JPH03120919A - Annunciating circuit to outrange of talking zone for radio telephone set - Google Patents

Abstract

PURPOSE:To improve the accuracy of talking outrange-zone notice by outputting a talking out-zone detection signal in response to an output from a signal strength detection circuit and an output of a noise detection circuit. CONSTITUTION:When the output of a signal intensity detection circuit 16 reaches a level corresponding to a noise level in a reception input level A, a variable resistor 18 is adjusted so that an output of a comparator 19 reaches an L level. When a mobile station is parted from a base station and the reception input level reaches a reception input level A or below, the output of the comparator 19 reaches an L level, a control circuit 14 outputs a driving signal accordingly to annunciate representing the residence at the outrange of talking zone. On the other hand, when the reception input level is high and the modulation at a high frequency is deep, the harmonic component of the reception signal is increased, it is extracted by a BPF 10 and even when a DC signal of the noise detection circuit 19 is increased, since the voltage fed to a noninverting input terminal of the comparator 19 is increased in response to the reception input level, the output of the comparator 19 keeps an H level. Thus, mis-decision is avoided.

Description

[Detailed description of the invention] (b) Industrial application field The present invention relates to an out-of-call area notification circuit for a wireless telephone device.

(B) Conventional technology Conventionally, in a wireless telephone device, in order to ensure a predetermined call quality, the range within which the mobile station can maintain the call quality (hereinafter referred to as
When the communication area (referred to as the calling area) reaches the limit, the user is notified by an alarm or the like.

As a receiving system of the wireless telephone device of this type, the one shown in FIG. 5 is known.

In Fig. 5, (1) is a receiving antenna, (2) is a high 1d wave amplification circuit that amplifies the high frequency signal from the receiving antenna (1), and (3) is a high frequency signal from the high frequency amplification circuit (2) and a local A mixing circuit mixes the local oscillation signal from the oscillation circuit (4) and derives a predetermined intermediate frequency signal; (5) is an intermediate frequency amplification circuit that amplifies the intermediate frequency signal from the mixing circuit (3); ) is a detection circuit that detects the intermediate frequency signal from the intermediate frequency amplifier circuit (5), (7) is a low frequency amplifier circuit,
(8) is a speaker, and (9) is a noise detection circuit connected to the output end of the detection circuit (6).
For example, 8~IOK! A bandpass filter (BPF) (10) whose center frequency is 1o
) and a rectifier circuit (11) that rectifies the signal that has passed through the circuit. (I2) is a comparator in which the rectified output from the rectifier circuit (11) is supplied to the inverting input terminal, and the reference voltage set by the variable resistor 5 (13) is supplied to the non-inverting input terminal. (14) is a wireless A control circuit made of a microcomputer that controls various operations of the telephone device, and when the output signal from the comparison 5 (12) becomes L level, it supplies a drive signal to the notification circuit (15) made of a speaker, etc. being done. Note that the notification circuit (15) can use not only audio notification but also visual notification using a display or the like, or a combination of both.

Since the signal and noise characteristics with respect to the received input level generally change as shown in FIG. 6(a), the comparator (12
) is the reference voltage supplied to the non-inverting input terminal of the
), if the receiving input level is set to a voltage value corresponding to the noise level at the receiving input level A of The output of (12) becomes L level (
In response to this, the control circuit (14) outputs a drive signal to make a speaker sound, for example, to notify that the user is out of communication range.

(c) Problems to be Solved by the Invention According to the above-described conventional technology, malfunctions tend to occur because out-of-communication area detection is performed only based on the level of noise components contained in the detected output signal.

In other words, when the degree of modulation of the transmitted signal is high, phase shift distortion occurs in the intermediate frequency amplifier circuit of the receiving system, resulting in harmonic components (secondary or third harmonic components of the modulation frequency) of the received signal after detection. increases (see Figure 6(d)).

Therefore, even if the receiving input level is high, if the modulation degree is high, the harmonic components will be extracted by the BPF (10), and if the level exceeds the reference voltage, compare! (12
) becomes L level (see FIG. 6(e)), causing the problem that the control circuit (14) erroneously determines that the received input level has decreased.

(d) Means for Solving the Problems In view of the above points, the present invention provides a signal strength detection system that is provided in a receiving system of a wireless telephone device and outputs a DC signal indicating the level of a signal received by the receiving system. a noise detection circuit that is provided in the reception system of the wireless telephone device and outputs a DC signal indicating the level of the if acid component contained in the signal received and demodulated by the reception system; The present invention is characterized by comprising an out-of-call detection circuit that outputs an out-of-call detection signal in accordance with the output from the out-of-call detection circuit and the noise detection circuit, and a notification circuit that is driven based on the output from the out-of-call detection circuit.

Further, the out-of-communication area detection circuit has one input terminal supplied with the DC output of the noise detection circuit, and the other input terminal divided into voltages by a resistor connected between a predetermined potential point and the output terminal of the signal strength detection circuit. The device is characterized in that it is equipped with a comparator to which a voltage is supplied.

Furthermore, the out-of-call detection circuit includes a comparator, one input terminal of which is supplied with the DC output of the noise detection circuit, and the other input terminal of which is supplied with a reference voltage divided by a voltage dividing resistor; It is characterized by comprising a semiconductor switching element connected in parallel with at least one of the piezoresistors and whose conduction is controlled by the DC output of the signal strength detection circuit.

Furthermore, the out-of-communication area detection circuit includes a first comparator, one input terminal of which is supplied with the DC output of the noise detection circuit, and the other input terminal of which is supplied with the first reference voltage; The second comparator is supplied with the DC output of the intensity detection circuit and the second reference voltage is supplied to the other input terminal, and the OR circuit is supplied with the outputs of the first and second comparators. It is characterized by

(E) Function According to the present invention, an out-of-call-area notification signal is output in response to a DC signal indicating the received signal level from the signal strength detection circuit and a DC signal indicating the level of the noise component from the noise detection circuit. . For example, by changing the noise detection level according to the received signal level, a highly accurate out-of-call area notification signal can be created.

(F) Embodiment FIG. 1 is a diagram showing an embodiment of the present invention, and the same parts as in FIG. 5 are given the same reference numerals and their explanation will be omitted.

In FIG. 1, (16) is a signal strength detection circuit that is supplied with an intermediate frequency signal from the intermediate frequency amplifier circuit (5) and outputs a DC signal proportional to the received signal level by rectifying the intermediate frequency signal; (17) is an out-of-call detection circuit that outputs an out-of-call detection signal according to the DC signal from the noise detection circuit (and) and the DC signal from the signal strength detection circuit (16); The DC signal is connected to the inverting input terminal, the power supply (+B) and the signal strength detection circuit (16)
The comparators (19) each have a non-inverting input terminal supplied with a DC voltage from a slider of a variable resistor (18) connected between the output terminal of the variable resistor (18) and the output terminal of the variable resistor (18).

Now, since the output signal from the signal strength detection circuit (16) changes as shown by the dashed line in FIG. The divided voltage changes as shown by the broken line in FIG. 2(b).

Therefore, the variable resistor (18) is adjusted so that when the output of the noise detection circuit (16) reaches a voltage value corresponding to the noise level at reception input level A, the output of the comparator (19) becomes L level. If this is done, when the mobile station moves away from the base station and the reception input level becomes below the reception power level A, the output of the comparator (19) will become 1. In response to this, the control circuit (14) outputs a drive signal to, for example, make a speaker sound, thereby notifying that the communication area is out of range.

On the other hand, when the received input level is high and the modulation at high frequencies is deep, the harmonic components of the received signal increase, which causes B T
Even if the DC signal extracted at 3F (10) and output to the noise detection circuit (9) increases, the voltage supplied to the non-inverting input terminal of the comparator (19) also increases in accordance with the receiving input level. Therefore, the output of the comparator (19) continues to be at the H level (see FIGS. 2(d) and 2(e)).

Therefore, there is no possibility of erroneous determination as in the conventional case.

FIG. 3 is a diagram showing a second embodiment of the out-of-call detection circuit, in which the out-of-call detection circuit (17°) is connected to the noise detection circuit (9).
The DC signal from the variable resistor D (20) is input to the inverting input terminal.
and a comparator (23) whose non-inverting input terminals are supplied with DC signals from a voltage divider circuit (22) consisting of a resistor (21) and a resistor (21), respectively.
and a transistor (24) whose collector-emitter path is connected in parallel with the resistor (21) constituting the voltage dividing circuit (22).
), an inverter (25) connected to the base of this transistor (24), and a Schmitt circuit (26) to which a DC signal from a signal strength detection circuit (16) is supplied.

If the trigger level of the Schmitt circuit (26) is set to the DC signal level from the signal strength detection circuit (16) corresponding to the reception input level B in FIG. 2(b), the reception input level will be When the level is higher than the level B, the output of the Schmitt circuit (26) is H level and the output of the inverter (25) is L level, so the transistor (24) is turned off and the non-inverted state of comparison 5 (23) A reference voltage set by a variable resistor (20) and a resistor (21) is supplied to the input terminal.

If this basic in-pressure is set higher than the maximum level of the DC signal from the noise detection circuit (9), the output of the comparison D (2:D) continues at 1 level.

On the other hand, when the received input level is equal to or higher than the level B, the output of the Schmi7) circuit (26) is at L level, and the inverter (
Since the output of transistor (25) becomes H level, the output of transistor (25) becomes H level.
1) is turned on and the resistor (21) is shorted.

As a result, the reference voltage supplied to the non-inverting input terminal of the comparison S (23) is determined by the division ratio of the variable resistor (20), so the reference voltage set by the division ratio is
If the voltage value is adjusted to correspond to the noise level at the human input level, when the receiving input level decreases to below the receiving input level A, the output of the comparator 23 (23) becomes L level.

FIG. 4 is a diagram showing a third embodiment of the out-of-call detection circuit, in which the out-of-call detection port 'R1 (■'') is connected to the noise detection circuit (9
) is connected to the inverting input terminal of the variable resistor (27
), a first comparator (28) whose non-inverting input terminal is supplied with a first reference voltage set at
A second comparator (30) is supplied with a DC signal from 16) to its non-inverting input terminal, and a second reference voltage set by the variable resistor (29) is supplied to its inverting input terminal; 01 (circuit (
31).

If the first reference voltage is set to a voltage value corresponding to the noise level at reception input level A and the second reference voltage is set to the DC signal level at reception input level B, the reception input level will be equal to the level B. When it is larger than
Second comparison! Since the output of (30) becomes H level, the output of OR circuit (31) becomes H level regardless of the output of the first comparator <2g>.

- On the other hand, when the input level to the receiver (below level A), the outputs of the first comparator (28) and the second comparator 15 (30) both become L level, so the output of the OR circuit (31) is It becomes L level.

It goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made.

(G) Effects of the Invention According to the present invention, since the out-of-call detection signal is output according to the output from the signal strength detection circuit and the output from the noise detection circuit, the reception input level is high and the signal is modulated. Even if the communication area is deep, the out-of-call area detection signal is not output as in the conventional case, and the degree of opening of the out-of-call area notification can be increased.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing each characteristic. FIG. A diagram showing the relationship between the noise, the output from the signal strength detection circuit, and the non-inverting input of the comparator with respect to the reception input level, (c) is a diagram showing the relationship between the comparator output and the reception input level, (d)
is a diagram showing the relationship of the comparator input to the modulation degree, and the same figure (e
) is a diagram showing the relationship between the comparator output and the modulation degree, FIG. 3 is a diagram showing a second embodiment of the out-of-call detection circuit, FIG. 4 is a diagram showing a third embodiment of the out-of-call detection circuit, and FIG. The figure shows a conventional example, FIG. 6 shows its characteristics, and (a) shows the signal and noise characteristics with respect to the received input level.
Figure (b) is a diagram showing the relationship between noise and the non-inverting input of the comparator with respect to the received input level, Figure (c) is a diagram showing the relationship between the comparator output and the received input level, and Figure (d) is a diagram showing the relationship between the noise and the non-inverting input of the comparator. Diagram showing the relationship of comparator input to degree, same figure (e)
FIG. 2 is a diagram showing the relationship between the comparator output and the modulation degree. (9)...Noise detection circuit, (lO)...BPF, (
11)... Rectifier circuit, (14)... Control circuit, (1
5)...Notification circuit, (16)...Signal strength detection circuit, (17) (17') (17'')...Out of communication range detection circuit, (18) (20) (27) (29) ... Variable resistor, (19) (23) ... Comparator, (28) ... First comparator, (30) ... Second comparator, (31) ...
OR circuit.

Claims (4)

[Claims] (1) A signal strength detection circuit provided in a receiving system of a wireless telephone device and outputting a DC signal indicating the level of a signal received by the receiving system; a noise detection circuit that outputs a DC signal indicating the level of noise components contained in the signal received and demodulated by the
The out-of-call area detection circuit outputs an out-of-call area detection signal in accordance with the output from the signal strength detection circuit and the output from the noise detection circuit, and the notification circuit is driven based on the output from the out-of-call area detection circuit. An out-of-call area notification circuit for a wireless telephone device, characterized in that: (2) The out-of-call detection circuit has one input terminal supplied with the DC output of the noise detection circuit, and the other input terminal divided by a resistor connected between a predetermined potential point and the output terminal of the signal strength detection circuit. 2. The out-of-communication area notification circuit for a wireless telephone device according to claim 1, further comprising a comparator to which the voltage applied is supplied. (3) The out-of-call area detection circuit includes a comparator, one input terminal of which is supplied with the DC output of the noise detection circuit, and the other input terminal of which is supplied with a reference voltage divided by a voltage dividing resistor; Claim 1, further comprising a semiconductor switching element connected in parallel with at least one of the voltage dividing resistors and whose conduction is controlled by the DC output of the signal strength detection circuit.
An out-of-call area notification circuit for the wireless telephone device described above. (4) The out-of-call detection circuit has one input terminal supplied with the DC output of the noise detection circuit, and the other input terminal supplied with the first
a first comparator to which a reference voltage is supplied; a second comparator to which one input terminal is supplied with the DC output of the signal strength detection circuit and the other input terminal is supplied with a second reference voltage; 2. The out-of-call area notification circuit for a wireless telephone device according to claim 1, further comprising an OR circuit supplied with the output of the second comparator.