JPH05244033A - Dual-band radio communication device - Google Patents

Abstract

PURPOSE:To reduce the size of the device by inputting the fundamental frequency of the output of a local oscillation circuit for transmission or its multiplied frequency to a mixer and converting a common IF signal into an RF signal of a 1st or 2nd band. CONSTITUTION:For transmission using the 1st band, a switch 6 is set to a terminal (a), the fundamental wave of a frequency synthesizer 4 is inputted as a local oscillation signal to the mixer 3, and the IF signal is converted up to the transmission frequency of the 1st band. Then a 1st RF circuit 7 removes an image frequency component and the signal is sent. For transmission using the 2nd band, the switch 6 is set to a terminal (b), the output of the synthesizer 4 is inputted to a doubler circuit 5, and a generated 2nd higher harmonic is used as the local oscillation signal to convert an IF signal up to the transmission frequency of the 2nd band by the mixer 3, thereby transmitting the signal. Thus, circuits shared for communication in the 1st and 2nd bands are increased to reduce the size of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual band wireless communication device. In particular, it relates to compatible digital car phones.

[0002]

2. Description of the Related Art In Japan, the service of a digital car telephone system is scheduled to start in 1993. The frequency bands assigned to this are:
There are two bands, 800MHz band and 1.5GHz band.

The base station transmission frequency in this 800 MHz band is
810 to 826 MHz, and the mobile station transmission frequency is 940 to 956 MHz. This 800 MHz band will be allocated to existing analog car phone carriers such as NTT (registered trademark). The base station transmission frequency in the 1.5 GHz band is 14
77-1489MHz and 1501-1513MHz. Also this 1.5G
The mobile station transmission frequency in the Hz band is 1429 to 1441 MHz and 1
453 to 1465 MHz. This 1.5GHz band will be allocated to new operators such as Japan Telecom.

By the way, there is a demand for a compatible digital car telephone which is capable of communicating by connecting to both the 800 MHz band and the 1.5 GHz band. This compatible digital car telephone is technically a dual band wireless communication device. By the way, a conventional dual-band wireless communication device used for amateur radio or the like includes a transmission system circuit and a reception system circuit for each band. That is, the conventional dual-band wireless communication device has two transmission system circuits and two reception system circuits, and selects one of them according to the band to be used for communication.

[0005]

In the conventional dual band radio communication device, the transmission / reception system circuit has two circuits for each.
Since it is composed of a system, there is a problem that the circuit becomes large.

[0006]

According to the present invention, a mixer local oscillation input for up-converting a transmission intermediate frequency signal (transmission IF signal) to a transmission radio frequency signal (transmission RF signal) in a transmission system mixer circuit (3). As a local oscillator circuit for transmission
It is characterized in that the RF signal of the first or second band is generated from the common transmission IF signal by selecting either the component of the fundamental frequency of the output of (4) or the multiplied frequency thereof.

Further, according to the present invention, when the receiving RF signal is down-converted into the receiving IF signal by the receiving mixer circuit (15), the output of the receiving local oscillator circuit (14) is used as the local oscillation input of the mixer (15). Of the fundamental frequency or the frequency multiplication frequency of the corresponding frequency component is input and the received radio frequency signal (reception RF signal) of the first or second band is received as a common reception intermediate frequency signal (reception IF signal). ) To enable dual band reception.

[0008]

Since the present invention has the above-mentioned configuration, the output of the transmitting / receiving local oscillation circuit (14) for the second band is created by the multiplied frequency.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a compatible digital car telephone will be described with reference to FIG. This compatible digital car phone can communicate in both 800MHz band and 1.5GHz band. The communication frequency of this compatible digital car phone in the 1.5 GHz band is 1453 MHz to 1465 MHz.
z, the reception frequency is possible only in the 12MHz band of 1501-1513MHz.

(1) is a modulator. This modulator (1) outputs a modulated wave. (2) is a transmission system IF signal processing circuit (transmission IF circuit). The transmission IF circuit (2) up-converts the modulated wave up to a transmission intermediate frequency (transmission IF frequency) of 429 MHz. (3) is a mixer. The mixer (3) multiplies the signal of the transmission IF frequency by a local oscillation signal corresponding to the transmission channel from the frequency synthesizer (4) and up-converts it to a radio frequency.

(4) is a frequency synthesizer. This frequency synthesizer (4) has a built-in local oscillation circuit, and the oscillation frequency of this local oscillation circuit is changed by changing the set value of the internal program divider. Generally, the channels of digital car phones are 25 KHz intervals,
The oscillation frequency of 25 KHz is changed by changing at least the minimum unit of the set value. However, in this embodiment, since the output of the local oscillation circuit is doubled by the doubler circuit as will be described later, at the time of transmission in the 800 MHz band, the minimum unit of the set value of the program divider is changed to obtain the oscillation frequency of 12.5 KHz. Designed to be changed.

(5) is a doubler circuit. (6) is a switch circuit. (7) and (8) are first and second transmission system radio frequency signal processing circuits (first and second transmission RF circuits). The first transmission RF circuit (7) removes the image frequency component of the 800 MHz band transmission signal and amplifies the power. Further, the second transmission RF circuit (8) removes the image frequency component of the 1.5 GHz band transmission signal and performs power amplification.

(9) is an antenna selector. (10) is an antenna. (11) is a receiving RF circuit. The reception system RF circuit (11) amplifies a reception signal and removes an interference wave. (12) is a switch circuit.

(13) is a doubler circuit. (14) is a frequency synthesizer. Like the frequency synthesizer (4), this frequency synthesizer (14) has a built-in local oscillation circuit, and the oscillation frequency of the local oscillation circuit is changed by changing the set value of the internal program divider. In addition, when receiving in the 800MHz band, it is designed to change the oscillation frequency of 12.5KHz by changing the minimum unit of the setting value of the program divider.

(15) is a mixer. This Mixer (15)
Converts the received signal to a received 1IF frequency of 129 MHz. To this end, the mixer (15) multiplies the received signal and the local oscillation signal to perform down conversion. (16) is
It is a reception system intermediate frequency signal processing circuit (reception IF circuit).
The reception IF circuit (16) performs interference wave removal, conversion to a second IF frequency of 450 KHz, waveform shaping, and signal amplification.

(17) is a demodulation circuit. First, the operation of the transmission system will be described. The modulated wave generated by the modulator (1) is up-converted to the transmission IF frequency by the transmission IF circuit (2). Further, this signal is up-converted by a mixer (3) to a radio frequency corresponding to the transmission channel. This mixer (3) uses the local oscillator signal from the frequency synthesizer (4) and the IF for this up-conversion.
Cross with the frequency.

FIG. 2 shows a method of deriving the transmission IF frequency and the oscillation frequency of the local oscillation circuit of the frequency synthesizer (4).
This will be described with reference to FIG. In FIG. 2, (Frt1) is the transmission center frequency of the first band. (BW1) is the transmission frequency width of this first band. (Frt2) is the transmission center frequency of the second band. (BW2) is the transmission frequency width of this second band. (Fit) is the IF frequency.

Thus, the first band (Frt1 ± BW1 / 2),
There are two transmission frequency bands (Frt2> Frt1) different in the second band (Frt2 ± BW2 / 2), and it is considered that signals in either of these bands are output for communication. The modulated signal converted into the frequency (Fit) by the transmission IF circuit is further multiplied by the local oscillation signal by the mixer (3) as shown in FIG. 3 and up-converted to the radio frequency.

The local oscillation frequency band of the mixer (3) at this time is Flt ± BW / 2. BW is a large value of BW1 and BW2. Then, assuming that Flt = Frt2-Frt1, Fit = Frt1-Flt ... [Condition 1], (Frt2 ± ΔFt) −2 · (Flt ± ΔFt / 2) = Fit ΔFt: Actual in the second band Is the deviation between the transmission frequency and the center frequency (Frt2).

That is, when the transmission IF frequency and the local oscillation frequency are selected as in [Condition 1], the RF component of the first band is determined by the sum component of the fundamental waves of the transmission IF frequency and the local oscillation frequency.
Can produce a signal. On the other hand, the radio frequency of the second band can be created by the sum component of the transmission frequency signal and the doubled signal of the local oscillation frequency.

It is determined according to this [Condition 1]. Local oscillation frequency (Flt) = Frt2-Frt1, = 2nd band transmission frequency-1st band transmission frequency = (1453 to 1465MHz)-(940 to 956MHz) = 1459MHz-948MHz = 511MHz Transmission IF signal (Fit) = Frt1- Flt = 1st band transmission frequency-local oscillation frequency = 948MHz-511MHz = 437MHz The IF frequency is 437MHz and the transmission frequency synthesizer oscillation frequency is 511 ± 8MHz.

In other words, when used as an 800 MHz band transmitter, the switch (6) selects the terminal a, and the fundamental wave of the frequency synthesizer (the frequency component corresponding to the channel to be transmitted within the range of 519 ± 8 MHz) is locally transmitted. Mixer as oscillating signal
940-956M when the transmission IF signal is up-converted in (3)
It is converted to the transmission radio frequency of the first band of Hz. The first transmission RF circuit (7) removes this image frequency component, amplifies the power, and then passes through the antenna selector (9) to the antenna (10).
Power is released from the air into the air.

When used as a transmitter in the 1.5 GHz band, the switch (6) selects the terminal b and inputs the output of the frequency synthesizer into the frequency doubler circuit (13) to generate the second harmonic ( If the transmission IF signal is up-converted by the mixer (3) with the frequency component corresponding to the channel to be transmitted within the range of 1022 ± 6 MHz) as the local oscillation signal, 1
It can be converted to the transmission radio frequency of the second band from 453 to 1465 MHz.

The second transmission RF circuit (8) removes the image frequency components and amplifies the power, and then the antenna (10) emits power to the air through the antenna selector (9). Next, the operation of the receiving system will be described. Antenna (1
The received signal received at 0) is input to the receiving RF circuit (11) via the antenna selector (9).

Here, after the signal is amplified and the interference wave is removed, the received signal is multiplied by the local oscillation signal so as to be down-converted by the mixer (15) so as to be converted into the received first IF frequency. A method of deriving the reception IF frequency and the oscillation frequency of the local oscillation circuit of the frequency synthesizer (14) will be described with reference to FIGS.

In FIG. 4, (Frr1) is the reception center frequency of the first band. (BW1) is the reception frequency width of this first band. (Frr2) is the transmission center frequency of the second band. (BW2) is the transmission frequency width of this second band. (Fir) is the reception IF frequency. Like this first
Band _{(Frr1 ± BW 1/2)} , there are two reception frequency bands (Frr2> Frr1) is different in the second band _{(Frr2 ± BW 2/2)} , it receives an RF signal in either of these bands.

The received RF signal is mixed by a mixer (15) as shown in FIG.
In this case, the signal is multiplied with the local oscillation signal and down-converted to the reception IF frequency. The local oscillation frequency band of the mixer (15) at this time is Flr ± BW / 2. At this time, if Flr = Frr2-Frr1, Fir = Frr1-Flr ... [Condition 2], then (Frr2 ± ΔFr) −2 · (Flr ± ΔF _R / 2) = Fir ΔFr: Second band It is the deviation between the actual reception frequency at and the center frequency Frr2.

That is, when the reception IF frequency and the local oscillation frequency are selected as in [Condition 2], the difference component between the RF signal of the first band and the fundamental wave of the local oscillation frequency becomes the reception IF frequency Fir. On the other hand, the difference component between the RF signal of the second band and the doubled signal of the local oscillation frequency is the same as the reception IF frequency (Fi
r), the reception frequency signals of two different bands can be converted into a common reception IF frequency.

The reception IF frequency is 129 MHz and the transmission frequency synthesizer oscillation frequency is 689 ± 8 MHz. The reception IF frequency and the reception frequency synthesizer frequency are determined according to the above [condition 2]. Local oscillation frequency (Flr) = Frr2-Frr1 = Second band reception frequency-First band reception frequency = (1501 to 1513MHz)-(810 to 826MHz) = 1507MHz-818MHz = 689MHz Reception IF signal (Fir) = Frr1 to Flr = First band reception frequency-Local oscillation frequency = (810 to 826 MHz) -689 MHz = 818 MHz-689 MHz = 129 MHz The reception IF frequency is 129 MHz and the oscillation frequency is 689 ± 8 MHz.

That is, when used as an 800 MHz band receiver, the switch (12) selects the terminal a and sets the fundamental wave of the frequency synthesizer (frequency component corresponding to the channel to be received within the range of 519 ± 8 MHz). It is supplied to the mixer (15) as a local oscillation signal. This local oscillator signal allows the mixer
(15) down-converts the reception RF signal of the first band to the reception first IF frequency of 129 MHz.

This signal is further input to the reception system IF circuit (16) to be subjected to interference wave elimination processing, conversion to the second IF frequency (450 KHz), waveform shaping processing and signal amplification processing, and then the demodulator.
Output to (17). It is demodulated by this demodulator (17). 1.5G
When used as a Hz band receiver, the switch (12) selects the b terminal and outputs the output of the frequency synthesizer (14) to a doubling circuit (1
The second harmonic (the frequency component corresponding to the channel to be received in the range of 1378 ± 6 MHz) generated by inputting to 3) is supplied to the mixer (15) as a local oscillation signal. Mixer (1
5) thereby down-converts the received RF signal of the second band.

In this way, even when receiving in the 1.5 GHz band, it is possible to convert to the receiving first IF frequency of 129 MHz as in the case of receiving in the 800 MHz band. This is further input to the reception system IF circuit (16) to remove the interference wave, convert it to the second IF frequency (450 KHz), shape the waveform, and amplify the signal. After that, it is demodulated by the demodulator (17). The doubling circuits (5) and (13) of the above-mentioned embodiment double the output of the frequency synthesizer, but this doubling circuit may be replaced with, for example, a filter circuit for extracting the second harmonic.

Next, with reference to FIGS. 6 and 7, an example different from the present application will be shown for reference. This example is a frequency synthesizer that obtains a high local oscillation frequency without using a doubling circuit. In the figure, (18) and (26) are resistors. (19) (27)
Is a variable capacitor. (20) (21) (23) (28) (29) are capacitors. (24) and (31) are switches. (25) (3
2) is a buffer amplifier. (30) is a tapped inductor.

In FIG. 5, the double frequency signal is obtained by doubling the fundamental wave, but as shown in FIG. 6, the parallel resonance capacitance (23) for one resonator (22) is switched to the switch (24 It is also possible to obtain a double frequency signal by switching with). Further, as shown in FIG. 7, the oscillation band of the oscillation frequency is switched by switching the inductance capacity of the tapped inductor (30) of the resonance circuit with the switch (31).

In the examples of FIGS. 6 and 7, one local oscillator circuit for transmission or one local oscillator circuit for reception is provided as one resonator.
It is characterized in that it is constituted by (22), and oscillates at the fundamental wave and twice the frequency by changing the peripheral circuit configuration or the circuit constant.

[0036]

As described above, according to the present invention, since many circuits that can be shared in communication in the first and second bands of the communication device are included, it is advantageous for downsizing the wireless communication device. As described above, according to the present invention, since the common transmission IF signal is converted into the radio signal of the first or second band, the miniaturization of the dual band radio communication device is realized by including many circuits which can be shared for transmission of different bands. it can.

Further, according to the present invention, since the reception signal of the first or second band is converted into a common reception IF signal,
It is possible to reduce the size of the dual band wireless communication device by including many circuits that can be shared for reception of different bands.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining derivation for setting a transmission IF frequency value according to the embodiment.

FIG. 3 is a diagram for explaining derivation for setting a transmission IF frequency value according to the embodiment.

FIG. 4 is a diagram for explaining derivation for setting a reception IF frequency value according to the embodiment.

FIG. 5 is a diagram for explaining derivation for setting a reception IF frequency value according to the embodiment.

FIG. 6 is a diagram showing a configuration of an oscillation frequency switching type local oscillation circuit.

FIG. 7 is a diagram showing a configuration of an oscillation frequency switching type local oscillation circuit.

[Explanation of symbols]

 (2) ・ ・ ・ ・ ・ ・ Transmission system IF circuit, (3) ・ ・ ・ ・ ・ ・ Mixer (transmission system mixer circuit), (4) ・ ・ ・ ・ ・ ・ Frequency synthesizer (local oscillation circuit), (5 ) ··· Double multiplication circuit (multiplication wave output circuit), (6) ··· Switch (selective output means), (12) ··· Switch (selective output means), (13 ) ・ ・ ・ ・ ・ Doubler circuit (Multiplier wave output circuit), (14) ・ ・ ・ ・ ・ Frequency synthesizer (Local oscillator circuit), (15) ・ ・ ・ ・ ・ Mixer (Receiver mixer circuit) (16)・ ・ ・ ・ ・ Reception system IF circuit.

Claims (6)

[Claims] 1. A transmission mixer circuit (3) for up-converting a transmission intermediate frequency signal into a radio frequency signal of the first or second band, a transmission local oscillation circuit (4), and this local oscillation circuit (4). ), And outputs a frequency multiplied by this output frequency, and a multiplied wave output circuit (5) corresponding to the up-conversion to the first or second band. And a selective output means (6) for selectively outputting the output of the local oscillator circuit (4) and the output of the local oscillator circuit (4) to the transmitting mixer circuit (3). 2. A receiving system mixer circuit (15) for down-converting a radio frequency signal of the first or second band into a receiving intermediate frequency signal, a receiving local oscillating circuit (14), and the local oscillating circuit (14). ), And outputs a frequency multiplied by this output frequency, and a multiplied wave output circuit (13) corresponding to reception of the radio frequency signal of the first or second band. 13) and the output of the local oscillator circuit (14) are selectively supplied to the receiving mixer circuit (1
A dual band wireless communication device comprising: a selective output means (12) for outputting to 5), and converting the received radio frequency signal of the first or second band into a common received intermediate frequency signal. 3. The dual band wireless communication device according to claim 1, wherein the multiplied wave output circuit (5, 13) is a doubled circuit. 4. The dual band wireless communication device according to claim 1, wherein the multiplied wave output circuit (5, 13) is a second harmonic extraction circuit. 5. The frequency difference between the center oscillation frequency of the transmitting local oscillator circuit (4) and the transmission radio frequency of the first band, and the frequency difference between the multiplication frequency and the transmission radio frequency of the second band. The dual-band wireless communication device according to claim 1, wherein the central oscillation frequency of the transmitting local oscillation circuit (4) is set to be equal. 6. The frequency difference between the center oscillation frequency of the reception local oscillator circuit (14) and the reception radio frequency of the first band, and the frequency difference between the multiplication frequency and the reception radio frequency of the second band are mutually different. The second dual-band wireless communication device according to claim 2, wherein the central oscillation frequencies of the receiving local oscillation circuits (14) are set to be equal.