JP2656387B2 - Convolver output stabilizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a convolution output stabilizing apparatus for a convolver used in a receiving section of a spread spectrum communication apparatus.

[0002]

2. Description of the Related Art In recent years, with the spread of cordless telephones and the like, the demand for wireless terminals and the like has increased, and various radio waves have come to fly more in homes and offices.

[0003] The frequency resources of such radio waves are limited, and in consideration of the effective use of radio waves in the future, radio terminals of the normal system will cause more interference than ever, and their characteristics are likely to deteriorate. Become.

[0004] Therefore, a spread spectrum communication system (hereinafter referred to as SS) has been proposed as a radio system excellent in interference and noise resistance.
Has been attracting attention.

[0005] In simple terms, this system spreads transmission radio waves several hundred times as wide as the band to be transmitted and transmits the transmission radio waves, thereby apparently lowering the transmission level (does not affect other radio equipment). ), And the receiver demodulates the data by collecting the radio waves dropped to the low level.

FIG. 2 shows a schematic configuration (reception unit) of a radio unit of a direct spreading system using a convolver in a reception unit as a conventional SS system. In the figure, 1 is a receiving antenna,
2 is a BPF (bandpass filter), 3 is a Mix (frequency converter), 4 is an oscillator, 5 is a variable attenuator, 6 is an amplifier, 7 is a detector, and 8 is an error amplifier. The transmission spread signal received by the antenna 1 is band-separated by the BPF 2, unnecessary components are removed, and the frequency is converted by the MiX 3 and the oscillator 4.

After that, the frequency-converted signal becomes 6
, And becomes one input of the convolver 13.

The level of this signal is simultaneously detected by an envelope detector 7, compared with a predetermined level by an error amplifier 8, outputs a voltage of the difference, controls a variable attenuator 5, and controls a convolver 13. It is also used in an AGC configuration (part (A) in the figure) that keeps input power to a constant level despite fluctuations in the received signal.

A part (B) in the figure is a REF (reference) signal oscillating part, which supplies a spread signal of a predetermined level to the other input of the convolver 13.

Reference numeral 9 denotes an oscillator, 10 denotes MiX, 11 denotes a spread code generator, and 12 denotes an amplifier. Thirteen surface acoustic wave elements (convolvers) play an important role in demodulation of SS, and perform a product-sum operation of two input signals.

Reference numeral 14 denotes an amplifier, and reference numeral 15 denotes an envelope detector, which detects the level of the convolution output here and outputs it to a code synchronization unit (not shown) for use in code synchronization.

[0012]

In the above-mentioned prior art, the attenuation factor of the variable attenuator 5 in the AGC section of the section (A) surrounded by a broken line is changed according to the level of the received spread signal. The control is performed in accordance with the control voltage to keep the input power of the convolver constant.

[0013] In the case of SS communication, the transmission signal has a very wide band (for example, several hundred times as large as the band of the signal to be transmitted), so that the transmission level is considerably low legally and in terms of power consumption. Must be. Therefore, the reception level becomes a weak radio wave that is buried in environmental noise.

Therefore, in a convolver whose output efficiency is not so large, the dynamic range of the AGC of the receiving section must be widened.

Further, since the signal has a wide band, in a shielded place or a place where there are many reflective objects, for example, the signal drops sharply due to the influence of multipath due to reflection, which may cause a decrease in the signal level as a whole. There is.

Conversely, when a strong external wave is temporarily received, the gain of the AGC is set high, so that the received AGC exceeds the range of the received AGC, and there is a possibility that the received AGC may fall into a region where the AGC cannot be performed. .

In such a state, in the conventional apparatus, the output level of the convolver fluctuates, adversely affecting code synchronization by envelope detection, causing loss of code synchronization and lowering the error rate. There is a disadvantage of inviting.

[0018]

According to the present invention, in order to solve the above-mentioned problems, a spread spectrum signal to be received is collected.
Input to the first input terminal of the
The signal is input to a second input terminal of the convolver and the reception is performed.
Between the power spread spectrum signal and the reference spread signal.
Combo that stabilizes the output of the convolver that performs the product-sum operation
Luba output stabilizing device, wherein the spectrum to be received is
Ram-spread signal, and the reception obtained by the detection is detected.
According to the level of the spread spectrum signal to be
1 to be received at the input terminal
And means for controlling so as to put No. a certain level, the receiving
The level of the spread spectrum signal to be
Operates at the following time, and the reference input to the second input terminal
The level of the spread signal for use in the spectrum to be received.
Means for varying according to the level of the spread signal.
The bolver output stabilizing device is used as a means.

[0019]

According to the present invention, the envelope detection output detected in the reception AGC (part A) is used not only for supplying a constant power to one input of the convolver, but also for detecting the output of the convolver. By using it to keep one input power constant, it is possible to keep the total input power of the convolver constant, and to keep the convolution output constant even if the input level of the received wave exceeds the control range of the received AGC. Can be.

That is, the envelope detection output is fed back to the REF (reference) signal generation section in FIG. 2 (B), and the error amplifier is operated only when the received signal level becomes lower than a predetermined level. By controlling the provided variable attenuator, the convolution output can be made constant.

[0021]

FIG. 1 is a schematic block diagram showing an embodiment of the present invention. In the drawing, reference numerals 1 to 15 are the same as those of the conventional example shown in FIG.

The main feature of the present invention is that R in FIG.
The 16 second error amplifiers, 1
7 is provided with a second variable attenuator and has an AGC function like the receiving section.

In FIG. 1, a signal received by a receiving antenna 1 is converted to a desired frequency by a frequency converter (MiX) 3, amplified through a variable attenuator 5, and supplied to one input signal of a convolver 13. Becomes At this time, the input signal level is detected by the envelope detector 7 and the output control voltage of the first error amplifier 8 amplifies the error between the detected voltage level and the set voltage. , One input signal of the convolver 13 is kept constant with respect to the fluctuation of the input signal. 9 to 15 in the figure are the same as those in the conventional example.

The present embodiment is different from the prior art in that a second error amplifier 16 and a second variable attenuator 17 are added to the REF (reference) signal generating section shown in FIG.

For example, when the input signal from the antenna 1 drops to an extremely low level and exceeds the variable range of the first variable attenuator of 5 (due to radio wave reflection, etc.
This causes a drop in the received waveform, resulting in a lowering of the level), the input to the convolver 13 also drops, and the level of the convolver output also drops accordingly.

Therefore, in this embodiment, a second error amplifier 16 is provided so as to operate only when the output of the first envelope detector 7 falls below a predetermined level, and a second variable attenuator is provided. A voltage for controlling the attenuator 17 is generated by the second error amplifier 16 to control the amount of attenuation of the attenuator 17.

FIG. 3 shows the input power P ₁ to one side of the convolver with respect to the first envelope detection output of the conventional example.

[0028] When the detection output V ₁ or less, the attenuation factor of the attenuator becomes a 0 dB, P ₁ even become lowered proportionally it for the following input.

Therefore, in this embodiment, the detection output is sent to the second error amplifier 16 and the predetermined comparison voltage of the second error amplifier 16 is set lower than V ₁ , so that the first envelope detection output becomes V _1. The second variable attenuator 17 is controlled by operating the second error amplifier only in the following cases.

[0030] Figure 4 shows the relationship between the other input power P ₂ of the convolver 13 when operating the second error amplifier 16 of such embodiment the detection output. As shown in FIG. 4, when a detection output of V ₁ or less, is an output control voltage from the second error amplifier, lowers the attenuation rate of the second variable attenuator 17 according to a decrease in the level of P _1, the P ₂ The level is controlled to increase, and the total power of the two inputs to the convolver 13 is kept constant.

Here, when the detection output is V ₂ or more, the total power increases, but there is no problem because the large convolver output does not affect the second envelope detection.

FIG. 5 shows the relationship between the first envelope detection output and the convolver output P ₀ of this embodiment.

In the embodiment of the present invention, the control of the power input is performed by controlling the variable attenuator, but the amplifier may be controlled.

[0034]

As described above, when a weak radio wave is received and the dynamic range of the received AGC is exceeded, the power of one side input of the convolver is controlled in accordance with the detection output, thereby providing a comprehensive system. AGC range can be widened.

Therefore, the reduction in the level of the arriving radio wave caused by the presence of a shield or reception at a long distance can be effectively reduced by the AG.
This can be prevented by operating C. As a result, the convolver output can be kept constant over a wide range of reception levels, and code synchronization can be achieved well.
The effect of contributing to the improvement of the error rate is obtained.

[Brief description of the drawings]

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

FIG. 2 is a configuration block diagram of a conventional example.

Figure 3 is a graph representing the relationship between the input power P ₁ and the detection output of the one side of the convolver prior art.

FIG. 4 is a graph showing a relationship between input power P ₂ to the other of the convolver and detection output according to the embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a convolver output P ₀ and a detection output in the embodiment of the present invention.

[Description of sign]

 Reference Signs List 1 receiving antenna 2 BPF 3 Mix 4 oscillator 5 first variable attenuator 6 amplifier 7 first envelope detector 8 first error amplifier 9 oscillator 10 Mix 11 spreading code generator 12 amplifier 13 surface acoustic wave element (convolver) 14 amplifier 15 Envelope detector 16 Second error amplifier 17 Second variable attenuator

Claims (2)

(57) [Claims] A spread spectrum signal to be received is controlled by a controller.
Input to the first input terminal of the VOLBA and add the reference spread signal to the
Input to the second input terminal of the convolver, and
Product of the spread spectrum signal and the reference spread signal
A convolver that stabilizes the output of a convolver that performs a sum operation
An output stabilizing device for detecting the spread spectrum signal to be received,
Of the spread spectrum signal to be received obtained by
The reception signal input to the first input terminal according to the level.
To keep the spread spectrum signal to a certain level.
Means for controlling the level of the spread spectrum signal to be received is a predetermined level.
Operates when the level is below the level and inputs to the second input terminal
The level of the reference spread signal is determined by the
Means to vary according to the level of the spread spectrum signal.
Convolver output stabilizing device. 2. The apparatus according to claim 1, wherein the variable means includes a switch to be received.
Variable attenuation according to the level of spread spectrum signal
Variable attenuator or spread spectrum to be received
Includes an amplifier that varies the amount of amplification according to the signal level
The convolver output stabilizing device according to claim 1.