JP4521827B2 - Communication device - Google Patents

Description

  The present invention relates to a communication apparatus such as a mobile body identification apparatus that performs wireless communication with a mobile information communication body.

  Mobile object identification devices using IC tags and reader / writers that use radio frequency bands, IC chips and antennas, and systems using the same have been put into practical use in various fields such as distribution, transportation, and medical care. Yes.

  In such a mobile unit identification device, power is transmitted and supplied from a reader / writer (interrogator) to an IC tag (responder) via an antenna to perform data communication with each other. A signal having a burst waveform having a fixed period (Tfp) is transmitted from the reader / writer (interrogator) to the IC tag (responder) for synchronization when responding from the IC tag (responder). Thereafter, the IC tag (responder) responds with information as a change in the intensity of the reflected radio wave.

  A configuration and operation related to a conventional communication apparatus are disclosed in Patent Document 1. This technique will be described in detail with reference to FIG. 4 and FIG. FIG. 4 is a block diagram for explaining a receiving unit configuration in an example of a conventional communication device configuration. FIG. 5 is a schematic diagram of signal waveforms showing an operation in each block of an example of a conventional communication apparatus configuration (FIG. 4).

  As shown in FIG. 4, the received signal 52 received by the antenna 41 is amplified by a low noise amplifier (LNA) 48 for high frequency signals. Thereafter, the frequency conversion unit 42 multiplies the local oscillation signal 51 and frequency-converts it to an intermediate frequency signal 53. Furthermore, the frequency-converted intermediate frequency signal 53 is subjected to passband limitation by a filter 43 that is a low-pass filter (LPF) and reaches the demodulator 45. Thereafter, the demodulator output signal 56 from the demodulator 45, which is a demodulator (DEMOD), is output to the comparator by a decoder 46, which is a decoder (DECODE), which is set to a desired reception sensitivity. It is converted into a signal 57.

  As shown in FIG. 5, the received signal 52 received by the antenna 41 is affected by a burst wave having a period Tfp. As a result, the information data at “1” is amplitude-modulated at a specific frequency Fd in the Tfp section, and the information data at information “0” is unmodulated. The received signal 52 and the local signal 51 are converted into an intermediate frequency signal 53 by the frequency converter 42. Further, the frequency-converted intermediate frequency signal 53 is subjected to passband limitation by the filter 43 and reaches the demodulator 45, and becomes a demodulator output signal 56 from the demodulator 45. Thereafter, the demodulator output signal 56 is converted into a comparator output signal 57 by the decoder 46 set to a desired reception sensitivity. Here, it is shown that there is a difference in the waveform difference between the originally desired signal 59 and the comparator output signal 57.

JP-A-8-079102

  In the above-mentioned Patent Document 1, a large signal 53a other than data information appears in the intermediate frequency signal 53 for each burst wave period Tfp, and the voltage amplitude is 10 times or more larger than that of the original information signal 53b. The influence of the burst wave appears not only in the intermediate frequency signal 53 but also in the demodulator output signal 56 and the comparator output signal 57 obtained by demodulating the intermediate frequency signal 53. As a result, the waveform is significantly different from the originally desired signal 59. That is, there is a problem that when the waveform has an allowable discriminating position (time) that has a small deviation width and cannot be discriminated between “0” and “1” when the discrepancy exceeds a certain level, normal information cannot be reproduced. .

  In order to perform higher-speed data communication, it is necessary to reduce the burst wave period Tfp. However, due to the influence of the large signal 57a other than the data signal, a period of a certain period or more is required in order to obtain normal information reception, and there is a problem that the performance of the IC tag (responder) cannot be brought out sufficiently. .

  The present invention has been made to solve the above-described problems, and its technical problem is to provide a communication device that facilitates discrimination of data information, shortens a burst wave, and improves communication speed. .

According to a first aspect of the present invention for achieving the above object, there is provided a frequency converter that converts a local oscillation signal and a received signal into an intermediate frequency signal, a filter unit that limits the band of the intermediate frequency signal, and a signal that has passed through the filter unit. a communication apparatus comprising a signal amplifier for amplifying, a demodulator for demodulating the signal amplified by the signal amplifier, and a comparator for digitizing the desired reference voltage of the demodulated signal, By connecting a synchronization signal, which is a control signal synchronized with the burst wave of the transmission signal, to the power supply unit of the signal amplification unit, it was controlled to disconnect and connect the power supply unit of the signal amplification unit for each period of the burst wave It is a communication device.

According to a second aspect of the invention for achieving the above object, there is provided a frequency converting unit for converting a local oscillation signal and a received signal into an intermediate frequency signal, a filter unit for band-limiting the intermediate frequency signal, and a signal that has passed through the filter unit. a communication apparatus comprising a signal amplifier for amplifying, a demodulator for demodulating the signal amplified by the signal amplifier, and a comparator for digitizing the desired reference voltage of the demodulated signal, switching circuitry which is placed before the input to the demodulator is installed, to the switching circuit, by adding a synchronization signal which is a control signal synchronized with a burst wave of a transmission signal for each cycle of the burst wave A communication device that controls opening and closing of the switching circuit.

  According to the present invention, a frequency conversion unit that converts a local oscillation signal and a reception signal into an intermediate frequency signal, a filter unit that limits the band of the intermediate frequency signal, a signal amplification unit that amplifies the signal that has passed through the filter unit, and a signal In a communication device including a demodulator that demodulates the signal amplified by the amplifier and a comparator that digitizes the demodulated signal with respect to a desired reference voltage, a signal is amplified by adding a synchronization signal as a control signal By controlling the power supply of the part, installing a switch part consisting of a switching circuit installed before input to the demodulator, and adding a synchronization signal that is a control signal, thereby controlling the opening and closing of the switching circuit, Eliminates unnecessary signals for each period of width modulation (ASK modulation: Amplitude Shift Keying) that occurs during frequency conversion in a multiplier that performs frequency conversion, or hinders information discrimination Can be reduced to no level it is. As a result, it is possible to easily determine the data information. Further, it is possible to eliminate the period limitation of the burst wave or shorten the period. As a result, the communication speed can be improved.

  A communication apparatus according to the best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of a receiving unit according to a first example of a communication apparatus of the present invention. FIG. 2 is a schematic diagram of signal waveforms showing the operation in each block of the example of the communication apparatus of the present invention (FIGS. 1 and 3). FIG. 3 is a block diagram illustrating the configuration of the receiving unit according to the second example of the communication apparatus of the present invention.

  A first example of the communication apparatus of the present invention will be described in detail below with reference to FIGS. 1 and 3. As shown in FIG. 1, a reception signal 22 received by an antenna 1 is input to a frequency conversion unit 2 that is a multiplier that performs frequency conversion together with a local oscillation signal 21, and is frequency-converted to an intermediate frequency signal 23. The pass band is limited by a filter 3 which is an LPF (Low Pass Filter), becomes a filter pass signal 24, and is input to an amplifier 4 which is an amplifier (AMP). A synchronization signal (control signal 28), which is a control signal (CTL Sig), is applied to the power supply unit of the amplification unit 4. Here, the unnecessary signal 23a, which is a large signal other than the data information, can be removed by cutting off the power supply of the amplifying unit 4 every burst wave period Tfp. Thereafter, the amplifier output signal 25 from which the unnecessary signal 23a has been removed becomes a demodulator output signal 26 by the demodulator 5 which is a demodulator (DEMOD), and a reference voltage level 26a is obtained so as to obtain a desired reception sensitivity. The comparator output signal 27 is obtained by the decoder 6 which is a decoder (DECODE) which is a comparator set with the.

  As the control signal 28, a signal used when forming a burst wave of a transmission signal can be used as it is, so that it is not necessary to create a new signal. Further, by removing the burst wave interval Tw, the accuracy of removing unnecessary signals is further improved.

  According to the present invention, since the demodulated signal does not include unnecessary signals other than information data, the reference voltage level of the decoder 6 unit can be set small, the sensitivity is increased, and communication with a farther IC tag is possible. Become. In addition, since the receiving circuit side is not easily restricted by the period of the burst wave, the performance of the IC tag can be shortened to the upper limit, and the communication speed can be improved.

  Further, a received signal amplifier corresponding to the intermediate frequency after frequency conversion, which is not a high frequency amplifier, can be used. As a result, the range of component selection is expanded, and inexpensive component selection is possible.

  A second example of the communication apparatus of the present invention will be described in detail below with reference to FIGS. As shown in FIG. 2, the received signal 22 received by the antenna 11 is input to the frequency conversion unit 12 that is a multiplier that performs frequency conversion together with the local oscillation signal 21, is frequency-converted to an intermediate frequency signal 23, and a low-pass filter ( A pass band is limited by a filter 13 which is an LPF (Low Pass Filter), which becomes a filter pass signal 24 and is input to an amplifier 14 which is an amplifier (AMP). Further, the signal amplified by the amplifying unit 14 is input to a switch 17 provided with a switch unit including a switching circuit installed before input to the demodulating unit 15. A synchronization signal (control signal 28), which is a control signal (control signal: CTL Sig), is added to the control unit of the switch 17 provided with a switch unit composed of a switching circuit installed before the input to the demodulator 15 and burst. The switch 17 is opened and closed every wave period Tfp. As a result, the amplifier output signal 25 from which the unnecessary signal 23a which is a large signal other than the data information is removed can be transmitted to the demodulator 15. Thereafter, the amplifier output signal 25 from which the unnecessary signal 23a, which is a large signal other than the data information, is removed becomes the demodulator output signal 26 by the demodulator 15, and the reference voltage level 26a is set so as to obtain a desired reception sensitivity. The data comparator output signal 27 is obtained by the decoder 16.

  As the synchronization signal (control signal 28), which is a control signal (CTL Sig), the signal used when forming the burst wave of the transmission signal can be used as it is, and there is no need to create a new signal. Further, by removing the burst wave interval Tw, the accuracy of removing unnecessary signals is further improved.

  According to the present invention, since the demodulated signal does not include unnecessary signals other than information data, the reference voltage level of the decoder 16 unit can be set small. As a result, the sensitivity becomes higher and communication with a farther IC tag becomes possible. In addition, since the burst wave period makes it difficult to receive restrictions on the receiving circuit side, the performance of the IC tag can be shortened to the upper limit, and the communication speed can be improved.

  Further, a received signal amplifier corresponding to the intermediate frequency after frequency conversion, which is not a high frequency amplifier, can be used. As a result, the range of component selection is expanded, and inexpensive component selection is possible.

  As described above, according to the present invention, it is possible to provide a communication device that facilitates discrimination of data information, shortens the burst wave, and improves the communication speed.

The block diagram explaining the receiving part structure which concerns on the 1st example of the communication apparatus of this invention. The block diagram explaining the receiving part structure which concerns on the 2nd example of the communication apparatus of this invention. The schematic of the signal waveform which shows the operation | movement in each block of the example (FIG. 1 and FIG. 2) of the communication apparatus of this invention. The block diagram explaining the receiving part structure in an example of the conventional communication apparatus structure. The schematic of the signal waveform which shows the operation | movement in each block of an example (FIG. 4) of a conventional communication apparatus structure.

Explanation of symbols

1, 11, 41 Antenna 2, 12, 42 Frequency converter 3, 13, 43 Filter 4, 14 Amplifier 5, 15, 45 Demodulator 6, 16, 46 Decoder 17 Switch 48 Low noise amplifier 21, 51 Local signal 22, 52 Reception signal 23, 53 Intermediate frequency signal 24 Filter pass signal 25 Amplifier output signal 26, 56 Demodulator output signal 27, 57 Comparator output signal 28 Control signal 53a, 57a Large signal 53b other than data information Original information signal 59 Originally desired signal 23a Unnecessary signal 26a Reference voltage level

Claims (2)

A frequency conversion unit that converts a local oscillation signal and a reception signal into an intermediate frequency signal, a filter unit that band-limits the intermediate frequency signal, a signal amplification unit that amplifies a signal that has passed through the filter unit, and the signal amplification unit a demodulator for demodulating the amplified signal, the communication device including a comparator for digitizing the demodulated signals to a desired reference voltage, the power supply unit of the signal amplifier, the burst of the transmitted signal A communication apparatus characterized by controlling connection / disconnection of the power supply unit of the signal amplification unit for each period of the burst wave by adding a synchronization signal which is a control signal synchronized with a wave . A frequency conversion unit that converts a local oscillation signal and a reception signal into an intermediate frequency signal, a filter unit that band-limits the intermediate frequency signal, a signal amplification unit that amplifies a signal that has passed through the filter unit, and the signal amplification unit a demodulator for demodulating the amplified signal, the communication device including a comparator for digitizing the demodulated signals to a desired reference voltage, the installed switching prior to input to the demodulator characterized by installing the circuits, the switching circuit, by adding a synchronization signal which is a control signal synchronized with a burst wave of a transmission signal, that controls the opening and closing the switching circuit in each cycle of the burst wave A communication device.

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