US 6,172,978 B2Granted

Tandem relay device

AssigneeMitsubishi Denki Kabushiki Kaisha

InventorsWataru Fushimi, Yoshihiko Shirokura, Yukimasa Sugino, Hideaki Ebisawa, Yushi Naito

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Abstract

In establishing an audio one link connection wherein an audio signal is not encoded/decoded in a relay station, loud noises may be produced if the states of two audio tandem relay devices which make a pair during relay are changed from a normal connection state to a relay connection state at different times. In order to solve this problem, comfort noise generators are provided. In detail, when a first pattern signal is detected while a relay call is connected via a relay exchange, switches are switched to be connected at a contact point 1, and a switch is at a contact point 2. Upon detection of a second pattern signal, the switches are connected at the contact points 2, while the switches are connected at the contact points 2. With this arrangement, outputs from the comfort noise generators are selected and outputted during a period from first pattern signal detection to second pattern signal detection, during which the states of the two devices of a pair are different. As a result, occurrence of loud noises is prevented.

Claims15

Dependent claims

An audio tandem relay device for relaying an audio signal inputted from a line as ATM cells to a second audio tandem relay device via an exchange, comprising:

a cell disassembly for disassembling a received ATM cells inputted from the line into an encoded audio signal;
an audio decoder for decoding the encoded audio signal into the audio signal;
a pseudo audio signal generator for generating a pseudo encoded audio signal by converting the encoded audio signal, the pseudo audio signal having a data rate unchanged from that of the encoded audio signal and a transmission rate capable of being handled by the exchange;
a first pattern inserter for inserting a first pattern signal into the audio signal so that the second audio tandem relay device may identify that the current transmission is a relay transmission;
a second pattern inserter for inserting a second pattern signal into the pseudo encoded audio signal so that the second audio tandem relay device may identify that it is in a relay exchange state;
an audio encoder for encoding an audio signal received from the exchange;
a transmission rate recoverer for changing the pseudo encoded audio signal when received from the exchange into an encoded audio signal having an original transmission rate;
a cell assembly for assembling an ATM cell from the encoded audio signal to output to the line;
a first pattern detector for detecting the first pattern signal included in a signal from the exchange;
a second pattern detector for detecting the second pattern signal included in a signal from the exchange;
a first comfort noise generator for outputting a comfort noise to the line through the cell assembly upon detection of the first pattern signal;
a second comfort noise generator for outputting a comfort noise to the exchange through the second pattern inserter upon detection of the first pattern signal;
a first switch for switching its connection from the first pattern inserter to the second pattern inserter upon detection of either the first pattern signal or the second pattern signal to thereby connect the second pattern inserter to the exchange;
and
a second switch for switching its connection from the audio encoder to the transmission rate recoverer upon detection of the second pattern signal to thereby connect the transmission rate recoverer to the cell assembly.

12 more elements

An audio tandem relay device for relaying an audio signal inputted from a line as ATM cells to a second audio tandem relay device via an exchange, comprising:

a cell disassembly for disassembling a received ATM cells inputted from the line into an encoded audio signal;
an audio decoder for decoding the encoded audio signal into the audio signal;
a pseudo audio signal generator for generating a pseudo encoded audio signal by converting the encoded audio signal, the pseudo audio signal having a data rate unchanged from that of the encoded audio signal and a transmission rate capable of being handled by the exchange;
a first pattern inserter for inserting a first pattern signal into the audio signal so that the second audio tandem relay device may identify that the current transmission is a relay transmission;
a second pattern inserter for inserting a second pattern signal into the pseudo encoded audio signal so that the second audio tandem relay device may identify that it is in a relay exchange state;
an audio encoder for encoding an audio signal received from the exchange;
a transmission rate recoverer for changing the pseudo encoded audio signal when received from the exchange into an encoded audio signal having an original transmission rate;
a cell assembly for assembling an ATM cell from the encoded audio signal to output to the line;
a first pattern detector for detecting the first pattern signal included in a signal from the exchange;
a second pattern detector for detecting the second pattern signal included in a signal from the exchange;
a comfort noise generator for outputting a comfort noise to the exchange through the second pattern inserter upon detection of the first pattern signal or during a predetermined period of time after detection of the second pattern signal;
a first switch for switching its connection from the first pattern inserter to the second pattern inserter upon detection of either the first pattern signal or the second pattern signal to thereby connect the second pattern inserter to the exchange;
and
a second switch for switching its connection from the audio encoder to the transmission rate recoverer upon detection of the second pattern signal to thereby connect the transmission rate recoverer to the cell assembly.

11 more elements

An audio tandem relay device for relaying an audio signal inputted from a line as ATM cells to a second audio tandem relay device via an exchange, comprising:

a cell disassembly for disassembling a received ATM cells inputted from the line into an encoded audio signal;
an audio decoder for decoding the encoded audio signal into the audio signal;
a pseudo audio signal generator for generating a pseudo encoded audio signal by converting the encoded audio signal, the pseudo audio signal having a data rate unchanged from that of the encoded audio signal and a transmission rate capable of being handled by the exchange;
a first pattern inserter for inserting a first pattern signal into the audio signal so that the second audio tandem relay device may identify that the current transmission is a relay transmission;
a second pattern inserter for inserting a second pattern signal into the pseudo encoded audio signal so that the second audio tandem relay device may identify that it is in a relay exchange state;
an audio encoder for encoding an audio signal received from the exchange;
a transmission rate recoverer for changing the pseudo encoded audio signal when received from the exchange into an encoded audio signal having an original transmission rate;
a cell assembly for assembling an ATM cell from an encoded audio signal to output to the line;
a cell assembly for assembling an ATM cell from the encoded audio signal to output to the line;
a first pattern detector for detecting the first pattern signal included in a signal from the exchange;
a second pattern detector for detecting the second pattern signal included in a signal from the exchange;
a comfort noise generator for outputting a comfort noise to the line through the cell assembly for a predetermined period of time after establishment of a relay call;
a first switch for switching its connection from the first pattern inserter to the second pattern inserter upon detection of either the first pattern signal or the second pattern signal to thereby connect the second pattern inserter to the exchange;
and
a second switch for switching its connection from the audio encoder to the transmission rate recoverer upon detection of the second pattern signal to thereby connect the transmission rate recoverer to the cell assembly.

12 more elements

An audio tandem relay device for relaying an audio signal inputted from a line as ATM cells to a second audio tandem relay device via an exchange, comprising:

a cell disassembly for disassembling a received ATM cells inputted from the line into an encoded audio signal;
an audio decoder for decoding the encoded audio signal into the audio signal;
a pseudo audio signal generator for generating a pseudo encoded audio signal by converting the encoded audio signal, the pseudo audio signal having a data rate unchanged from that of the encoded audio signal and a transmission rate capable of being handled by the exchange;
a first pattern inserter for inserting a first pattern signal into the audio signal so that the second audio tandem relay device may identify that the current transmission is a relay transmission;
a second pattern inserter for inserting a second pattern signal into the pseudo encoded audio signal so that the second audio tandem relay device may identify that it is in a relay exchange state;
an audio encoder for encoding an audio signal received from the exchange;
a transmission rate recoverer for changing the pseudo encoded audio signal when received from the exchange into an encoded audio signal having an original transmission rate;
a cell assembly for assembling an ATM cell from the encoded audio signal to output to the line;
a first pattern detector for detecting the first pattern signal included in a signal from the exchange;
a second pattern detector for detecting the second pattern signal included in a signal from the exchange;
a comfort noise generator for outputting a comfort noise to the to the line through the cell assembly upon detection of the first pattern signal;
a first switch for switching its connection from the first pattern inserter to the second pattern inserter to thereby connect the second pattern inserter to the exchange upon detection of the second pattern signal, and during a period of time which lasts from detection of a first pattern signal until detection of a second pattern signal by the pair audio tandem relay device;
and
a second switch for switching its connection from the audio encoder to the transmission rate recoverer upon detection of the second pattern signal to thereby connect the transmission rate recoverer to the cell assembly.

11 more elements

An audio tandem relay for selectively relaying an audio signal composed of ATM cells that may be pre-encoded from a line to a second audio tandem relay comprising:

a cell disassembly for disassembling each received ATM cell inputted from said line to develop an encoded audio signal;
an audio decoder for decoding the encoded audio signal into the audio signal, said audio decoder being selectively enabled;
an audio encoder for encoding an audio signal received from the exchange, said audio encoder being selectively enabled;
a cell assembly for assembling an ATM cell inputted from the encoded audio signal to output to the line;
a pattern inserter for inserting at least one pattern signal into the audio signal, the pattern signal identifying whether the current transmission is a relay transmission;
a first comfort noise generator for outputting a comfort noise to the line through the cell assembly during switching between relay transmission and enabling of said audio decoder and encoder;
and
a second comfort noise generator for outputting a comfort noise to the exchange during switching between relay transmission and enabling of said audio decoder and encoder.

5 more elements

Dependencies are inferred from the claim text.