Abstract:
A modular digital recording system that records audio on digital audio tapes provides redundancy and the ability to record audio while listening to portions of audio that had been recorded on the DAT. The system uses a hard disc that receives audio for recording simultaneously with the DAT. When one wishes to listen to a voice message, one can activate the hard disc to listen to a particular message while the DAT is still recording. The system is modular so that the capacity can be expanded as required. The system includes a LAN adapter so that the system can providing networking access.

Description:
This is a continuation of U.S. patent application Ser. No. 08/100,944, filed Aug. 3, 1993 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     In the field of voice processing, there are circumstances in which it is necessary that audio, such as conversations, be recorded and the time when such recordings took place be established. Systems capable of providing this requirement have been commercially available for a long period and are referred to as recording loggers, or loggers for short. Prior systems have worked rather well, but were based for a long time on analog technology. Because of this, the prior logger systems were physically large and the tapes that recorded audio for archival purposes were also large, thus requiring a large amount of storage space. 
     To overcome these drawbacks of prior analog loggers, digital loggers have recently been developed and offered commercially. Although such digital loggers have advantages over the prior analog loggers, they still have short-comings in terms of networking expandability and voice capacity. It is an object of the invention to provide a digital logger that overcomes these disadvantages. In addition, it is an object of the invention to provide a digital logger that is modular in construction so that the capacity of such logger can be increased conveniently and economically and software can be upgraded as required. 
     SUMMARY OF THE INVENTION 
     The modular digital recording logger of the invention provides advantages not only over prior analog loggers, but over prior digital recording loggers as well. The digital logger of this invention has a basic unit that comprises four primary components, an audio card that monitors audio sources (such as telephones), a main card that processes audio, a host computer that controls the overall operation and memory. 
     The audio card serves the main functions of communicating with the audio sources, converting received analog signals to digital signals and directing the audio signals through a time division multiplexed (TDM) bus to the main, or application card. 
     The application card communicates with the audio card through the TDM bus to monitor the status of the audio cards, when there is more than one, and determine which needs service. The application card packages received data, executes speech compression and expansion, performs VOX and performs other functions. The application card is attached to an ISA bus as are a computer, such as a personal computer, a LAN adapter and a SCSI adaptor. The computer stores the operating instructions and supervises and coordinates the activities of the other components of the logger system. The SCSI adaptor is in communication with at least one digital audio tape (DAT) drive and at least one hard disc drive. The system is modular so that the capacity of the system can be expanded as required readily at a minimum cost and software can be modified conveniently as desired. In addition, the LAN adapter allows each logger of the invention to be part of a networked system that include other digital loggers and workstations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows a functional block diagram of a modular digital recording logger constructed in accordance with the present invention; 
         FIG. 2  is a top plan schematic view of the components of the logger of  FIG. 1  shown in a housing; and 
         FIG. 3  is a block diagram showing a plurality of the loggers of  FIG. 1  connected in a network. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to  FIG. 1 , a digital modular recording logger is shown at  10  and includes a pair of audio circuit boards  12 a,  12 b which will hereinafter be referred to as audio cards. Only two audio cards  12  are shown, but a larger number of audio cards can be included in the system. For example, where thirty two recording channels are required, eight digital audio cards  12  would be required, as it will be described in the description that follows. The audio cards  12 a,  12 b are in communication with an audio application processing circuit board  14 , which hereinafter will be referred to as the main card, through a time division multiplexed (TDM) bus  16 . Once more, only one main card  14  is shown and described, but it will be appreciated that where more audio cards are required, (e.g., eight), more main cards also may be needed, (e.g., four), upon the particular architecture of the audio cards and main cards. The main card  14  communicates with a personal computer through an ISA bus  22 . The computer has a CPU and RAM  23  and is in communication with a small computer system interface (SCSI) adaptor  18  through the ISA bus  22 . The SCSI host adaptor  18  can be any of a number of commercially available adaptors such as an Adapdec 1542 adaptor available from Adapdec Corporation. 
     The combination of the CPU  20  and RAM  23  can be any personal computer such as an IEE  996  standard PC/AT. 
     Also tied to the CPU  20  is a clock  34 . The LAN adapter  24  provides the opportunity for network connection, as it will be described hereinafter with reference to FIG.  3 . 
     The SCSI host adaptor  18  communicates with a pair of tape drives  26 a,  26 b each of which is capable of driving a digital audio tape (DAT)  28 a,  28 b, respectively. The tape drives  26 a,  26 b are in communication with the SCSI host adaptor  18  through a SCSI bus  30 . Also in communication with the SCSI host adaptor  18  through the SCSI bus  30  are two disc drives  32 a,  32 b. The number of DAT&#39;s  28  and disc drives  26  can vary to customize the system  10  to the operative channel requirements, but where the tapes are redundant, only one disc drive need be used. 
     A plurality of audio sources such as telephones  36 a,  36 b,  36 c . . .  36 n are shown. These represent any telephones outside of the system  10  that are able to communicate with the system  10  through communication lines  37 . The system  10  can monitor a number of different types of audio devices, including a private branch exchange (PBX)  38  to which a plurality of telephones  40 a and  40 b are connected. Other audio sources include radio, central office lines, microphones, speakers and the like. 
     As shown in  FIG. 1 , the audio card  12 a has four ports and is able to communicate with the lines  39  (channels) connecting the telephones  40 a with the PBX  38  so as to receive audio signals therefrom. More specifically, the audio cards  12 a,  12 b receive audio from two sources, an internal telephone  40  and an external telephone  36 . The audio card  12 b also has four ports, with three of the ports communicating with communication lines  39 b leading to telephones  40 b and the PBX  38 . One of the ports is connected to a speaker  41 , thereby allowing messages to be heard, as it will be described hereinafter. The communication lines  39  transmit audio from the PBX  38  and telephones  40  to the audio cards  12 . 
     The audio cards  12  can be of the type shown and described in co-pending patent application Ser. No. 07/815,205 and entitled Audio Circuit Board for a Modular Digital Voice Processing system, filed Dec. 31, 1991, now Ser. No. 102,678, filed Aug. 5, 1993, the disclosure of which is hereby incorporated by reference. The system  10  can be activated in one of two ways, either through the audio card detecting a telephone  40  going off hook, or through a VOX operation controlled by the main card  14  which is activated upon the main card receiving an audio signal from one of the audio cards. 
     The audio card  12  converts the analog signals received from the communication lines  39  from analog to digital and will transmit the signals onto the TDM bus  16  under control of the main card  14 . The main card  14  monitors the status of the audio cards  12 a,  12 b to see which audio card needs service and upon responding thereto, the audio is sent over the TDM bus  16 . The main card  14  can be of the type shown and described in copending application Ser. No. 07/816,404, filed Dec. 31, 1991, now U.S. Pat. No. 5,404,455, and entitled Time Division Multiplexer Chip, the disclosure of which is hereby incorporated by reference. As stated previously, only two audio cards  12  are shown in  FIG. 1 , but more audio cards can be added to the system as required. 
     The main card  14  receives the digital audio signals from the audio cards  12  and compresses the data, as for example from 64K bits per second to 13K bits per second of audio and packages the audio into 2048 byte messages. This data is then sent across the ISA bus  22  to the CPU  20  that serves as a traffic director for the entire system  10 . The data is stored in the RAM  23  prior to being transmitted to SCSI host adapter  18  and onto the the tapes  28  and discs  32  where the data is stored permanently. 
     Because DAT recording is relatively fast compared to channel data rates i.e., the DATs are capable of receiving data faster than data is digitized by the system, the data is first written into and stored on the RAM  23  and will be transmitted to the DATs  28  at a rate that is compatible with the capability of the DATs. At the same time, data is written into the disc files  32 . 
     The two tapes  26 a,  26 b, can be used either independently to achieve greater capacity, or simultaneously to achieve redundancy. When used independently, more data can be written to the tapes. When they are used simultaneously, one tape  28 a will serve as a backup for the other tape  28 b. In this way, if either of the tapes is destroyed for any reason, there is always a backup. 
     The disc files  32 a and  32 b duplicate what is recorded on each of the DATs  28 . Clearly, if the DATs  28 a,  28 b are being used in a redundant manner, only one disc  32  is required to record the audio. In fact, one disc  32  can be partitioned with a portion duplicating the data on one DAT  28 a and the other portion duplicating the data on a second DAT  28 b when the DATs are run sequentially. The primary function served by the disc file  32  is to allow one to listen to previously written recorded data without interfering with the functions of the DATs  28 . In addition, the discs  32 a,  32 b can serve the function of back-ups for the DATs  28 a,  28 b. 
     When one wishes to listen to audio that had been recorded at a particular time, this can be accomplished by inputting a request to the CPU  20  requesting that a message on a particular channel and at the given time be delivered over the speaker  41 . 
     The time data is stored on the DATs  28  and discs  32  under control of the CPU  20 . An input is made into the system  10 , as by a network or serial port connection for the time and channel for a particular message. The host adaptor  18  will search the disc  32  for the address of the specific time and channel and will retrieve the audio from the disc  32 . While this is occurring, the DATs  28 a,  28 b are capable of continuing to record audio. 
     The audio recovered from the disc  32 a will be transmitted to the main card  14  where decompression will take place and the data will be expanded, as for example, from 13K bits per second to 64K bits per second. The data will then be transmitted to the audio card  12 b where it will be converted from digital to analog and eventually will be heard over the speaker  41 . 
       FIG. 2  is a top plan schematic view that demonstrates the modularity of the system  10  and how its capacity can be readily expanded as required. A housing  52  has a base  54  that receives the various cards of the system as will be described. One or more main cards  14 a,  14 b will be received within and supported by the base  54 , as will a plurality of audio cards  12 a,  12 b. Once more, although three audio cards  12  are shown, it will be appreciated that a greater or lesser number can be used and one main card is capable of monitoring and servicing a plurality of audio cards, two as shown in FIG.  1 . 
     Each main card  14  will be connected logically to an audio card  12 a, but it is not necessary that the audio card be connected physically to the main card to which it is connected logically because of the TDM function of the system. In addition, an audio card  12 c can be physically attached to a dummy card  34  that can provide an electrical connection but no logic. Thus, one main card  14 a can be connected logically through the TDM bus  16  to two audio cards  12 a,  12 c. 
     The housing base  54  also supports the CPU  20  which is connected with the main cards  14  through the bus  16 . The SCSI adaptor  18  is in communication with the main cards and with the CPU  20  through the ISA bus  22 . In this way, cards  12 a,  14  can be added or eliminated from the system  10  in accordance with requirements thereof because of the time division multiplexing capability of the system. As a main card  14  and audio card  12  are added they will be connected to the appropriate busses and supported by the base  54 . The base  54  also supports a clock buffer  58  that provides timing for the TDM bus and provides additional drive for the ISA bus and the components attached thereto. 
       FIG. 3  is a schematic view showing how the invention can be networked to include a number of systems  10  connected as nodes, and workstations  60 . Where a large number of telephone conversations are to take place and recorded, as for an example at a brokerage firm, a large number (e.g. 160) of conversations may need to be recorded. In this instance, one system  10  would not be capable of servicing that many calls. 
     In  FIG. 3 , several workstations  60  are connected to a LAN bus  64  and are several of nodes  10 . Each workstation is a personal computer  60  with a main card  14 , an audio card  12  and a LAN adapter  62 . A speaker  41  is attached to each workstation  60 . In addition, the number of workstations  60  can be increased so that access to the systems  10  at a number of different locations can be achieved and one would be able to monitor and have access to any audio data as required. 
     When audio is to be retrieved, the processing will take place in a node  10  as described previously, with the exception that compressed audio is sent by the LAN adapter  24  ( FIG. 1 ) over the LAN bus  64  ( FIG. 3 ) and received by the LAN adapter  62  of the requesting workstation  60 . The compressed data is then processed by the main/audio cards,  14 ,  12  and subsequently audio is heard over the speaker  41 . 
     Thus, what has been shown and described is a digital recording logger that is modular in construction, is capable of using digital audio tapes in an effective manner and can be networked to provide a plurality of workstations and nodes. 
     The above embodiments have been given by way of illustration only, and other embodiments of the invention will be apparent to those skilled in the art from consideration of the detailed description. Accordingly, limitations on the instant invention are to be found only in the claims.