JPH1041786A - Digital portable telephone device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain low costs, low current consumption, and high communication connection reliability by stable frequency precision without necessitating any high precise reference frequency generating part, or continuously operating AFC control. SOLUTION: A controlling part 8 reads an initial control signal corresponding to the temperature data of a temperature detecting part 12 from an initial signal storage part 13, and transmits it to an AFC part 6. The AFC part 6 transfers the initial control signal to a reference frequency generating part 5 for generating a corresponding reference frequency, and a corresponding station generating signal is supplied from a frequency generating part 4 to a receiving part 2 and a transmitting part 3. The AFC part 6 compares a signal obtained by converting a signal with frequency deviation from the base station of the receiving part 2 into an intermediate frequency with the output of the reference frequency generating part 5, changes the value of the control signal so as to be matched with the deviation, and controls the reference frequency. When the AFC control is completed, the control part 8 judges whether or not the electric field intensity and data error rate presumed value of the received signal fulfill a prescribed condition, and writes the temperature data and the value of the control signal obtained when the prescribed condition is fulfilled in the initial signal storage part 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital portable telephone device, and more particularly to a digital portable telephone device, which determines a frequency to be transmitted / received on a radio channel based on a changeable reference frequency, and communicates with each of a plurality of base stations via the radio channel. The present invention relates to a digital mobile phone device of a digital mobile communication system for transmitting and receiving information such as voice between digital modulation and demodulation.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional digital cellular phone of this type includes a common unit 101 and a receiving unit 102.
, Transmission section 103, frequency generation section 104, reference frequency generation section 105, AFC section 106, modulation and demodulation section 107
, Control unit 108, operation unit 109, display unit 110
And a handset 111. The signal (carrier signal) on the radio channel received by the common unit 101 via the antenna is passed to the receiving unit 102, mixed with the local oscillation signal and replaced with the intermediate frequency signal, and further transmitted to the modem unit 1.
07 and the AFC unit 106. The intermediate frequency signal supplied from the receiving unit 102 is demodulated by the modulation / demodulation unit 107, passes through the control unit 108, and is output from the handset 111 as an audio signal. On the other hand, the sound input to the handset 111 is digitally modulated by the modem 107 through the control unit 108, converted to a signal (carrier signal) on a wireless channel by the transmission unit 103, and amplified. After, common use section 1
01 and transmitted. Further, an operation unit 109 and a display unit 110 that provide convenience for making a call are connected to the control unit 108.

A frequency generator 104 receives a reference frequency signal from a reference frequency generator 105, generates a local oscillator signal with an accuracy equal to the frequency accuracy of the reference frequency signal by a PLL, and generates a local oscillator signal with a receiver 102 and a transmitter 103. To supply. The reference frequency generator 105 is required to output a stable frequency in a certain range with respect to the ambient temperature. However, the digital portable telephone device is also required to be small, light, and inexpensive, and the output frequency accuracy and stability of the reference frequency generation unit 105 cannot be increased so much. For this reason, the frequency of the local oscillation signal also tends to fluctuate, and transmission and reception at a desired frequency on a wireless channel may not be possible. On the other hand, the output frequency accuracy of the reference frequency generation means in each base station of the digital mobile communication system,
The degree of stability is extremely high, and a carrier signal transmitted and received on a wireless channel can have a very small frequency deviation from a specified frequency. The deviation amount is slightly different for each base station. Therefore, on the digital mobile phone device side, it is necessary to match the frequency deviation in transmission / reception of the own device with the frequency deviation of the carrier signal of the connected base station, that is, the frequency deviation of the corresponding intermediate frequency signal, AFC control for frequency (a
automatic frequency contro
l: automatic frequency control). AF in the prior art
In the C control, first, the AFC unit 106 sends one determined initial control signal to the reference frequency generation unit 105, and the reference frequency generation unit 105 generates a frequency at the value of the given initial control signal. , The AFC unit 106, the receiving unit 102
The value of the control signal is changed to match the frequency deviation of the intermediate frequency signal supplied from
(See JP-A-3-162016).

[0004]

The problems of the above-mentioned conventional digital portable telephone device are that an extremely high frequency accuracy is required for the output of the reference frequency generation unit, and that the output of the reference frequency generation unit is high over a wide range even when the temperature changes. Need stability.
This is expensive. The reason is that in the digital mobile communication system, even if the receiving station oscillation frequency is slightly shifted, the signal cannot be received.
Further, the temperature of the external environment changes drastically with the movement of the digital cellular phone device, and the transmitting unit generates extreme heat during a call, so that the temperature change range is widened. Further, if the AFC control is performed in a state where the signal cannot be received, the frequency of the reference frequency generation unit may converge to an illegal radio wave or the like, and the digital mobile phone device is out of the service area and is fatal. Further, as a means for solving this problem, there is a means for constantly operating the AFC control, but this is an inappropriate solution in a digital portable telephone device which uses a battery as a power supply due to a large current consumption.

[0005] Further, when the reception electric field condition is not good, A
When the FC control is performed, the frequency of the reference frequency generator may not exactly match the frequency deviation of the base station. The reason is that in a state where the received electric field is low, there is also an effect of fading, and the intermediate frequency signal supplied to the AFC section has a large amount of phase noise, so that frequency counting cannot be performed accurately and frequency comparison is erroneous. Similarly, if the AFC control is performed in a state where the reception quality state is not good, the frequency of the reference frequency generation unit may not exactly match the frequency deviation of the base station. The reason is that in a state where the reception quality is poor due to an interference interference wave or the like, the interference wave is superimposed on the intermediate frequency signal supplied to the AFC unit, so that the frequency count cannot be performed accurately and the frequency comparison is erroneous.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-cost telephone connection without requiring a high-precision reference frequency generation unit, and a stable frequency accuracy while preventing an increase in current consumption without performing AFC control continuously. It is an object of the present invention to provide a digital mobile phone device for improving the degree.

[0007]

A digital portable telephone device according to the present invention determines a frequency to be transmitted / received on a radio channel based on a changeable reference frequency, and communicates with each of a plurality of base stations via the radio channel. In a digital mobile phone device of a digital mobile communication system for transmitting and receiving information such as voice by digital modulation and demodulation between, a control signal is input,
A reference frequency generation unit that outputs the reference frequency according to the value of the control signal with a change due to a temperature change, and receives a signal on a wireless channel from the base station, and a local oscillation signal based on the reference frequency. A receiving unit that mixes and converts the signal into an intermediate frequency signal and outputs the signal to the modem unit, and an initial control signal that specifies an initial value of the control signal is input, and the frequency of the output signal of the receiving unit and the reference frequency generating unit The frequency of the output signal is compared with the output signal of the reference frequency generation unit, the frequency deviation of the output signal of the reception unit is changed as needed from the initial value so as to match the frequency deviation of the output signal of the reception unit The control An AFC section that outputs the signal as a signal to the reference frequency generation section, a temperature detection section that measures the internal temperature of the apparatus and outputs the data as temperature data, the temperature data of the temperature detection section, The AFC at temperature indicated by over data
An initial signal storage unit that stores a pair of an initial value to be a value of the control signal of the unit, and a corresponding initial value that is read from the initial signal storage unit according to the temperature data from the temperature detection unit; A control unit that outputs the control signal to the AFC unit.

In the above configuration, the temperature detection unit may be installed close to the reference frequency generation unit, or if the electric field intensity of the reception signal of the reception unit is higher than a predetermined threshold, A configuration in which the storage content of the storage unit is rewritten, or a configuration in which the storage content of the initial signal storage unit is rewritten when the estimated value of the reception data error rate in the modulation / demodulation unit is lower than a predetermined threshold value can be adopted.

As described above, the digital portable telephone device of the present invention stores information when the ACF operation was previously completed for each temperature when performing the AFC operation, and uses this information as an initial control signal. AFC operation can always be performed from the signal reception state, and AFC can be completed accurately. Further, it is possible to accurately detect the temperature of the reference frequency generation unit, and prevent transmission of an erroneous initial control signal. Further, since it is possible to prevent a signal at the time of AFC completion which may be erroneous under a condition of a weak electric field or an interfering wave from being stored, it is possible to prevent transmission of an erroneous initial control signal.

[0010]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the digital mobile phone device of the present embodiment includes a common unit 1, a receiving unit 2, a transmitting unit 3, a frequency generating unit 4, a modem unit 7, an operating unit 9, a display unit 10, It comprises a handset 11, a reference frequency generating section 5, an AFC section 6, a control section 8, a temperature detecting section 12, and an initial signal storing section 13 having the characteristic functions of the present invention. Further, the temperature detecting section 12 is installed close to the reference frequency generating section 5.

As in the prior art, a signal of a carrier frequency on a radio channel transmitted from a base station (not shown) and received by the common unit 1 is passed to a receiving unit 2 and mixed with a local oscillation signal to produce an intermediate frequency signal. The signal is replaced by a signal, and further supplied to the modem unit 7 and the AFC unit 6. The electric field strength information detected by the reception unit 2 and the reception data error rate information estimated by the modulation / demodulation unit 7 are passed to the control unit 8. The intermediate frequency signal supplied from the receiving unit 2 is demodulated as an audio signal by the modem unit 7, passes through the control unit 8, and audio information is output from the handset 11. On the other hand, the voice information input to the handset 11
The signal is digitally modulated by the modulation / demodulation unit 7 through the control unit 8, converted into a signal of the carrier frequency on the radio channel by the transmission unit 3, amplified, and then supplied to the common unit 1 and transmitted to a base station (not shown). Is done. Further, an operation unit 9 and a display unit 10 that provide convenience for making a call are connected to the control unit 8. The frequency generator 4 includes a reference frequency generator 5
Receiving the supply of the reference frequency signal from the PLL and generating a local oscillation signal with an accuracy equal to the frequency accuracy of the reference frequency signal by the PLL;
This local oscillation signal is supplied to the receiving unit 2 and the transmitting unit 3.

FIG. 2 is a block diagram showing a detailed configuration of the reference frequency generator 5 and the temperature detector 12. The reference frequency generation unit 5 includes a crystal oscillator (XTAL) 51, an oscillation circuit unit 52 including a transistor, a resistor, a capacitor, and the like.
It oscillates and outputs at a frequency (reference frequency) determined from the voltage-controlled variable capacitance element 53 such as a varicap. When the control voltage applied to the variable capacitance element 53 is changed, the capacitance changes and the oscillation frequency changes. The control voltage is generated in the control voltage generator 54 according to the value of a control signal input from the outside. The oscillation frequency also changes due to the temperature change of the XTAL 51. However, since the frequency correction means by the temperature detection unit 12 is separately provided, the frequency accuracy for the temperature change in the reference frequency generation unit 5 alone needs to be high. And it can be configured at a lower cost. The temperature detector 12 includes a temperature-sensitive element 121 such as a thermistor whose resistance value changes according to a temperature change, and a lead wire 12.
And a converter 122 connected to the temperature-sensitive element 121 via the reference numerals 3 and 124 and outputting temperature data according to the resistance value. The temperature sensitive element 121 is located near the package of the reference frequency generation unit 5, more preferably, the XT in the package.
By arranging it in the immediate vicinity of the AL 51, the temperature of the reference frequency generator 5 can be accurately measured.

Next, the operation of the AFC control of the present invention will be described with reference to the flowchart of FIG. 3 together with FIGS.

The frequency of the carrier signal transmitted and received by each base station of the digital mobile communication system does not completely match the specified frequency of the corresponding radio channel, and there is some deviation. The amount of deviation is different for each base station. Although different, it is much more accurate and more stable than the reference frequency of the digital portable telephone device. Therefore, it is necessary for the digital portable telephone device to match the frequency deviation in transmission and reception of the own device with the frequency deviation of the carrier signal of the connected base station (the frequency deviation of the corresponding intermediate frequency signal). That is,
It is necessary to deviate the output frequency of the reference frequency generator 5 for generating a local signal for intermediate frequency conversion by the deviation. This deviation control is performed under the control of the controller 8 under the control of the AFC
This is performed by the unit 6 with reference to the initial signal storage unit 13. At this time, the frequency stabilization control for the temperature change is performed using the temperature detection unit 12 and the initial signal storage unit 13.

First, the control unit 8 reads the temperature data output of the temperature detection unit 12 (step S1), then searches the initial signal storage unit 13, and writes the written initial control signal (control value) for each temperature. Among these, an initial control signal corresponding to the temperature data is read out (step S2) and sent to the AFC unit 6 (step S3). The AFC unit 6 passes the initial control signal to the reference frequency generation unit 5, and
Generates a frequency (reference frequency) at a given value of the initial control signal. The frequency generator 4 supplies a local oscillation signal based on the frequency to the receiver 2 and the transmitter 3. Receiver 2
Converts the carrier signal received from the base station into an intermediate frequency signal according to the local oscillation signal. The transmitting unit 3 converts the modulated signal into a carrier signal according to the local oscillation signal and transmits the carrier signal to the base station.

The AFC unit 6 compares the intermediate frequency signal supplied from the receiving unit 2 with the output of the reference frequency generating unit 5,
The oscillation frequency of the reference frequency generator 5 is controlled by changing the value of the control signal so as to match the frequency deviation of the signal supplied from the receiver 2. For example, when the local oscillation signal frequency is set lower than the radio carrier signal frequency, if the frequency of the reference frequency signal is higher / lower, the local oscillator signal frequency is also higher / lower, and the intermediate frequency signal, that is, the receivable carrier wave The frequency of the signal is conversely low / high. In this way, the frequency deviation of the oscillation frequency of the reference frequency generator 5 is controlled so that the reception target signal can be accurately received. The AFC unit 6 that has successfully completed the oscillation frequency control sends the AFC signal to the control unit 8.
Notify the FC completion signal and the control signal (control value) given last to the reference frequency generator 5 (step S).
4). Upon receiving the notification of the AFC completion signal, the control unit 8 sets the electric field strength information output from the reception unit 2 to a predetermined value (for example, 20d).
Bμ), and when the estimated value of the received data error rate output from the modulation and demodulation unit 7 is less than a predetermined value (for example, 0.1%), the temperature data from the temperature detection unit 12 and the AFC unit at that point in time, respectively. 6 is written (rewritten) into the initial signal storage unit 13. Alternatively, when both of the above conditions are satisfied, that is, when the electric field intensity information output from the receiving unit 2 is higher than a predetermined value and the modulation / demodulation unit 7
May be written (rewritten) to the initial signal storage unit 13 when the received data error rate estimated value output by the controller is smaller than the predetermined value (step S).
6 to S10).

Note that a fixed initial control signal table is written in the initial signal storage unit 13 as initial data of a control signal value (control value) corresponding to a temperature when the digital cellular phone device is manufactured. Table 1 shows a configuration example of this table. Each initial control value can be rewritten under the above-described conditions. The adjustment at the factory is generally performed at 25 ° C., and the control value (127 in the example of Table 1) at this time is separately stored as a fixed value.

[0019]

[Table 1]

[0020]

As described above, according to the present invention, the following effects can be obtained. The first effect is that the frequency accuracy of the reference frequency generator can be reduced. Thus, an inexpensive digital mobile phone can be provided. The reason is that the initial signal storage unit stores the control signal of the reference frequency generation unit that matches the base station frequency deviation under good reception conditions for each temperature, so that an appropriate control signal is always stored in the reference frequency generation unit. This is because it can be given as an initial value.

The second effect is that a signal can always be received. As a result, it is possible to provide a digital mobile phone capable of reliably establishing a call connection. The reason is that the initial signal storage unit always stores the control signal of the reference frequency generation unit that matches the base station frequency deviation under good reception conditions where the reception electric field strength and the reception data error rate are good, so that it is always appropriate. This is because a signal can always be received by giving such a control signal to the reference frequency generator as an initial value.

A third effect is that the AFC control can be performed intermittently. This makes it possible to provide a digital mobile phone that consumes less current. The reason is that the initial signal storage unit stores the control signal for the reference frequency generation unit that matches the base station frequency deviation under good reception conditions for each temperature, so that an appropriate control signal is always stored in the reference frequency generation unit. This is because it can be given as an initial value.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a detailed configuration of a reference frequency generator and a temperature detector in FIG. 1;

FIG. 3 is a flowchart illustrating an example of an AFC control operation according to the present invention.

FIG. 4 is a block diagram showing a conventional digital mobile phone device.

[Explanation of symbols]

 Reference Signs List 2 receiving unit 3 transmitting unit 4 frequency generating unit 5 reference frequency generating unit 6 AFC unit 7 modem unit 8 control unit 12 temperature detecting unit 13 initial signal storage unit 51 crystal unit (XTAL) 121 temperature-sensitive element

Claims (4)

[Claims] 1. A transmission / reception frequency on a radio channel is determined based on a changeable reference frequency, and information such as voice is digitally modulated / demodulated with each of a plurality of base stations via the radio channel. A reference frequency generating unit that receives a control signal and outputs the reference frequency according to the value of the control signal while fluctuating due to a change in temperature; and Receiving a signal on the wireless channel of, and mixing with a local oscillation signal based on the reference frequency, converts the signal into an intermediate frequency signal, and outputs the signal to the modulation / demodulation unit, and an initial control signal that specifies an initial value of the control signal. The frequency of the output signal of the reference frequency generator is compared with the frequency of the output signal of the receiver and the frequency of the output signal of the reference frequency generator. An AFC unit that outputs a value changed as needed from the initial value so that the number deviation matches the frequency deviation of the output signal of the reception unit as the control signal to the reference frequency generation unit; A temperature detector that measures and outputs the temperature data, a pair of the temperature data of the temperature detector, and an initial value to be used as a value of the control signal of the AFC unit at a temperature indicated by the temperature data. An initial signal storage unit that reads the corresponding initial value from the initial signal storage unit according to the temperature data from the temperature detection unit, and outputs the read initial value to the AFC unit as the initial control signal. Digital mobile phone device. 2. The digital portable telephone device according to claim 1, wherein said temperature detecting section is installed close to said reference frequency generating section. 3. The digital portable telephone device according to claim 1, wherein the storage content of said initial signal storage unit is rewritten when the electric field intensity of the reception signal of said reception unit is higher than a predetermined threshold. 4. The digital portable telephone device according to claim 1, wherein the storage content of said initial signal storage unit is rewritten when the received data error rate estimation value in said modem unit is lower than a predetermined threshold value.