JP3213544B2 - Analog cordless telephone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an analog cordless telephone.

[0002]

2. Description of the Related Art In an analog cordless telephone,
When receiving an incoming call from outside, or when requesting a call from the slave unit to the master unit,
When necessary information must be exchanged between the master unit and the slave unit, a control signal of a predetermined format is wirelessly exchanged. For example, the master unit transmits a control signal notifying the incoming call to the slave unit when an incoming call is received from the outside, and receives a control signal from the slave unit when receiving a call request from the slave unit and receives the control signal from the slave unit. Make a connection with
Processing such as transmitting a control signal indicating the result is performed. Also, in the slave unit, when a call request from the slave unit, in addition to transmitting a control signal notifying the call request to the base unit,
When an incoming call is received from the outside, processing such as receiving a control signal transmitted from the base unit and transmitting a control signal indicating that communication is possible to the base unit is performed.

FIG. 3 is a diagram showing an example of a format of a control signal. The control signals shown in FIG.
Includes security code, channel code, control code, etc. A group of these data is hereinafter referred to as “one frame”. However, the parts of “data pre-processing” and “data post-processing” in the figure are not included in one frame. Here, the header is a code representing a control signal, and 16 bits are allocated. In this example, a binary 16-bit code representing “9336” is used.
STD-13 (Radio System Development Center)
Its use is recommended by the standard.

[0004] The security code is a code determined in advance between a pair of a master unit and a slave unit, and is used to identify whether or not the control code is a control signal from the master unit or the slave unit corresponding to the own unit. Used. The channel code is a code indicating the frequency of a carrier wave used for communication between the master unit and the slave unit, and the control code is information exchanged by a control signal such as an incoming call from outside or a call request. Is a code representing the type of

[0005] When the reception of the header is detected in the slave unit, the control unit of the slave unit mutes (hereinafter referred to as "RXMUTE") to prevent leakage of data noise from the speaker. Specifically, in the process of demodulating and amplifying the received signal, control is performed so that amplification is not performed, so that sound is not output from the speaker. This is because the voice signal and the control signal during a call use the same channel, and if the control signal is demodulated and amplified as it is and output from the speaker, large noise will result. After that, the security code is sequentially checked, and if all are present, RXMUTE is continuously applied for one frame, and if the security code is incorrect, RXMUTE is released at that point. Similarly, a mute is used in the master unit. The mute in this case is for preventing data noise leakage from the transmitted voice to the other party via the line.

The operation of muting will be further described with the slave unit as a representative. The control unit of the slave unit first needs to determine whether or not the header has been received. However, since the control signal is sent as pulse data as shown in FIG. It must be determined whether the signal represents data. Here, since 16 bits are represented by a 16-millisecond signal in the header, the control unit of the slave unit determines whether the signal having the same logical value is transmitted depending on how many milliseconds the signal representing the same logical value is transmitted. It is necessary to determine how many bits are represented.

A software timer is used for measuring the pulse width. Specifically, when the reception signal changes from low level to high level, and when it changes from high level to low level, by generating an interrupt,
The software timer is started, and when the next interrupt occurs, the value of the counter incremented by the software timer is taken out and the pulse width is measured. By comparing the measured pulse width with a predetermined threshold value, it is determined how many bits of data the pulse width of the received signal represents.

In the conventional analog cordless telephone, in determining the data at this time, a variation due to hardware and a variation in pulse width due to a flight distance or the like are taken into consideration.
The threshold value for identifying whether the data is data for two bits or two bits is set to 1.5 milliseconds. That is, if the pulse width is 0.5 to 1.5 milliseconds, 1 millisecond, that is, 1 bit of data is recognized, and if the pulse width is 1.5 to 2.5 milliseconds, 2 milliseconds; That is, it was recognized as data of 2 bits. FIG. 4 shows the timing of RXMUTE when a regular header is received.

[0009]

By the way, 1.5 milliseconds, which is a threshold value for discriminating between 1-bit data and 2-bit data, is approximately equivalent to a frequency. 333 Hz. In an analog cordless telephone, a receivable frequency band is often set to about 300 Hz to 3.4 KHz in accordance with a voice band, but in the above-described conventional analog cordless telephone, the frequency is about 333 Hz (the audio When a signal that is within the range of a band is continuously received, a micro control unit (hereinafter, “MC”) that measures the reception time
U ") is erroneously determined to have been received due to a measurement error. More specifically, as shown in FIG.
If it is necessary to generate an interrupt at the time point B and measure the pulse width, but at the time point A an interrupt having a higher priority than the processing related to the activation of the software timer occurs, the activation of the software timer starts. Are delayed, and the timing of the measurement start is shifted to the point of A '. On the other hand, since the priority of the increment processing of the counter of the software timer is usually given to the highest priority, the deviation of the activation timing of the software timer directly leads to a pulse width measurement error. That is, when the signal between AB is slightly longer than 1.5 milliseconds, the pulse width between AB, which should be originally determined to be 2 bits of data, becomes shorter than the actual pulse width due to the delay of the measurement start. Since it is measured, it is erroneously determined that it represents one-bit data.

As a result, as shown in FIG.
When the signal of Hz is received continuously, for example, the portion indicated by A and B in the same figure is erroneously determined to be a signal of 1 bit, so that the received signal represents “9336”. , And an erroneous determination is made that the header has been received. If it is determined that the header has been received, the slave unit-side control unit performs RXMUTE, so that there is a problem that, in particular, if the event occurs during a call, the call may be adversely affected.

The present invention has been made in view of the above problems, and provides an analog cordless telephone which does not adversely affect a call due to erroneous determination of a pulse width even when a signal of the above-described frequency is continuously received. The purpose is to:

[0012]

In order to solve the above-mentioned problems, an analog cordless telephone according to the present invention transmits a digital control signal of a predetermined format between a parent and a child prior to or accompanying an analog call. In an analog cordless telephone that intersects, receiving means for receiving a digital control signal, measuring means for measuring the duration of the same logical value in the digital control signal, duration measured by the measuring means, and a plurality of times related to the duration Determining means for determining the bit length of the same logical value based on the predetermined threshold value, and when the determining means determines that the digital control signal has the predetermined bit length, thereafter, during a predetermined period of time. Over the plurality of predetermined threshold values, it is determined whether the predetermined threshold value is the predetermined bit length or a bit length one less than the predetermined bit length. And a threshold changing means for reducing the threshold.

In the above-mentioned analog cordless telephone, the predetermined bit length may be two.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a slave unit of the analog cordless telephone according to the present embodiment. The analog cordless telephone shown in the figure includes an antenna 101, a duplexer 102, a receiving unit 10
3, SP amplifier 104, speaker 105, control unit 10
6, an operation unit 107, a microphone 108, a switch 109, a transmission unit 110, a secondary battery 111, a regulator 112, and switches 113 and 114.

The control unit 106 controls the logical value judgment unit 10
61, bit length determination unit 1062, software timer 1
063, threshold holding section 1064, code determination section 106
5. Includes RXMUTE control unit 1066. Antenna 10
1 transmits and receives wireless signals. Duplexer 1
02 is used to share one antenna for transmission and reception.

The receiving section 103 includes an RF amplifier, a local oscillation circuit, a mixer, an IF amplifier, and a detector.
01 extracts the received data from the radio signal received,
It is sent to the P amplifier 104 and the control unit 106. Control unit 106
Is the analysis of the received control signal, the control of RXMUTE, etc.
Controls the entire slave unit. Specifically, a microcomputer such as "LC66 series" manufactured by Sanyo Electric Co., Ltd. can be used.

The logical value determining unit 1061 determines whether the received signal received from the receiving unit 103 is a signal representing a logical value “0” (low level) or a signal representing a logical value “1” (high level). Is determined. The bit length determination unit 1062 calculates
Upon receiving the determination by the logical value determining unit 1061, the receiving unit 10
3 to determine how many bits of the determined logical value the signal represents. Specifically, as described above, when the logical value represented by the received signal changes from a low level to a high level and when the logical value changes from a high level to a low level, the software timer 1063 is started by hardware-based interrupt processing. Then, the pulse width is measured by the interrupt processing due to the next change in the logical value, and the software timer 1063 is restarted.

The bit length determination unit 1062 compares the measured pulse width with the threshold value held in the threshold value holding unit 1064, so that the received signal represents the number of bits of the logical value. Is determined. The judgment result is
The data is sequentially sent to the code determination unit 1065 and stored in the buffer. In addition, the bit length determination unit 1062 switches the threshold value held in the threshold value holding unit 1064 as necessary. Switching of the threshold value will be described later in detail.

The code determination unit 1065 sequentially stores the determination results sent from the threshold value holding unit 1064 in a buffer, and determines whether or not the header is a predetermined header. If it is determined that the header has been received, RX
RXMUTE is instructed to the MUTE control unit 1066. R
The XMUTE control unit 1066 controls RXMUTE according to the instruction of the code determination unit 1065. In particular,
When the reception of the header is recognized by the code determination unit 1065, control is performed to apply RXMUTE to the SP amplifier 104, and output of sound from the speaker 105 is stopped. If the security code does not match after that, RXMUTE is released at that point,
If the security codes also match, RXMUTE continues to be applied over one frame.

The transmitting section 110 includes a local oscillator circuit and an RF amplifier, modulates and amplifies the control signal generated by the control section 106 and the audio signal input from the microphone 108, and outputs the modulated signal from the antenna 101. Next, processing contents of the control unit 106 in the analog cordless telephone according to the present embodiment will be described. FIG. 2 is a flowchart showing the detailed processing contents of the control unit 106.

The control section 106 first measures the pulse width of the received signal sent from the receiving section 103 (S20).
1). Specifically, the logical value determination unit 1061 determines whether the received signal is at a low level or a high level, and based on the determination, the bit length determination unit 1062 determines
An on-edge (when the signal changes from low level to high level) and an off-edge (when the signal changes from high level to low level) of the received signal are detected. Further, as described above, when an on-edge or an off-edge is detected, an interrupt process is generated and the software timer 1 is activated.
The pulse width measured at 063 is measured, the contents of the software timer 1063 are cleared, and the processing is restarted.

Next, the bit length determination unit 1062 refers to the threshold value holding unit 1064 and determines that the threshold value for determining 1 ms data and 2 ms data is 1.35 ms. It is determined whether or not there is (S202). If the threshold value is not 1.35 milliseconds (S202: No), it is determined whether the pulse width is 0.5 to 1.5 milliseconds (S203), and the pulse width is 0.5 to 1.5 milliseconds. If the signal is 1.5 ms, the signal is recognized as a 1 ms signal (S204), the data is stored in a buffer provided in the code determination unit 1065 (S205), and the processing of the control unit 106 ends. I do. In this way, the determination result is sequentially stored in the buffer, and the header recognition is performed by sequentially determining the storage result for every 8 bits.

On the other hand, if the pulse width is not 0.5 to 1.5 milliseconds in step S203, it is next determined whether or not the pulse width is 1.5 to 2.5 milliseconds. (S206) If the pulse width is 1.5 to 2.5 milliseconds, the signal is recognized as a 2 millisecond signal (S207), and the threshold for pulse width measurement is changed to 1.35 milliseconds. (S2
08), the data is stored in the buffer (S205), and the processing of the control unit 106 ends.

In step S206, if the pulse width is not 1.5 to 2.5 milliseconds, it is determined that the received signal is noise (S209), and the processing of the control unit 106 ends. When it is determined in step S202 that the threshold value of the pulse width is 1.35 milliseconds,
This means that it is determined that a signal of 2 milliseconds has already been received. In this case, bit length determination section 1062
Determines whether the pulse width is 0.5 to 1.35 milliseconds (S210). If it is determined that the pulse width is 0.5 to 1.35 milliseconds, the received signal is recognized as a 1 millisecond signal (S211), the data is stored in a buffer (S212), and " It is determined whether or not a signal representing "9336" has been received (S213). More specifically, if the first 8 bits of data stored in the buffer are data representing “93”, and if the next 8 bits are a signal representing “36”, a signal representing “9336” Is determined to have been received.

When the input of the signal “9336” is recognized (S213: Yes), it is recognized that the header has been received, and the RXMUTE control unit 1066 instructs the RXMUTE control unit 1066 to perform RXMU.
An instruction to apply TE is sent (S214). further,
The threshold value of the pulse width is changed from 1.35 milliseconds to 1.5 milliseconds (S215), and the process of the control unit 106 ends.

In step S210, the pulse width is set to 0.
If it is determined that the pulse width is not 5 to 1.35 milliseconds, it is determined whether the pulse width is 1.35 to 2.5 milliseconds (S216), and the pulse width is 1.35 to 2.5. In the case of milliseconds, it is recognized that a signal of 2 milliseconds has been received (S21).
7), proceed to step S212. If it is determined in step S216 that the pulse width is not 1.35 to 2.5 milliseconds, the received signal is determined to be noise (S218), and the threshold of the pulse width is set to 1.35 milliseconds. Is changed to 1.5 milliseconds (S215), and the control unit 106
Is completed.

As described above, when the reception of the signal of 2 milliseconds is detected, the threshold value for determining whether the signal is a signal of 1 millisecond or a signal of 2 milliseconds is set to 1.5 milliseconds. From 1.
By changing it to 35 milliseconds, even if the interrupt for instructing the software timer to start measuring the bit width is delayed by an interrupt with a higher priority, 2
The signal representing the data for one bit is not erroneously determined to be the signal representing the data for one bit. When the header is “9336”, the call to the telephone call due to the occurrence of RXMUTE due to the erroneous detection of the header is prevented. This has the effect that adverse effects can be prevented.

In this embodiment, the header is "9
336 "has been described in detail, but even if a problem occurs using another header, the cause is a delay in the start of measurement of the software timer due to the occurrence of a higher priority process such as an interrupt. , It can be easily applied. In the present embodiment,
Although the application example of the analog cordless telephone to the slave unit has been described in detail, the analog cordless telephone may be applied to the master unit. In this case, mute is applied to transmission of the transmission voice to the other party via the line, but the detection of the header is exactly the same, and the control unit of the master unit is provided with the respective components of the control unit 106 of FIG. What is necessary is just to have the structure provided with.

[0029]

As is apparent from the above description, the analog cordless telephone according to the present invention is an analog cordless telephone which wirelessly exchanges a digital control signal of a predetermined format between a parent and a child prior to or accompanying an analog call. In a telephone, receiving means for receiving a digital control signal, measuring means for measuring the duration of the same logical value in the digital control signal, duration measured by the measuring means, and a plurality of predetermined thresholds related to the duration A determination unit that determines the bit length of the same logical value based on the above, if the determination unit determines that the digital control signal has a predetermined bit length, then, over a predetermined period, Out of the predetermined threshold values, the threshold value for determining whether the bit length is the predetermined bit length or the bit length one less than the predetermined bit length is reduced. And a Kusuru threshold change means.

When the determining means determines that the digital control signal has a predetermined bit length, the threshold changing means changes the threshold value of the plurality of predetermined threshold values for a predetermined period thereafter. By reducing the threshold value for determining whether the bit length is the predetermined bit length or one less than the bit length, the software timer for measuring the pulse width of the received signal has a smaller bit length. Even if the interrupt for instructing the start of the width measurement is delayed due to the occurrence of an interrupt having a higher priority, there is an effect that a two-bit signal is not erroneously determined to be a one-bit signal. As a result, even if successive identical voice frequencies in a call are similar to the control signal, it is not erroneously determined that the header of the control signal has been received.
It is possible to prevent the UTE from adversely affecting the call.
Specifically, it is possible to prevent the adverse effect that the received voice is intermittent when applied to the child device, and to prevent the adverse effect that the transmitted voice from the line to the other party is intermittent when applied to the parent device. . .

In the above-mentioned analog cordless telephone, the predetermined bit length can be two. Setting the predetermined bit length to 2 has the effect of preventing erroneous determination of data when "9336" is used as the header.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an analog cordless telephone according to an embodiment of the present invention.

FIG. 2 is a flowchart showing processing contents of a control unit of the analog cordless telephone according to one embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a format of a control signal.

FIG. 4 is a diagram for explaining data determination when a regular header is received.

FIG. 5 is a diagram for explaining a pulse width measurement error by an MCU.

FIG. 6 is a diagram for explaining erroneous data determination when a signal having a frequency of 333 Hz is continuously received in a conventional analog cordless telephone.

[Explanation of symbols]

 101 antenna 102 duplexer 103 receiving unit 104 SP amplifier 105 speaker 106 control unit 107 operating unit 108 microphone 109 switch 110 transmitting unit 111 secondary battery 112 regulator 113 switch 114 switch 1061 logical value determining unit 1062 bit length determining unit 1063 software timer 1064 Threshold value holding unit 1065 Code judgment unit 1066 RXMUTE control unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-162488 (JP, A) JP-A-6-104893 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 7/24-7/26 102 H04Q 7/00-7/38

Claims (2)

(57) [Claims] 1. An analog cordless telephone which wirelessly exchanges a digital control signal of a predetermined format between a parent and a child prior to or accompanying an analog call. Measuring means for measuring the duration of the logical value, and the duration measured by the measuring means, based on a plurality of predetermined thresholds for the duration, determining means for determining the bit length of the same logical value, When the determination unit determines that the same logical value has a predetermined bit length, thereafter, for a predetermined period, the predetermined bit length of the plurality of predetermined threshold values, An analog cordless telephone comprising: threshold changing means for reducing a threshold for determining whether the bit length is one less than the bit length. 2. The analog cordless telephone according to claim 1, wherein said predetermined bit length is two.