JPH0360233A - Synchronizing system for master/slave radio telephone sets - Google Patents

Abstract

PURPOSE:To simply preserve privacy by transmitting a synchronizing signal synchronizing with the frequency variation period of a transmission reception signal generated in a master machine to a subordinate machine from the transmitting part of the master machine together with communicated contents, and at the child machine, extracting the synchronizing signal from a reception signal, and executing the frequency variation of the transmission reception signal as synchronizing with this synchronizing signal. CONSTITUTION:The master machine shown in a figure is provided with receiving parts 10a to 10e of the same number as the number of the subordinate machines and transmitting parts 12a, 12b of the same number as or more than the number of connected telephone lines 11a, 11b. The synchronizing signal synchronizing with the frequency variation period of the transmission reception signal generated in the master machine is transmitted to the subordinary machine from the transmitting parts 12a, 12b of the master machine together with the communicated contents, and at the subordinate machine, the synchronizing signal is extracted from the reception signal, and the frequency variation of the transmission reception signal is executed as synchronizing with this synchronizing signal. Accordingly, each transmission frequency of the master machine and the subordinary machine is varied periodically as synchronizing with each other, and the synchronization of the frequency variation of both can be simply executed. Thus, the privacy can be preserved through simple configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a synchronization method for a wireless parent-child telephone, and more particularly, to a synchronization method for a wireless parent-child telephone that performs wireless communication between a base unit and a slave unit.

(Prior Art) There have conventionally been wireless parent-child telephones in which a parent device and a child device are connected wirelessly.

Conventional SaW child phones perform carrier sense to find unused frequencies from among multiple frequencies (channels), and use the unused frequencies as the base phone.

This is assigned as a transmission frequency to each handset, thereby allowing communication between the base unit and handsets while avoiding interference with other wireless telephones.

[Problem to be solved by the invention]

In the conventional wireless parent-child episode 1 above, after carrier sense, the parent device,
Since the transmission frequency of each handset is fixed and the content of the call is emitted as radio waves, the content of the call can be intercepted even by a general receiver, and there is a problem in that the confidentiality of the telephone conversation is impaired.

The present invention has been made in view of the above points, and is a Domei system for wireless parent-child telephones that can maintain confidentiality without leakage of calls due to interception, and allows easy synchronization of variable frequencies between the base unit and slave units. The purpose is to provide

[Means to solve the problem]

In the wireless parent-child telephone synchronization system of the present invention, the first frequency variable means makes the transmission frequency of the transmitting section and the reception frequency of the receiving section different from each other and periodically varies them.

The synchronization signal generation and transmission means generates a synchronization signal synchronized with the variable period of the transmission frequency and reception frequency of the base unit, and transmits it from the transmitter of the base unit to the slave unit.

The synchronization signal extraction means extracts a synchronization signal from the reception signal received by the receiver of the slave device.

The second frequency variable means varies the receiving frequency of the receiving section and the transmitting frequency of the transmitting section of the slave unit in synchronization with the synchronizing signal extracted by the synchronizing signal extracting means.

(Function) In the present invention, a synchronization signal synchronized with the variable frequency cycle of the transmitting/receiving signal generated by the base unit is transmitted from the transmission unit of the base unit to the slave unit along with the call content, and the slave unit extracts the synchronization signal from the received signal. In order to change the frequency of the transmitted and received signals in synchronization with this synchronization signal, the transmission frequencies of the base unit and slave unit are periodically varied in synchronization with each other, making it easy to synchronize the frequency changes of both units. Even if a general receiver can intercept the call for a very short time, the content of the call cannot be known, and confidentiality can be maintained.

〔Example〕

FIG. 1 shows a block diagram of an embodiment of a master device according to the present invention.

In the figure, the base unit has the same number of receiving units 10a to 10 as the number of slave units.
6 and the telephone line 11a to be connected.

The number of transmitters 12a and 12b greater than the number of transmitters 11b is provided.

The frequency switching signal generating section 15 is supplied with the clock generated by the clock generating section 16 and generates a frequency switching signal and a frequency switching synchronization signal for each of the receiving sections 10a to 10e and the transmitting sections 12a and 12b. The frequency switching synchronization signal is shown in Figure 2 (
As shown in A), for example, it is a pulse signal with a period of 1 second,
In synchronization with this, five phases are determined as shown by the low level in each of FIGS. The frequency switching signal generating section 15 transmits the frequency f in phase a to the receiving section 10a.
+ (e.g. 46.61 MH2), phase bt
- frequency f2 (e.g. 4B, 63 MH7), 7
AIDS C with frequency f3 (e.g. 46.67 MHz
> , in phase d the frequency ft (e.g. 46.71
Ml-IZ), in phase e, supplies a frequency switching signal having the frequency fs (for example, 46.73M day l) as the receiving frequency, and similarly to the receiving units 10b to 10e and the transmitting unit 12a.

A frequency switching signal having a frequency as shown in Table 1 is supplied to each of the 12b in each phase. Note that the transmission frequency f
6. For example, each f7 is 46.77 MH2.

46.81 MH7.

Table 1 The synchronization signal generator 17 delays the frequency switching synchronization signal for a predetermined period of time, and generates a synchronization signal with a frequency of about 300 to 500 Hz during the H level period of the delayed frequency synchronization signal every fixed time (for example, 1 minute). The signal is supplied to the transmitting sections 12a and 12b. If the frequency switching synchronization signal is transmitted as it is, the delay of the predetermined time will be caused by the delay caused by the transmitting sections 12a and 12b of the base unit, and the reception unit 31 and synchronization signal extraction unit 33 of the slave unit, which will cause the frequency switching signal between the base unit and the slave unit to be delayed. Since a phase shift occurs in the signal, a time period is set in advance to eliminate this phase shift.

Each of the transmitting units 12a and 12b superimposes a synchronizing signal on the audio supplied from the two signal lines 18a and 18b of the switching circuit 18, and then performs FM modulation, and converts the FM modulated signal to a transmission frequency specified by the frequency switching signal. (fs or fy) and transmits from the antenna 19.

Further, the signals received by the antenna 19 from the slave units are supplied to the receiving units 108 to 10e, and each of them performs tuning of the reception frequency (f+ to fs) indicated by the frequency switching signal and FM demodulation. The receiving units 108 to 108 each supply the demodulated audio to code extractors 21a to 21e, which separate the control code included in the demodulated signal, and the code analysis unit 22 analyzes the supplied control code and performs switch control. 23 or the tone generating section 25, and the switch control section 23 accordingly controls the switches 24a to 24h in the switching circuit 18, the line connection switch 26a,
26b.

A telephone line 1 is connected to each movable contact of the switches 24a and 24b.
1a and 11b are connected, and switches 24c to 24c are connected to each other.
The movable contacts of the switch 4o are supplied with the demodulated output sounds of the receivers 10a to 10e, and the movable contacts of the switch 24h are supplied with sounds such as the hold tone 2 mid-talk tone generated by the tone generator 25. Under the control of the switch control section 23, the switches 24a to 24h disconnect the respective VJ contacts from the two signal systems 1118a and 18b, or connect them to either of them. Line connection switch 26a.

26b each corresponds to a hook switch of an ordinary telephone,
Connect/disconnect the telephone line.

FIG. 3 shows a block diagram of an embodiment of the slave device.

In the figure, the signal received by the antenna 30 from the main unit is supplied to the receiving section 31, and the receiving section 31 receives the receiving frequency (f) indicated by the frequency switching signal from the frequency switching signal generating section 32.
s, fy) and FM demodulation. The synchronization signal extraction section 33 extracts a synchronization signal superimposed on the demodulated audio every minute and supplies it to the frequency switching signal generation section 32 . In synchronization with this synchronization signal, the frequency switching signal generating section 32 uses the clock from the clock generating section 34 to control the transmitting section corresponding to itself within group 1 in phases a to e shown in FIG. 2(B) to (F). The transmitting section 35. generates a frequency switching signal that determines the frequency (which one of f+ to f5) and a frequency switching signal that determines the frequency (fs or f7) of the designated receiving section. Receiving section 31
supply to.

Further, the demodulated audio output from the receiving section 31 is supplied to a subtraction circuit 37. Here, the sound obtained by the microphone 38 is amplified by an amplifier 39 and then supplied to the transmitter 35 and also to the delay circuit 41, where it is delayed for a predetermined time and then supplied to the subtraction circuit 37. The subtracter 37 subtracts and eliminates the own sound included in the demodulated sound, and the remaining sound is amplified by the amplifier 42 and produced by the speaker 43.

The delay time of the delay circuit 41 is such that a signal modulated and transmitted from the transmitter 35 is received by the receiver 31 via the base unit, and
This is the time required to demodulate the signal and supply it to the subtraction circuit 37.

The code extraction unit 46 separates the control code included in the demodulated audio, and this control code is analyzed by the code analysis unit 47. According to the analysis result, an instruction is issued to the tone generation unit 44, and the frequency switching signal generation unit 32, an instruction is given as to which of the transmitting sections 12a and 12b of the base unit the receiving frequency should correspond to.

The tone generating section 44 generates sounds such as a chord tone, a ring tone, and a hold tone in response to instructions from the code analyzing section 47 and operations of each key on the key operating section 45, and transmits them to the amplifier 42 and the transmitting section 3.
Supply to 5. The transmitting unit 35 mixes the audio from the amplifier 39 and the audio from the tone generating unit 44, performs M modulation, and converts the M modulated signal to the transmission frequency indicated by the frequency switching signal (
f+ to fs) and is transmitted from the antenna 30. If this handset is compatible with the receiving section 1oa of 11 devices, the transmission frequency of the transmitting section 35 from the time the synchronization signal arrives is in the order of phases a to e in the column of the receiving section 10a in Table 1. Variable.

FIG. 4 shows an operation flowchart of the base unit.

In the figure, when the base unit is powered on, the transmission frequency of the transmitter 12a is set to f7 (step 50), and a synchronization signal is fixedly transmitted from the transmitter 12a every time the timer setting time (i.e. 1 minute) is reached (step 50). Steps 51 and 52>. This is repeated until there is a call from the telephone line or the handset (CALL) (step 53), and when there is a call, it is determined in step 54 whether or not the call is from the handset.

In the case of a call from a handset, it is determined whether an intercom mode (INTCM) code that instructs an extension call between handsets is specified (Step 55) 1. In the case of intercom mode, carrier sensing is performed (step 56). Carrier sensing is to detect whether frequencies f1 to f5 are being used in the phase at that point. For example, if frequency f1 is being used, carrier sensing is performed. (NG
) Change the frequency to, for example, f2 (Step 57) Continue carrier sense, and if there is an empty frequency, OK> Use that empty frequency to call the receiving handset (Step 58), and then call the handset from this handset. Wait for a response (ACK) (step 59). If there is no response, a ringtone is sent to the calling side handset in step 60 and the process returns to step 58. If there is a response, the ringing sound to the calling side handset is stopped. Step 6
1>, each transmission frequency (fs, f7) and each reception frequency (f+ to fs) shown in Table 1 are switched, ie, call control is performed (step 62). Furthermore, timer setting time (1 minute)
A domei signal is sent every time (steps 63 and 64).

After this, it is determined whether a conference mode (CONF) code that instructs a call between an outside line and multiple handsets has been specified (step 65). In this case, the process moves to step 66, but in other cases, In step 67, the receiver is hung up (ON HOOK), and it is determined whether the call has ended or not. If not, the process returns to step 62, and if it has ended, the process returns to step 51.

In the case of conference mode, the C0NF code is analyzed in step 66 to determine which handset is to participate in the call, and the handset to participate is called (step 70).

After this, wait for a response from this slave unit (step 71).
If there is no response, a ring tone is transmitted to the telephone line and handset that are already on the call (step 72), and if there is a response, the movable contact of the switch corresponding to the handset to participate in the switching circuit 18 is activated. Signal line 18 that is already making a call
step 73), step 62
Proceed to. For example, when a telephone call is being made between the telephone line 11a and a handset corresponding to the receiving section 10a (switches 24b, 2
4c is connected to the signal line 18a), when the handset corresponding to the receiving unit 10b is to participate in the conference mode, the movable contact of the switch 24d is connected to the signal line 18a.

If it is determined in step 55 that the called party is not in intercom mode and that the called party is on a telephone line, then in step 75 it is determined whether the telephone line is free, and if it is free, the switch 24a or 24b is connected to the signal line 18a or 18b. Step 76>, the process proceeds to step 62 to connect the vacant line.

If the line is not free, in step 56 the frequency "1" is
In the same way as when it is determined that the carrier is full, in which all carriers .about.f5 are used, the process proceeds to step 77, where a busy tone is generated for the calling side line or handset. The generation of this busy tone is repeated until the caller becomes ON HOOK (step 78), and the process returns to step 51 after ON date 00.

Further, if it is determined in step 54 that the call is from a telephone line, carrier sense is performed in step 80, and if OK, the process proceeds to step 57, and if NG, the frequency (f+~fs
), and if the carrier is full, in step 82 the telephone line that is making the call is left with a busy tone and the telephone line is not connected, and in step 51
Return to

FIG. 5 shows an operation flowchart of the handset.

In the figure, when the handset is powered on, the reception frequency is set to f7 (step 90), a synchronization signal is extracted (step 91), and when this is extracted, the frequency switching signal generator 32 is set to f7. (Step 92). If this extraction is not found, it is determined in step 93 whether the call has been made by picking up the handset of the own machine (OFF day 00K) or if the call has been received from another party, and if neither is the case, the process returns to step 91.

If there is a transmission from your own aircraft, in step 94 the frequency is set to <f+~fs.
), and if it is NG, change the frequency setting (step 95), and if the carrier is full, turn it on.
A busy tone is generated for the own machine until HOOK is detected (Steps 96 and 97), and the process returns to Step 91. If the carrier sense is OK, a code instructing the intercom mode is sent only in the case of the intercom mode (step 99), and the process proceeds to step 100. In step 100, each transmitting frequency (f+~fs) and each receiving frequency (fs,
F7) Performs respective switching, that is, call control. After this, synchronization is performed only when a synchronization signal is received.
Steps 101 and 102), and further conference mode (CONF
> (step 104), and if the conference mode is selected, proceed to step 104; otherwise, it is determined whether the ON port is 00K or not (step 109). If the call continues, the process returns to 100 and the call is terminated. Once completed, the process returns to step 90.

When the conference mode is entered, a code instructing the conference mode is sent in step 104, and it is determined whether the slave device of the called party to participate in the conference is OFF HOOK (step 105). If this is an OFF HOOK, that is, the called party's handset is already busy, a busy tone is sent (step 106), and the process proceeds to step 100. This is O
In the case of N-00, wait for the called party's handset to answer the call in order to participate in the conference (step 107), and when the called party answers the call, transmit frequency (f+~fs) and receive frequency (fa, f7). Perform call control, which is switching (
Step 108), proceed to step 109. If the duration of the call exceeds a predetermined time, a timeout process is performed (step 110), an interrupt signal is sent to interrupt the call (step 111), and step 10
Proceed to step 9. (CALL)
If so, generate a ring tone on the own machine and make it sound from the speaker 43 (Step 115), and repeat until the handset of the own machine is picked up, that is, OFF HOOK is reached (Step 116).
〉. When the handset of the own machine is picked up, the ringer is stopped (step 117), the received code is analyzed and controlled (step 118), and a corresponding response (ACK) is issued.
Step 119>, Step 110
Proceed to. In this code analysis, it is determined whether the call is coming from a telephone line or a handset, and which of the transmitting sections 12a and 12b the receiving frequency of the receiving section 31 corresponds to, etc.

In this way, a periodic signal synchronized with the frequency variable period of the transmitting/receiving signal generated by the base unit is transmitted from the transmitter of the base unit to the slave unit along with the call content, and the slave unit extracts the synchronization signal from the received signal and converts the synchronization signal The frequency of the transmitted and received signals is varied in synchronization with the For this reason, the transmission frequencies of the base unit and slave unit are synchronized with each other and are varied periodically, making it easy to synchronize the frequency changes of both units, which is extremely short-term with ordinary receivers. Even if it is possible to intercept the call, the contents of the call cannot be known, and confidentiality can be maintained.

Furthermore, since the synchronization signal is superimposed on the call content and transmitted by the base unit, there is no need for a dedicated transmission frequency for transmitting this synchronization signal, and the configuration of the base unit and slave unit is simple, and the transmitting and receiving signal band is simple. is small.

〔Effect of the invention〕

As described above, according to the synchronization method of the wireless parent-child phone of the present invention, it is possible to maintain confidentiality without leakage of calls due to interception, and it is easy to perform frequency variable synchronization between the parent device and the child device.
It is extremely useful in practice.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the base device according to the present invention, Fig. 2 is a diagram for explaining the frequency switching phases of the present invention, and Fig. 3 is an implementation of the slave unit according to the present invention. FIG. 4 is an operational flowchart of an embodiment of the master device, and FIG. 5 is an operational flowchart of an embodiment of the slave device. In the figure, 10a to 10e, 31 are receivers, 11a, 11b are telephone lines, 12a, 12b, 35 are transmitters, 15 is a clock generator, 17.32 is a frequency switching signal generator, 18 is a switching circuit, 21a 21e is a code extraction section, 22 is a code analysis section, 23 is a switch control section, 25.44 is a tone generation section, 33 is a synchronization signal extraction section, 37 is a subtraction circuit, 41 is a delay circuit, 45 is a key operation section, 50 to 119 indicate steps.

Claims (1)

[Claims] In a synchronization method of a wireless parent-child phone that performs wireless communication between a base unit and a slave unit, the transmitting frequency of the transmitting unit of the base unit and the receiving frequency of the receiving unit are made different from each other, and a first frequency variable means that varies the frequency; a synchronization signal generation and transmission means that generates a synchronization signal synchronized with the variable period of the transmission frequency and reception frequency of the base unit and sends it from the transmission section of the base unit to the slave unit; a synchronization signal extraction means for extracting a synchronization signal from the reception signal received by the reception section of the slave device; and a reception frequency of the reception section of the slave device and a transmission frequency of the transmission section in synchronization with the synchronization signal extracted by the synchronization signal extraction means. and second frequency variable means for varying the frequency.