JPH1174938A - Ask modulated wave communication device, data carrier and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a ratio of a carrier transmission time in a data transmission period and also to reduce power consumption of a data carrier in a period when a carrier is not sent by sending and receiving data in a period from a blank period of an inputted ASK modulated wave till the next blank period. SOLUTION: A switching control circuit 13 controls a switch circuit 12 so that data may be transmitted in a 1st ASK modulation form that sends a carrier in an entire period in which data is sent and in a 2nd ASK modulation form that sends a carrier in half of a data sending period and makes the other half period blank in a data transmission period in which one-bit digital data is transmitted. That is, data is sent and received in a period from a blank period of an inputted ASK modulated wave till the next blank period, and information is not included in the blank period at all. Then, it can reduce power consumption by stopping an operation in the blank period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ASK modulated wave communication device, a data carrier and a communication system.
It is suitable for use in communication between a data carrier without a power source and an interrogator.

[0002]

2. Description of the Related Art In communication with a data carrier having no power supply, a communication device called an interrogator emits a high-frequency magnetic field to supply operating power of the data carrier. That is, the data carrier obtains the operating power from the voltage induced in the antenna coil. Here, in order to extend the communication distance, the antenna coil of the data carrier may be tuned to the signal frequency transmitted from the communication device.

In order to extend the communicable distance, a signal frequency transmitted from a communication device is fixed and a signal is continuously transmitted as much as possible (a method in which a period of interruption due to modulation is short). Is valid.

[0004] The ASK modulation method has a constant signal frequency, so that the use of a tuned antenna circuit in a data carrier can improve the reception efficiency. This is advantageous for receiving power, and is often used in data carrier communication. It's being used.

[0005]

SUMMARY OF THE INVENTION However, ASK
In the modulation method, there is a period during which the signal amplitude decreases or disappears. Therefore, the data carrier needs to operate with the charge charged in the ripple filter of the power supply until the signal amplitude disappears. In addition, there is a problem that the internal state and data must be held during the period when there is no signal input.

Therefore, when designing a data carrier circuit, modulation is performed in the negative direction only for as short a period as possible on the transmission band, and a signal is supplied continuously during other periods. The period modulated in the negative direction is
There has been a demand for a design to reduce the capacitance value required for the ripple filter by minimizing the circuit operation in the data carrier and reducing the power consumption. In addition, it is necessary that the operation required to receive the data is simple and the current consumption is small.

[0007] At the same time as the above-mentioned demands, it is desired that, like a general communication system, it is resistant to noise, requires a narrow transmission band, and can easily perform demodulation. I have.

In view of the above problems, the present invention makes it possible to increase the ratio of the carrier transmission time during the data transmission period and to reduce the power consumption of the data carrier during the period during which no carrier is transmitted. The purpose is to.

[0009]

An ASK modulated wave communication apparatus according to the present invention comprises: an oscillating means for oscillating a carrier having a predetermined frequency;
Switching means for intermittently switching the carrier wave output from the oscillating means, and switching control means for controlling a switching operation of the switching means in accordance with digital data to be transmitted, wherein the switching control means is a 1-bit digital In a data transmission period for transmitting data, a first ASK modulation mode for transmitting the carrier for all periods for transmitting the data, and transmitting the carrier for a half of the data transmission period, and transmitting the other half of the data. Second ASK with blank period
The switching means is controlled so as to transmit the digital data in a modulation mode.

Another feature of the ASK modulated wave communication apparatus of the present invention is that a period for transmitting data in the first ASK modulation mode and a period for transmitting data in the second ASK modulation mode. Is characterized by having the same length.

Another feature of the ASK modulation wave communication apparatus of the present invention is that a period during which data is transmitted in the first ASK modulation mode is a period during which data is transmitted in the second ASK modulation mode. It is characterized in that it is half as long as.

Another feature of the ASK modulated wave communication apparatus of the present invention is that the data of "1" is transmitted in the first ASK modulation mode and the second AS
It is characterized by transmitting "0" data in the K modulation mode.

In the data carrier of the present invention, a blank period detecting means for detecting a blank period in the input ASK modulated wave, and a blank period is detected after the blank period detecting means detects the blank period. And a demodulation means for demodulating input data in accordance with a detection result of the time detection means.

According to another feature of the data carrier of the present invention, the time detecting means includes a signal received from when the blank period detecting means detects a blank period until the next blank period is detected. Is detected, and the time when the signal is continuously transmitted is detected.

Further, the communication system of the present invention includes the AS
It is characterized by comprising a K-modulated wave communication device and the data carrier.

[0016]

Since the present invention has the above technical means, data is transmitted and received in a time period from a blank period to the next blank period in an input ASK modulated wave, and no information is included in the blank period. Therefore, the data carrier does not need to recognize the length of the blank period during which no carrier is transmitted, and only needs to recognize that the carrier has not been transmitted. It is possible to reduce the number and to simplify the configuration of the data demodulation circuit. Also,
Since the ratio of the carrier transmission time in the data transmission period can be increased, the communication distance can be extended, and the ripple capacitor of the power supply can be reduced as much as possible.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ASK modulated wave communication device, a data carrier and a communication system according to the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which an ASK modulated wave communication device 10 and a data carrier 20 are arranged.
FIG. 3 is a diagram showing a state in which communication is performed between the server and the server;

The ASK modulated wave communication device 10 is a communication device called an interrogator, which transmits and receives data to and from the data carrier 20 and supplies operating power of the data carrier 20.

In the present embodiment, the ASK modulated wave communication device 10 includes a carrier oscillator 11 provided as an oscillating means for oscillating a carrier wave of a predetermined frequency, and a switching device for intermittently switching the carrier wave output from the carrier oscillator 11. A switching circuit provided as a means, a switching control circuit provided as switching control means for controlling a switching operation of the switching circuit according to digital data to be transmitted, and an output of the switching control circuit at a predetermined level. And an antenna circuit 15 that converts a transmission signal output from the amplifier 14 into a high-frequency magnetic field and radiates it into the air.

The antenna circuit 15 is constituted by a parallel resonance circuit including a coil L and a capacitor C. High frequency magnetic field (radio wave) radiated from the antenna circuit 15
Is an antenna circuit 21 provided on the data carrier 20
And the received signal is input into the data carrier 20. The antenna circuit 21 is also configured by a parallel resonance circuit including a coil L and a capacitor C.

As will be described later in detail with reference to FIG. 2, in the data transmission period for transmitting 1-bit digital data, the switching control circuit 13 transmits the carrier for all the periods for transmitting the data. The digital data is transmitted in a first ASK modulation mode to be transmitted, and in a second ASK modulation mode in which the carrier is transmitted for a half period of the data transmission period and the other half period is blank. The switch circuit 12 is controlled at the same time.

Hereinafter, a data transmission method according to the present embodiment will be described.
This will be described in detail with reference to FIG. In FIG.
When transmitting “1” data, the first specified time T
For one period, the carrier signal is transmitted continuously.

When transmitting "0" data, a carrier signal is transmitted for a second specified time T2 which is a half of the first specified time T1, and thereafter, a third signal is transmitted. The transmission of the carrier signal is stopped during the specified time T3.

Here, so that T1 = T2 + T3,
By setting each specified time, the time for sending data "1" and the time for sending data "0" can be made uniform, so that the data rate can be made constant. When giving priority to the communication speed, T1 = T2 = T3 may be set as described later, and each specified time may be determined according to the band of the transmission path.

By transmitting data as described above, assuming that the period of transmitting 1-bit data is 128 cycles, as shown in FIG. , 64 cycles of the carrier signal, and the remaining 64 cycles are blank periods by performing 100% negative modulation.

When transmitting "1" data, a carrier signal is transmitted for the entire period of transmitting 1-bit data. That is, a carrier signal for 128 cycles is transmitted. Then, when transmitting "0" data, a carrier signal for 64 cycles is transmitted as described above. Therefore, data "1"
When transmitting "0" and "0" continuously, as shown in FIG. 2B, a carrier signal of 192 cycles is transmitted following the blank period.

Hereinafter, similarly, when data of "1", "1", and "0" are transmitted, "128 + 128 + 64 = 3"
20 ", a carrier signal for 320 cycles is transmitted, and a blank period for 64 cycles is formed.

In this embodiment, as described above, the data transmission rate is determined in the first to third specified times in which 100% ASK modulation is performed. What is required is not limited to the data carrier, but is the same as in a general communication system.

When demodulating a signal transmitted by the above-described transmission method, a negative modulation (blank period) for transmitting data "0" and a negative modulation for transmitting data "0" next are performed. What is necessary is just to detect the time when the signal continues. Specifically, if the wave number of a signal received during continuous transmission is detected, transmission data can be demodulated well.

If there is an upper limit on the number of data "1" s continuously transmitted, the processing is not performed each time data "1" is received, and the number of data "1" s continuously transmitted is determined. After that (that is, after detecting the negative modulation), it may be sent to the internal processing circuit.

Since the data "0" and "1" are transmitted as described above, according to the transmission method of the present embodiment, the negative modulation does not continue, and the time during which the negative modulation lasts. No information is given to the width. Therefore, when demodulating the transmitted signal, it is only necessary to detect the presence of negative modulation, and there is an advantage that it is not necessary to detect the maintenance time. For this reason, the effect that power consumption in the negative modulation period can be significantly reduced can be obtained.

Hereinafter, the ASK modulation method according to the present embodiment will be described in detail with reference to FIGS. FIG.
FIG. 3 is a circuit diagram illustrating a configuration example of a data carrier that receives a signal transmitted by the ASK modulation method according to the present embodiment. FIG. 4 is a waveform chart showing the operation of each part of the data carrier shown in FIG.

In FIG. 3, the first Schmitt gate 1
Is that the threshold voltage is as high as about 0.8 Vdd and the width of the hysteresis is large.
The output is designed to be at the "L" level when the input voltage is high.

On the other hand, the second Schmitt gate 2 has a low threshold voltage of about 0.2 Vdd and a small hysteresis width so that the input voltage is low when the input voltage is low. Designed.

The power supply to the second Schmitt gate 2 is performed via a P-type MOS transistor 3, and the output terminal is connected to GND via an N-type MOS transistor 4. The gates of the P-type MOS transistor 3 and the N-type MOS transistor 4 are connected to the output terminal of the first Schmitt gate 1. The output terminal of the second Schmitt gate 2 is
The input terminal of the counter 5 and the clock input terminal of the internal circuit 7 are also connected.

The first counter 5 is a 7-digit binary counter. When it counts from 0 to 127, it returns to 0 again at the next input, and derives a count signal to the input terminal of the second counter 6. ing.

The second counter 6 has a 5-digit value of 2 in this example.
6 shows a binary counter. This is because, in the system, the period during which the data “1” is continuous is 24 or less, so that it is possible to count more.

The output of the second counter 6 is connected to the input terminal array of the internal register 8. The output terminal of the first Schmitt gate 1 is connected to the data strobe terminal of the internal register 8 and to the reset terminals of the first and second counters 5 and 6.

The time constant of the ripple filter provided on the input side of the first Schmitt gate 1 is set small so as to be several times the period of the frequency of the signal transmitted from the communication device. Therefore, when the signal is negatively modulated, the signal immediately follows the signal, and the rectified voltage changes. This is because the hysteresis of the first Schmitt gate 1 remains rippled because the time constant of the input ripple filter is small as described above, so that the first Schmitt gate 1 is not operated.

Therefore, the negative modulation of the input signal can be detected by the first Schmitt gate 1. At this time, the first
Of the Schmitt gate 1 becomes “H”. As a result, the P provided on the power supply side of the second Schmitt gate 2
Since the type MOS transistor 3 is turned off, the operation of the second Schmitt gate 2 stops, and current consumption stops flowing. At this time, since the N-type MOS transistor 4 is turned on, the output of the second Schmitt gate 2 is fixed at "L".

On the other hand, as soon as a signal starts to be supplied from the communication device, the first Schmitt gate 1 detects this. At this time, since the output of the first Schmitt gate 1 becomes "L", the P-type MOS transistor 3 is turned on. As a result, the second Schmitt gate 2 operates, and outputs a pulse whose waveform is shaped based on the voltage obtained by rectifying the signal from the communication device.

The second Schmitt gate 2 has a hysteresis for stabilizing the operation. Therefore, there is no inconvenience of outputting a halfway signal such that a circuit receiving a clock signal is driven to malfunction.

Next, the operation of the data carrier of the present embodiment configured as described above will be described in detail with reference to the waveform diagram of FIG. In FIG. 4, (A) shows a waveform of a signal transmitted from the antenna circuit 15, and a blank period during which a carrier signal is not transmitted is 100% negative modulation.

FIG. 3B shows a signal waveform received by the antenna circuit 21. Due to a delay in response due to the presence of the tuning circuit, an amplitude is generated even in the 100% negative modulation portion.

(C) is a waveform in the power supply rectifier circuit composed of the diode D1 and the capacitor C1, and the AC voltage induced by the antenna circuit 21 is converted into a DC voltage.

FIG. 4D shows a waveform on the input side of the first Schmitt gate 1. The first Schmitt gate 1 is turned on in order to prevent the first Schmitt gate 1 from malfunctioning due to the ripple. The threshold value TH1 is different from the threshold value TH2 for turning off.

(E) shows a waveform on the output side of the first Schmitt gate 1, and (F) shows a waveform on the input side of the second Schmitt gate 2. (G) shows the waveform on the output side of the second Schmitt gate 2. (D) ~
As is clear from (G), the second Schmitt gate 2
Derives, as a clock signal, a signal obtained by half-wave rectifying an input signal while the first Schmitt gate 1 is on.

The operation of each unit will be described below. On the data carrier 20 side, when a signal is started to be supplied from the ASK modulated wave communication device 10, the rectifier circuit immediately rectifies the signal received by the coil L of the antenna 21 and rectifies it. An operating current is supplied to the internal circuit 7.

The start of signal reception from the communication device 10 is also detected by the first Schmitt gate 1, and when the first Schmitt gate 1 is turned on, the first and second counters 5 and 6 receive signals. The reset control is released, and the second Schmitt gate 2 is operated.

Thus, the clock signal supplied from the second Schmitt gate 2 is supplied to the first counter 5 and the second
The counter 6 starts counting. In addition, as described above, the internal circuit 7 starts operating when the operating current is supplied.

Here, when a negative modulation is applied to the signal from the communication device 10, the first Schmitt gate 1 detects this and makes its output "H". Thereby, the intermediate result obtained from the count result is taken into the internal register 8, and the count values of the first counter 5 and the second counter 6 are reset.

When the output of the first Schmitt gate 1 becomes "H", the operation of the second Schmitt gate 2 stops as described above. Thus, the clock signal from the second Schmitt gate 2 stops. The internal circuit 7 to which the clock signal is no longer supplied stops the operation while maintaining the state immediately before. As a result, the current consumption in the data carrier is extremely small.
The internal state and data can be held sufficiently.

The count result of the second counter 6 taken into the internal register 8 indicates the continuous number of the received data "1". Note that the remaining data of the first counter 5 is discarded.

This is, as shown in FIG.
This is because even if the signal is transmitted while keeping the specified time accurately, the response may be delayed due to the presence of the tuning circuit in the transmission path, and the detected wave number may not be accurate. For this reason, the effect of the waveform delay in the transmission path is eliminated by truncating in the above method.

In this example, receiving the signal wave 128 times means receiving the data "1" once, and the signal wave 64 times is the signal of the signal received when the data "0" was sent last. The wave number.

Therefore, the first and second counters 5, 6
If you read the count value of all at once, it should be 128 × N + 6
Should be 4. Here, N is the number of times data "1" is continuously transmitted.

However, as described above, since the wave number cannot be detected accurately, 128 × N + 64−64 to
When the count value reaches 128 × N + 64 + 63,
It is determined that data “1” has been received N times. And
If negative modulation is detected, it is determined that data "0" has been received once.

Since data transmission and reception are performed as described above, in the ASK modulation method according to the present embodiment, the data carrier only needs to detect the wave number of a continuously transmitted carrier signal. Can be easily configured.

In addition, it is possible to increase the proportion of time for transmitting a signal during the period of transmitting data and to reduce the current consumption of the data carrier during the non-feeding period due to negative modulation, thereby extending the communication distance. Further, since the ripple filter capacitor of the power supply can be reduced, it can be built in the IC, and can be reduced in size at low cost.

Next, a data transmission method according to a second embodiment will be described with reference to FIG. As described above, in the data transmission method shown in FIG. 2, the period for transmitting data in the first ASK modulation mode and the period for transmitting data in the second ASK modulation mode are set to the same length. However, in the second embodiment, the period during which data is transmitted in the first ASK modulation mode is set to half the length of the period during which data is transmitted in the second ASK modulation mode.

That is, also in this embodiment, the period during which data "0" is transmitted is 128 cycles, which is the same as that in the first embodiment. The period corresponding to 64 cycles is a blank period with 100% negative modulation.

On the other hand, the period for transmitting data “1” is set to 64 cycles, which is half the length of the period for transmitting data “0”, and the carrier signal is transmitted in all the periods. Therefore, in this case, when data "1" and "0" are continuously transmitted, a carrier signal is transmitted for 128 cycles and a blank period of 64 cycles is formed subsequently.

In transmitting "1", "1", and "0", the carrier signal is transmitted for 192 cycles, and a blank period of 64 cycles is formed subsequently. By doing so, the time required to transmit data "1" is only half the time required in the first embodiment, so that the data transmission rate can be improved.

FIG. 6 shows an example in which half-wave rectification is performed in the circuit shown in FIG. 3, but full-wave rectification is performed. That is, the diodes D3 to D6 are provided instead of the diode D1 in FIG. 3, and the power supply rectifier circuit is a full-wave rectifier circuit. On the input side of the first Schmitt gate 1, a diode D8 is provided in addition to the diode D7 to perform full-wave rectification.

In the above-described embodiment, "1" data is transmitted in the first ASK modulation mode, and "0" data is transmitted in the second ASK modulation mode. However, data of “0” may be transmitted in the first ASK modulation mode, and data of “1” may be transmitted in the second ASK modulation mode.

[0066]

According to the present invention, as described above, according to the present invention, in a data transmission period for transmitting 1-bit digital data, the first ASK for transmitting the carrier for all the periods for transmitting the data. A second ASK in which the carrier is transmitted for a half period of the data transmission period and the other half period is blank.
Since the digital data is transmitted in the modulation mode, data is transmitted and received according to the time from the blank period to the next blank period in the input ASK modulated wave, and no information is included in the blank period. You can do so. Therefore, it is not necessary for the data carrier to recognize the length of the blank period in which no carrier is sent, and it is only necessary to recognize that the carrier is no longer sent.
During that period, the operation can be stopped to reduce power consumption.

Thus, the configuration of the data demodulation circuit in the data carrier can be simplified. Further, in each data transmission period, the carrier signal is transmitted at least for half the period, so that the ratio of the carrier transmission time can be increased. This makes it possible to send a large amount of operating power to the data carrier. In addition, the current consumption of the data carrier can be reduced during the non-power supply period due to the negative modulation. As a result, the communication distance can be increased, and the ripple capacitor of the power supply can be reduced as much as possible.

According to the present invention, the data carrier only needs to detect the time during which the carrier signal has been continuously transmitted, so that the data demodulation circuit can be simplified.

Further, according to the present invention, the ripple filter capacitor of the power supply can be reduced, so that the IC
And can be manufactured inexpensively and can be made smaller.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention and showing a state in which communication is performed between an ASK modulated wave communication device and a data carrier.

FIG. 2 is a diagram illustrating a period for transmitting data in a first ASK modulation mode and a period for transmitting data in a second ASK modulation mode.

FIG. 3 is a circuit diagram showing a configuration example of a data carrier.

FIG. 4 is a waveform chart showing the operation of each part of the circuit of FIG. 3;

FIG. 5 is a diagram illustrating a second embodiment and explaining a period for transmitting data in a first ASK modulation mode and a period for transmitting data in a second ASK modulation mode.

FIG. 6 is a circuit diagram showing a configuration example of a data carrier that is subjected to full-wave rectification.

[Description of Signs] 1 First Schmitt gate 2 Second Schmitt gate 3 P-type MOS transistor 4 N-type MOS transistor 5 First counter 6 Second counter 7 Internal circuit 8 Internal register 10 ASK modulated wave communication device 11 Carrier oscillator 12 Switch circuit 13 Switching control circuit 14 Amplifier 15 Antenna circuit 20 Data carrier 21 Antenna circuit

Claims (7)

[Claims] An oscillator configured to oscillate a carrier having a predetermined frequency; a switching unit configured to intermittently output the carrier output from the oscillator; A first ASK modulation mode for transmitting the carrier for all periods of transmitting the data in a data transmission period for transmitting 1-bit digital data; Controlling the switching means so as to transmit the digital data in a second ASK modulation mode in which the carrier is transmitted for a half of the period and the other half period is blank. Modulated wave communication device. 2. The period for transmitting data in the first ASK modulation mode and the period for transmitting data in the second ASK modulation mode have the same length. ASK modulated wave communication device. 3. The apparatus according to claim 1, wherein a period for transmitting data in the first ASK modulation mode is half as long as a period for transmitting data in the second ASK modulation mode. ASK modulated wave communication device. 4. The method according to claim 1, wherein data of “1” is transmitted in the first ASK modulation mode, and data of “0” is transmitted in the second ASK modulation mode.
4. The ASK modulated wave communication device according to any one of 3. 5. A blank period detecting means for detecting a blank period in an input ASK modulated wave, and a time for detecting a time from when the blank period detecting means detects a blank period to when a blank period is detected next time. A data carrier comprising: a detection unit; and a demodulation unit that demodulates input data according to a detection result of the time detection unit. 6. The time detecting means detects the wave number of a signal received from the time when the blank period detecting means detects the blank period to the time when the blank period is next detected, and the signal is continuously transmitted. 6. The time of arrival is detected.
Data carrier as described in. 7. A communication system comprising: the ASK modulated wave communication device according to claim 1; and the data carrier according to claim 5.