JPH0456529A - Radio receiver - Google Patents

Abstract

PURPOSE:To accurately impart amplitude fluctuation information to an equalizer section by providing a band pass filter for detecting an electric field strength level in addition to a band pass filter for limiting the band of a demodulated signal on this receiver. CONSTITUTION:A band pass filter 32 is provided while being branched on the input of a band pass filter 31 for limiting the band of a demodulated signal and the pass band width of the band pass filter 32 is selected differently from that of the band pass filter 31. An electric field strength detector 34 is connected to the band pass filter 32 to detect an electric field strength level of a reception signal at a change in the level of a required speed and inputs the detected electric field strength signal 7 to an equalizing section 5. Thus, amplitude change information is obtained by the equalizing section 5 independently of the band limit of an intermediate frequency signal for demodulation with fidelity and the section 5 executes the equalization of a signal with a proper amplitude and waveform.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a radio reception device, and particularly to a radio reception device that receives and demodulates a high frequency signal modulated by digital data and corrects the demodulated digital data by an equalizer. Regarding equipment.

[Conventional technology]

Conventionally, this type of radio receiving apparatus has been configured as shown in the block diagram shown in FIG. In FIG. 2, a high frequency received signal modulated by digital data is input to an antenna 1. In FIG. The received signal is received by a radio frequency section (RF) 2 that receives and amplifies the received signal and converts the frequency into an intermediate frequency signal.
．． The intermediate frequency signal is passed through a band pass filter (IF-FIL) 3
After passing through the intermediate frequency section (IP) 3 where the band is limited by 1 and amplified by the amplifier (IF-AMP) 33,
It is demodulated into digital data by M>4. The demodulated data is corrected by an equalizer (EQL) 5 for effects such as multipath fading occurring in the radio propagation path of the received signal, and is output as a data signal (DATA) 6. On the other hand, the intermediate frequency signal branched from the amplifier 33 in the intermediate frequency section 3 is sent to an electric field strength detector (
LEV DET) 34, and a field strength signal (LEVEL>7), which is reception level information of the received signal, is obtained.The field strength signal 7 is input to the equalization unit 5 as a control signal, and is also sent out of the device. is also output as a received electric field monitor signal.

[Problem to be solved by the invention]

Generally, in the above-mentioned type of radio receiving apparatus, the band of the signal input to the demodulator is often made narrower than the signal band of the received signal in order to reduce the noise input to the demodulator. This band limitation is primarily performed by a band pass filter in the intermediate frequency section. Assuming that the pass band of the band pass filter is B and the symbol rate of the received signal is 1/T, the degree of band limitation is expressed by the product of (data bit interval T) - B and T, that is, BT.

Then, when B T = 0.5, the symbol is
The response will be halved.

By the way, when correcting deterioration in the amplitude and waveform of demodulated data caused by multipath fading using the equalization section,
It is necessary to capture amplitude fluctuations caused by multipath fading, ie, amplitude fluctuations in units of one symbol, as information. In the above-described conventional radio receiving apparatus, field strength detection is performed using a signal that has passed through a band-pass filter, and the obtained field strength signal is input to the equalization section as amplitude fluctuation information.

For this reason, if the band limit is strengthened to reduce noise, it becomes difficult to obtain correct amplitude fluctuation information, and the equalizer cannot perform an appropriate amplitude equalization operation.

[Means to solve the problem]

The radio receiving device according to the present invention includes a high frequency section that receives and amplifies a high frequency signal modulated by digital data and converts the frequency into an intermediate frequency signal, and a high frequency section that receives the intermediate frequency signal and whose band is limited by a first band pass filter. an intermediate frequency section that outputs reception level information of the high frequency signal received by the intermediate frequency signal and field strength detector; and a demodulation section that demodulates the band-limited intermediate frequency signal into demodulated data;
In the radio receiving device that corrects the signal of the demodulated data using the received level information, the intermediate frequency signal input to the field strength detector has a second band having a wider bandwidth than the bandwidth of the first band pass filter. Bandwidth limited by pass filter.

〔Example〕

Next, the present invention will be explained with reference to the drawings. Ru.

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

A high frequency received signal modulated by digital data input from the antenna 1 is converted into an intermediate frequency signal by the high frequency section 2 and input to the intermediate frequency section 3. Here, the intermediate frequency signal is divided into two parts, one of which is filtered by the bandpass filter 31.
and the other are input to the band pass filter 32, respectively. The intermediate frequency signal is filtered by the bandpass filter 31 to limit the band to BT≦1 (for example, BT = 0.6) to reduce noise.
). The band-limited intermediate frequency signal is sent to the demodulator 4.
The signal is quadrature detected and demodulated into digital data.

The demodulated data is corrected by the equalizer 5 for data waveform deterioration due to multi-pulse fading.

Deterioration of demodulated data due to multipath fading occurs when high frequency signals passing through radio propagation paths with different delay times are combined, and is greatest when the difference in delay time is equal to the data bit interval T. At this time, the received signals may cancel each other out, and the amplitude is greatly attenuated in units of one bit. The equalization unit 5 estimates the influence of multipath fading using this amplitude change information and phase change information obtained from demodulated data subjected to orthogonal detection, and corrects the demodulated data. Therefore, it is necessary for the electric field strength signal 7 to faithfully provide the equalization unit 5 with changes in the level of the received signal. That is, it must respond to changes in the speed of the symbol rate of the received signal. For example, the symbol rate is 300K
Even with an input signal of bps, the output signal of the bandpass filter 31 whose signal band is limited to B T = 0.6 becomes difficult to respond to amplitude changes having frequency components of 180 KHz or higher. .

The phenomenon described above is shown in the response diagram of the electric field strength signal in FIG. FIG. 3(a) shows the true electric field strength of the received signal, indicating that there is attenuation over one symbol length (T).

FIG. 3(b) shows the response to FIG. 3(a>) when the received signal is band-limited to BT=1, and FIG. 3(C) similarly shows the response when BT<1.

In the embodiment shown in FIG. 1, a band-pass filter 32 is provided branching off to the input side of a band-pass filter 31 that performs band-limiting for demodulation. This band pass filter 32
The passband width of the bandpass filter 31 is set to a value different from that of the bandpass filter 31, for example, BT=1. A field strength detector 34 is connected to the bandpass filter 32 and detects the field strength level of the received signal by changing the level at a required speed, and the detected field strength signal 7 is input to the equalization section 5. . As a result, the equalizer 5 can faithfully obtain amplitude change information regardless of the band limit of the intermediate frequency signal for demodulation, and can perform appropriate equalization of the amplitude and waveform.

〔Effect of the invention〕

As explained above, the radio receiving device according to the present invention includes, in addition to the bandpass filter for band-limiting the signal to be demodulated,
By providing a bandpass filter for detecting the electric field strength level, amplitude fluctuation information can be accurately provided to the equalizer. As a result, deterioration in the amplitude and waveform of demodulated data due to multipath fading, etc. can be corrected by leveraging the ability of the equalizer, reducing the transmission signal error rate of communication systems using this radio receiving device, and improving line quality. It has the effect of improving the

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a radio receiving device according to the present invention, FIG. 2 is a block diagram of a conventional radio receiving device,
FIG. 3 is a response diagram of the electric field strength signal. DESCRIPTION OF SYMBOLS 1... Antenna, 2... High frequency part, 3... Intermediate frequency part, 4... Demodulation part, 5... Equalization part, 6... Data signal, 7... Electric field strength signal , 31.32... bandpass filter, 33... amplifier, 34... electric field strength detector.

Claims (1)

[Claims] a high frequency section that receives and amplifies a high frequency signal modulated by digital data and converts the frequency into an intermediate frequency signal; an intermediate frequency signal inputted with the intermediate frequency signal whose band is limited by a first band pass filter; and a field strength detector. an intermediate frequency section that outputs reception level information of the received high frequency signal; a demodulation section that demodulates the band-limited intermediate frequency signal into demodulated data; and a radio that corrects the demodulated data using the reception level information. In the receiving device, the intermediate frequency signal input to the field strength detector is band-limited by a second band-pass filter having a wider bandwidth than the first band-pass filter. Wireless receiving device.