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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to a method and system for radio communication between at least one parent communication unit and a plurality of slave communication units.
Such a radio communication system includes a cordless telephone system for providing radio communication of a handset with a telephone network. In order to permit a plurality of handsets to come into contact with each telephone line, it is
desirable that the cordless telephone system be of the multi-channel access type where one of the handsets shares a plurality of communication channels with the other handsets. With the multi-channel access type cordless telephone system, one handset
can communicate through a searched available channel with the telephone line or another handset. A frequency band is used in communication from the former to the latter and another frequency band is used in communication from the latter to the former.
One problem which occurs with this type of radio communication system is that when two or more handsets make answers, in a short interval, to an incoming call transmitted through a telephone line, none of the handsets can communicate with the
telephone line due to radio interference between answer signals transmitted from the handsets. Thus, the need exists for a practical approach which permits communication of the telephone line with one handset which makes an answer to the incoming call
at a time earlier than the other handsets like wire telephone systems.
SUMMARY OF THE INVENTION
Therefore, a main object of the invention is to provide an improved radio communication method and system which is free from the problems associated with conventional radio communication systems.
It is another object of the invention to provide a radio communication method and system which permits a parent communication unit to come into contact with only one slave communication unit which makes a called-person's answer to a call signal
transmitted from the parent communication unit to a plurality of slave communication units.
It is still another object of the invention to provide a radio communication method and system which permits any of the slave communication units to make a called-person's answer to an incoming call transmitted through an outside line.
It is still another object of the invention to provide a radio communication method and system which permits a slave communication unit to transmit a call while a parent communication unit transmits a call signal to a plurality of slave
communication units.
It is still another object of the invention to provide a radio communication method and system which permits each slave communication unit to make an answer to an incoming call transmitted through a selected one of a plurality of outside lines.
It is still another object to provide a radio communication method and system which can transfer conversation from one slave communication unit to another slave communication unit.
It is still another object to provide a radio communication method and system which can return one slave telephone unit into an initial condition communicating with a parent communication unit when no called-person's answer signal is transmitted
from another slave communication unit to which conversation is to be transferred from the one slave communication unit.
It is still another object of the invention to provide a radio communication method and system which utilizes a plurality of control channels to prevent interference of control signals transmitted from respective parent communication units.
It is still another object of the invention to provide a radio communication method and system which can maintain proper telephone line controls and can perform rapid channel settings even when it is subject to radio interference.
It is still another object of the invention to provide a radio communication method and system which can detect a speech quality reduction of any cause.
There is provided, in accordance with the invention, a method for radio communication between at least one parent communication unit and a plurality of slave communication units. The method comprises the steps of: specifying a representative
slave communication unt for one of the slave communication units; transmitting a call signal from the parent communication unit; transmitting an automatic answer signal from the representative slave communication unit automatically in response to receipt
of the call signal; when a called-person's answer is made to the call signal by one of the slave communication units, transmitting a called-person's answer signal from the one slave communication unit; detecting the presence of interference between the
automatic answer signal and the called-person's answer signal; terminating the transmission of the called-person's signal from the one slave communication unit when the interference occurs; transmitting an identification signal from the one slave
telephone unit to identify that the called-person's answer signal was transmitted from the one slave communication unit; and transmitting a specification signal from the parent communication unit in response to receipt of the identification signal to
specify the one slave communication unit as a slave communication unit communicable with the parent communication unit.
In another aspect of the invention, a radio communication system is provided for radio communication between at least one parent communication unit and a plurality of slave communication units. The system comprises one of the slave communication
units being specified as a representative slave communication unit; means for transmitting a call signal to the slave telephone units; means for detecting the presence of interference between an automatic answer signal transmitted in response to the call
signal from the representative communication unit and a called-person's answer signal transmitted from one of the slave telephone units which makes a called-person's answer to the call signal; means for transmitting an interference indication signal when
the interference is detected; means for receiving an identification signal transmitted from the one slave communication unit; and means responsive to the identification signal for transmitting a specification signal to specify the one slave communication
unit as a slave communication unit communicable with the parent communication unit.
In another aspect of the invention, a radio communication system is provided for radio communication between at least one parent communication unit and a plurality of slave communication units. The system comprises one of the slave communication
units being specified as a representative communication unit; means for transmitting a called-person's answer signal from one of the slave telephone units when the one slave communication unit makes a called-person's answer to a call signal transmitted
from the parent communication unit; means for terminating the transmission of the called-person's answer signal from the one slave telephone unit in response to receipt of an interference indication signal transmitted from the parent communication unit
when interference is detected between an automatic answer signal transmitted from the representative slave communication unit and the called-person's answer signal; means for transmitting an identification signal; and means for receiving a specification
signal from the parent communication unit which transmits the specification signal in response to receipt of the identification signal, the specification signal specifying the one slave communication unit as a slave communication unit communicable with
the parent communication unit.
In another aspect of the invention, a method is provided for radio communication between a plurality of parent communication units and a plurality of slave communication units. The method comprises the steps of: specifying one of the slave
communication units as a representative slave communication unit; transmitting a call signal from one of the parent communication units; transmitting an automatic answer signal from the representative slave communication unit automatically in response to
receipt of the call signal; when a called-person's answer is made to the call signal by one of the slave communication units, transmitting a called-person's answer signal from the one slave communication unit; detecting the presence of interference
between the automatic answer signal and the called-person's answer signal; terminating the transmission of the called-person's answer signal from the one slave communication unit when the interference is detected; transmitting an identification signal
from the one slave communication unit to identify that the called-person's answer signal was transmitted from the specification signal from the one parent communication unit in response to receipt of the identification signal to specify the one slave
communication unit as a slave communication unit communicable with the one parent communication unit.
In another aspect of the invention, a radio communication system is provided for radio communication between a plurality of parent communication units and a plurality of slave communication units. The system comprises one of the parent
communication units being specified as a first representative communication unit; means for transmitting a call signal to the slave communication units; means for detecting the presence of interference between an automatic answer signal transmitted from
the first representative communication unit and a called-person's answer signal transmitted from one of the slave communication units which makes a called-person's answer to the call signal; means for transmitting an interference indication signal when
the interference is detected; means for receiving an identification signal from the one slave communication unit; means for transmitting a specification signal to specify the one slave communication unit as a communicable slave communication unit; and
means for specifying another slave communication unit as a second representative slave communication unit when the first representative slave communication unit makes a called-person's answer.
In another aspect of the invention, a radio communication system is provided for radio communication between a plurality of parent communication units and a plurality of slave communication units. The system comprises means for receiving a
representative slave communication unit specifying signal from one of the parent communication units; means for transmitting an automatic answer signal in response to a call signal from the one parent communication unit in the case of receipt of the
representative slave unit specifying signal; means for transmitting a called-person's answer signal when a called-person's answer is made to the call signal; means for terminating the transmission of the called-person's answer signal in response to
receipt of an interference indication signal transmitted when interference is detected between the automatic answer signal and the called-person's answer signal; means for transmitting an identification signal; and means for receiving a slave
communication unit specifying signal transmitted from a parent communication unit which received the identification signal, the slave communication unit specifying signal specifying a communicable slave communication unit.
In another aspect of the invention, a method is provided for radio communication between at least one parent communication unit and a plurality of slave communication units. The method comprises the steps of: transmitting a transfer request
signal through a first channel from a first slave communication unit, the transfer request signal including information specifying a slave communication unit to which transfer is requested; transmitting a transmission inhibit signal through the first
channel from the parent communication unit to inhibit the signal transmission from the first slave communication unit after the transfer request signal is received; transmitting a transfer request receipt signal through a second channel from the parent
communicatioin unit to a second slave communication unit; transmitting an answer signal through the second channel from the second slave communication unit in response to receipt of the transfer request receipt signal; making a channel change to the
first channel for the second slave communication unit; transmitting a called-person's answer signal through the first channel when the second slave communication unit makes a called-person's answer; transmitting a conversation start signal through the
first channedl from the parent communication unit to the first and second slave communication units; making conversation through the first channel from the first slave communication unit to the second slave communication unit in response to receipt of
the conversation start signal; transmitting a conversation end signal through the first channel from the first slave communication unit; and making a channel change to the second channel for the first slave communication unit.
In another aspect of the invention, a method is provided for radio communication between at least one parent communication unit and a plurality of slave communication units. The method comprises the steps of: transmitting a transfer request
signal through a first channel from a first slave communication unit, the transfer request signal including information specifying a slave communication unit to which transfer is requested; transmitting a transmission inhibit signal through the first
channel to inhibit the signal transmission from the first slave communication unit after the transfer request signal is received; transmitting a transfer request receipt signal through a second channel from the parent cmmunication unit to a second slave
communication unit; transmitting an answer signal through the second channel from the second slave communication unit in response to receipt of the transfer request receipt signal; making a channel change to the first channel for the second slave
communication unit; transmitting a non-modulated carrier through the first channel from the second slave communication unit; transmitting a hold release signal through the first channel when the first slave communication unit releases its hold condition;
transmitting an interference indication signal through the first channel when the parent communication unit detects interference between the non-modulated carrier and the hold release signal; re-transmitting the hold release signal through the first
channel from the first slave communication unit in response to receipt of the interference indication signal; transmitting a conversation end signal in response to receipt of the re-transmitted hold release signal; and making a channel change to the
second channel for the second slave communication unit.
In another aspect of the invention, a method is provided for radio communication between at least one parent communication unit and a plurality of slave communication units. The method comprises the steps of: transmitting a transfer request
signal through a first channel from a first slave communication unit, the transfer request signal including information specifying a slave communication unit to which transfer is requested; transmitting a slave communication unit specifying signal
through the first channel from the parent communication unit in response to receipt of the transfer request signal, the slave communication unit specifying signal specifying a second slave communication unit as the slave communication unit to which
transfer is requested; making conversation through the first channel from the first slave communication unit to the second slave communication unit in response to receipt of the slave communication unit specifying signal; transmitting a called-person's
answer signal when a called-person's answer is made by the second slave communication unit; transmitting an interference indication signal from the parent communication unit when interference is detected between a voice signal transmitted from the first
slave communication unit and the called-person's answer signal transmitted from the second slave communication unit; transmitting a conversation end signal through the first channel from the first slave communication unit; and terminating the signal
transmission from the first slave communication unit in response to receipt of the interference indication signal.
In another aspect of the invention, a multi-channel access type of cordless telephone system is provided for radio communication between a plurality of slave telephone units and a plurality of outside lines. The system comprises a control
station including a plurality of parent communication units for communication with the slave communication units, and another parent communication for scanning channels assigned for conversation to search an available channel and/or controlling the slave
communication units through a control channel to permit radio communication.
In another aspect of the invention, a method utilizing a plurality of communication channels is provided for radio communication between a plurality of communication units. The method comprises the steps of: providing a plurality of control
channels for controlling the communication channels; and changing the control channels in a predetermined sequence.
In another aspect of the invention, a radio communication system is provided. The system comprises means for inputting a voice signal having a frequency band, means for producing predetermined speech quality monitoring data monopolizing a
frequency band except for the frequency band of the voice signal, means for frequency-multiplex transmitting the voice signal and the predetermined speech quality monitoring data, means for receiving the frequency-multiplex transmitted voice signal and
speech quality monitoring data, means for separating the frequency-multiplex transmitted speech quality monitoring data from the frequency-multiplex transmitted voice signal, and means for detecting the speech quality based upon a comparison of the
separated speech quality monitoring data with the predetermined speech quality monitoring data.
In another aspect of the invention, there is provided a method utilizing a plurality of channels for radio communication between a plurality of parent communication units and a plurality of slave communication units. The method comprises the
steps of: transmitting a communication channel specifying signal through a first communication channel from one of the parent communication units, the communication channel specifying signal specifying the first communication channel; making a channel
change to the first communication channel for available ones of the slave communication units in response to receipt of the communication channel specifying signal; transmitting a call signal through the first communication channel from a parent
communication unit to which the first communication channel is assigned, the call signal including information indicating an outside line through which an incomming call is transmitted; transmitting a called-person's answer signal through the first
communication channel when a called-person's answer is made by one of the slave communication units to which the first communication channel is assigned, the called-person's answer signal including information indicating the one slave communication unit;
transmitting a slave communication unit specifying signal through the first communication channel from the one parent communication unit in response to receipt of the called-person's answer signal, the slave communication unit specifying signal
specifying a slave communication unit communicable with the one parent communication unit; transmitting a channel specifying signal through the first communication channel from the one parent communication unit in response to receipt of the
called-person's answer signal, the channel specifying signal specifying a channel except for the first communication channel; and making a channel change from the first communication channel to the channel specified by the channel specifying signal for
the slave communicatin units except for the slave communication unit specified by the slave communication unit specifying signal.
BRIEF DESCRIPTION OF THE DRAWINGS
This invention will be described in greater detail by reference to the following description taken in connection with the accompanying drawings, in which like numerals identify like elements in the several figures and in which:
FIG. 1 is a schematic block diagram showing one embodiment of a cordless telephone system made in accordance with the invention;
FIG. 2 is a block diagram showing the detailed arrangement of each of the parent telephone units used in the cordless telephone system;
FIG. 3 is a block diagram showing the detailed arrangement of each of the slave telephone units used in the cordless telephone system;
FIG. 4 is a plan view of the control panel provided for each of the slave telephone units;
FIG. 5 is a flow diagram illustrating the programming of the digital computer included in the control station of the cordless telephone system;
FIG. 6 is a flow diagram illustrating the programming of the digital computer included in each of the slave telephone units of the cordless telephone system;
FIG. 7 is a diagram used in explaining the operation of the cordless telephone system of the invention where one of the slave telephone units transmits a called-person's answer signal at a time earlier than the representative slave telephone
unit;
FIGS. 8A and 8C are flow diagrams illustrating the programming of the digital computer included in the control station;
FIGS. 9A to 9C are flow diagrams illustrating the programming of the digital computer included in each of the slave telephone units;
FIG. 10 is a diagram used in explaining the operation of the cordless telephone system;
FIGS. 11, 12 and 13 are diagrams used in explaining the transfer operation of the cordless telephone system of FIG. 1;
FIG. 14 is a diagram used in explaining the operation of the cordless telephone system employing a plurality of control channels;
FIG. 15 is a flow diagram used in explaining the control channel monitoring operation of the slave telephone units; and
FIG. 16 is a flow diagram used in explaining the operation of the cordless telephone system.
DETAILED DESCRIPTION OF THE INVENTION
With reference to the drawings, wherein like numerals refer to like parts in the several views, and in particular to FIG. 1, there is shown a schematic diagram of a cordless telephone system embodying the invention. The cordless telephone system
includes a parent station 100 and a group 200 including a number n of slave telephone units (STU) S1, S2, . . . Sn. The control station 100 comprises an interface section 101, a switching circuit 102, a control circuit 103, and a control section 104.
The parent station 100 also comprises a group 105 including a number m of parent telephone units (PTU) P1, P2, . . . Pm, an available channel detection unit 106, a control unit 107, and a tone generator circuit 108.
The available channel detector unit 106 scans the available channels and the control unit 107 permits communication with the slave telephone units Sl, S2, . . . Sn through control channels. Normally, these functions of the units 106 and 107 are
performed in each of the parent telephone units. It is noted, therefore, that the units 106 and 107, which are substantially the same in structure as the parent telephone units, may be referred to as parent telephone units. In addition, the units 106
and 107 may be removed from the parent station 100. The tone generator circuit 108 produces dial-tone, busy-tone and ring-tone signals to the parent telephone units P1, P2, . . . Pm, 106 and 107.
The control section 104 employs a digital computer to have a stored program control. The control section 104 communicates with the rest of the control station 100 via data bus 109. The control section 104 receives information from the parent
telephone units P1, P2, . . . Pm, 106 and 107 and controls the switching circuit 102 through the control circuit 103. The control circuit 103 operates on command from the control section 104 to cause the switching circuit 102 to select an available
channel connected to the corresponding one of the parent telephone units P1, P2, . . . Pm. The interface section 101 operates on command from the control section 104 to connect the selected channel through one of the outside lines 1, 2, . . . 1 to the
private branch exchange (PBX) station or the telephone network.
Referring to FIG. 2, each of the parent telephone units P1, P2, . . . Pm includes a handset 111 which is shown as including a microphone 112 and a speaker 113 for voice audio. The video audio from the microphone 112 is amplified or attenuated
by the microphone amplifier 114. The amplified or attenuated signal is applied from the microphone amplifier 114 through a bandpass filter 126 and an adder 127 to an FM modulator 115 where it is FM modulated. The FM modulated signal is applied from the
FM modulator 115 to a transmitter 116, and thereafter to an aerial 118 through an antenna coupler 117. The radio signal thus transmitted arrives at the slave telephone units S1, S2, . . . Sn. A radio signal transmitted from a slave telephone unit is
received through the antenna coupler 117 by a receiver 119. The received signal is applied from the receiver 119 to an FM demodulator 120 where it is FM demodulated. The FM demodulated signal is applied from the FM demodulator 120 through a bandpass
filter 129 to a speaker-amplifier 121 where it is amplified and is thereafter transmitted to the speaker 113.
The parent telephone unit also includes a control circuit 124 employing a digital computer to have a stored program control. The control circuit 124 receives information from the signal receipt line and controls the signal transmission line.
For this purpose, the control circuit 124 receives a carrier detection signal indicative of the presence of conversation on this telephone line from the receiver 119, an automatic answer signal or a called-person's answer signal from the FM demodulator
120, and a speed quality monitor signal through a low pass filter 130 from the FM demodulator 120. The control circuit 124 also receives an interference detection signal from an interference detection circuit 123 when interference occurs. The
interference detection circuit 123 is arranged in the connection from the receiver 119 to the control circuit 124 for producing the interference detection signal indicative of the presence of interference of radio signals transmitted from a plurality of
slave telephone units. The control circuit 124 has functions of controlling the gain of the microphone amplifier 114, producing a call signal and an interference detection signal to the FM modulator 115, producing a speech quality control signal through
a low pass filter 128 to the adder 127, and turning on and off the transmitter 116. In addition, the control circuit 124 specifies a frequency used in the communication and produces a frequency command signal to cause a frequency synthesizer 122 to
control the FM modulator 115 in such a manner as to make the communication at a frequency specified by the control circuit 124. It is to be noted that the components 127, 128 and 130 used in controlling the speech quality are optional.
FIG. 3 illustrates the detailed arrangement of each of the slave telephone units S1, S2, . . . Sn. The arrangement of FIG. 3 utilizes a number of the components previously described, and like reference numerals in FIG. 3 indicate like parts as
described with reference to FIG. 2. The chief difference between the parent and slave telephone units is that the interference detection circuit 123 is removed and a control panel 125 communicates with the control circuit 124.
Referring to FIG. 4, the control panel 125 is shown as including four busy indicators 201 to 204. Each of the busy indicators 201 to 204 will come on when the corresponding telephone line is held and will come on and off when the corresponding
telephone line is busy. The control panel 125 also includes an outside line pushbutton 205, and extension pushbutton 206, a hold pushbutton 207, a channel switch pushbutton 208, a hook pushbutton 209, a hold answer pushbutton 210, and a keyboard 211.
The keyboard 211 includes pushbuttons used to enter a desired telephone number. The outside line pushbutton 205, labeled "OUT" is pushed to transmit a call to an outside line or to answer to a call from an outside line. The extension pushbutton 206,
labeled "EXT" is used to transmit a call to another slave telephone unit or to answer to a call from another slave telephone unit. The hold pushbutton 207, labeled "HOLD" is used to temporarily hold the conversation through an outside line. The channel
switch pushbutton 208, labeled "CH-SW" is used to select another channel when interference occurs. The hook pushbutton 209, labeled "HOOK" is used to temporarily hook the telephone line. The hold answer pushbutton 209, labeled "H-AND" is used to answer
to the held outside line while pushing dial buttons of the keyboard 211 corresponding to the number of the outside line. Each of the pushbuttons 205 to 210 contains a light which comes on when the corresponding pushbutton is pushed. When the
conversation continues, a light 213 comes on. An end pushbutton 212, labeled "END" is used to terminate the conversation.
FIG. 5 is a flow diagram illustrating the programming of the digital computer 124 included in each of the parent telephone units P1, P2, . . . Pm as it is used to control the corresponding parent telephone unit for transmitting a call to the
slave telephone units S1, S2, . . . Sn. It is now assumed that each of the parent telephone units includes the functions of the available channel detection unit 106 and the control unit 107 and that the first slave telephone unit S1 is a representative
slave telephone unit.
The computer program is entered at the point 502. At the point 504 in the program, a call signal is transmitted to call one of the slave telephone units. For this purpose, the digital computer 124 searches for an available channel, selects a
carrier frequency corresponding to the found available channel for the modulator 115, and causes the transmitter 116 to transmit the modulated call signal through the antenna coupler 117 to the aerial 118.
At the point 506 in the program, a determination is made as to whether or not the parent telephone unit receives an automatic answer signal from the representative slave telephone unit S1. The representative slave telephone unit S1 is arranged
to automatically transmit an answer signal when it receives a call signal transmitted from the parent telephone unit. If the answer to this question is "no", the program returns to the point 506. This operation is repeated until the answer to this
question is changed to "yes".
At the point 508 in the program, another determination is made as to whether or not interference occurs. To make this determination, the digital computer 124 employs the interference detection signal fed from the interference detection circuit
123. If the answer to this question is "yes", then it means that at least one of the handsets 111 of the slave telephone units S2, S3, . . . Sn is in the off-hook position causing transmission of a called-person's answer signal from the corresponding
slave telephone unit (in this case S2) and this called-person's answer signal interferes with the automatic answer signal automatically transmitted from the representative slave telephone unit S1, and the program proceeds to the point 510. At the point
510, an interference indication signal is produced and transmitted from the parent telephone unit to the slave telephone unit S2. The slave telephone unit S2 responds to the interference indication signal transmitted from the parent telephone unit
automatically by interrupting the transmission of the called-person's answer signal in order to avoid the interference. Similarly, the representative slave telephon | | |
