causing difficult problems associated with frame formatting. More specifically, ADPCM compression produces one 4-bit range coefficient and one 4-bit filter coefficient for each channel in 28 frame audio samples. Thus, if 102 channels of ADPCM compressed digital audio (6 PA channels, 24 PESC audio channels, 72 VSCU audio channels) are distributed throughout the passenger entertainment system 100, these will be The 4-bit range coefficient and 4-bit filter coefficient shall be provided for each of the 102 channels. In the worst case scenario, the transmission of range filter (R / F) coefficients would require a block of 816 bits of data dedicated to the range filter coefficients, with each frame of compressed digital audio. In contrast, when the frame format according to the present invention is utilized, only 32 bits are provided per frame to accommodate range filter (R / F) coefficients. This actual reduction in the number of bits per frame required to accommodate the range filter (R / F) coefficients is performed by staggering the range filter coefficients across the multiple frames shown in Table 2. . More specifically, as shown in FIGS. 11, 12 (a) and (b), the range filter (R / F) coefficient 908 corresponding to only four channels of compressed digital audio data is one predetermined frame. , Range filter (R / F) coefficients 908 corresponding to separate groups of four channels are provided in successive frames. In this method, range filter (R / F) coefficients 908 corresponding to all 102 compressed digital audio channels are supplied over the process of a total of 26 frames (for example, frame Nos. 2 to 26 shown in Table 2). . Furthermore, it is preferred here that the PA and audio data are staggered over the course of the 28 frames (ie 1 sample per channel per frame). More specifically, each sample of PA or audio data has 8 channels (or timeslots). Thus, 28 samples of each group of 8 channels (ie one sample per frame) are provided in each block of PA and audio data. The samples are arranged so that the first sample (sample 1) of a given group of eight channels is in the frame containing the range filter (R / F) coefficient 908 corresponding to the first channel of this group. For example, since the range filter (R / F) coefficient 908 corresponding to audio channel No. 1 is located in frame No. 3, the first sample of audio channel Nos. 1 to 8 (sample No. 1) is also It is located in frame No. 3. Similarly, since the range filter (R / F) coefficient 908 corresponding to audio channel No. 9 is located in frame No. 5, the first sample of audio channel Nos. 9 to 16 (Sample No. 1) Is also located in frame No. 5. It is also confirmed here that the coaxial transmission cable preferably arranges even audio samples in odd frames and odd audio samples in even frames. Here, and also with reference to Figures 13 (a) and 13 (b), this is because the digital audio data received by the audio formatter 808 during a given frame is simultaneously sent to the coaxial downlink (not shown). Because there is no. Instead, the digital audio data received by audio formatter 808 during one frame is sent on the coaxial downlink during the next frame. In addition, the range filter data 908 received by the audio formatter 808 in one frame is split and sent on the coaxial downlink in the process of the next two frames. When digital audio data is received by the audio buffer, the digital audio data from a given frame is stored in the current data register during this frame and sent to the output register during the next frame. In contrast, the range filter data is read out and sent out as soon as the register assigned to it is full (every two frames). For this reason, the audio sampling rate of the audio formatter 808 and audio buffer 81 0 should be equal to the frame transfer rate (that is, approximately equal to 37.8 kHz), and synchronization within the passenger entertainment system 100 should be consistent with this frame transfer rate. It is desirable to be maintained on a rate basis. Since the format can be modified considerably in accordance with the invention, it is not intended to limit the invention to the particular frame formats shown in Figures 11, 12 (a), 12 (b), 13 (a), 13 (b). Should be understood, For example, the composite PCM data signal includes a plurality of compression blocks having F frames per block, C digital audio channels per frame and P compression parameters per channel per block, and any of these parameters. It will be seen that (especially the number C of digital audio channels provided per frame) can vary. However, it is preferable here to allocate N time slots per frame for the compression parameters (N is an integer greater than or equal to (C × P) / F) and to select a group of compression factors (N of the compression factors above). Either multiplexer 14 or IVAS gate array 310 or 410, depending on the case, will be configured to assign each group (including each group) to the selected frame in each compressed block. For sync signals 904 and 905, a single audio sync pattern 904 (as shown in FIG. 11) is provided in the composite PCM data signal, one for every 28 frames, and the inverse of this pattern is the frame sync pattern 905. Are supplied between all other frames, as shown in FIGS. 12 (a) and 12 (b). Referring again to FIG. 10, audio buffer 810 has four pairs of 4-bit shift registers, 12 8-bit shift registers, and 4 16-bit shift registers (none shown). A pair of 4-bit shift registers is used to obtain left and right channel audio samples for each of up to four passenger seats. As each pair of samples is taken, the contents of each pair of shift registers are sent to a single 8-bit shift register. These channels are then sent out of the 8-bit shift register as a single 8-bit signal with two multiplexed and compressed digital audio channels. The resulting signal is then sent to one input of ADPCM gate array 706. The remaining eight 8-bit shift registers are used to obtain the compression factor for the left and right channels for each of up to four passenger seats. When the compression (range filter) coefficients are obtained, they are sent to a 16-bit shift register and then out on the same multiplexed output line as the corresponding compressed digital audio sample. Control of the data selection process is controlled by timing control logic 812, which generates control signals that enable the shift register to send on the selected audio channel. More specifically, the timing control logic 812 allows the shift register to receive the data located in the selected channel number time slot in response to a signal received from, for example, a digital passenger control unit (DPCU) 134. To do. To provide the channel number information, a counter is used that is reset by the timing control logic 812 of the sync signal when it is received. Thus, when the channel number selected by the Digital Passenger Control Unit (DPCU) 134 reaches the timing control logic 812, the data located in the corresponding time slot is sent to the shift register. Thus, in operation, a pair of first shift registers takes an audio data sample from the composite PCM data stream and sends this sample to the second register of this pair. Then, the second shift register sends the acquired samples to the ADPCM interface as the first shift register gets another sample from the next frame of the PCM data stream. It will be appreciated that in the "zero channel" mode described above, the channel number of the non-existent channel is provided to the timing control logic 812 by the digital passenger control unit (D PCU) 134. Since the timing control logic 812 does not receive the data corresponding to the selected channel, new data will not be entered in the first shift register, and if data is already entered in the first shift register, such data will be lost. It is repeatedly sent to the second shift register and finally sent to the PDPCM gate array 708. Timing control logic 812 controls all synchronous operations within IVAS gate arrays 310, 410 and 708. For example, when the IVAS gate array 310, 410 or 708 acts as a demultiplexer, the control logic 812 directs the selected audio channel to the audio buffer 810 and divides the clock to ensure the proper timing reference for the serial interface. Timing control logic 812 also decodes the address so that appropriate registers (not shown) can be used for communication with microcontroller 430 or 718 or central processing unit 316. IVCP communication controller 814 manages the communication protocol between IVAS gate array 706 (of SEB 130) and in-seat video cassette player (IVCPs) 138. The PSS / CPMS buffer 816 has a 16-bit shift register, mod 8-bit counter, 32-byte FIFO, status register, control register, 16-bit address register, and control logic (none shown). This hardware will operate in one of two modes, depending on whether the IVAS gate array is located in the Seat Electronics Box (SEB) or the Passenger Entertainment System Controller (PESC) 122. Controlled. When placed in the seat electronics box (SEB) 130, the PSS / CPMS buffer 816 is configured to perform the receive function. Message start byte 920 (shown in FIG. 11) is used to establish the start and end of the message. Each byte in the message start byte 920 except the first bit 921 corresponds to one data byte 924 in the CPMS field 906. When message start bit 922 is high, this channel is idle, or a new message begins in message byte 924, which corresponds to message start bit 922. Message data is present when the message start byte 922 is low. After the message is complete, the message start bit returns high for the next data byte. This indicates that the message has ended and a new message is potentially about to start. The control logic also compares the address field in each message with the address of the local unit. A suspend signal can be provided to the microcontroller 718 when the addresses are the same. When located in the passenger entertainment system controller (PESC) 122, the PSS / CPMS buffer 816 performs the reverse of the functions performed in the seat electronics box (SEB) 130. More specifically, PSS / CPMS buffer 816 receives messages from the microcontroller interface, one byte at a time. The bytes are waiting in queue in the FIFO. Timing control logic 812 generates an envelope signal when the PSS / CPMS buffer places data in the serial bit stream (PCM data signal). While the envelope is running, the wait byte is strobed into the shift register and sent out. Furthermore, as mentioned above, the message start message byte is inserted before the message byte. The control logic also checks if the first byte of the message is the first byte after the message start byte. Manchester encoder 818 encodes the formatted bitstream and generates programmable synchronization patterns at the appropriate times. The Manchester encoder 818 has a 16-bit register, a 16-bit shift register, a multiplexer, multiple gates, and flip-flops (none shown). During most downlink frames, the sync pattern is always loaded into the shift register. When the sync has to be transmitted, the shift register sends out the sync at twice the bit rate. An XOR gate is used to control the sync polarity. The multiplexer selects between sync or data based on an external control signal (a sync enable signal provided by the timing control logic 812). Flip-flops are used to reclock (retime) the edges after encoding the data. The present invention is capable of various modifications and of multiple alternative implementations, and specific presentations and illustrations are merely described in detail in the drawings and specification. However, this is not intended to limit the invention to the specific systems and methods disclosed, but on the contrary, the invention is within the spirit of the invention as defined by the appended claims. Includes all possible changes, equivalents and alternatives within.

────────────────────────────────────────────────── ─── Continuation of front page    (81) Designated countries EP (AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, LU, M C, NL, PT, SE), AU, GB, JP (72) Inventor Remer, Ji-Youn, Yi.             United States California             92653 Laguna Hills, Grissom               Road 25291 (72) Inventor Frost, William, Erlint             Jinnia             United States California             92675 San Fern Capistrano,             Country Hills Road 29231

Claims (1)

[Claims]   1. A digital audio signal distribution system for commercial aircraft and other vehicles. hand,   Multiple digital audio sources, each capable of producing a compressed digital audio signal output Bio signal source;   A plurality of signal input terminals for receiving the compressed digital audio signal output A multiplexer having the compressed digital audio signal. Capable of time-domain multiplexing the signal outputs to generate a single composite data signal;   For receiving the composite data signal, a desired channel is selected from the composite data signal. Demultiplexer with selectable channels;   For receiving the selected channel from the demultiplexer, A decompression circuit that can decompress the channel and generate a decompressed digital output signal. Road; The decompressed digital output signal is for receiving the decompressed digital output signal. Digital-to-analog converter that can convert output signals to analog audio signals ,   Equipped with.   2. Sends the composite data signal from the multiplexer to the demultiplexer Further comprising a signal distribution network,   The digital audio signal distribution system according to claim 1.   3. The composite data signal is F frames per block, per frame C digital audio channels and P per channel per block A plurality of compressed blocks having a number of compression parameters;   N time slots per frame for the compression parameters The multiplexer is configured to allocate and its N is (C × P) / F is an integer greater than   The multiplexer applies to the selected frame (s) within each compressed block Assign a selection group with a number N,   The digital audio signal distribution system according to claim 1.   4. A passenger entertainment system for a commercial aircraft or other vehicle, comprising:   Multiple digital audio sources, each capable of producing a compressed digital audio signal output Bio signal source;   Multiple analog audio signal sources, each capable of producing an analog audio signal. Source;   Each can generate an analog video signal and an analog audio signal of the video source. Multiple video signal sources;   The analog audio signal of the video source and the analog audio signal of the video source To receive, These analog signals can be converted to digital format by multiple analog devices. Digital converter;   Before converted from the analog-digital converter to digital format A plurality of digital signal compression circuits for receiving the digital signal, The signal compression circuit converts the signal converted into a digital format into the digital signal. Audio signal source generated by the audio signal source Something that can be compressed into a compatible format;   Generated by the digital audio signal source and the digital signal compression circuit A multiplexer for receiving the compressed digital audio signal, The multiplexor multiplexes the signals sent to it to create a composite digital audio data. Data signals can be formed;   Receiving the analog video signal generated by the video signal source Multiple video signal modulators for Where the analog video signal can be modulated by wave number;   A plurality for receiving the modulated analog video signal from the video signal modulator These RF signal combiners combine the signals sent to them. And capable of forming a composite RF video signal;   A base for receiving the composite digital data signal and the composite RF video signal. This is a baseband / RF signal combiner that is a baseband / RF signal combiner. Ina is in front The composite digital audio data signal and the composite RF video signal are combined to form a composite signal. Where a combined RF video / digital audio data signal can be formed;   For receiving said composite RF video / digital audio data signal So, this composite RF video / digital audio data signal can There are few parts that can be separated into RF video data component and digital audio data component. At least one RF signal separator;   From the baseband / RF signal separator to the RF video / digital audio Demultiplexing for receiving the digital audio data component of the audio data signal. A lexer, if the demultiplexer is the digital audio data component From which you can select the desired digital audio channel;   To receive a selected digital audio channel from the demultiplexer The digital signal decompression circuit of the Digital audio that expands the selected channel from the digital audio format. Decompressible to audio format;   For receiving the expanded channel from the digital signal decompression circuit A digital-to-analog converter, this digital-to-analog converter Convert the expanded channel to analog format, Audio channel What you can send to   From the RF signal separator to the composite RF video / digital audio data An RF tuner suitable for receiving the RF video component of a signal, the R tuner comprising: The F tuner selects the desired video channel from the RF video components and For providing selected video channels to video monitors;   Is provided.   5. The composite digital audio data signal has F frames per block. , C digital audio channels per frame and channels per block A plurality of compressed blocks having P compression parameters per channel,   Allocate N timeslots per frame for the compression parameters The multiplexer is configured such that N is (C × P) / F or more. Is an integer of;   The multiplexer applies to the selected frame (s) within each compressed block Assign a selection group with a number N,   The passenger entertainment system of claim 4.   6. The carrier frequency is variable from 135 MHz to 300 MHz and is programmable. The passenger entertainment of claim 4 Ment system.   7. Digital audio to multiple remote locations within a commercial aircraft or other passenger vehicle. A method of distributing a bio signal:   Generating a plurality of compressed digital audio signal outputs;   Providing the compressed digital audio signal output directly to a multiplexer;   The compressed digital audio signal output is multiplexed in the time domain to generate a composite digital audio signal. Forming the audio data signal;   From the multiplexer to a demultiplexer located at a remote location, the composite demultiplexer Sending digital audio data signals;   Selecting a channel from the composite digital audio data signal;   Decompressing the selected channel to form a decompressed digital audio signal. When;   Converting the decompressed digital audio signal into an analog signal;   Providing the analog signal to an audio transducer;   A method comprising the steps of:   8. The composite PCM data signal has F frames per block, C digital audio channels per channel, per channel per block Comprising a plurality of compressed blocks having P compression parameters,   The time domain multiplexing steps are:   Allocate N timeslots per frame for the compression parameters Provided that N is an integer greater than or equal to (C × P) / F; and   The selection group having the compression coefficient N in the selected frame (s) in each compressed block. Assigning loops;   The method of claim 7, comprising the steps of:   9. With the noise cancellation headset of the passenger entertainment system A method of generating an analog audio signal with no amplitude variation used by:   Generating a digital signal having a repeating sample pattern;   Providing the digital signal to a digital-to-analog converter;   Converting the digital signal into an analog format;   It is equipped with each step of.   Ten. Digital audio to multiple remote locations within a commercial aircraft or other passenger vehicle. Is a method of distributing audio signals. hand:   Multiple compressed digital audio signal outputs with predetermined data sampling data To occur;   Providing the compressed digital audio signal output directly to a multiplexer;   The compressed digital audio signal output is multiplexed in the time domain to generate a composite digital audio signal. Forming the audio data signal;   From the multiplexer to a demultiplexer located at a remote location, the composite demultiplexer Sending digital audio data signals;   Selecting a channel from the composite digital audio data signal;   Decompressing the selected channel to form a decompressed digital audio signal. When;   Converting the decompressed digital audio signal into an analog signal;   Providing the analog signal to an audio transducer;   Detected frame transfer approximately equal to the data sampling rate Synchronize each of the above steps based on rate;   It is equipped with each step of.