JPH04243327A - Selective call radio receiver - Google Patents

Abstract

PURPOSE:To always attain the best tuning state by adjusting automatically an antenna tuning section with respect to a change in an antenna length in the mount state, to reduce the cost by reducing the adjustment process at the manufacture and repair and to improve the reliability without damage to components and defect in adjustment. CONSTITUTION:An AC/DC conversion section 13 converts an output signal of a radio section 3 into a DC signal corresponding to the amplitude of the signal and comparators 101-104 convert the converted DC signal into a 4-bit digital signal corresponding to the amplitude and outputs the signal. An output control section 16 controls transfer gates 109-113 based on the digital signal and a clock signal from a signal control section 9 to give a control voltage to varactor diodes 204-206 thereby bringing the best tuning state to the antenna tuning.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention is utilized for antenna tuning means of a radio selective calling receiver. In particular, the present invention relates to antenna tuning means that accommodates changes in antenna length of an antenna having a structure that can be worn on the human body.

0002

2. Description of the Related Art FIG. 6 is a block diagram of a conventional radio selective call receiver.

Conventionally, as shown in FIG. 6, a radio selective calling receiver receives a radio calling signal using, for example, a band type antenna 1, and an antenna tuning section 2A receives a radio calling signal using a capacitor 210,
211, 212 and a variable capacitor 213 to perform tuning and impedance matching, and supply a radio paging signal to the radio section 3 most efficiently.

The radio section 3 amplifies this radio paging signal, mixes it with an input signal from a local oscillator 4, performs frequency conversion, and outputs an intermediate frequency signal. A limiter 5 limits the amplitude of the radio paging signal converted to an intermediate frequency, and a discriminator 6 performs DC detection. When the output of the radio paging signal is small, there is a lot of noise, so a low-pass filter (LP
F) After passing through 7, the waveform is shaped by a comparator 8 and provided to a signal control section 9.

When a call signal is input, the signal control unit 9 establishes bit synchronization and frame synchronization by detecting a synchronization signal, and then synchronizes the subsequent individual call signal with the call number previously stored in the individual signal storage unit 10. After comparison and verification, if it is determined that the call is from the user, the speaker 11 notifies the user of the call.

[0006]

[Problems to be Solved by the Invention] However, in such conventional radio selective calling receivers, in order to maximize reception sensitivity at a specific reception frequency, an antenna tuning circuit is artificially set for the reception frequency. Therefore, an antenna adjustment process must be provided during manufacturing or repair, which is a drawback of increasing costs. Additionally, due to mechanical adjustments such as variable capacitors,
There were also drawbacks such as component damage and poor adjustment, which degraded reception reliability.

[0007] In addition, with this type of band antenna, the length of the antenna may change depending on the physique of the person wearing it.
There was a drawback that the antenna tuning would shift due to differences in the dielectric constant of the human body.

The present invention solves the above-mentioned drawbacks, and provides a radio selective calling receiver that can automatically adjust the antenna tuning section in response to changes in antenna length when worn, and can always maintain the best tuning state. The purpose is to provide

[0009]

[Means for Solving the Problems] The present invention provides an antenna for receiving a radio paging signal, a tuning means connected to the antenna for tuning and impedance matching, and converting an output signal of the tuning means into an intermediate frequency signal. A radio means, a detection means for direct current detection of the output signal of the radio means, and a clock signal that is synchronized based on the output signal of the detection means, determines its own calling signal, and notifies that there is a call. In the radio selective calling receiver, the tuning means includes an element that performs tuning and impedance matching by changing reactance based on an input control voltage, and adjusts the output signal of the radio means to its amplitude. AC/DC conversion means for converting the DC signal into a corresponding DC signal;
A digital conversion means that outputs a multi-bit digital signal corresponding to the voltage value of the converted DC signal, and a control voltage that applies the control voltage to the element based on the output digital signal to achieve the best tuning state. The invention also includes an output control means for performing control.

Further, in the present invention, the above-mentioned antenna has a structure that can be attached to a human body, and has a characteristic that its inductive reactance component changes depending on the attached human body.

Further, in the present invention, the above element may be a variable capacitance diode.

[0012] Further, in the present invention, the AC/DC converting means includes a preamplifier section for amplifying the output signal of the wireless means, and an AC/DC converter section for converting the output signal of the preamplifying section into a DC signal. , and a hold section that temporarily holds the output signal of the AC/DC converter and outputs it based on the clock signal.

Further, in the present invention, the digital conversion means includes a plurality of first resistors that divide the input first reference voltage, and an output signal of the AC/DC conversion means and the divided first reference voltage. A plurality of comparators each inputting a voltage and outputting a multi-bit digital signal can be included.

Further, in the present invention, the output control means includes an output control section that outputs a control signal based on the clock signal and the output signal of the AC/DC conversion means, and a plurality of output control sections that divide the input second reference voltage. and a plurality of transfer gates that output the control voltage based on the divided second reference voltage and the output control signal.

[0015]

[Operation] The elements of the tuning means perform tuning and impedance matching by changing the reactance based on the input control voltage. The AC/DC conversion means converts the output signal of the wireless means into a DC signal according to its amplitude. The digital conversion means outputs a multi-bit digital signal corresponding to the voltage value of the converted DC signal. The output control means applies the control voltage to the element based on the output digital signal to perform control so as to achieve the best tuning state.

[0016] As described above, the antenna tuning section can be automatically adjusted in response to changes in the antenna length in the installed state, and the best tuning state can always be achieved.

[0017]

Embodiments Examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a wireless selective call receiver according to an embodiment of the present invention. In FIG. 1, the radio selective paging receiver includes an antenna 1 for receiving a radio paging signal, and an antenna 1 for receiving a radio paging signal.
an antenna tuning section 2 as a tuning means connected to the antenna for tuning and impedance matching, and a radio section 3 as a radio means for converting the output signal of the antenna tuning section 2 into an intermediate frequency signal.
and a local oscillator 4, a limiter 5 and a discriminator 6 as detection means for DC detection of the output signal of the radio section 3.
, a low-pass filter 7 and a comparator 8, and a signal control unit 9 as a signal control means that synchronizes based on the output signal of the comparator 8, generates a clock signal, judges its own call signal, and notifies that there is a call. , an individual signal storage section 10 , and a speaker 11 .

The feature of the present invention is that the antenna tuning section 2 includes an element that performs tuning and impedance matching by changing the reactance based on the input control voltage, and capacitors 201 to 203.
AC/DC conversion means for converting the output signal of the radio section 3 into a DC signal according to the amplitude thereof, digital conversion means for outputting a multi-bit digital signal corresponding to the voltage value of the converted DC signal, and this output. and an output control means for applying the control voltage to the element based on the digital signal so as to achieve the best tuning state.

Further, the antenna 1 has a structure that can be worn on a human body, and has a characteristic that its inductive reactance component changes depending on the human body on which it is attached.

Furthermore, the above element is a variable capacitance diode 2
04 to 206.

[0021] Furthermore, the AC/DC converting means includes the radio section 3.
a preamplifier 12 that amplifies the output signal of the preamplifier 1;
AC/DC converter 13 that converts the output signal of No. 2 into a DC signal.
and a hold section 14 that temporarily holds the output signal of the AC/DC converter 13 and outputs it based on the clock signal.

Furthermore, the digital conversion means includes bleeder resistors 105 to 108 as a plurality of first resistors that divide the first reference voltage inputted from the reference potential generation section 15.
and a plurality of comparators 101 to 10 which respectively input the output signal of the hold section 14 and the divided first reference voltage and output multi-bit digital signals.
4 including.

Further, the output control means divides a second reference voltage input from the reference potential generation section 15 and an output control section 16 that outputs a control signal based on the clock signal and the output signals of the comparators 101 to 104. Bleeder resistors 114 to 118 serve as a plurality of second resistors to
and a plurality of transfer gates 109 to 113 that output the control voltage based on the divided second reference voltage and the output control signal.

The operation of the radio selective calling receiver having such a configuration will be explained. FIG. 2 is a schematic diagram of a wireless selective calling receiver of the present invention. FIG. 3 is a flowchart showing the operation of the wireless selective calling receiver of the present invention. FIG. 4 is a time chart of each signal of the radio selective calling receiver of the present invention. FIG. 5 is a diagram showing the tuning state of the syntenna tuning section of the radio selective calling receiver of the present invention.

In FIG. 1, a radio paging signal received by an antenna 1 is supplied to a radio section 3 by an antenna tuning section 2 in the most efficient manner. The radio section 3 amplifies the input radio paging signal, mixes it with a local oscillation frequency signal supplied from the local oscillator 4, and performs frequency conversion. For example 455K
Output as a Hz intermediate frequency signal.

The output of the radio section 3 is input to the limiter 5 and also to the preamplifier section 12. The limiter 5 amplifies and limits the amplitude of the input radio paging signal, and then outputs it to the discriminator 6. The discriminator 6 performs FM detection on the amplitude-limited signal and sends it to the low-pass filter 7 as a calling signal. A low-pass filter 7 removes noise components from the calling signal, a comparator 8 shapes the signal, and the signal is then sent to a signal control section 9 . The signal control unit 9 establishes synchronization using the synchronization signal of the calling signal, compares the individual calling signal following the synchronization signal with the calling number stored in advance in the individual signal storage unit 10, and determines that the call is the own call. Then, the speaker 11 notifies the user that there has been a call.

Next, the antenna tuning means of the present invention will be explained.

The input stage of the radio section 3 is usually a high frequency amplifier circuit using transistors, and the input impedance is capacitive. Therefore, the antenna 1 and the antenna tuning section 2 perform impedance matching using inductive impedance, and tuning is performed so that the signal received by the antenna 1 can be most efficiently input to the radio section 3. In this embodiment, the antenna tuning section 2 is composed of capacitors 201 , 202 , 203 and variable capacitance diodes 204 , 205 , 206 .

FIG. 2 shows a perspective view of this embodiment. Figure 2 (a
) is the initial state, and FIG. 2(b) is the installed state. For example, since the length l1 of the band type antenna 1 changes to l2, the tuning capacity in the antenna tuning section 2 changes. In the conventional receiver shown in FIG.
In order to adjust the tuning point using the variable capacitor 213 so that the sensitivity is maximized in the initial state of (a),
In the mounting state shown in FIG. 2(b), the best tuning point cannot be obtained.

By the way, in this embodiment, the intermediate frequency signal output from the radio section 3 is amplified by the preamplifier section 12 with a wide dynamic range within a range that does not saturate, and then
Give to 3. The AC/DC converter 13 rectifies and smoothes the input AC signal and converts it into a DC signal. This DC signal is temporarily held in the next stage hold section 14, and the signal control section 9
The output is performed sequentially according to the clock signal supplied from the

The voltages temporarily held by the hold section 14 are input to comparators 101 to 104, respectively. Comparators 101 to 104 are connected to bleeder resistors 105 to 108 to receive the reference voltage output from the reference potential generator 15.
The voltages divided by are also input respectively. Comparators 101 to 104 compare the voltage input from the hold section 14 with the voltage output from the reference potential generation section 15 and input after being divided by the bleeder resistor, and compare the voltage input from the hold section 14 with the voltage input after being divided by the bleeder resistor. It outputs as an "H" or "L" digital signal depending on the comparison value with the divided reference voltage. In this embodiment, the data is converted to 4 bits, but the number of bits can be changed as necessary.

The 4-bit binary signals output from the comparators 101 to 104 are input to the output control section 16. The output control section 16 includes comparators 101 to 104.
Transfer gate 109 ~
A control signal for controlling 113 is output based on a clock signal supplied from signal control section 9.

Transfer gates 109 to 113 are supplied with voltages obtained by dividing the reference potential output from reference potential generation section 15 by bleeder resistors 114 to 118, respectively. Each transfer gate is controlled "on" or "off" by a control signal from the output control unit 16, and a voltage corresponding to the operation is applied to the variable capacitance diodes 204 to 206.
supply to.

Since the capacitance value of the variable capacitance diodes 204 to 206 changes depending on the voltage applied to the cathode side, the impedance of the antenna tuning section 2 changes,
The output level of the wireless section 3 changes.

Here, when the output level of the radio unit 3 decreases because the antenna length changes and the output level of the radio unit 3 decreases, the output level of the radio unit 3 becomes smaller, even though it was tuned in the initial state. The transfer gate is controlled so that the output is maximized, that is, the best tuning point is obtained according to the antenna length.

In FIG. 3, since the antenna is tuned in the initial state, it is not tuned to the antenna length in the installed state. Therefore, since the output level of the wireless section 3, that is, the input level of the output control section 16 is small (S1), the output control section 16 attempts to raise the level.

For example, variable capacitance diodes 204 to 2
It is assumed that the antenna tuning at the antenna length in the attached state is achieved in the direction in which the capacitance of 06 decreases, and the output level of the radio unit 3 increases. The output control unit 16 turns on the transfer gate (S2) and increases the voltage supplied to the variable capacitance diode (S3). Here, transfer gate 113 → transfer gate 109 are turned on in this order.
do. As this supplied voltage increases, the capacitance value of the variable capacitance diode decreases (S4), and the output level of the wireless section 3 increases.

That is, comparators 101 to 104
The level input to the output control unit 16 increases, and reaches its maximum level at the best tuning point for the antenna length, but thereafter the tuning point shifts and the level becomes smaller. The output control unit 16 turns on the transfer gate from the direction in which the input level increases to the direction in which it decreases (S5). When the input level decreases, the transfer gate is
"off" (S6), and lower the voltage supplied to the variable capacitance diode (S7). Here, transfer gate 11
3 → Transfer gate 109 is turned off in this order. The capacitance value of the variable capacitance diode increases (S8),
The tuning point of the antenna tuning section 2 becomes the best again, and the input level becomes maximum.

However, if the capacitance value becomes too large, the tuning point will shift and the level will become smaller. Therefore, the output control section 16 stores the maximum input level value, and determines the point of change by comparing it with this maximum level value. Then, the transfer gate is controlled again so that the tuning point becomes the best, and the level is maximized (S10).

Thereafter, since the output control section 16 stores the maximum level value, it operates to maintain the maximum level point, that is, the best tuning point.

The operations described above are performed when the length of the antenna changes in the installed state. In addition, since the antenna length changes even when returning from the attached state to the initial state, the tuning point is changed according to the antenna length according to the flow described above, and the antenna tuning section 2 changes the tuning point according to the antenna length. The best matching point will always be obtained.

FIG. 4(a) shows the waveform of the intermediate frequency signal output from the radio section 3, and FIG. 4(b) shows the waveform of the signal amplified by the preamplifier section 12. What was in tune in the state of FIG. 2(a) is now out of tune due to the change in antenna length in the attached state of FIG. 2(b), and therefore the detected amplitude level is initially small. According to the flowchart shown in FIG. 3, the amplitude level gradually increases as the synchronization is achieved, and eventually the amplitude level becomes stable at the maximum level. FIG. 4C shows a waveform obtained by rectifying an AC signal in the AC/DC converter 13, which is further smoothed and converted into a DC signal, held in the hold unit 14, and input to each of the comparators 101 to 104 as shown in FIG. (d) It is. It is converted into a DC voltage according to the amplitude level shown in FIG. 4(a). VS1, VS2, VS3, and VS4 are output from the reference potential generation section 15, and are connected to the bleeder resistors 105 to 105.
108 and indicates the reference voltage level input to each comparator. In Figure 4(d), VS1<VS
The relationship is 2<VS3<VS4. FIG. 4(e) shows the comparator 101, and FIG. 4(f) shows the comparator 102.
, FIG. 4(g) shows the comparator 103 and FIG.
h) represent the output waveforms of the comparator 104, respectively.

In this embodiment, the output control unit 16 controls the transfer gates (109 to 113) so that the maximum voltage is applied to the variable capacitance diodes 204 to 206 when all 4-bit outputs of the comparators are "H". I got it under control. Figure 4(i) shows the variable capacitance diode 20.
4 to 206 are shown. VSt
1, VSt2, VSt3, VSt4, VSt5
is output from the reference potential generation section 15, and the bleeder resistor 1
Each transfer gate 1 after division by 14 to 118
09 to 113 indicate the reference voltage levels input.

FIG. 4(j) shows changes in the capacitance values of the variable capacitance diodes 204 to 206 due to voltage application to the cathode side. The higher the voltage, the smaller the capacitance, and the lower the voltage, the larger the capacitance. Therefore, when the antenna length changes, the tuning capacitance of the antenna tuning section 2 is changed due to changes in voltage and capacitance, so that optimal tuning and impedance matching conditions can be obtained.

FIG. 5 shows the state of the antenna tuning section 2 as seen from the radio section 3 according to this embodiment. Figure 5(a)
indicates that the antenna is not tuned when the antenna is attached. Since it is not tuned, the reception frequency does not peak at F0 and the reception level is also small. Variable capacitance diode 20
FIG. 5(b) shows a state in which the capacitances of 4 to 206 are varied and tuning is achieved at the receiving frequency F0 with the antenna length in the attached state.

However, the output control section 16 still has the problem of FIG.
) cannot be determined to be the best point, and as the capacitance is further changed, the tuning shifts again as shown in Fig. 5(c). However, this time it can be determined that the state shown in FIG. 5(b) is the best. In other words, by memorizing the maximum value of the amplitude level (the best state of tuning), the capacitance is changed in the opposite direction to the previous one, so that the tuning becomes the best again, as shown in Figure 5(d). Make it.

The operations described above are performed instantaneously to follow changes in the tuning point.

[0048]

[Effects of the Invention] As explained above, the present invention has the excellent effect of automatically adjusting the antenna tuning section in response to changes in the antenna length when the antenna is being worn, so that the best tuning state can always be achieved. . In addition, there are advantages in that adjustment steps during manufacturing and repair can be reduced, reducing costs, and reliability can be improved without damage to parts or poor adjustment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a wireless selective call receiver according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a wireless selective call receiver of the present invention.

FIG. 3 is a flowchart showing the operation of the wireless selective calling receiver of the present invention.

FIG. 4 is a time chart of each signal of the wireless selective call receiver of the present invention.

FIG. 5 is a diagram showing the tuning state of the antenna tuning section of the radio selective calling receiver of the present invention.

FIG. 6 is a block diagram of a conventional wireless selective call receiver.

[Explanation of symbols]

1 Antenna 2, 2A Antenna tuning section 3 Radio section 4 Local oscillation section 5 Limiter 6 Discriminator 7 Low pass filter 8, 101 to 104 Comparator 9 Signal control section 10 Individual signal storage section 11 Speaker 12 Preamplification section 13 AC DC conversion section 14 Hold section 15 Reference potential generation section 16 Output control section 105 - 108 , 114 - 118 Bleeder resistor 109 - 113 Transfer gate 201
~203, 210 ~212 Capacitor 20
4 to 206 Variable capacitance diode 207 Resistor 213 Variable capacitor 301 Output waveform of radio unit 3 302 Output waveform of preamplifier 12 303 Rectification waveform in AC/DC converter 13 304 Output waveform of hold unit 14 305 Comparator 101
Output waveform 306 of comparator 102 Output waveform 307 of comparator 103 Output waveform 308
Output waveform of the comparator 104 309 Voltage applied to the variable capacitance diode 310 Change in capacitance value of the variable capacitance diode 311 Tuning state in the initial wearing state 312 Best tuning state 3 in the process of changing tuning
13 Too much change 314 Out of synchrony
Final best tuning state l1, l2 antenna length

Claims (6)

[Claims] [Claim 1] An antenna for receiving a radio paging signal;
A tuning means connected to the antenna for tuning and impedance matching, a radio means for converting the output signal of the tuning means into an intermediate frequency signal, a detection means for direct current detection of the output signal of the radio means, and a detection means for direct current detection of the output signal of the radio means. In a radio selective calling receiver comprising a signal control means that synchronizes based on an output signal, generates a clock signal, judges its own calling signal, and notifies that there is a call, the tuning means controls an input control voltage. It includes an element that performs tuning and impedance matching by changing the reactance based on the
AC/DC conversion means for converting the output signal of the wireless means into a DC signal according to the amplitude thereof; digital conversion means for outputting a multi-bit digital signal corresponding to the voltage value of the converted DC signal; and output control means for applying the control voltage to the element based on the digital signal generated by the receiver so as to achieve the best tuning state. 2. The radio selective calling receiver according to claim 1, wherein said antenna has a structure that can be attached to a human body, and has a characteristic that its inductive reactance component changes depending on the human body attached. 3. The radio selective calling receiver according to claim 1, wherein said element is a variable capacitance diode. 4. The AC/DC converting means includes a preamplifier for amplifying the output signal of the wireless means, an AC/DC converter for converting the output signal of the preamplifying unit into a DC signal, and an AC/DC converter for converting the output signal of the preamplifier into a DC signal. 2. The radio selective calling receiver according to claim 1, further comprising a hold section that temporarily holds the output signal of the conversion section and outputs it based on the clock signal. 5. The digital conversion means includes a plurality of first resistors that divide the input first reference voltage, and inputs the output signal of the AC/DC conversion means and the divided first reference voltage, respectively. 2. The radio selective calling receiver according to claim 1, further comprising a plurality of comparators for outputting a multi-bit digital signal. 6. The output control means includes an output control section that outputs a control signal based on the clock signal and the output signal of the AC/DC conversion means, and a plurality of second reference voltages that divide the input second reference voltage. The radio selective calling receiver according to claim 1, comprising a resistor and a plurality of transfer gates that output the control voltage based on the divided second reference voltage and the output control signal.