摘要:
A system and method for transparently transmitting aural signals across a wide area network (WAN). The system of present invention is connected to one or more of a private branch exchange, a key telephone system, a telephone, a facsimile machine, and a modem, for example. In the case of voice transmission, a user places a telephone call using the same procedure that is used when placing a telephone call over a conventional public switched network. The aural signals are translated into a format that is compatible with the local area network (LAN) and the translated signals are transmitted to a router or a switch that connects the LAN to the WAN. The data is transmitted across the WAN to a router or switch coupled to a second LAN. The data is then sent to a destination central site unit or PC which translates the signal into a format that is compatible with the telephone system connected thereto. The present invention provides a voice quality that approaches, equals, or exceeds the voice quality of conventional telephone switched networks. This high voice quality is achieved by utilizing a high quality voice digitization algorithm, by ensuring a low maximum network delay, by dynamically compensating for variations in network delay, and by using a forward error correction technique that can recreate lost or delayed signals in a manner that recreates the signal so the lost signal is typically not detectable by a user.
摘要:
Modulated data information having an individual one of different baud rates and aural information are converted at a transmitter from analog to digital form. A controller separately identifies the digitized aural and modulated data information and, if modulated data, identifies the baud rate of such modulated data. The aural information is separately transformed. For modulated data, the information is separately processed in accordance with the different baud rates. The individual ones of aural and modulated data are then introduced to a common line for packetizing. The beginning of each packet is labelled to identify whether the packet contains aural information (such as voice or music) or modulated data (such as modem or facsimile), and, if modulated data, the particular baud rate of such information. An individual code identifies the end of each packet. The packetized information is then multiplexed in a common bus with other packetized aural and data information. At a receiver connected to the common bus, the multiplexed information is separated into the different packets. The packetized information representing individual ones of aural information (such as voice or music) and modulated data (such as music or facsimile information) is separated, in accordance with the packet labels, into aural information and modulated data and, if modulated data, is introduced to an individual one of different modulators each operative at an individual one of the different baud rates. The aural information is then transformed substantially to its original form at the transmitter and the modulated data is separately processed in accordance with the different baud rates.
摘要:
A system and method for transmitting aural signals across a wide area network (WAN) from a local phone coupled to a computer, e.g., a PC-phone, to a remote phone coupled to a KTS, PBX, or PSTN, for example. This capability is provided by the gateway unit of the present invention. The system of the present invention is quickly installed in a server or a personal computer coupled to a local area network. The system is connected to one or more of a PSTN, a private branch exchange, a key telephone system, a telephone, a facsimile machine, and a modem. In the case of voice transmission, a gateway unit translates received telephony signal into a format that is compatible with the telephone system or equipment connected thereto. The present invention can provide a voice quality that approaches, equals, or exceeds the voice quality of conventional telephone switched networks. This high voice quality is achieved by utilizing a high quality voice digitization algorithm on both the PC-phone and the gateway, by ensuring a low maximum network delay between the PC-phone and the gateway, by permitting a dynamic compensation for variations in network delay, and by utilizing a forward error correction technique for transmission over WANs that can recreate lost or delayed signals in a manner that recreates the signal so the lost signal is typically not detectable by a user.
摘要:
A vane for a gas turbine engine comprising a hollow body externally of aerofoil form. The inner surface of the body is provided with confronting grooves, extending in a direction along the length of the aerofoil form, at a location intermediate the leading and trailing edges of the aerofoil form for receiving two inserts. The first insert comprises two perforated panels situated inside a trailing region of the aerofoil form and defining therewith one or more air passages between the insert and the wall of the body. The first insert has portions which engage in the grooves in the wall of the body, and is provided with confronting grooves extending in a direction along the length of the aerofoil form at a location intermediate the leading and trailing edges of the aerofoil form. The second insert comprises a first panel extending across the void in the body, and has edges which engage in the confronting grooves in the first insert. The second insert has a second panel closing at least part of an end of the void in the body.