JP2919204B2 - Transceiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used for digital radio communication. In particular, it is suitable for use in a digital cordless telephone system. In particular, the present invention relates to a technique for improving deterioration of received signal error rate characteristics due to a carrier frequency drift of a mobile station apparatus and a technique for controlling a transmission frequency.

[0002]

2. Description of the Related Art In a mobile communication system, in order to simplify a circuit configuration, a base station apparatus and a mobile station apparatus commonly use a reference clock signal generation source which is a reference although the communication frequencies of a transmitter and a receiver are different. There are many things to do. In this case, if a drift occurs in the reference clock signal generation source, a drift occurs in the transmission frequency as well as the reception frequency.
To prevent this, the frequency accuracy of the reference clock signal generation source may be increased. However, providing a temperature control circuit or the like in the mobile station device has a problem from the viewpoint of reducing the size and weight of the mobile station device. However, this is possible in the base station device.

[0003] Therefore, if the transmission frequency accuracy of the base station device is increased, the mobile station device can maintain the accuracy of the transmission and reception frequency by following the frequency. A conventional example of this will be described.

Japanese Patent Application Laid-Open No. 63-256012 discloses that a mobile station apparatus is provided with a plurality of receivers each having a slightly different reception frequency, and a receiver having a maximum reception electric field level is selected from the receivers. There is disclosed a system that includes a changeover switch that provides an intermediate frequency output to a mobile station and follows the transmission frequency of a base station device.

Japanese Unexamined Patent Publication No. 63-256010 discloses a mobile station apparatus having a frequency synthesizer for providing a local oscillation frequency to a receiver, in which a circuit for detecting a reception electric field level of the receiver is provided. Is controlled by the control unit only when is equal to or more than a predetermined value, thereby improving frequency stability accuracy and reducing power consumption.

Japanese Patent Application Laid-Open No. 63-280520 discloses a system in which two reference oscillators are provided as control inputs of a frequency synthesizer of a receiving section of a mobile station apparatus, and a reference oscillator having a maximum received electric field level is selected. It has been disclosed.

Japanese Patent Application Laid-Open No. 63-281526 discloses that a second IF frequency and a second local oscillation frequency of a mobile station device are measured by separate frequency counters, an operation is performed between the two count values, and the nominal frequency data is calculated. A method is disclosed in which a reference oscillator is controlled as compared with the method described above to achieve high frequency stability.

Japanese Unexamined Patent Publication No. 63-281527 discloses that a second IF of a receiver of a mobile station device is obtained by multiplying a frequency of a reference oscillator in a mobile radio by measuring a second IF frequency. A method of obtaining high frequency stability by correcting the oscillation frequency of an oscillator is disclosed.

[0009]

Although these systems are all excellent systems, the frequency is measured by a counter or by a complicated calculation, and the frequency is changed by changing the frequency of the synthesizer. Switching is performed by switching a plurality of receivers or reference oscillators.

In a digital cordless telephone system, a downlink control burst from a base station to a mobile station has a configuration in which signals addressed to multiple stations are sequentially transmitted, and when a time interval between bursts of a downlink control burst in one base station is long. It takes time for the mobile station to accurately follow the transmission frequency to the base station transmission frequency by such a method, and the time from when the power of the mobile station is turned on to when it can be actually used becomes longer.

The present invention has been made in such a background, and when the frequency of a reference clock signal generation source of a mobile station device is controlled based on the transmission frequency of a base station, the transmission frequency is changed. It is an object of the present invention to provide a transmission / reception device that can be performed in a short time.

[0012]

According to the present invention, there is provided a receiving circuit for a phase-modulated radio signal, a detecting unit for determining the sign of an output signal of the receiving circuit by phase detection, and a generating unit based on data to be transmitted. A phase modulation unit that orthogonally modulates the modulated input signal, and a transmission circuit that transmits an output of the phase modulation unit, the detection unit includes a delay detection circuit that detects a phase of an output signal of the reception circuit, A sign determination circuit for determining the sign of the detected phase, a phase displacement detection circuit for detecting a phase displacement of the phase modulation signal from outputs of the sign determination circuit and the delay detection circuit, and a phase displacement detection circuit And a means for correcting a signal provided to the code determination circuit from the detection result of the above.

Here, the feature of the present invention resides in that the phase modulation section includes means for giving a phase rotation to the modulation input signal based on a detection result of the phase displacement amount detection circuit.

Preferably, the means for giving a phase rotation includes a ROM in which a signal level value corresponding to a speed converted in advance is written at an address of an output value of the phase displacement amount detection circuit.

[0015]

The phase shift amount detection circuit detects the phase shift amount by inputting the delay-detected signal and the signal whose sign is determined. This phase shift is an error between the frequency of the received wave and the reception frequency of the receiver, and the error rate of the output of the code determination circuit is corrected based on the phase shift.

Further, this phase displacement amount is input to a phase modulation section of the transmitter, and the transmission angular frequency is changed by a phase rotation speed conversion circuit. This phase rotation speed conversion circuit
A transmission angular frequency corresponding to the input phase shift amount is read from the ROM table. Thereby, a phase shift can be given to the input signal of the quadrature modulation circuit.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

The present invention provides a receiving circuit 1 for a phase-modulated radio signal, a detecting unit 3 for determining the sign of an output signal of the receiving circuit 1 by phase detection, and a modulation input generated based on data to be transmitted. A phase modulation unit 4 for orthogonally modulating a signal, and a transmission circuit 2 for transmitting an output of the phase modulation unit 4;
The detection unit 3 includes a delay detection circuit 5 that detects the phase of the output signal of the reception circuit 1, a sign determination circuit 7 that determines the sign of the detected phase, and an output of the sign determination circuit 7 and the output of the delay detection circuit 5. And a phase shift amount detecting circuit 8 for detecting a phase shift amount of the phase modulation signal from the input signal, and a multiplier 6 as means for correcting a signal given to the sign determination circuit 7 based on the detection result of the phase shift amount detecting circuit 8. Device.

Here, a feature of the present invention is that the phase modulation section 4 includes a phase rotation speed conversion circuit 10 as a means for applying a phase rotation to the modulation input signal based on the detection result of the phase displacement detection circuit 8. Including. Receiving circuit 1
The transmission circuit 2 is supplied with a reference clock signal from a common reference clock signal generation circuit 14.

The phase rotation speed conversion circuit 10 includes a ROM in which a signal level value corresponding to a speed converted in advance is written at an address of an output value of the phase displacement amount detection circuit 8.

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a block diagram of the detection unit 3. FIG. 3 is a block diagram of the phase modulator 4. The description will be made on the assumption that the apparatus according to the embodiment of the present invention transmits and receives a phase modulation wave by π / 4 shift QPSK. π / 4 shift Q
Input signal of the PSK, rx (nT1) = exp [j · _{[(ω rx + Δω) nT1 +} Δφ ]] However, the receiver receiving frequency: omega _rx: modulation phase information: demodulation in Δφ = π / 4 time nT1 data sequence For example, (0,0) 3π / 4 Demodulated data sequence at time nT1 For example, (0,1) 5π / 4 Demodulated data sequence at time nT1 For example, (1,1) 7π / 4 Demodulated data sequence at time nT1 For example, (1,0) ) Angular frequency error: Δω = (Angular frequency of received wave) − (Received angular frequency of receiver) Symbol period: T1 Further, the output of delay detection circuit 2 is expressed by the following equation.

U ′ (nT1) = exp [j · (Δφ + ΔΩ)] Here, ΔΩ = Δω · T1. Further, the complex expression of the output signal of the sign determination circuit 7 is u (nT1) = exp [j · Δφ] Therefore, the output of the complex conjugate circuit 21 is u ^* (nT1) = exp [−j · Δφ] . Accordingly, the output of the multipliers 20, It can be seen that the frequency error is detected. In addition,
Since the phase of the received signal slightly fluctuates due to thermal noise or the like, the detected frequency error is averaged by the moving average circuit 22, and the effect of the fluctuation due to noise is removed. The output of the moving average circuit 22 is
To obtain a complex conjugate and multiplying the complex conjugate with the output of the delay detection circuit 5 by the multiplier 6 to obtain the output of the delay detection circuit 5 having no frequency error (see Japanese Patent Application Laid-Open No. 3-85044).

In FIG. 3, baseband generating circuit 13
Is T2, and the roll-off filter 2
4 ₁ of the output i (KT2), roll-off filter 24 ₂
Is the output of q (kT2), the signal b (kT2) on the complex plane is Here, θ = tan ⁻¹ [q (kT2) / i (kT2)]. The carrier to the quadrature modulation circuit 9 is represented by c (kT2) = exp [j · ω _tx kT2]. If no error is detected in the phase displacement amount detection circuit 8 of the receiver, the output of the quadrature modulation circuit 9 is Becomes Next, when an error is detected in the phase displacement amount detection circuit 8 of the receiver, the phase rotation speed conversion circuit 10 outputs a signal converted to v (kT2) = exp [j · (ΔΩ / m)]. Is done. Here, m = T1 / T2. At this time, the output of the multipliers 1 1, the y (kT2) = exp [j · (ΔΩ / m · k ) ]. At this time, the output of the quadrature modulation circuit 9 is tx ′ (kT2) = c (kT2) · y (kT2) · b (kT2) = exp [j · [(ω _tx kT2 + ΔΩ / m · k) + θ]] Become. Here, since it is ΔΩ / m = ΔωT2, tx ' (kT2) = exp [j · _{[(ω tx + Δω) kT2 +} θ ]] next, it is understood that the transmission angular frequency is offset by [Delta] [omega. For the phase rotation speed conversion circuit 10, for example, cos (ΔΩ) and sin (ΔΩ) are converted to cos (ΔΩ).
/ M) and sin (ΔΩ / m).

For the phase rotation speed conversion circuit 10, for example, cos (ΔΩ) and sin (ΔΩ) are converted to cos
To convert to (ΔΩ / m) and sin (ΔΩ / m)
This is realized by the M table.

[0025]

As described above, according to the present invention, when the frequency of the reference clock signal generation source of the mobile station is controlled based on the transmission frequency of the base station, the transmission frequency of the mobile station is changed. Can be controlled in a short time. As a result, the time from when the power of the mobile station device is turned on until it can be used is shortened, and a mobile communication system with high frequency accuracy can be realized even if the circuit configuration of the mobile station device is simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a detection unit.

FIG. 3 is a block diagram of a phase modulation unit.

[Explanation of symbols]

Reference Signs List 1 reception circuit 2 transmission circuit 3 detection section 4 phase modulation section 5 delay detection circuit 6, 11, 20 multiplier 7 sign determination circuit 8 phase displacement amount detection circuit 9 quadrature modulation circuit 10 phase rotation speed conversion circuit 12 complex number multiplier 13 base Band generation circuit 14 Reference clock signal generation circuit 21, 23 Complex conjugate circuit 22 Moving average circuit 24 ₁ , 24 ₂ Roll-off filter 25 Impulse generator 26 IQ separation circuit

Claims (2)

(57) [Claims] A receiving circuit for receiving a phase-modulated wireless signal;
A detector for determining the sign of the output signal of the receiving circuit by phase detection, a phase modulator for orthogonally modulating a modulated input signal generated based on data to be transmitted, and a transmitting circuit for transmitting the output of the phase modulator The detection unit includes: a delay detection circuit that detects a phase of an output signal of the reception circuit; a sign determination circuit that determines a sign of the detected phase; and a sign determination circuit and the delay detection circuit. A transmitting / receiving apparatus comprising: a phase displacement amount detection circuit that detects a phase displacement amount of the phase modulation signal from an output; and a unit that corrects a signal provided to the sign determination circuit based on a detection result of the phase displacement amount detection circuit. The transmission / reception device, wherein the modulation unit includes means for giving a phase rotation to the modulation input signal based on a detection result of the phase displacement amount detection circuit. 2. The method according to claim 1, wherein the means for giving a phase rotation is a ROM in which a signal level value corresponding to a speed converted in advance is written in an address of an output value of the phase displacement amount detection circuit.
The transmission / reception device according to claim 1, comprising: