JPH03232322A - Digital radio receiver - Google Patents

Abstract

PURPOSE:To obtain a signal with the optimum reception sensitivity by deciding either interference phasing or attenuation phasing according to reception levels in the prescribed frequency bands of received signals on a main side and a space diversity(SD) side and selecting the reception signal with the less bit error rate(BER). CONSTITUTION:In the case of generating the interference phasing or the attenuation phasing in a reception coefficient on the main side or the SD side, signals are outputted from reception parts 1 and 4 and equalizers 2 and 5. In such a case, the reception levels are detected by sweep detection parts 3 and 6 while being swept at every several MHzs, for example. Then, a control part 7 decides whether the degradation of the reception level is the interference phasing or the attenuation phasing, and based on the decided result, the BER corresponding to the interference phasing or the BER corresponding to the attenuation phasing is calculated. Next, the BER of two reception systems are compared and a selective signal is generated to select the reception signal with the less BER. According to this selective signal, a selective part 8 selects the reception signal from the sweep detection part 3 or 6 and sends it to an ACC amplifier 9.

Description

[Detailed Description of the Invention] [Summary] Regarding a space diversity type digital radio receiving device, a digital radio capable of performing the best fading equalization regardless of whether interferential fading or attenuation fading occurs. The purpose is to XIM the receiving device, and it includes a sweep detection section that detects the reception level in a predetermined frequency band of the received signal that has been equalized from the main reception section through equal weight, and a sweep detection section that detects the reception level in a predetermined frequency band of the received signal that has been equalized from the main reception section through equal weight and equalization. a sweep detector for detecting the reception level of the received signal in a predetermined frequency band; A control unit that generates a selection signal for determining the bit error rate corresponding to the fading and selecting the output of the sweep detection unit with the better bit error rate, and the output of both sweep detection units based on the selection signal. Select AG
It consists of a selection section that sends data to a demodulation section via a C amplifier.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a digital radio receiver, and particularly to a space diversity digital radio receiver.

In order to transmit radio signals through the air, it is necessary to overcome various obstacles, and in particular, in digital (micro) concentrator systems, it is necessary to create a system with high equalization ability against the occurrence of interferometric fading.

For this reason, a space diversity (hereinafter simply referred to as SD) combining method has been adopted, but since the equalization ability of this method is not extremely good, it is possible to improve the quality of a better radio link. There is a need.

[Conventional technology and issues]

In conventional digital radio equipment, the in-phase phase synthesis method, minimum amplitude deviation within frequency band synthesis method, etc. have been adopted as methods for combining the main reception section and the SD reception section in order to equalize interferometric fading. None of these methods can completely cancel the interference waves, leaving a deep region with locally attenuated amplitude within the frequency band, which causes bit errors.

On the other hand, in the case of attenuated fading, in which the incoming signal level decreases over the entire frequency band, an AGC amplifier is provided on each of the main side and SD side, so the AGC amplifier amplifies not only the signal but also the noise, which is then synthesized. As a result, noise is added. In other words, when the incoming signal level on the main side decreases, noise is amplified along with the signal by the A and GC amplifiers, but when this is combined with the incoming level on the SD side, the S/N increases by the amount of noise on the main side.
This will result in a worsening of N.

Therefore, an object of the present invention is to realize a digital radio receiving apparatus that can perform the best equalization of fading, regardless of whether interferential fading or attenuated fading occurs.

[Means to solve the problem]

In order to achieve the above object, the digital radio receiving device according to the present invention, as shown in principle in FIG. A sweep detection unit 3 that detects the reception level, a sweep detection unit 6 that detects the reception level in a predetermined wave number band of the reception signal equalized from the space diversity reception unit 4 through the equal weight 5, and each sweep detection unit 3 .6 determine whether interferential fading or attenuation fading has occurred in the received signal, find the bit error rate corresponding to the fading, and select the sweep detector with the better bit error rate. a control unit 7 that generates a selection signal for selecting the output of 3.6, and a selection unit that selects the output of both sweep detection units 3.6 based on the selection signal and sends it to the demodulation unit via the AGC amplifier 9. 8.

Further, in the present invention, the control section 7 controls each sweep detection section 3,
When it is determined from the output of 6 that both interferential fading and attenuation fading have occurred in the received signal, the bit error rate corresponding to each fading is determined, and the one with the worse bit error rate is selected,
Furthermore, the sweep detection unit 3 has a better bit error rate.
A selection signal for selecting the output of No. 6 may be generated.

[Operation] The operating principle of the present invention shown in FIG. 1 will be explained below with reference to FIG. 2.

Figure 2 (a) shows the case where coherent fading ■ exhibiting local dip attenuation or attenuating fading ■ exhibiting overall attenuation occurs in the main side or SD side optical receiving system as shown by dotted lines. A frequency spectrum is shown, and a signal with such a frequency spectrum is transmitted to the receiver 1.
．． 4 and the equalization amount 25, the reception level is detected by the wave number of a predetermined number of points obtained by sweeping, for example, several MHz by the sweep detecting section 3.6 (FIG. 4(b)).

The reception levels detected by the sweep detectors 3 and 6 are then checked by the control unit 7 to determine whether the deterioration of the reception level is due to interferential fading (Fig. Based on this determination result, the control unit 7 further performs the determination (FIG. 3D).
The bit error rate (hereinafter simply referred to as BER) corresponding to the maximum in-band attenuation (Dimb deviation) of coherent fading, as shown in Figure 1, or the average attenuation of attenuated fading, as shown in (A) ■ in the same figure. The BER is calculated (see figure ((to)).

The reason why both characteristics ■ and ■ exist is that the attenuation area (attenuation power) is different between coherent fading and attenuated fading, as shown in the figure.

In this case, when it is determined that both coherent fading and attenuated fading have occurred (as shown in figure (a)), the BER corresponding to each fading is determined, and the You can also choose one.

Then, the control section 7 compares the BERs of the two receiving systems thus obtained and generates a selection signal for selecting the received signal with the better BEH.

The selection section 8 selects the received signals from the sweep detection sections 3 and 6 based on the selection signal from the control section 7, and sends them to the modulation section (not shown) via the C amplifier 9 ((e) in the figure).

As a result, the received signal with better BER can be selected for both interferential fading and attenuated fading, and the AGC amplifier can also amplify only the one with better reception sensitivity.

〔Example〕

FIG. 3 shows an embodiment of the sweep detection section 3.6 shown in FIG. a vCO (voltage controlled oscillator) that receives a control voltage signal and generates a desired frequency signal and supplies it to the mixer 32; an LPF (low pass filter) that receives the output of the mixer 32;
An amplifier 35 that amplifies the output of the LPF 34;
The wave detector 36 detects the DC component of the wave detector 36, and the DC amplifier 37 amplifies the DC output of the wave detector 36.

The sweep detectors 3 and 6 take the difference between the frequency of the output signal (IF band) from the equalization amount of 2.5 and the frequency of the output signal from vC033, and calculate the reception level at a predetermined frequency via the LPF 34. The detected signal is output as a DC signal by an amplifier 35, a wave detector 36, and a DC amplifier 37. When the control voltage signal from the control section 7 changes, the reception level at the next predetermined frequency is detected, and in this way, the in-band frequencies are sampled by a predetermined number of times and the reception level is sent to the control section 7. I have to.

In addition, as a detection method, always measure the overall level with a wide band at all times, and when the level drops, change to a narrow band and sweep the detection band. Alternatively, there is a method of detecting the in-band deviation in detail.

FIG. 4 shows an embodiment of the control section 7 shown in FIG.
D side BER) E peak 72 and these BER) E peak 7
1.72 and a comparator 73 for comparing each output.

Among these, the configuration of the BERX output section 7 section 71 is the same,
In the example of the BER calculation unit 71, an A/D converter 41 that inputs the reception level signal output from the sweep detection unit 3;
A program and a BER characteristic map (FIG. 2(d)) stored in the ROM 43 after receiving the output of the A/D converter 41
CP that executes the algorithm shown in FIG.
U42, a launch circuit 44 that latches the output of this CPU 42, a D/A converter 45 that converts the output of the latch circuit 44 into an analog signal, and is controlled by the CPU 42 to generate the sweep frequency of the sweep detector 3. , and a D/A converter 47 that converts the output of the VCO control circuit 46 into an analog signal.

The BERX output section 7 construction section 71 in FIG. 4 will be explained with reference to the flowchart in FIG. 5.

First, the CPU 42 inputs the reception level outputted from the sweep detection section 3 (in this case, the reception rail on the main side) for each frequency sample, and inputs the reception level output from the sweep detection section 3 to a built-in memory (not shown).
(Step Sl in FIG. 5).

By performing this storage operation by sweeping within the frequency band, the reception levels corresponding to a predetermined number of frequency samples are stored in the CPU 42, and these data are used to store the received levels corresponding to a predetermined number of frequency samples. First check whether or not coherent fading is occurring.
2), if it has not occurred, then Fig. 2 (a) ■
It is checked whether attenuated fading as shown in (step S3) is occurring.

As a result, if no attenuated fading has occurred, the selection section 8 will not perform any switching.

Incidentally, especially when no abnormality is recognized in the wireless line, it may be decided in advance to select one of the receiving systems.

When it is determined in step S3 that attenuated fading has occurred, the corresponding BER is determined from the ROM 43 that stores a map of attenuated fading characteristics as shown in FIG. ).

Further, when it is determined in step S2 that coherent fading has occurred, it is checked whether attenuated fading has also occurred (step S5), and when it is determined that attenuated fading has not occurred,
The corresponding BER is determined from the ROM 43, which stores a map of coherent fading characteristics as shown in FIG. 2(d) (2), and is output (step S6).

When it is determined in step S5 that attenuated fading has also occurred, B based on both ■ and ■ in FIG. 2(d)
The ER is determined, and the worse one is selected and output.

The BER output from the CPU 42 is latched by the latch circuit 44 and then converted to an analog signal by the D/A converter 45 and output to the comparator 73.

In this way, the BERs calculated from the BER calculating sections 71 and 72 are given to the comparator 73 as analog signals for comparison, and a selection signal is outputted so that the one with the better BER is selected. It will be given to

FIG. 6 shows an embodiment of the present invention. In this embodiment, the selection section 8 is specifically shown, and the reception section, equalization amount, sweep detection section, and control section are shown in detail. It is the same camphor tree as in Figure 1.

In this embodiment, variable attenuators 81 and 82 are provided on the output sides of sweep detectors 3 and 6, respectively.
The outputs of I and 82 are combined by a combination Fj 83. For example, when the SD side is selected, the attenuation gain of the attenuator 82 is O.
dB, and the main side that is not selected is several tens of dB.
dB (60dB to 100dB that does not affect the SD side)
By attenuating the voltage up to the maximum, a substantially uninterrupted selection switching circuit is formed.

FIG. 7 shows a modification of the present invention, in which the embodiment of FIG. 2 is extended and a conventional phase synthesis method is employed to equalize fading.

In the figure, a receiver, an equalizer, a sweep detector, a variable attenuator,
and a synthesizer are the same as those shown in FIG. 6, but here, each output of the equalizer 2.5 is phase-adjusted (delay-adjusted) by a phase synchronization section 1213, and the phase difference is determined by iil! Gobe 1 Kusube 1
4, the infinite phase shifter 11 using the local oscillation frequency of the main side receiving section 1 is controlled to control the local oscillation frequency on the SD side to synchronize the phases of both receiving systems, and also to synchronize the phases of both receiving systems. The IF band optical reception signals outputted from sections 12 and 13 are synthesized by the synthesizer 15, and then sent to another sweep detection section 2.
By sweeping at 0, the control unit 70 transmits an attenuation gain control signal to the attenuators 81, 84, and 82 to select the one that provides the best BER based on the reception levels from the three sweep detectors 3, 20, and 6. The receive signal with the best reception sensitivity is output from the combiner 83 by
It can be sent to GC amplification 9.

Furthermore, RF! In order to carry out the present invention, for example, a sweep detection section may be provided in the receiving section and detection may be performed using a micrometer before being demodulated to the IFW.

However, using the microwave band is expensive and
Furthermore, since it depends on the microwave frequency, it is more practical to perform it under IFI.

〔Effect of the invention〕

As described above, in the digital radio receiving device according to the present invention, the reception level in a predetermined wave number band of the reception signal on the main side and the SD side is detected while sweeping the frequency, and the detected reception level causes interference fading. The system is configured to determine whether the fading is occurring or attenuated fading is occurring, determine the bit error rate corresponding to the fading, and select the received signal with the better bit error rate, regardless of the type of fading. This has the advantage that a signal with optimal reception sensitivity can be obtained and only one AGC amplifier is required for the selected reception signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a digital radio receiving device according to the present invention, FIG. 2 is a diagram illustrating the principle of the present invention, and FIG. 3 is a block diagram showing an embodiment of a sweep detection section used in the present invention. FIG. 4 is a block diagram showing an embodiment of the control unit used in the present invention; FIG. 5 is a flowchart showing the BER of the control unit in FIG. 4; FIG. 7 is a block diagram showing an embodiment of the invention, particularly the selection section. FIG. 7 is a block diagram showing a modification of the invention. In FIG. 1, 1.4... Receiving section, 2.5... Equal stopper, 3.6... Sweep detection section, 7... 1iIJ control section, 8... Selection section, 9 ...AGC amplifier. In the figures, the same reference numerals indicate the same or corresponding parts. Figure 1 S Temple / Figure 3 Figure 4 Algorithm for calculating B E R Figure 5

Claims (2)

[Claims] (1) A sweep detection unit (3) that detects the reception level in a predetermined frequency band of the received signal equalized from the main reception unit (1) via the equalizer (2), and a space diversity reception unit (4). Equalizer (5)
A sweep detection unit (6) detects the reception level in a predetermined frequency band of the received signal equalized through Alternatively, it is determined whether attenuated fading is occurring, the bit error rate corresponding to the fading is determined, and a selection signal is generated for selecting the output of the sweep detector (3) or (6) with the better bit error rate. a control unit (7) that generates a signal, and a selection unit (8) that selects the outputs of both sweep detection units (3) and (6) based on the selection signal and sends it to the demodulation unit via the AGC amplifier (9). A digital radio receiving device characterized by comprising: (2) The control unit (7) controls each sweep detection unit (3) (6
), when it is determined that the received signal has both interferential fading and attenuated fading, the bit error rate corresponding to each fading is determined, and the one with the worse bit error rate is selected,
In addition, the sweep detection unit with a better bit error rate (3
2. The digital radio receiving apparatus according to claim 1, wherein the digital radio receiving apparatus generates a selection signal for selecting the output of (6).