JPH06188751A - Dual-mode radio transmitter - Google Patents

Abstract

PURPOSE:To decrease the circuit scale and further reduce the size and weight of the whole device by using only one frequency synthesizer. CONSTITUTION:An analog FM modulation part 3 is provided with an analog signal processing part 31 and a complex base band signal generation part 32. A series of signal processes for FM modulation imposed on a digitized sent speech signal is performed by those circuits and after integration and multiplication by a coefficient kf for determining an FM frequency shift are performed, an FM complex base band signal is generated. Then the FM complex base band signal is supplied to an quadrature modulator 8 through a signal selection part 5, which imposes orthogonal modulation on a sent radio carrier signal with the FM complex base band signal to obtain an FM-modulated sent radio carrier, thereby performing transmission.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transmitter used in a mobile radio communication device such as a car telephone device, a portable telephone device, a cordless telephone device, and the like, and particularly to a transmission function by an analog modulation system and a digital modulation system. And a dual mode wireless transmitter having a transmitting function according to the present invention.

[0002]

2. Description of the Related Art Recently, a system adopting a dual mode wireless communication system has been proposed as one of mobile wireless communication systems. The dual mode is a system that uses both an analog mode and a digital mode.

In the analog mode, the communication device on the transmission side transmits, for example, a carrier wave FM-modulated by a voice signal and data, and the communication device on the reception side receives a modulated wave sent from the transmission side and performs FM demodulation. This is a method for reproducing voice and data. On the other hand, in the digital mode, in the communication device on the transmission side, the audio signal and the data are encoded to generate a transmission data bit stream, and the wireless carrier wave is, for example,
/ 4 Shifted QPSK (π / 4 Shifted, quadrature phase
shift keying) method, digitally modulates and transmits, and in the communication device on the receiving side, after receiving the modulated wave sent from the device on the transmitting side and digitally demodulating,
This is a method of reproducing a voice signal and data by decoding the demodulated signal.

FIG. 7 is a circuit block diagram showing a configuration of a transmission system of a dual mode radio communication device conventionally used in this type of system. In the figure, first, when the analog mode is set, the audio signal output from the microphone 1 is input to the analog baseband signal processing unit 33, where the bandpass filtering, level compression, pre-emphasis, limiting and After signal processing for analog FM modulation such as low-pass filtering is performed, the PLL modulator 34
Entered in. In this PLL modulator 34, an intermediate frequency signal FM-modulated by the analog baseband signal output from the analog baseband signal processing unit 33 is generated, and this intermediate frequency signal is generated from the frequency synthesizer 14 in the mixer 35. It is mixed with the transmission local oscillation signal and frequency-converted into a modulated carrier having a radio transmission channel frequency. Then, the modulated carrier wave is band-limited by the band-pass filter 36 and then input to the change-over switch 15. At this time, the changeover switch 15 is controlled so as to selectively output the signal output from the bandpass filter 36 according to an instruction from a control circuit (not shown). Therefore, the modulated carrier output from the band pass filter 36 is supplied to the power amplifier 9. The modulated carrier wave is power-amplified by the power amplifier 9 so that the transmission output level becomes a predetermined level, and then radiated from the antenna 11 via the antenna duplexer 10.

On the other hand, when the digital mode is set, the audio signal output from the microphone 1 is
After the excess frequency component is removed by the bandpass filter 45, it is input to an analog-digital converter (ADC) 46 having a non-linear conversion characteristic, where it is first converted into a PCM signal. This PCM signal is input to the transmission data generator (COD) 43. In the transmission data generation unit 43, encoding processing necessary for digital transmission such as voice encoding and error correction encoding is performed, and thereby a bit stream of transmission data is generated. This bit stream is a complex baseband signal generator 44.
Entered in. The complex baseband signal generation unit 44 generates each π / 4 shift QPSK-modulated complex baseband signal of a sine component and a cosine component.
These complex baseband signals are converted back into analog signals by digital / analog converters (DACs) 61 and 62, and then the low-pass filters 71 and 72 are used.
After removing unnecessary frequency components outside the band with mixer 8
1, 82. These mixers 81 and 82 are
The quadrature modulator 8 is configured with the π / 2 phase shifter 83 and the combiner 84. In the quadrature modulator 8, the wireless carrier signal generated from the frequency synthesizer 13 is divided by a π / 2 phase shifter 83 into two series of wireless carrier signals having a phase difference of π / 2 from each other. The signals are mixed in the mixers 81 and 82 with the complex baseband signals supplied from the low-pass filters 71 and 72, and then combined by a combiner 84. Then, the quadrature modulator 8 generates a π / 4 shift QPSK modulated wave. This π / 4 shift QPSK modulated wave is selected by the changeover switch 1
Input to 5. At this time, the changeover switch 15 is controlled so as to selectively output the signal output from the quadrature modulator 8 according to an instruction from a control circuit (not shown).
Therefore, the π / 4 shift QPSK modulated wave output from the quadrature modulator 8 is supplied to the power amplifier 9. Then, the π / 4 shift QPSK modulated wave is power-amplified to a predetermined transmission output level by the power amplifier 9, and then radiated from the antenna 11 via the antenna duplexer 10.

Reference numeral 12 denotes a receiving circuit (RX) which is a part of the receiving system. In this receiving circuit 12, a radio signal sent from a base station (not shown) is frequency-converted into an intermediate frequency signal or a baseband signal. To be done.

[0007]

However, in the transmitter of such a conventional dual-mode wireless communication device, an analog modulation system circuit and a digital modulation system circuit are constructed independently of each other. Therefore, the PLL modulator 34,
Three frequency synthesizers including a frequency synthesizer 14 for analog local oscillation and a frequency synthesizer 13 for quadrature modulation have been required. Here, the frequency synthesizer includes a reference oscillator, a frequency divider, a phase comparator, a loop filter and a voltage controlled oscillator (VCO),
The circuit mounting area is generally larger than other circuits. Therefore, the circuit scale of the transmitter is likely to increase in size, which has been a major obstacle in reducing the size and weight of the wireless communication device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a frequency synthesizer.
An object of the present invention is to provide a dual-mode wireless transmitter that can reduce the circuit scale and further reduce the size and weight of the entire device.

[0009]

In order to achieve the above object, the present invention provides a dual mode radio transmitter having a transmission function by an analog modulation system and a transmission function by a digital modulation system, wherein an analog modulation system is provided with an analog signal. Complex signal generating means is provided in addition to the baseband signal processing means, and the complex signal generating means determines the frequency shift after integrating the analog baseband signal output from the analog baseband signal processing means. And a first complex baseband signal that is analog-modulated based on the analog baseband signal multiplied by this coefficient. Then, the first complex baseband signal and the second complex baseband signal output from the digital modulation processing means are selectively selected by the signal selecting means and supplied to the quadrature modulating means. The modulation means modulates the radio transmission carrier in quadrature.

[0010]

As a result, according to the present invention, in the state where the analog modulation system is selected, an analog modulation system is analog-modulated, but the apparent configuration is a complex baseband obtained by the digital modulation system. A complex baseband signal having the same configuration as the signal is created, and this complex baseband signal is supplied to the quadrature modulation means for digital modulation to modulate the radio carrier. For this reason, only the quadrature modulation means for digital modulation needs to be provided in the frequency conversion section necessary for obtaining the modulated wireless carrier wave, and the frequency conversion means for analog modulation becomes unnecessary. That is, the quadrature modulation means of the digital modulation system can be shared in the digital mode and the analog mode. Therefore, it is possible to use only one frequency synthesizer for frequency conversion, which makes it possible to miniaturize the circuit scale of the transmitter, and further to further miniaturize and reduce the weight of the dual-mode wireless communication device. Become.

[0011]

EXAMPLES The present invention will be described below based on examples.

1 and 2 are circuit block diagrams showing the configuration of a transmission system of a dual mode radio communication apparatus according to an embodiment of the present invention. Incidentally. In the figure, the same parts as those in FIG.

The transmitted voice signal output from the microphone 1 is first input to the analog / digital converter 2. The analog-to-digital converter 2 is composed of a low-pass filter 21, an oversampling type analog-to-digital converter (ADC) 22, and a decimation filter 23. The transmission voice signal is digitalized by these circuits. Converted to a signal. This digitized transmission voice signal is branched into two, one is input to the analog FM modulator 3 and the other is input to the digital modulator 4.

Of these, the digital modulator 4 is composed of a bandpass filter 41, a PCM compression circuit 42, a transmission data generator (COD) 43, and a complex baseband signal generator 44. In the band pass filter 41,
Band limitation of the digitized transmission voice signal input from the analog / digital converter 2 is performed. PCM
The compression circuit 42 converts the digitized transmission voice signal output from the band pass filter 41 into a PCM compression code. In the transmission data generation unit 43, the digitized transmission voice signal that has been PCM compression coded, that is, PCM
Information compression coding, error correction coding and T
A series of processes for digital radio transmission, such as DMA frame generation, is performed to generate a bit stream of transmission data. The complex baseband signal generator 44 outputs a π / 4 shift QP from the bit stream.
Processing is performed to generate the SK-modulated complex baseband signal. And this π / 4 shift QPSK
The modulated complex baseband signal is input to the signal selection unit 5.

On the other hand, the analog FM modulator 3 comprises an analog signal processor 31 and a complex baseband signal generator 32. The analog signal processing unit 31 includes a band pass filter 311 and a level compressor (CO
MP) 312 and pre-emphasis processing unit (P / E) 3
13, an amplitude limiter (LIM) 314, a low pass filter 315, and an integrating circuit 316. The band pass filter 311 limits the band of the digitized transmission voice signal input from the analog / digital conversion unit 2. The level compressor 312 performs level compression processing on the digitized transmission voice signal. In the pre-emphasis processing unit 313, in order to improve the S / N, the pre-emphasis processing is performed to deepen the modulation as the frequency of the digitized transmission voice signal increases. The amplitude limiter 314 performs amplitude limiting processing on the digitized transmission voice signal output from the pre-emphasis processing unit 313. Low pass filter 315
Then, the excess harmonic component contained in the signal output from the amplitude limiter 314 is removed. In the integration circuit 316, integration processing is performed as one of the steps for converting the digitized transmission voice signal output from the amplitude limiter 315 into an FM modulated wave.

The complex baseband signal generator 32 is shown in FIG.
, A coefficient multiplier 321, a residue circuit 322, a cosine signal generation circuit 323, and a sine signal path generation circuit 3
24 and. The coefficient multiplier 321 multiplies the digitized transmission voice signal output from the analog signal processing section 31 by a coefficient for giving a frequency shift of FM modulation. The remainder circuit 322 has, for example, an input / output characteristic as shown in FIG. 6, and according to this input / output characteristic,
Processing is performed to keep the range of the phase of the digitized transmission voice signal output from the coefficient multiplier 321 within the range of -π to + π. In the cosine signal generation circuit 323 and the sine signal generation circuit 324, the remainder circuit 3 is used.
A cosine signal and a sine signal are generated based on the digitized transmission voice signal output from 22. These cosine signal and sine signal are input to the signal selection unit 5 as signals representing the real part component and the imaginary part component of the FM-modulated complex baseband signal.

The signal selection section 5 is provided with a pair of changeover switches 51 and 52 which are interlocked with each other as shown in FIG. 4, for example. These changeover switches 51 and 52 perform a switching operation according to a changeover control signal output from a control circuit (not shown) of the wireless communication device. When the analog mode is set, the FM-modulated complex baseband signal output from the analog FM modulator 3 is selected and output. On the other hand, when the digital mode is set, it is output from the digital modulator 4. And outputs the selected complex baseband signal which is π / 4 shift QPSK modulated.

The complex baseband signal selected and output from the signal selection unit 5 is input to the digital / analog converters (DAC) 61, 62 of the digital / analog conversion unit 6 for each of its real part component and imaginary part component, and these DAC
At 61 and 62, the analog signals are restored. This analog complex baseband signal is input to the low-pass filters 71 and 72 of the low-pass filter unit 7 for each real part component and imaginary part component, and unnecessary harmonic components are removed here. Then, the complex baseband signals output from the low pass filters 71 and 72 are input to the quadrature modulator 8.

The quadrature modulator 8 is a π / 2 phase shifter for generating two signals having a phase difference of π / 2 with each other based on the transmission radio carrier signals output from the mixers 81 and 82 and the frequency synthesizer 13. 83 and a combiner 84. The mixers 81 and 82 receive the real part component and the imaginary part component of the complex baseband signal output from the low-pass filters 71 and 72, respectively, and the transmission wireless carrier signal output from the π / 2 phase shifter 83. Mixing. The combiner 84 adds and combines the signals output from the mixers 71 and 72. By mixing and synthesizing these, a transmission radio carrier signal quadrature-modulated by the complex baseband signal is obtained. The quadrature-modulated transmission radio carrier signal is amplified by the power amplifier 9 to a predetermined transmission output level, and then supplied to the antenna via the antenna duplexer 10 and radiated from the antenna 11.

Next, the operation of the transmission system configured as above will be described. First, in the state where the digital mode is set, the following modulation operation is performed. That is, the transmitted voice signal output from the microphone 1 is digitized by the analog / digital converter 2 and then input to the digital modulator 4. Then, in the digital modulator 4, the digitized transmission voice signal is converted into PCM.
After compression coding, information compression coding and error correction coding are performed, and further converted into a transmission data bit stream corresponding to the TDMA frame. Also, based on the bit stream of the transmission data, the complex baseband signal generation unit 44 generates a complex baseband signal that is π / 4 shift QPSK modulated, and the π / 4 shift QPSK complex baseband signal is generated by the signal selection unit. It is output to 5. At this time, switching is controlled so that the signal selection unit 5 selectively outputs the signal output from the digital modulation unit 4 in accordance with the switching control signal output from the control circuit (not shown). Therefore, the complex baseband signal output from the modulator 4 passes through the signal selector 5 and is supplied to the digital / analog converter 6. Then, the π / 4 shift QPSK complex baseband signal is converted into an analog signal by the digital-analog conversion unit 6, and then input to the quadrature modulator 8 via the low pass filter 7. Therefore, in the quadrature modulator 8, the transmission radio carrier signal is quadrature-modulated by the π / 4 shift QPSK complex baseband signal. The modulated carrier wave output from the quadrature modulator 8 is radiated from the antenna 11 via the antenna duplexer 10 after the transmission output level is set to a predetermined value by the transmission amplifier 9.

On the other hand, when the analog mode is set, the following modulation operation is performed. That is, the transmitted voice signal output from the microphone 1 is analog
After being digitized by the digital conversion unit 2, it is input to the analog FM modulation unit 3. This analog FM modulator 3
In the above, the digitized transmission voice signal is first subjected to processing for FM modulation such as band-pass filtering, level compression, pre-emphasis, limiting and low-pass filtering in order by the analog signal processing unit 31, Integrated. That is, when the transmitted voice signal after the low-pass filtering process is m (t), the transmitted voice signal by the integration is

[0022]

[Equation 1] Becomes

Next, the integrated transmission voice signal is multiplied by the coefficient k _f for determining the frequency shift of FM modulation in the coefficient multiplier 321 of the complex baseband signal generator 32.

[0024]

[Equation 2]

Further, the phase characteristic is corrected in the remainder circuit 332. The correction of the phase characteristic is performed in order to simplify the process for generating the cosine signal and the sine signal in the subsequent stage. That is, the transmission voice signal output from the coefficient multiplier 331 may have a phase range exceeding -π to + π. Therefore, in the remainder circuit 332, the phase range is corrected so that the phase range of the transmission voice signal falls within the range of −π to + π according to the input / output phase characteristic shown in FIG. At this time, since the cosine function and the sine function change with the angle 2π as one cycle, even if correction is performed according to the input / output characteristics shown in FIG. 6, the result does not change.

When the phase-corrected signal is input to the cosine signal generation circuit 323 and the sine signal generation circuit 324, the cosine signal generation circuit 323 and the sine signal generation circuit 324 respectively calculate the following signals based on the above signals. A cosine signal and a sine signal such as These cosine signal and sine signal correspond to the real part component and the imaginary part component of the complex baseband signal, respectively. That is, the analog FM modulation section 3 outputs an FM modulation signal whose apparent configuration is equivalent to the π / 4 shift QPSK complex baseband signal output from the digital modulation section 4 described above.

This FM complex baseband signal is input to the signal selection unit 5. At this time, the signal selection unit 5 is controlled so as to selectively output the FM complex baseband signal output from the analog FM modulation unit 3 according to the switching control signal output from the control circuit (not shown). Therefore, the FM output from the analog FM modulator 3 is
The complex baseband signal passes through the signal selection unit 5 and is supplied to the digital / analog conversion unit 6. Then, the FM complex baseband signal is converted into an analog signal by the digital / analog converter 6, and then is input to the quadrature modulator 8 through the low pass filter 7. Therefore, in the quadrature modulator 8, in the mixers 81 and 82, the transmission wireless carrier signal generated by the π / 2 phase shifter 83 and the F
The M complex baseband signal is mixed, and the mixed outputs are combined by the combiner 83 and output. This output is s
If you inω _c t and cosω _c t,

[0028]

[Equation 3]

It becomes That is, the quadrature modulator 8 outputs the FM modulated wave signal FM-modulated by the transmitted voice signal m (t). The FM output signal is radiated from the antenna 11 via the antenna duplexer 10 after the transmission output level is set to a predetermined value by the transmission amplifier 9.

As described above, in this embodiment, the analog FM modulator 3 is provided with the analog signal processor 31 and the complex baseband signal generator 32, and these circuits are used for FM modulation of the digitized transmission voice signal. An FM complex baseband signal is generated after performing a series of signal processing and multiplying by a coefficient k _f for integrating and determining the FM frequency shift. Then, this FM complex baseband signal is supplied to the quadrature modulator 8 via the signal selection unit 5,
The quadrature modulator 8 quadrature modulates the transmission radio carrier signal with the FM complex baseband signal,
The FM-modulated transmission wireless carrier is obtained and transmitted.

Therefore, in this embodiment, the analog F
The PLL circuit for obtaining the FM-modulated intermediate frequency signal from the M modulation section can be eliminated, and the quadrature modulator 8 used to generate the π / 4 shift QPSK modulation carrier is used as the FM modulation carrier. Since it can also be used as a circuit for obtaining the signal, a conventional high frequency circuit for FM transmission can be dispensed with. Therefore, in the past, 3
The required frequency synthesizer can be replaced with only the frequency synthesizer 13 for quadrature modulation, and thus the circuit scale of the transmission system can be reduced. Therefore, it is possible to reduce the size and weight of the dual-mode wireless communication device.

Further, according to the present embodiment, since the analog FM modulating section 3 which is conventionally composed of an analog circuit is composed of a digital circuit, it can be realized by one integrated circuit together with the digital modulating section 4. As a result, the circuit scale of the transmission system and the configuration of the dual mode wireless communication device can be further reduced.

The present invention is not limited to the above-described embodiment, but the configuration of the FM modulator and its processing contents, the configuration of the digital modulator, the configuration of the signal selector, the type of the wireless communication device, etc. Various modifications can be implemented without departing from the scope of the present invention.

[0034]

As described above in detail, according to the present invention, the analog modulation system is provided with a complex signal generating means in addition to the analog baseband signal processing means, and the complex signal generating means allows the analog baseband signal processing means to be operated. The analog baseband signal output from is multiplied by a coefficient for determining the frequency shift after integration, and the first complex base analog-modulated based on the analog baseband signal multiplied by this coefficient. A band signal is generated. Then, the first complex baseband signal and the second complex baseband signal output from the digital modulation processing means.
The complex baseband signal of 1) is selectively selected by the signal selecting means and supplied to the quadrature modulating means, and the quadrature modulating means quadrature-phase modulates the radio transmission carrier.

Therefore, according to the present invention, the number of frequency synthesizers is only one.
As a result, it is possible to provide a dual-mode wireless transmitter that can realize a further reduction in size and weight of the entire device.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a configuration of a front stage portion of a transmission system of a dual mode wireless communication device according to an embodiment of the present invention.

FIG. 2 is a circuit block diagram showing a configuration of a latter part of a transmission system of a dual mode wireless communication device according to an embodiment of the present invention.

FIG. 3 is a circuit block diagram showing a configuration of an analog signal processing section shown in FIG.

FIG. 4 is a circuit block diagram showing a configuration of a complex baseband signal generator shown in FIG.

FIG. 5 is a diagram showing an example of a configuration of a signal selection unit.

6 is a diagram showing phase input / output characteristics in the residue circuit of the complex baseband signal generation unit shown in FIG.

FIG. 7 is a circuit block diagram showing an example of a configuration of a transmission system of a conventional dual mode wireless communication device.

[Explanation of symbols]

1 ... Microphone 2 ... Analog / digital converter 3 ... Analog FM modulator 4 ... Digital modulator 5 ... Signal selector 6 ... Digital
Analog conversion unit 7 ... Low-pass filter unit 8 ... Quadrature modulator 9 ... Transmission power amplifier 10 ... Antenna duplexer 11 ... Antenna 12 ... Reception unit 13 ... Frequency synthesizer 21 ... Low pass filter 22 ... Oversampling type analog Digital converter 23 ... Decimation filter 31 ... Analog signal processor 32 ... Complex baseband signal generator 41 ... Bandpass filter 42 ... PCM compression circuit 43 ... Transmission data generator 44 ... Complex baseband signal generator 51, 52 ... Switching Switch 61, 62 ... Digital / analog converter 71, 72 ... Low-pass filter 81, 82 ... Mixer 83 ... .pi. / 2 phase shifter 84 ... Combiner 311 ... Band pass filter 312 ... Level compressor 313 ... Pre-emphasis processing Part 314 ... Amplitude limiter 315 ... Low-pass filter 16 ... integrating circuit 321 ... coefficient multiplier 322 ... remainder circuit 323 ... cosine signal generating circuit 324 ... sign signal path generating circuit

Claims (1)

[Claims] 1. A dual mode radio transmitter having a transmission function by an analog modulation system and a transmission function by a digital modulation system, and an analog for performing predetermined analog baseband signal processing on an input baseband signal and outputting the analog signal. The baseband signal processing means and the analog baseband signal output from the analog baseband signal processing means are integrated and then multiplied by a predetermined coefficient, and the analog baseband signal multiplied by this coefficient is calculated. Analog modulation processing means for generating and outputting a first complex baseband signal that has been analog-modulated based on the above, and a predetermined bit encoding processing for the input baseband signal to generate a transmission bitstream, The second digitally modulated signal based on this transmission bit stream
Digital complex processing means for generating and outputting the complex baseband signal, the first complex baseband signal output from the analog modulation processing means, and the second complex baseband signal output from the digital modulation processing means. Signal selecting means for selectively selecting and outputting the baseband signal, and quadrature phase modulation of the carrier signal corresponding to the radio transmission frequency by the complex baseband signal output from the signal selecting means, and output And a quadrature modulation means for performing the dual mode radio transmitter.