JPH10135799A - Pulse signal receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse signal receiver in which a level of a received pulse signal is adjusted in an optional timing even when suppressing the number of components. SOLUTION: Let resistance of 1st and 2nd resistors 11, 12 be respectively R1 , R2 , then a resistance between an input of a 1st stage amplifier and ground is R2 when a switch 13 is open. The resistance between the input and Sround is R1 .R2 /(R1 +R2 ) when the switch 13 is closed. A level of a pulse signal gets higher when the switch 13 is open than that when the switch 13 is closed by matching an input impedance of the 1st stage amplifier with an output impedance of a signal reception section 1 when the resistance is R2 . An arithmetic section 7 sets the level of the pulse signal lower by closing usually the switch 13 and when a predetermined pattern is represented by the received pulse signal, the switch 13 is open to increase the level of the pulse signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse signal receiving apparatus for receiving and processing a pulse signal propagated by an electromagnetic wave or an ultrasonic wave.

[0002]

2. Description of the Related Art In this type of apparatus, the level of a received pulse signal is not constant but fluctuates, so that it is necessary to control the amplification factor of the received pulse signal.

For example, Japanese Patent Application Laid-Open No. 7-38342 discloses a "preamplifier" as shown in FIG.

In FIG. 1, a signal receiving unit 101 receives a light pulse, performs photoelectric conversion on the light pulse, and applies a pulse signal to a preamplifier unit 102. This preamplifier unit 102
Comprises a first-stage amplifier 103, a middle-stage amplifier 104, and a second-stage amplifier 105, and amplifies a pulse signal at each stage, and then outputs the pulse signal.

The amplification factor of the preamplifier unit 102 is determined by the impedance of the resistor 107 and the variable impedance unit 108.

On the other hand, the pulse signal output from the first-stage amplifier 103 is applied to a signal synthesizing unit 110 and a peak detecting unit 111 via a level shift amplifier 109. The peak detecting unit 111 detects the peak value C of the pulse signal, and adds the peak value C to the signal combining unit 110 while holding the peak value C.

The signal synthesizing unit 110 synthesizes the pulse signal B and the peak value C, and applies the synthesized value B + C to the variable impedance unit 108. The variable impedance 108 changes its own impedance value at any time according to the composite value B + C. Thereby, the amplification factor of the preamplifier unit 102 is adjusted.

[0008]

However, the above-mentioned conventional preamplifier requires a signal synthesizing section 110 and a peak detecting section 111, and thus has a drawback that the number of components is large. In addition, this causes an increase in cost and power consumption, and makes it difficult to miniaturize the product.

Further, the basic principle is that the impedance value is controlled by feeding back the voltage level of the received signal. Therefore, the impedance value of the variable impedance 108 is changed at an arbitrary timing to increase the amplification factor. It could not be adjusted and did not provide such an application.

Therefore, the present invention is to solve such a problem of the prior art, and it is possible to adjust the level of a received pulse signal at an arbitrary timing while suppressing an increase in the number of parts. It is an object of the present invention to provide a simple pulse signal receiving device.

[0011]

In order to solve the above problems, the present invention provides a signal receiving means for receiving and outputting a propagated pulse signal, and amplifying the pulse signal from the signal receiving means. In a pulse signal receiving apparatus including at least an amplifying means, a waveform shaping means for shaping a pulse signal from the amplifying means, and an arithmetic means for inputting a pulse signal from the waveform shaping means, a pulse input to the waveform shaping means is provided. The apparatus further comprises level changing means for changing the level of the signal, and the arithmetic means controls the level changing means in response to a predetermined pattern represented by the pulse signal from the waveform shaping means, thereby controlling the pulse signal. The level has changed.

That is, if a predetermined pattern is represented by the pulse signal, the calculating means changes the level of the pulse signal in response to the pattern. Therefore, if the pulse signal representing this pattern is received by the signal receiving means, the level of the pulse signal can be changed at this reception timing.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of the pulse signal receiving apparatus of the present invention. In the figure,
The signal receiving unit 1 receives a pulse signal of an electromagnetic wave (light or radio wave), converts the pulse signal into an electric signal, and adds the electric signal to the signal amplifying unit 2. The signal amplifying unit 2 amplifies the pulse signal and applies the pulse signal to the waveform shaping unit 6. The waveform shaping unit 6 shapes the waveform of the pulse signal, and adds the pulse signal that has become a square wave to the arithmetic unit 7. In this way, a series of pulse signals are applied to the arithmetic unit 7, and the arithmetic unit 7 performs various processes in response to the codes indicated by these pulse signals.

On the other hand, a variable impedance section 8 is interposed between the input side of the signal amplification section 2 and the ground. The variable impedance unit 8 includes first and second resistors 11 and 12 and a switch 13 as a switching element. The second resistor 12 is inserted between the input side of the signal amplifying unit 2 and the ground. And the switches 13 are arranged in series and inserted between the input side of the signal amplifier 2 and the ground. Therefore, the series circuit including the second resistor 12, the first resistor 11, and the switch 13 is connected in parallel between the input side of the signal amplifier 2 and the ground.

If the input impedance of the signal amplifier 2 is matched with the output impedance of the signal receiving section 1 by changing the impedance of the variable impedance section 8,
The output level of the signal amplifying unit 2 increases, and if there is no matching, the output level of the signal amplifying unit 2 decreases.

The operation unit 7 controls the switch 13 through the signal line 14. The signal line 14 is activated, the switch 13 is turned on, or the signal line 14 is deactivated, and the switch 13 is deactivated.
Turn off.

The operation unit 7 normally includes the switch 1
3 is turned off, a pulse signal from the waveform shaping unit 6 is input, and when a predetermined pattern is represented by the pulse signal, the switch 13 is turned off.

When the switch 13 is off, only the second resistor 12 is inserted between the input side of the signal amplifier 2 and the ground,
The input side of the signal amplifier 2 is grounded via the second resistor 12. When the switch 13 is on, the first and second resistors 11 and 12 are connected in parallel and inserted between the input side of the signal amplifier 2 and the ground, and the input side of the signal amplifier 2 is connected to the first and second resistors. Grounded via 11 and 12.

Here, assuming that the resistance values of the first and second resistors 11 and 12 are R ₁ and R ₂ , when the switch 13 is off, the resistance value between the input side of the signal amplifier 2 and the ground is R ₂ . Become. When the switch 13 is on, the resistance value between the input side of the signal amplification unit 2 and the ground is R ₁ * R ₂ / (R ₁ + R ₂ ).
Becomes The resistance value between the input side of the signal amplification unit 2 and the ground is R ₂
In this case, if the input impedance of the signal amplifying unit 2 is matched with the output impedance of the signal receiving unit 1, the level of the pulse signal is higher when the switch 13 is off than when the switch 13 is on. Become.

That is, the arithmetic unit 7 normally includes the switch 1
Turn on 3 and lower the level of the pulse signal,
When a predetermined pattern is represented by the input pulse signal, the switch 13 is turned off to increase the level of the pulse signal.

FIG. 2 shows another embodiment of the pulse signal receiving apparatus of the present invention. In FIG. 1, FIG.
The same reference numerals are given to the portions that perform the same operations as those of the device described above for convenience of explanation.

Here, the signal amplifying section 2 includes a first-stage amplifier 3, a middle-stage amplifier 4, and a second-stage amplifier 5. A variable impedance section 21 different from that shown in FIG. 1 is used. This variable impedance section 21 is interposed between the input and output of the first-stage amplifier 3 of the signal amplification section 2 and the output of this first-stage amplifier 3 is connected to the variable impedance section. The signal is fed back to the input side of the first-stage amplifier 3 via the section 21.

The variable impedance 21 includes first and second
Resistors 22 and 23 and switch 2 as a switching element
4, the second resistor 23 is inserted between the input and output of the first-stage amplifier 3, and the first resistor 22 and the switch 24 are arranged in series and inserted between the input and output of the first-stage amplifier 3. Therefore,
A series circuit including the second resistor 23, the first resistor 22, and the switch 24 is connected in parallel between the input and output of the first-stage amplifier 32.

If the impedance of the variable impedance section 21 is changed, the amount of feedback to the input side of the first-stage amplifier 3 changes, so that the output of the first-stage amplifier 3 can be changed. For example, if negative feedback is performed, the output of the first-stage amplifier 3 increases as the impedance of the variable impedance unit 21 increases.

Here, assuming that the resistance values of the first and second resistors 22 and 23 are R ₁ and R ₂ , when the switch 24 is off, the resistance value of the variable impedance section 21 is R ₂ .
When the switch 24 is on, the resistance value of the variable impedance section 21 is R ₁ * R ₂ / (R ₁ + R ₂ ).
R ₂ > R ₁ * R ₂ / (R ₁ + R ₂ ), and the output of the first-stage amplifier 3 increases as the impedance of the variable impedance section 21 increases, so that when the switch 24 is off, the switch 24 The output of the first-stage amplifier 3 becomes larger than when it is on, and the level of the pulse signal becomes higher.

That is, the arithmetic unit 7 normally includes the switch 2
Turn on 4 and lower the level of the pulse signal,
When a predetermined pattern is represented by the input pulse signal, the switch 13 is turned off to increase the level of the pulse signal.

As described above, in each of the above embodiments, when a pulse signal having a predetermined pattern is input, the level of the pulse signal applied to the waveform shaping section 6 at this input timing is increased.

The arithmetic unit 7 can also be used for other functions. Conversely, the arithmetic unit in an existing device may fulfill the role of the arithmetic unit 7. Since the hardware can be unified, development costs and product costs can be reduced, products can be downsized, and power consumption can be reduced.

Further, the arithmetic section 7 can control the variable impedance section in a time-division manner.

Next, an application example of the pulse signal receiving apparatus of the present invention will be described. This pulse signal receiving device is used for industrial equipment,
Railway, logistics, can be applied to communication systems in the field of construction, for example, a transponder mounted on a mobile,
A fixed station-side interrogator for exchanging data signals with the transponder, and a communication system called a non-contact mobile object identification device for identifying a mobile object in a non-contact manner; The pulse signal receiving device of each embodiment can be applied.

Here, when the transponder on the mobile side is in a standby state in which no communication is performed, it is necessary to reduce power consumption, and thus the transponder is in a low power consumption mode. In this low power consumption mode, it is impossible to process the data signal by the transponder. For this reason, the interrogator on the fixed station side transmits a data signal from this interrogator to the transponder,
A predetermined control signal is transmitted to this transponder,
This transponder is switched from the low power consumption mode to the normal signal processing mode. This control signal is composed of a simplified pattern (one bit or a short bit string) and is easily identified on the transponder side.

Also, since the data signal is composed of a large number of bit strings, if it is accurately identified, it is more difficult to identify the data signal than the control signal.

Therefore, in the transponder, the minimum reception level required for identifying the control signal and the minimum reception level required for identifying the data signal are different from each other. That is, as shown in FIG. 3, the control signal receiving area 31 of the transponder and the data signal receiving area 32 of the transponder are substantially different from each other, and the former is wider. In such a state, a situation may occur where the control signal can be identified but the data signal cannot be identified.

Therefore, when the transponder is in the standby state, the control signal receiving area 31 is changed to the data signal receiving area 3.
It is desirable to reduce to about 2.

For this purpose, for example, the pulse signal receiving device of the first embodiment shown in FIG. 1 may be applied to a transponder. In this case, in the standby state of the transponder, the operation unit 7 activates the signal line 14, turns on the switch 13, and lowers the level of the pulse signal output from the signal amplification unit 2. At this time, if the transponder is sufficiently close to the interrogator and the reception level of the control signal (pulse signal) is not sufficiently high, the control signal cannot be identified by the waveform shaping unit 6, and the control signal is calculated. It cannot be input to the unit 7. That is, the control signal receiving area 31 of the transponder is reduced to about the data signal receiving area 32.

In this standby state, when a control signal is input to the arithmetic unit 7, the arithmetic unit 7 deactivates the signal line 14, turns off the switch 13, and outputs the signal from the signal amplifying unit 2. The level of the pulse signal to be increased. Thereby, the data signal (pulse signal)
Are sufficiently identified by the waveform shaping unit 6, and the data signal is input to the arithmetic unit 7. That is, the data signal reception area 32 maintains a normal size.

Referring to FIG. 4, the operation of the pulse signal receiving apparatus applied to this transponder will be described more specifically. First, let the output impedance 33 of the signal receiving unit 1 be ρ,
When receiving the voltage level V _out of the signal receiving unit 1, the signal line 14 deactivates, the resistance value between the ground and the input side of the signal amplifier 2 is taken as R _2, the input voltage V of the variable impedance unit 8 _in1 is represented by the following equation (1).

V _in1 = V _out · R ₂ / (R ₂ + ρ) (1) Further, the signal line 14 is activated, and the resistance value between the input side of the signal amplification unit 2 and the ground is R ₁ * R _2. / (R ₁ + R ₂ )
, The input voltage V of the variable impedance section 8
_in2 is represented by the following equation (2).

V _in2 = V _out · A · R ₂ / (A · R ₂ + ρ) = V _out · R ₂ / (R ₂ + ρ / A) (2) where A = R ₁ / (R ₁ + R) ₂ )

Here, since A <1, it follows that ρ <ρ / A, and the relationship of V _in1 > V _in2 always holds. When the input impedance >> R ₂ of the signal amplifier 1, the voltages V _{in1,
Assuming} that V _in2 is the input voltage to the signal amplifier 2 and the level of the received signal of the transponder is constant, the signal line 14
The input voltage of the signal amplifying unit 2 is higher when the signal is deactivated than when the signal is activated.
That is, by appropriately selecting R ₁ + R ₂ , it is possible to set a wider or narrower reception area when the signal line 14 is inactive than when the signal line 14 is active.

The present invention is not limited to the above embodiments, and can be modified without departing from the scope of the present invention. For example, the configuration of the amplifier can be variously modified. Further, the present invention can be applied not only to communication of pulse signals by electromagnetic waves but also to communication of pulse signals by ultrasonic waves.

[0042]

As described above, according to the pulse signal receiving apparatus of the present invention, the arithmetic means inputs the pulse signal from the waveform shaping means and converts the pulse signal into a predetermined pattern represented by the pulse signal. By controlling the level changing means in response, the level of the pulse signal input to the waveform shaping means is changed. Therefore, when the pulse signal of this pattern is received by the signal receiving means, the level of the pulse signal can be changed at this reception timing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a pulse signal receiving apparatus according to the present invention;

FIG. 2 is a block diagram showing a second embodiment of the pulse signal receiving apparatus according to the present invention;

FIG. 3 is a diagram schematically showing a reception area of a transponder in a communication system to which the pulse signal receiving device according to the present invention is applied;

FIG. 4 is a block diagram used to explain the operation of the pulse signal receiving device of FIG. 1 in more detail;

FIG. 5 is a block diagram showing a conventional preamplifier.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 signal receiving unit 2 signal amplifying unit 3 first stage amplifier 4 middle stage amplifier 5 second stage amplifier 6 waveform shaping unit 7 operation unit 8,21 variable impedance unit 11,22 first resistor 12,23 second resistor 13,24 switch 14 signal line 31 Control signal receiving area 32 Data signal receiving area 33 Output impedance

Claims (3)

[Claims] 1. A signal receiving means for receiving and outputting a propagated pulse signal, an amplifying means for amplifying a pulse signal from the signal receiving means, and a waveform for shaping the pulse signal from the amplifying means. A pulse signal receiving apparatus comprising at least a shaping means and an arithmetic means for inputting a pulse signal from the waveform shaping means, further comprising a level changing means for changing a level of the pulse signal input to the waveform shaping means; A pulse signal receiving device that changes the level of the pulse signal by controlling the level changing unit in response to a predetermined pattern represented by the pulse signal from the waveform shaping unit. 2. The pulse signal receiving device according to claim 1, wherein said level changing means comprises a variable impedance interposed between an input side of said amplifying means and ground. 3. The level changing means comprises a variable impedance interposed between input and output of the amplifying means.
3. The pulse signal receiving device according to claim 1.