JPH0344246A - Data receiver - Google Patents

Abstract

PURPOSE:To attain excellent data reception even at a high frequency band by using 4 mixers so as to obtain an output signal of twice modulation frequency preserving phase inversion information corresponding to the polarity of the modulation frequency. CONSTITUTION:A data demodulation signal with the relation of in-phase or opposite phase to each other in response to a data is obtained from an output signal resulting from multiplication or exclusive OR from mixers 2, 3 of two low frequency output signals of orthogonal phase and an output signal resulting from multiplication or exclusive OR from mixers 12, 13 of one low frequency output signal and a signal phaseshifting it by 90 deg.. Thus, a signal with twice modulation frequency without phase inversion by the polarity of the modulation frequency is obtained and two output signals are in the relation of in-phase or opposite phase in response to the data, then the original data is easily demodulated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data receiver mainly applied to a direct conversion reception method.

BACKGROUND OF THE INVENTION Recently, a direct conversion receiver using frequency shift keying (FSK) No. 1 on a radio frequency carrier wave has been studied as a data receiver structure suitable for integrated circuits. .

For example, a configuration described in Japanese Unexamined Patent Publication No. 58-19038 is known. A conventional data receiver will be briefly described below with reference to FIG. In Figure 6 (
If C is the carrier frequency and δ is the FSK modulation frequency deviation, then 1, the received RF signal with frequency fc±δ is directly connected to the first
is applied to the second mixer circuit 62 through the mixer circuit 61 and the phase shifter 63.

Phase shifter 63 shifts the phase by 90' at carrier frequency fc. Local oscillator 64 operating at carrier frequency fc
has outputs feeding two mixer circuits 61 and 62. The outputs of mixer circuits 61 and 62 pass through low-pass filters 65 and 66, respectively. The outputs of filters 65 and 66 have a frequency difference between the input signal and the local oscillator. The output of filter 66 is then phase shifted by a second phase shifter 67 by 90° in the low frequency output signal. Both signals are applied to limiting amplifiers 68 and 69, respectively. The outputs of limiting amplifiers 68 and 69 are then treated as digital signals and processed in digital logic network 70.

Problems to be Solved by the Invention However, in the above configuration, if there is a frequency difference between the local oscillation frequency and the modulated carrier wave, one of the low frequency outputs after quadrature phase conversion will change depending on the difference between the positive and negative modulation frequencies. Although the frequency is high, the other low frequency output frequency is low, and there is a problem in that the error rate of data demodulation is significantly degraded due to the cause of the low frequency.

The present invention solves the above problems by increasing the frequency tolerance between the local oscillation frequency and the carrier wave that undergoes positive and negative modulation.
The purpose is to enable good data reception even in high frequency bands where frequency stability is disadvantageous.

Means for Solving the Problems In order to achieve the above object, the technical solution of the present invention is as follows:
An output signal obtained by multiplying two orthogonal phase low-frequency output signals by a mixer or performing an exclusive logical operation, and a multiplication by a mixer or an exclusive logical operation of one low-frequency output signal and a signal obtained by 90 degrees of phase with it. The data demodulation signal can be obtained from the output signal obtained by performing the above-mentioned data demodulation, and the data demodulation signal can be in phase with or out of phase with the other depending on the data.

In the present invention, if the modulation frequency can be increased during demodulation, the allowable range for the frequency deviation between the local oscillation frequency and the modulated carrier wave can be increased. Therefore, by multiplying the two orthogonal phase low frequency output signals by a mixer or using an exclusive OR operation, a signal with twice the modulation frequency that has phase inversion information corresponding to the positive or negative of the modulation frequency is obtained, and one low frequency output signal is obtained. By multiplying the frequency output signal and a signal obtained by shifting its phase by 90 degrees using a mixer or by performing an exclusive logic operation, a signal with twice the modulation frequency without phase inversion due to the positive or negative of the modulation frequency is obtained, and those two Since the two output signals are in phase or out of phase with each other depending on the data, it is possible to easily demodulate the original data.

EXAMPLE A first example of the present invention will be described below with reference to FIG. FIG. 1 is a circuit block diagram of a data receiver according to the present invention. In FIG. 1, 1 is an input signal, 2.3 is a first and second mixer that mixes the input signal 1 and the output of the local oscillator 4, and 5 is 90' that shifts the phase of the output of the local oscillator 4 by 90'. Phase shifters 6 and 7 are first and second low-pass filters. 8 is in phase
9 is a low frequency output signal (I signal) of e), and 9 is a low frequency output signal (Q signal) of quadrature phase. 10 is a 90' phase shift circuit for low frequency wide band, and 11 is its output signal. 12 is a third mixer that mixes the output of the low-pass filter 6 and the output of the phase shift circuit 10; 13 is a fourth mixer that mixes the outputs of the low-pass filters 6 and 7; 14 is a demodulation output signal D1.15; The demodulation output signal D3.16 is the 14.
A demodulation circuit performs demodulation from the demodulation output signals 15, D, and 17 is the demodulated output data.

The operation of the above configuration will be explained below.

First, when fc is the carrier frequency and δ is the modulation frequency deviation, the input signal 1 is a received RF signal with a frequency of fc±δ and is supplied to the first mixer 2 and the second mixer 3. The output of the local oscillator 4 operating at the carrier frequency fc is fed directly to the first mixer 2 on one side, and on the other side is a phase shifter 5 that shifts the phase by 90° in the local oscillation frequency band.
is supplied to the second mixer 3 through. 1st mixer 2
The output of passes through the first low-pass filter 6 and is in-phase (I
n phase) low frequency output signal (I signal) 8, and the output of the second mixer 3 is passed through the second low pass filter 7.
through the quadrature phase (Quadrature phase).
) is a low frequency output signal (Q signal) 9. Assuming that the frequency error between the carrier wave and the local oscillator 4 is Δf1, the phase error is 01, and the phase error of the phase shifter 100 in the local oscillation frequency band is θ3, it is expressed as follows according to fc+δ and fc-δ of the input signal. ■Signal 8 is a signal with no phase inversion depending on the positive or negative modulation frequency, and Q signal 9 is a signal that has phase inversion information corresponding to the positive or negative modulation frequency, that is, the transmitted data.■The phase relationship between the signal and Q signal is mutual. is perpendicular to

Here, the output of the I signal 8 and the I signal 8 passed through a phase shift circuit 10 with a low frequency wide band 90' phase shift, and the signal 11 are supplied to the third mixer 12, and the signal 8 and the Q signal 9 are sent to the fourth mixer 13
supply to. As the output of the third mixer 12, an output signal 14 of twice the modulation frequency without phase inversion depending on the positive or negative of the modulation frequency δ is obtained, and as the output of the fourth □ fuser 13, it corresponds to the positive or negative of the modulation frequency δ. Since it is possible to obtain an output signal 15 with twice the modulation frequency and which has phase inversion information, deterioration of the data demodulation error rate due to causes on the low frequency side becomes a problem, especially in low frequency output signals. However, the frequency is twice as high as in the conventional δ-Δf case, resulting in 2(δ-Δf), which increases the amount of modulated signal contained in one data during data demodulation, making it a much more advantageous demodulation format. becomes.

Furthermore, since these two output signals have the same or opposite phase relationship depending on the data, it is possible to easily obtain the demodulated output signal 17 of the original data using the demodulation circuit 16. becomes.

As is clear from the above description, according to this embodiment, the frequency tolerance between the carrier wave and the local oscillation frequency is increased, and good data reception is possible even in high frequency bands where frequency stability is disadvantageous. I can do it.

Note that in this embodiment, the first low-pass filter output signal 8
is used as the I signal, and the second low-pass filter output signal 9 is used as the Q signal, but the configuration may be reversed.

Next, a second embodiment of the present invention will be described below with reference to FIG. 2(a). FIG. 2 is a circuit block diagram of a data receiver according to the present invention. The difference from the configuration in FIG. 1 is that the first, second, and third limiting amplifiers 20.2
2.24, and first and second exclusive OR operating units 26 and 27, respectively.

In the above configuration, while the first embodiment performs analog signal processing, this embodiment performs the same operation as digital signal processing. This will be explained with reference to FIG. 2 (al) and FIG. 2 (b) showing a time chart of the waveform of a signal used in the data receiver according to the present invention. 8. The process up to the point where the Q signal 9 is obtained at the output of the second low-pass filter 7 is the same as the embodiment shown in FIG. Q
The signal is a signal that has phase inversion information corresponding to the positive or negative modulation frequency, that is, the transmission data 60, and includes the engineering signal 8 and the Q signal 9.
The phase relationships with are orthogonal to each other. ■The waveforms of signal 8 and Q signal 9 are shown in (b) and (c) of Figure 2 (bl), respectively.Here, when the transmission data 60 is "0", δ-Δ
It is assumed that this corresponds to the case of f, and is shown with a lower frequency.

■ The output signal 11 obtained by waveform shaping the signal 8 by the first limiting amplifier 20 and 21 (Fig. 2
The output signal waveform-shaped by the limiting amplifier 22 and 23 ((e) in FIG.
6, a signal 14 (() in FIG. 2 (bl)) with a double pit rate without phase inversion depending on the positive or negative modulation frequency, that is, not depending on the transmission data signal 60, can be obtained. The output from the first limiting amplifier 20 and the second
The output signal from the third limiting amplifier 24 provided after the low frequency output signal of
By supplying the data to the exclusive OR operator 27, the signal D*15 (in FIG. 7)) is obtained. Moreover, since these two output signals are in the same phase or opposite phase depending on the data, the demodulation circuit 16 can easily demodulate the original data (see Fig. 2(b)).
It becomes possible to do (su)).

If there is a frequency error Δf between the carrier wave and the local oscillator, the data rate of one modulation signal will increase according to δ + Δf and the data rate of the other modulation signal will increase according to δ - Δf at data '1# or 0''. However, even on the low side, the data rate of the modulated signal is twice as high as in the conventional case. Therefore, it is a much more advantageous demodulation format in data demodulation.

As is clear from the above description, according to this embodiment, the frequency tolerance between the carrier wave and the local oscillation frequency is increased, and good data reception is possible even in high frequency bands where frequency stability is disadvantageous. I can do it.

Note that even if the configuration is reversed for the I signal 8 and Q signal 9, the same operation as in this embodiment is performed and demodulation output signals D1 and D1 are obtained.

As is clear from the above explanation, the operating principle is the same for mixers that process analog signals and exclusive OR units that process digital signals, and as a mixed arithmetic unit based on these higher concepts, Similar principles can be applied.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 1ad, lb) shows the data after the first and second low frequency output signals of the data receiver in the present invention (
FIG. 1 is a circuit block diagram of FIG. 1 and FIG. 2 (A-A' line side in al).

In each of Figure 3 (al, (b)), 30.3
1.3234 is a mixer, 33 is a second low frequency wide band 90
' is a phase shift circuit. In the embodiment shown in FIG.
The other signal is a signal with no phase inversion caused by the transmitted data, which can be obtained by mixing and multiplying two input signals having a mutually orthogonal phase relationship by two mixers 30 and 31, or by using a low frequency wide band 90° phase shift circuit 33 and Two mixers 32
．． By mixing and multiplying by 34, each frequency is doubled, but one is a signal with phase inversion due to data and the other is a signal without phase inversion due to data, resulting in two output signals with mutually orthogonal phase relationship. is obtained, so that the circuit of the first embodiment can be connected afterwards, and it can be demodulated as an even higher low frequency output signal.

In addition, in either case of FIG. 3 (al or (bl), either input may be used as data on the phase inversion side.

Also, the frequency of the output signal of mixer 30.31 or mixer 32.34 is twice that of the input signal, but one is a signal with phase inversion due to data, and the other is a signal without phase inversion due to data, so that they are orthogonal to each other. Since the relationship of two signals related to the tank is maintained, this can be used in multiple stages.

Therefore, the demodulation format is much more advantageous in terms of frequency than the conventional case with respect to deterioration of the error rate of data demodulation due to causes on the low frequency side. Moreover, as shown in the first embodiment, from these two output signals, signals whose phase relationship is the same or opposite to each other depending on the transmitted data are sent to the third and fourth mixers 12 and 13. Since it is obtained as an output, the demodulation circuit 16 can easily demodulate the original data.

As is clear from the above description, according to this embodiment, the frequency tolerance between the carrier wave and the local oscillation frequency is further increased,
Good data reception can be achieved even in high frequency bands where frequency stability is disadvantageous.

FIGS. 4(a), (bl, and c) show the fourth
FIG. 2 is a circuit block diagram of a demodulation circuit 16 of the data receiver in the embodiment. First, in the case of Fig. 4(a), for example, the first
The output signal D114 of the third mixer 12 and the output signal D114 of the fourth mixer 13 and the output signal D15 of the fourth mixer 13 have a phase relationship of the same phase or opposite phase depending on the transmitted data. When these signals are supplied to the mixer 40, they are mixed and multiplied, and if they are in phase, a positive low frequency signal is output, and if they are in opposite phase, a negative low frequency signal is output. A data demodulated signal 17 can be obtained. Note that if the phases of the transmission data and the demodulated data are reversed due to the subsequent circuit configuration method for the first and second low-frequency output signals, the detector 41 includes phase inversion. Next, in the case of FIG. are signals whose phase relationship is the same or opposite depending on the data, so the data demodulated signal 17 can be obtained by supplying it to the exclusive OR operator 42. Depending on how the subsequent circuit for the second low-frequency output signal is configured, the phases of the transmitted data and the demodulated data may be reversed. An inverter 43 may be provided after 42 to invert the phase.

Furthermore, fine pulses may be generated due to errors in the calculations of the exclusive logic operator 42, but these can be removed by a low-pass filter called a data filter provided after these circuits. Further, the configuration according to this embodiment is particularly suitable for integrated circuit implementation.

Furthermore, if the demodulation circuit is configured as shown in the embodiment shown in FIG. 5, depending on the data "1# or 0", the state where there is a low frequency output signal or the state where the output signal is canceled out and becomes an almost constant signal is the sum amplifier. Since the signal is obtained as the output of U and the difference amplifier 45, the data demodulated signal 17 can be obtained by a circuit 46 that performs combined detection of these signals. In this case as well, if the phases of the transmitted data and demodulated data are reversed due to the circuit configuration method, the composite detection circuit 4 including the phase reversal
6, data can be demodulated by performing the same operation regardless of which side is the sum amplifier or which side is the input method of the difference amplifier.

Effects of the Invention As described above, the present invention can increase the allowable range for the frequency deviation between the local oscillation frequency and the carrier wave that is subjected to positive and negative modulation. As a result, good data reception is possible even in a high frequency band where frequency stability is disadvantageous, and its industrial effects are extremely large due to improved characteristics and compatibility with integrated circuits.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of a data receiver according to a first embodiment of the present invention, and FIG. FIG. 3 is a circuit block diagram of a part of a data receiver according to a third embodiment of the present invention, and FIGS.
The figure shows the fourth part of the demodulation circuit, which is the main part of the data receiver of the present invention.
, a circuit block diagram of the fifth embodiment, and FIG. 6 is a circuit block diagram of a conventional data receiver. 1... Input signal, 2, 3... Mixer, 4... Local oscillator, 5... Phase shifter, 6. 7...Low pass filter, 10...Low frequency wide band 90° phase shift circuit, 12.
13...Mixer, 20, 22.24...Limiting amplifier, 26.27...Exclusive OR operator.

Claims (12)

[Claims] (1) first and second mixers that mix an input signal and a local oscillation signal to generate a first low frequency output signal and a second low frequency output signal that are in a quadrature phase relationship with each other; a third mixer for mixing the first low-frequency output signal and a signal phase-shifted by the first low-frequency wideband 90-degree phase shift circuit; a third mixer that mixes two low frequency output signals, first and second; and a demodulation circuit that performs data demodulation using the output of the first mixer and the output of the second mixer. Data receiver with. 2. The data receiver according to claim 1, wherein data demodulation is performed by supplying the output of the third mixer and the output of the fourth mixer to an eighth mixer. (3) supplying the output of the third mixer to a sum amplifier and a difference amplifier, supplying the output of a fourth mixer to the sum amplifier and the difference amplifier, and supplying the output signal of the sum amplifier and the difference amplifier; 2. The data receiver according to claim 1, wherein the data receiver detects the output signal and demodulates the data. (4) The data receiver according to claim 1, wherein the first and second low frequency output signals are configured to be reversed. (5) The data according to claim 1, characterized in that exclusive OR operating units are used as the third, fourth, and eighth mixers, and limiting amplification means is provided before the exclusive OR operating units. Receiving machine. (6) first and second mixers that mix the input signal and the local oscillation signal to generate a first low frequency output signal and a second low frequency output signal that are in a quadrature phase relationship with each other; a fifth mixer having one or more stages for mixing two outputs of the outputs obtained by distributing the first low frequency output signal; and another output signal of the first low frequency output signal and the Second
a sixth mixer of one or more stages that mixes the low frequency output signal of the fifth and sixth mixers; one of the two output signals of the fifth and sixth mixers is mixed with the third low frequency output signal, and the other The fourth
a low frequency output signal, and the third low frequency output signal;
Similarly, the third low frequency output signal is mixed with a signal whose phase is shifted by the first low frequency broadband 90 degree phase shift circuit.
a mixer, a fourth mixer that mixes the third and fourth two low frequency output signals, and an output of the third mixer and an output of the fourth mixer to generate data. A data receiver having a demodulation circuit that performs demodulation. (7) The first low frequency output signal and the second low frequency output signal are connected between the first and second low frequency output signals and the third and fourth low frequency output signals.
A signal obtained by shifting the phase of the low frequency output signal by a second low frequency wideband 90 degree phase shift circuit is supplied to a sixth mixer, and the second low frequency output signal and the second low frequency wideband signal are phase shifted by a second low frequency wideband 90 degree phase shift circuit. a circuit that supplies the output of the 90 degree phase shift circuit to a seventh mixer, and uses the output of the sixth mixer and the output of the seventh mixer as third and fourth low frequency output signals. 7. The data receiver according to claim 6, characterized in that one or more stages are provided. (8) The data receiver according to claim 6, wherein data demodulation is performed by supplying the output of the third mixer and the output of the fourth mixer to an eighth mixer. (9) The output of the third mixer is supplied to a sum amplifier and a difference amplifier, the output of a fourth mixer is supplied to the sum amplifier and the difference amplifier, and the output signal of the sum amplifier and the difference amplifier are 7. The data receiver according to claim 6, wherein the data receiver detects the output signal and demodulates the data. (10) The data receiver according to claim 6, wherein the first and second low frequency output signals are configured to be reversed. (11) The data receiver according to claim 6, wherein the third and fourth low frequency output signals are configured to be reversed. (12) The data receiver according to claim 6, wherein exclusive OR operating units are used as the third to eighth mixers, and limiting amplification means is provided before the exclusive OR operating units.