Telephonic communications – Telephone line or system combined with diverse electrical... – Having transmission of a digital message signal over a...
Reexamination Certificate
2002-03-05
2004-01-27
Woo, Stella (Department: 2643)
Telephonic communications
Telephone line or system combined with diverse electrical...
Having transmission of a digital message signal over a...
C379S093310
Reexamination Certificate
active
06683944
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a voice transmitter for transmitting an audio signal and a DTMF signal (Dual Tone Multi-Frequency) by high-efficiency voice encoding technology.
2. Description of Related Art
FIG. 27
is a block diagram showing a conventional voice transmitter.
Referring to
FIG. 27
, reference numeral
8
denotes an input terminal of the voice transmitter;
9
an output terminal of the voice transmitter;
10
a voice encoding unit for encoding an audio signal;
11
a DTMF encoding unit for encoding a DTMF signal;
12
a DTMF detecting unit for detecting and judging whether or not an input signal is a DTMF signal; and
13
a selector for selecting an output of the voice encoding unit
10
or that of the DTMF encoding unit
11
under the control of the DTMF detecting unit
12
, and for outputting either of them.
Next, the operation of the conventional voice transmitter will be described.
In the voice encoding unit
10
and the DTMF encoding unit
11
, an inputted audio signal or a DTMF signal is encoded into digital data string. The voice encoding unit
10
encodes the signal by voice encoding technology. In addition, the DTMF encoding unit
11
decodes the DTMF audio signal into a DTMF numerical value. On the other hand, the DTMF detecting unit
12
detects and judges whether or not an input signal is a DTMF signal. If the input signal is a DTMF signal, the DTMF detecting unit
12
controls the selector
13
so that the output of the DTMF encoding unit
11
is selected. Otherwise, the DTMF detecting unit
12
controls the selector
13
so that the output of the voice encoding unit
10
is selected. The selector
13
selects an input signal in response to an instruction from the DTMF detecting unit
12
, and then outputs the selected signal to the transmission line side.
FIG. 28
is a block diagram showing a conventional voice encoder described in JP-A No. 8-307366.
Referring to
FIG. 28
, reference numeral
111
denotes an input terminal;
112
a DTMF detection circuit for detecting and judging whether or not a signal, which is inputted by the input terminal
111
, is a DTMF signal;
113
a DTMF encoder for encoding a DTMF signal; and
114
a voice encoder for encoding an audio signal. Reference numeral
112
a
denotes a switching circuit for selecting an output to the voice encoder
114
or that to the DTMF encoder
113
, and for outputting either of them under the control of the DTMF detection circuit
112
. Reference numeral
115
denotes an output selecting circuit for selecting an output of the voice encoder
114
or that of the DTMF encoder
113
under the control of the DTMF detection circuit
112
, and for transmitting the selected output to an output terminal
116
.
Next, the operation of the conventional voice encoder will be described.
In the DTMF signal detecting circuit
112
, an inputted audio signal or a DTMF signal is judged whether or not it is a DTMF signal. The switching circuit
112
a
, which is notified that the signal is a DTMF signal, connects an input signal from the input terminal
111
to the DTMF encoder
113
. The DTMF signal, which is given to the DTMF encoder
113
, is encoded (i.e., decoded), is converted into a DTMF numerical value, and is then output as an encoded DTMF signal. Moreover, the output selecting circuit
115
, which is notified that the signal is a DTMF signal, selects the output from the DTMF encoder
113
and outputs it to the output terminal
116
. On the other hand, if the DTMF detecting circuit
112
judged the signal not to be a DTMF signal, each of the switching circuit
112
a
and the output selecting circuit
115
, which is notified that the signal is not a DTMF signal, connects an input signal from the input terminal
111
to the voice encoder
114
, selects an output from the voice encoder
114
, and then outputs it to the output terminal
116
. In this case, the input signal is voice-encoded in the voice encoder
114
, and is output as an encoded audio signal.
Since the conventional voice transmitter and the voice encoder are configured as described above, if the transmitter detected and judged false an audio signal to be a DTMF signal during a telephone conversation, an output signal, which is decoded in the DTMF encoding unit
11
or in the DTMF encoder
113
, will be transmitted to a destination equipment. Thus, the destination side equipment, which is received this signal, is obliged to generate a DTMF signal based on the decoded signal. As a result, a destination caller will hear suddenly a sound of the DTMF signal, which gives an unpleasant feeling to the caller.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems, and an object thereof is to provide a high-quality voice transmitter, which does not give an unpleasant feeling to a caller, even when the transmitter detected and judged false an audio signal to be a DTMF signal during a telephone conversation, and which can transmit the a signal reliably when the DTMF signal is actually transmitted.
A voice transmitter according to the present invention for encoding and transmitting a DTMF signal and an audio signal, includes:
voice encoding means for performing voice-encoding of an inputted audio signal;
DTMF encoding means for performing encoding of an inputted DTMF signal;
voice-DTMF encoding means for performing voice encoding of an inputted audio signal and a DTMF signal;
a first selector for selecting the DTMF signal encoded in the DTMF encoding means, or the DTMF signal voice-encoded in the voice-DTMF encoding means;
DTMF transmission control means for monitoring quality of an input signal and a transmission line, congestion of the transmitter, or a call connection, and for controlling selecting operation of the first selector depending on the state;
DTMF detecting means for detecting that an inputted signal is a DTMF signal; and
second selector for selecting an output of the voice encoding means when the DTMF detecting means judged the inputted signal not to be a DTMF signal, and for selecting an output signal selected by the first selector when the DTMF detecting means judged the inputted signal to be a DTMF signal.
In the voice transmitter according to the present invention, the voice-DTMF encoding means voice-encodes both an audio signal and a DTMF signal at a higher speed than a voice-encoding speed of the voice encoding means.
In the voice transmitter according to the present invention, the voice-DTMF encoding means incorporates an encoding algorithm, which is specialized in a DTMF signal, and encodes the DTMF signal of poor voice quality at the same speed as a voice-encoding speed.
In the voice transmitter according to the present invention, the DTMF transmission control means is call connection state monitoring control means for monitoring a call connection state, and for, depending on the call connection state, controlling the first selector to select either an output of a DTMF encoding unit or that of a voice-DTMF encoding unit for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means is input-signal quality monitoring control means for monitoring quality of an inputted audio signal and a DTMF signal, and for, depending on the quality, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means is transmission-line quality monitoring control means for monitoring transmission quality on a transmission line, and for, depending on the transmission-line quality, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the transmission-line quality monitoring control means is data-error-rate monitoring control means for monitoring a data error rate on a transmission line,
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