JPH06296145A - Battery-driven transmitter-receiver - Google Patents

Abstract

PURPOSE:To make a battery-driven transmitter-receiver small in size and light in weight without deteriorating the performance. CONSTITUTION:After a base band circuit 32 converts a level of transmission data into a voltage within a predetermined level, a frequency modulator 33 applies FM modulation to the data at a predetermined intermediate frequency and transmits the result externally and a signal received externally is mixed with an intermediate frequency signal from the FM modulator 33 at a mixer 42 and the mixed signal is detected by a detection circuit 44 to obtain reception data in the transmitter-receiver. The frequency modulator 33 is operated at a region where a changing characteristic of an output frequency with respect to an input voltage is nonlinear and the base band circuit 32 converts the level of transmission data into a voltage range corresponding to the operating region of the frequency modulator 33 at transmission and applies the level of the data in the reception state so that the frequency outputted from the frequency modulator 33 is an intermediate frequency between a maximum and a minimum output frequency in the operating region of the frequency modulator 33 by the output voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a hand-operated battery-powered transceiver used in a specified low power radio station or the like.

[0002]

2. Description of the Related Art Conventionally, a battery-driven transceiver of this type has a structure shown in FIG. That is, the transmission data input to the transmission terminal 1 is level-converted into a voltage within a predetermined level range by the baseband circuit 2 and supplied to the FM modulator 3.
The FM modulator 3 receives the input voltage signal at a predetermined intermediate frequency f
FM modulation is performed by _LO , and the obtained modulation signal is supplied to the mixer 4.

The mixer 4 mixes the modulated signal with the high frequency signal from the local oscillation circuit 5 and converts it into a predetermined high frequency signal.
Then, the high-frequency signal from the mixer 4 is transmitted to the transmission output amplifier circuit 6
After being amplified to a predetermined level by, the signal is transmitted to the outside via the transmission / reception changeover switch 7 and the antenna 8.

Further, a radio signal from the outside is received by the antenna 8, and the received signal is supplied to the high frequency circuit 9 via the transmission / reception changeover switch 7. The high frequency circuit 9 amplifies the signal and supplies it to the first reception mixer 10.

The first receiving mixer 10 mixes the signal from the high-frequency circuit 9 with the high-frequency signal from the local oscillation circuit 5 to convert it into a first intermediate-frequency signal, and the first intermediate-frequency circuit 11
Is being supplied to. The first intermediate frequency circuit 11 amplifies the input intermediate frequency signal and supplies it to the second receiving mixer 12.

During reception, the FM modulator 3 operates as a local oscillator and supplies an intermediate frequency signal of frequency f _LO to the second receiving mixer 12. The second receiving mixer 12 mixes the input intermediate frequency signal with the intermediate frequency signal f _LO from the FM modulator 3, converts the mixed intermediate frequency signal into a second intermediate frequency signal, and supplies it to the second intermediate frequency circuit 13. There is. Second intermediate wave circuit 13
Amplifies the input intermediate frequency signal and supplies it to the detection circuit 14.

The detection circuit 14 detects the intermediate frequency signal and outputs the reception data to the reception terminal 15.

As shown in FIG. 5, the FM modulator 3 used in such a transmitter / receiver is composed of a voltage controlled crystal oscillation circuit composed of a variable capacitance diode 16, a crystal oscillator 17, a transistor 18, etc., and is inputted. The converted voltage signal V _in is converted into the frequency signal f _out and output. The voltage-frequency characteristic of the FM modulator 3 is as shown in FIG.
With the above, good linearity is obtained. Therefore, five 1.2V Ni-Cd batteries are used as a power source to generate a power source voltage of 5V, and the input voltage to the FM modulator 3 is set to a linear range of 2 to 5V. As a result, a desired frequency shift is obtained.

As shown in FIG. 7, the baseband circuit 2 is provided with a level conversion circuit 19 and a low-pass filter 20 and supplies a signal of 0 to 5 V input to an input terminal 21 to the level conversion circuit 19 to obtain this level. FM in the conversion circuit 19
In order to perform modulation in a range where the modulator 3 has good linearity, 2 to
Converted to 5V baseband signal and low pass filter 2
It is adapted to output to the output terminal 24 via 0.
The resistors 22 and 23 have a value of about 100 kΩ, for example, and can be ignored during transmission.

For example, if the output frequency when 2V is input to the FM modulator 3 is f ₂ , the output frequency when 5V is input is f _5, and the frequency at the time of modulation is f _LO , FM
Since the modulator 3 operates in the range of good linearity, the formula of f _LO = (f ₂ + f ₅ ) / 2 is satisfied at the time of transmission.

When receiving, the input terminal 2 of the baseband circuit 2
1 becomes a high impedance state, and a voltage having a value obtained by dividing the power supply voltage V _CC by the resistors 22 and 23 is generated at the input terminal 21. Since the FM modulator 3 operates in the range of good linearity, the resistance value ratio of the resistors 22 and 23 is set to 1: 1 and V _CC /2=2.5V is applied to the input terminal 21. Will occur. Then, the level conversion circuit 19 inputs 2.5V, level-converts this voltage to 3.5V which is an intermediate voltage in the range of 2 to 5V at which the FM modulator 3 operates, and outputs it.

When the output frequency when a voltage of 3.5 V is input to the FM modulator 3 is f _3.5 , f _LO = f _{3.5 as} shown in FIG.

As a result, the frequency output from the FM modulator 3 during transmission and the frequency output from the FM modulator 3 during reception are the same frequency f _LO .

[0014]

When the power supply voltage is set to 5V by using the five batteries as described above, the FM modulator 3 is used.
Since there is no problem because a good range of voltage-frequency characteristics of linearity can be used, in order to reduce the size and weight of the device,
When three 1.2V Ni-Cd batteries are used and the power supply voltage is set to 3V, the non-linear region of the voltage-frequency characteristic of the FM modulator 3 is used, and the difference between the oscillation frequency at the time of transmission and the oscillation frequency at the time of reception. Occurs. That is, when the input voltage is 3 V or less, the change in the output frequency increases as the input voltage decreases, as can be seen from FIG.

When the FM modulator 3 is operated in this nonlinear region, for example, when the output frequency when a voltage of 0.5 to 2.5 V is input to the FM modulator at the time of transmission is f _LO , the FM modulation at the time of reception is performed. A voltage of 1.5 V, which is an intermediate voltage of 0.5 to 2.5 V, is input to the container and the output frequency at that time is f
When _1.5, not the _{f LO = f 1.5, f LO} <f 1. 5
Becomes

As described above, when the conventional baseband circuit is used, if the number of batteries used is reduced and the power supply voltage is lowered, a difference occurs in the oscillation frequency of the FM modulator between transmission and reception, and as a result, There is a problem that deviation from the specified value of the transmission frequency from the antenna and deviation from the specified value of the local oscillation frequency at the time of reception occur, resulting in deterioration of performance such as increased leakage to adjacent channels and deterioration of reception sensitivity. It was

Therefore, according to the present invention, even if the number of batteries used is reduced and the power supply voltage is lowered, the deviation from the specified value of the transmission frequency at the time of transmission and the deviation from the specified value of the local oscillation frequency at the time of reception do not occur. Therefore, it is an object of the present invention to provide a battery-powered transceiver that can be made compact and lightweight without degrading its performance.

[0018]

According to the present invention, transmission data is level-converted by a baseband circuit into a voltage in a predetermined level range, then FM-modulated at a predetermined intermediate frequency by an FM modulator, and further, a local oscillator circuit is generated by a mixer. After being mixed with the high frequency signal of and converted to a predetermined high frequency signal, it is transmitted to the outside through the antenna, and the high frequency signal received from the outside from the antenna is mixed with the high frequency signal from the local oscillation circuit by the mixer and the predetermined frequency is mixed. In a battery-powered transceiver that converts to an intermediate frequency signal and further mixes with the intermediate frequency signal from the FM modulator to detect by a detection circuit to obtain received data, the FM modulator is
The baseband circuit is operated in a region where the change characteristic of the output frequency with respect to the input voltage is non-linear, and the baseband circuit converts the level of the transmission data in the voltage range corresponding to the operating region of the FM modulator at the time of transmission, and at the same time outputs the output voltage at the time of reception. The output voltage is level-converted so that the frequency output from the FM modulator becomes an intermediate frequency between the maximum and minimum output frequencies in the operating region of the FM modulator.

[0019]

In the present invention having such a configuration, during transmission, the transmission data is transmitted in the baseband circuit in a voltage range corresponding to the operating region of the FM modulator, that is, the region where the output frequency change characteristic with respect to the input voltage is non-linear. Convert the level with. Further, during reception, the baseband circuit level-converts the output voltage so that the frequency output from the FM modulator by the output voltage becomes an intermediate frequency between the maximum and minimum output frequencies in the operating region of the FM modulator. Thereby, the output frequency of the FM modulator at the time of transmission and the output frequency of the FM modulator at the time of reception can be set to the same desired intermediate frequency.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 33 is an FM modulator, 34 is a mixer, 35 is a local oscillator circuit, 36 is a transmission output amplifier circuit,
37 is a transmission / reception selector switch, 38 is an antenna, 39 is a high frequency circuit, 40 is a first receiving mixer, 41 is a first intermediate frequency circuit, 42 is a second receiving mixer, and 43 is a second intermediate frequency circuit. , 44 are detection circuits, which have the same configuration as that of FIG.

The transmission data input to the transmission terminal 31 is input to the baseband circuit 32. In addition, the detection circuit 4
The received data from No. 4 is output to the transmission terminal 45.

As shown in FIG. 2, the base band circuit 32 includes a semi-fixed resistor 46, between the input / output terminals 21 and 24.
A voltage divider circuit in which 47 is connected in series, a level conversion circuit 48 for converting the level of the voltage signal from the voltage division circuit, and a low-pass filter 20 for outputting the output of the level conversion circuit 48 to the output terminal 24. There is.

For example, three 1.2V Ni-Cd batteries are used as the power source of this device, and the power source voltage of 3V is obtained from these batteries.

In the baseband circuit 32, transmission data of 0 to 3 V is input to the input terminal 21 during transmission,
This data is converted into a voltage signal of 0.5 to 2.5 V by the level conversion circuit 48 and the low pass filter 20 and output to the output terminal 24.

The baseband circuit 32 sets the input terminal 21 in a high impedance state during reception, generates a voltage obtained by dividing the power supply voltage by the voltage dividing circuit at the input terminal 21, and supplies the voltage to the level conversion circuit 48. It is like this.

The FM modulator 33 has a voltage of 0.5V to 2.5V.
When operated in the range, frequency conversion is performed in the region where the voltage-frequency characteristic becomes non-linear as shown in FIG.
The oscillation frequency of the FM modulator 33 is adjusted so that a predetermined intermediate frequency f _LO can be obtained during transmission when it is operated in this nonlinear region.

When the FM modulator 33 is operated in this non-linear region, a predetermined intermediate frequency f _LO is obtained when the input voltage is V _LO (<1.5 V) as shown in FIG. 3 during reception. . From this, the baseband circuit 32 is
During reception, the semi-fixed resistors 46 and 47 are adjusted so that the voltage V _LO is output to the output terminal 24. That is, when the voltage-frequency characteristic at which the FM modulator 33 operates is as shown in FIG.
Assuming that the resistance value of the semi-fixed resistor 46 is R ₁ and the resistance value of the semi-fixed resistor 47 is R ₂ , R ₁ > R ₂ , that is, the voltage V _LO generated at the input terminal 21 is 3V / 2 = 1. It is set to be smaller than 5V.

In the embodiment having such a structure, 0 to 3 V is applied to the input terminal 21 of the baseband circuit 32 during transmission.
Transmission data is input, and this data is input to the level conversion circuit 48 and the low-pass filter 20 for 0.5 to 2.5.
It is converted into a V voltage signal and output to the output terminal 24.
As a result, a voltage signal of 0.5 to 2.5 V is input from the baseband circuit 32 to the FM modulator 33.

The FM modulator 33 inputs a voltage signal in the range of 0.5 to 2.5 V, frequency-converts it, and performs FM modulation at a predetermined intermediate frequency f _LO . Then, the obtained modulated signal is mixed with the high frequency signal from the local oscillation circuit 5 by the mixer 34 to be converted into a predetermined high frequency signal, and further, the transmission output amplification circuit 3
After amplifying to a predetermined level in 6, the transmission / reception changeover switch 37
And to the outside via the antenna 38.

At the time of reception, a voltage obtained by dividing the power supply voltage 3V by the semi-fixed resistors 46 and 47 is generated at the input terminal 21 of the baseband circuit 32. Then, this voltage is input to the level conversion circuit 48, and the voltage V _LO is output to the output terminal 24 via the low pass filter 20. As a result, the voltage V _LO is input from the baseband circuit 32 to the FM modulator 33.

The FM modulator 33 inputs the voltage V _LO , frequency-converts it, generates a predetermined intermediate frequency f _LO , and supplies it to the second mixer 42.

Therefore, at the time of reception, a radio signal from the outside is received by the antenna 38, and the received signal is amplified by the high frequency circuit 39 via the transmission / reception changeover switch 37 and input to the first reception mixer 40.

The first receiving mixer 40 is a high frequency circuit 39.
Is mixed with the high frequency signal from the local oscillator circuit 35 to be converted into a first intermediate frequency signal. This first intermediate frequency signal is amplified by the first intermediate frequency circuit 41 and then amplified by the second intermediate frequency circuit 41.
Input to the receiving mixer 42.

The second receiving mixer 42 mixes the input intermediate frequency signal with the intermediate frequency signal f _LO from the FM modulator 33 and converts it into a second intermediate frequency signal. The second intermediate frequency signal is amplified by the second intermediate frequency circuit 43, then detected by the detection circuit 14, and the reception data is output to the reception terminal 45.

As described above, in the case where the power supply voltage is set to 3 V and the FM modulator 33 is operated in the non-linear region of 0.5 V to 2.5 V, the intermediate frequency during transmission and the intermediate frequency generated during reception are defined by the frequency f _LO . Can be matched.

Therefore, even if the number of batteries used is reduced and the power supply voltage is lowered, there is no risk that the transmission frequency will deviate from the specified value during transmission or the local oscillation frequency will deviate from the specified value during reception. Thus, it is possible to reduce the size and weight without deteriorating the performance.

In the above embodiment, the baseband circuit 3
Although the voltage dividing circuit 2 is composed of a semi-fixed resistance, it is not necessarily limited to this, and a normal resistance may be used if the resistance value is determined by a test.

[0039]

As described above, according to the present invention, even if the number of batteries used is reduced and the power supply voltage is reduced, the intermediate frequency at the time of transmission and the intermediate frequency generated at the time of reception can be matched. There is no fear that the transmission frequency will deviate from the specified value or the local oscillation frequency will deviate from the specified value at the time of reception, and therefore the size and weight can be reduced without degrading the performance.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a configuration of a baseband circuit of the same embodiment.

FIG. 3 is a graph showing voltage-frequency characteristics in an operation region of the FM modulator according to the same example.

FIG. 4 is a block diagram showing a conventional example.

FIG. 5 is a diagram showing a configuration of an FM modulator of the conventional example.

FIG. 6 is a graph showing voltage-frequency characteristics of the FM modulator of the conventional example.

FIG. 7 is a diagram showing a configuration of a baseband circuit of the conventional example.

[Explanation of symbols]

 32 ... Baseband circuit 33 ... FM modulator 34, 40, 42 ... Mixer 35 ... Local oscillation circuit 38 ... Antenna 41, 43 ... Intermediate frequency circuit 44 ... Detection circuit

Claims (1)

[Claims] 1. A baseband circuit level-converts transmission data into a voltage within a predetermined level range, an FM modulator performs FM modulation at a predetermined intermediate frequency, and a mixer mixes it with a high-frequency signal from a local oscillation circuit to determine a predetermined frequency. After being converted to a high-frequency signal, it is transmitted to the outside through an antenna, and the high-frequency signal received from the outside through the antenna is mixed with a high-frequency signal from the local oscillator circuit by a mixer into a predetermined intermediate frequency signal. In a battery-driven transceiver for converting and further mixing with an intermediate frequency signal from the FM modulator to detect by a detection circuit to obtain received data, the FM modulator has a non-variable output frequency characteristic with respect to an input voltage. The baseband circuit is operated in a linear region, and at the time of transmission, the baseband circuit level-converts the transmission data within a voltage range corresponding to the operating region of the FM modulator. At the same time, at the time of reception, the output voltage is level-converted by the output voltage so that the frequency output from the FM modulator becomes an intermediate frequency between the maximum and minimum output frequencies in the operating region of the FM modulator. Battery-powered transceiver.