JP3116313B2 - Adjacent channel interference prevention method for cordless telephones, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing interference from adjacent channels in a cordless telephone or the like.

[0002]

2. Description of the Related Art In a cordless telephone or the like, an ID code (identification code) is assigned to each transmission / reception set.
When starting wireless communication, the ID code is collated between the transmitter and the receiver, and communication can be started only when the ID codes match. Also, first, the ID code is collated using the control channel, but after switching to the next communication channel, it is determined that the correspondence between the transmitter and the receiver is correct, and the ID code is not exchanged. That is, whether or not a transmitter and a receiver belong to the same set has not conventionally been regarded as a problem once a call is started.

[0003]

However, even during a call, a sub signal (for example, data for instructing call hold, data for instructing call termination, etc.) is superimposed on a main signal (a voice signal in a cordless telephone). May be sent,
In this case, since there is no ID code collation step in the exchange of the data (sub-signal), if another nearby transmission / reception set is using the adjacent communication channel, the transmission from the other set is not performed. When the end call data or the like is received by the own set that is currently in use, a trouble may occur in which the call is suddenly cut off even though the user does not press the end button.

Therefore, it is easily considered that an ID code is added before or after the sub signal to be transmitted during a call,
This ID code is collated between the transmitting side and the receiving side in the same manner as at the time of starting the call. However, the above causes another inconvenience as follows.

That is, since the above-mentioned sub-signal is superimposed on the main signal (voice data), noise such as "gagging" is emitted from a speaker (receiver) at the time of transmission, which causes discomfort to the user. At the time of transmitting the control data, a measure to mute the sound is always performed, and there is a problem that the longer the data length of the sub-signal, the longer the mute time of the sound. During muting, of course, voice calls cannot be made. The ID code is usually 25 bits.

Therefore, according to the present invention, the control data can be provided with the discriminability indicating its own set without unnecessarily extending the mute time, and the control data is reliably transmitted and received only between the transceivers of the same set. It seeks to provide a way.

[0007]

According to the method of the present invention, which solves the above-mentioned problem, a control signal is transmitted from a transmitting side to a receiving side while a voice signal is being transmitted from the transmitting side to the receiving side. In a cordless telephone that superimposes the signal on the audio signal and superimposes the control signal on the audio mute, the transmitting side matches the number of bits of the ID code of the transmitter itself with the number of bits of the control signal on the transmitting side. Encoding by exclusive OR operation of the same number of bits by using the same, the receiving side uses the received control signal by making the number of bits of the ID code of the receiver itself the same as the number of bits of the control signal. This is a method of decoding by exclusive OR operation of the same number of bits.

[0008]

FIG. 1 shows an example of a schematic configuration of a cordless telephone for carrying out the method of the present invention. This telephone comprises a paired master unit (1) and a slave unit (2), and the master unit (1) is connected to a line (4) via an NCU (3). The master unit (1) controls the connection with the NCU (3) or the slave unit (2), which is a connection device to the line (4).
PU (5), transmitting circuit (6), receiving circuit (7), transmitting / receiving antenna
(8), composed of a synthesizer (not shown) and the like. Cordless handset
(2) is a CPU (9) for controlling connection with the master unit (1), a key switch (10) for giving an operation instruction, a transmitting circuit (11), a receiving circuit
(12), a transmitting / receiving antenna (13), a synthesizer (not shown), and the like. The master unit (1) and the slave unit (2) have an identification number (ID code) to prevent erroneous connection on the control channel when a connection operation is performed from the slave unit (2) or the master unit (1). After confirming and confirming each other, the communication state is established on a predetermined available communication channel, and furthermore, a dialing to an outside line and / or input of a personal identification number or the like allows connection with the communication terminal apparatus of the other party through the line (4). .

After a communication line with an outside line is established,
When transmitting control data (for example, a hold instruction) as a sub signal, a signal is generated in a predetermined format shown in FIG. 2 for each data. That is, in this embodiment, 16
It is composed of a bit synchronization signal (14) of bits, a frame synchronization signal (16) of 16 bits, a data signal (16) of 25 bits indicating data content, and a parity signal (17) of 12 bits. Note that a 3-bit dummy signal may be added after the parity signal.

The data signal (16) is transmitted to a transmission circuit.
Before being sent to (6), according to the present invention, the ID code of the set and XOR (exclusive OR) are calculated in the CPU (5), and the bit synchronization signal (Xa) is obtained after being processed data (16a). 14), a frame synchronization signal (15), and a parity signal (17) are set and transmitted (S) through the transmission circuit (6).
(FIG. 2).

FIG. 3A shows an example of the above calculation. In this example, the data signal is “0100...” And the ID code signal is “100101. The exclusive OR of both signals is “110101...” At the bottom. In this example, the ID code signal is also 25 bits.

The control data received by the slave unit (2) is taken into the CPU (9) via the receiving circuit (12), and
In U (9), XOR is calculated again using the ID code signal. FIG. 3B shows an example of the calculation on the receiving side. That is, the upper row “110101...” Is the received processed data, the lower row “100101...” Is the ID code, and the lowermost row “01000. It is. As a matter of course, the control data returns to the control data before processing.

Here, if the ID code used for the logical operation on the transmitting side (master unit or slave unit) and the ID code used on the receiving side (slave unit or master unit) are different (that is, if the ID code is different from the transmitting side). When the set is not the same as that on the receiving side), the data whose processing has been canceled is random data having no context with the control data before processing.

Then, the control data whose processing has been canceled is compared with several types of control data stored in advance in the CPU (9) on the receiving side, and if it matches one of them, the control data is followed. (For example, hold or end the call)
If they do not match, an error occurs, and the control data is not accepted.

FIG. 4 is a flowchart showing the transmission and reception steps. FIG. 4A shows a transmission step. When any key switch is pressed during a call (S-1) (S-2), a code corresponding to the switch is read from the CPU 9 (S-3). ), XOR operation of the control code and the ID code of the transmitter is performed.
(S-4). Then, the processed data signal is transmitted together with the bit synchronization signal and the like (S-5).

FIG. 4B shows a reception step. When control data is received during reception (S-6), the control data is XORed using the ID code of the receiver (S-7). Then, the operation result data is compared with the data table in the CPU (5) to check whether there is any different control data within one bit, and if only one bit is different, the bit is corrected and corrected. The operation according to the control data is performed (S-8), and if there is a difference of 2 bits or more, an error is made (S-11). Judgment result (S-
9) If the data is legitimate data, the operation is performed (S-10).

In the above example, the length of the control data signal (25 bits) and the length of the ID code (25 bits) are the same. However, if the length of the control data signal is different from the length of the ID code. In this case, a part of the ID code can be used, or a part of the ID code can be used repeatedly. In the above example, the lower (or upper) ID code of the ID code is also used for the 12-bit parity signal (17).
Using the 12 bits, the XOR may be calculated on the transmitting side to process the data, and the XOR may be calculated on the receiving side to cancel the processing. According to the above, even if the ID code is a set having a difference of 1 bit, the C code on the receiving side can be set.
When an error check is performed in the PU, it is detected as an error of 2 bits or more.
S-10), adjacent interference can be more reliably prevented. further,
If exclusive OR is used as a logical operation, the operator sends,
Although there is an advantage that only one reception is required, it goes without saying that another logical operation may be used.

Although the above embodiment has been described using a cordless telephone, the main signal is a voice signal, but the main signal is not limited to this. That is, the present invention can be applied to various cordless telephones in which the main signal is an image signal (for example, fax, television still image, television moving image) or computer data.

[0019]

As described above, according to the method of the present invention, the ID code to be multiplied (performed by logical operation) is set to the same number of bits as the control signal, so that unpleasant noise accompanying the transmission of the control signal during a telephone call is obtained. Without unnecessarily extending the mute time (control signal superposition period) for reducing
Control signals can be transmitted and received between the same set. In addition, since the transmission and reception of the control signal is performed by encoding and decoding with the ID code of the transmitter or the receiver itself, the control signal can be reliably transmitted and received only between the same sets. A trouble such as causing an erroneous operation due to the influence of the above does not occur.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cordless telephone that implements the method of the present invention.

FIG. 2 is a diagram showing a format of a sub signal at the time of transmission / reception.

FIG. 3 is an explanatory diagram showing an example of a logical operation.

FIG. 4 is a flowchart showing respective steps on a transmitting side and a receiving side.

[Explanation of symbols]

 (1) Master unit (2) Slave unit (5) CPU (9) CPU (16) Data signal (16a) Processing data signal

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04M 1/00 H04M 1/24-1/258 H04M 1/58-1/62 H04M 1/66-1/82

Claims (1)

(57) [Claims] When a control signal is transmitted from a transmitting side to a receiving side while an audio signal is being transmitted from a transmitting side to a receiving side, the control signal is superimposed on the audio signal and a superimposing period of the control signal is provided. In a cordless telephone that mutes the audio, the transmitting side uses the control signal with the number of bits of the ID code of the transmitter itself matched with the number of bits of the control signal, thereby exclusion of the same number of bits.
Encoding by logical OR operation, the receiving side converts the received control signal to the number of bits of the ID code of the receiver itself,
A method for preventing adjacent channel interference in a cordless telephone, wherein decoding is performed by exclusive OR operation of the same number of bits by using the same number of bits of a control signal.