JP2006197295A - Filter bank receiver and radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter bank receiver and a radio communication system in which a plurality of frequency channels can be simultaneously received by using inexpensive components. <P>SOLUTION: The filter band receiver comprises: an input part for receiving a transmission signal from each of a plurality of transmitters each of which has an oscillator where oscillation frequency is fluctuated and transmits data by using the frequency oscillated from the oscillator as a carrier, amplifying the received signal and outputting the amplified signal as an input signal; a frequency channel separation part for separating the input signal into a plurality of frequency channels and outputting a separated signal in each frequency channel; and a demodulation part for demodulating the input signal in each frequency channel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a filter bank receiver and a wireless communication system for receiving signals of different frequencies from a plurality of transmitters, separating the signals according to each frequency channel by a filter bank, and inputting data from each transmitter. .

In recent years, product management systems that use wireless IC tags to identify and manage individual products have been used.
In the product management system using this tag, as the number of tags increases, a collision with a signal transmitted by another transmitter occurs, and the data reading rate deteriorates.
For this reason, a method of allocating a plurality of frequency channels in advance for each tag has been devised (for example, see Patent Document 1).
JP 07-283755 A

However, the wireless communication system disclosed in Patent Document 1 has a problem that an accurate clock is required for each tag, and a crystal oscillator is mounted on each tag, so that the manufacturing cost of the tag increases.
Further, in the wireless communication system, it is necessary to set a different frequency channel for each tag at the time of manufacturing the tag, and an adjustment process of the frequency channel is added to the tag manufacturing process, which increases the manufacturing cost. There is a problem.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a filter bank receiver and a wireless communication system that can simultaneously receive a plurality of frequency channels using inexpensive components.

  The filter bank receiver of the present invention has an oscillator whose oscillation frequency fluctuates, receives a transmission signal from each of a plurality of transmitters that transmit data using the oscillation frequency of this oscillator as a carrier wave, and amplifies the input signal. An input unit that outputs the output signal, a frequency channel separation unit that separates the input signal into a plurality of frequency channels and outputs a signal for each frequency channel, and a demodulation unit that demodulates the input signal for each frequency channel. Features.

  The filter bank receiver according to the present invention is characterized in that the frequency channel separation unit includes narrow band filters each corresponding to a narrow band obtained by dividing a range of fluctuation of the frequency oscillated by the oscillator into a plurality of parts.

  The filter bank receiver according to the present invention is characterized in that the narrow band filter is set to a frequency of another adjacent narrow band filter and a discontinuous frequency region in which a predetermined frequency range does not exist.

  In the radio communication system of the present invention, the transmitter has an oscillator whose frequency oscillates within a predetermined range, a pulse having a frequency oscillated by the oscillator as a carrier wave, and a modulation unit that modulates the carrier wave with data to be transmitted The transmitter is composed of a transmitter that amplifies the transmission signal modulated by the modulator and transmits it from the antenna, and the receiver receives the transmission signal from each of the plurality of transmitters, amplifies it, and outputs it as an input signal The transmitter comprising: an input unit; a frequency channel separation unit that separates the input signal into a plurality of frequency channels; and outputs a signal for each frequency channel; and a demodulation unit that demodulates the input signal for each frequency channel, Transmits predetermined data to the receiver.

  The radio communication system according to the present invention is characterized in that the frequency channel separation unit includes narrow band filters each corresponding to a narrow band obtained by dividing a frequency fluctuation range oscillated by the oscillator into a plurality of parts.

  The wireless communication system of the present invention is characterized in that the narrow band filter is set in a frequency region discontinuous with the frequency of another narrow band filter adjacent thereto.

  As described above, according to the filter bank receiver of the present invention, a carrier wave is obtained using an unstable and fluctuating oscillator as a source oscillation, and a transmission signal from a transmitter that transmits data is transmitted to a plurality of signals. Multiple narrowband subband filters are arranged in a filter bank configuration, and the frequency range of the filter bank is within the fluctuation range of the oscillator, so that collisions due to simultaneous transmission can be reduced at a lower cost than conventional ones. Can be reduced.

Hereinafter, a wireless communication system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a wireless communication system according to the embodiment.
In this figure, the transmitter 1 is a wireless IC tag (RF tag), for example, and includes an oscillator 2, a control unit 3, a modulation unit 4, and a transmission unit 5.
The receiver 10 is, for example, a tag reader, and includes a receiver 11, a frequency channel separator 12, and a signal processor 14.

Next, each part of the transmitter 1 will be described.
The oscillator 2 is a SAW (surface wave device) oscillator whose oscillation frequency fluctuates within a certain range, for example, and a clock having a frequency that randomly fluctuates over time in a frequency band (band) determined by specifications from the center frequency. Is output.
For example, the control unit 3 stores data unique to the transmitter 1 such as identification information of the transmitter, and performs transmission processing of this data at predetermined intervals.

The modulation unit 4 uses the clock output from the oscillator 2 as a carrier wave, modulates this carrier wave with data output from the control unit 3 by a predetermined modulation method, for example, amplitude modulation, and outputs the result as a transmission signal.
The transmitter 5 amplifies the transmission signal and transmits the transmission signal from the antenna to the space.
If the oscillator 2 is a SAW oscillator, for example, it has an oscillation frequency of 80 MHz to 150 MHz, and the fluctuation ratio is ± 0.025 to 0.0133%, and the fluctuation range of about ± 2 MHz is calculated. Yes, and the frequency deviation is ± 20 kHz.
Fluctuation within the range of 80 MHz → 78 MHz to 82 MHz 150 MHz → Fluctuation within the range of 148 MHz to 152 MHz

Next, each part of the receiver 10 will be described.
The receiving unit 11 amplifies the transmission signal of the transmitter 1 received via the antenna and outputs the amplified signal to the frequency channel separation unit 12.
Here, the antenna and reception unit 11 sets a frequency band including a fluctuation range of the oscillator 2 used in the transmitter 1 as a reception band.

The frequency channel separation unit 12 includes a plurality of narrow band (narrow band) filters.
Here, the frequency channel separation unit 12 includes narrow band filters each corresponding to a narrow band obtained by dividing the frequency fluctuation range oscillated by the oscillator 2 into a plurality of parts.
For example, the band of the narrow band is set to 20 kHz in consideration of the frequency deviation, and the band of the narrow band corresponds to the frequency channel of the carrier wave of the transmission signal of the transmitter 1.

Here, the fluctuation in the oscillator 2 in the transmitter 1 does not change abruptly, and gradually changes to a high frequency or a low frequency over time within the fluctuation range, and in the opposite direction when the limit of the range is reached. Change.
Therefore, the receiver 10 can receive the transmission signal from each transmitter 1 within the narrow band range.

Further, if the frequency transmitted by the oscillator 2 has a fluctuation of ± 2 MHz with respect to the center frequency of 80 MHz, the number of sub-bands (as a narrow band) is obtained by dividing the 4 MHz fluctuation range by the narrow-band band of 20 kHz. 200 is calculated, and in the calculation, the receiver 10 can be equipped with a filter bank having 200 frequency channels.
However, there are cases where the frequency of the transmission signal received when scanning is continuous between adjacent narrowband filters, and there is a situation where separation processing is difficult, so the frequency of each of the above narrowband filters is adjacent to the other narrowband filters. And set to a discontinuous frequency range.
That is, one or a plurality of narrow band filters adjacent to each other in the frequency sequence are thinned out to form a narrow band filter group in which the frequency sequence is discontinuous.

The demodulation unit 13 includes a plurality of narrow band demodulation units 131, 132, 133, 134,..., 13n corresponding to the narrow band filter in a one-to-one manner. The input signal from the band narrow band filter is demodulated in accordance with the modulation method of the modulation unit 4, and the demodulated data is output to the signal processing unit 14.
Each of the narrow band demodulating units 131, 132, 133, 134,..., 13n uses a high-precision crystal oscillator as an oscillator for generating a frequency corresponding to a carrier wave used for demodulation, and the frequency deviation is in the same range as the narrow band band. Is used for demodulation.
The signal processing unit 14 performs predetermined processing such as recognition of identification information of each transmitter 1 on the data from each narrowband demodulation unit 131, 132, 133, 134, ..., 13n.

With the above-described configuration, as shown in FIG. 2, the radio device 11 and the radio device 12 each have the oscillator 2 having the same center frequency. Located in different subbands.
For this reason, the transmission signals that are superimposed and input in the receiver 2 are separated by the frequency channel separation unit 12 without any collision between the transmission signals of the wireless device 11 and the wireless device 12. The narrowband demodulating unit demodulates.
Here, the wireless device 11 and the wireless device 12 have the same configuration as the wireless device 1.

It is a block diagram which shows the example of 1 structure of the radio | wireless communications system by one Embodiment of this invention. It is a conceptual diagram explaining operation | movement of the radio | wireless communications system of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11,12 ... Transmitter 2 ... Oscillator 3 ... Control part 4 ... Modulation part 5 ... Transmission part 10 ... Receiver 11 ... Reception part 12 ... Frequency channel separation part 13 ... Demodulation part 131, 132, 133, 134, 13n ... Narrow band demodulator

Claims (6)

An input unit that has an oscillator whose oscillation frequency fluctuates, receives a transmission signal from each of a plurality of transmitters that transmit data using the oscillation frequency of this oscillator as a carrier wave, and outputs the amplified signal as an input signal;
A frequency channel separation unit that separates the input signal into a plurality of frequency channels and outputs a signal for each frequency channel;
And a demodulator for demodulating an input signal for each frequency channel.   2. The filter bank receiver according to claim 1, wherein the frequency channel separation unit includes narrow band filters each corresponding to a narrow band obtained by dividing a range of fluctuation of the frequency oscillated by the oscillator into a plurality of parts.   3. The filter bank receiver according to claim 2, wherein the narrow band filter is set to a frequency of another adjacent narrow band filter and a discontinuous frequency region in which a predetermined frequency range does not exist. 4. The transmitter is
An oscillator whose frequency oscillates within a predetermined range;
A modulation unit that modulates the carrier wave with data to be transmitted, using a pulse of a frequency oscillated by the oscillator as a carrier wave;
A transmission unit that amplifies the transmission signal modulated by the modulation unit and transmits it from the antenna;
The receiver
An input unit that receives a transmission signal from each of the plurality of transmitters, amplifies and outputs the input signal, and
A frequency channel separation unit that separates the input signal into a plurality of frequency channels and outputs a signal for each frequency channel;
And a demodulator that demodulates the input signal for each frequency channel,
A wireless communication system for transmitting predetermined data from the transmitter to a receiver.   5. The wireless communication system according to claim 4, wherein the frequency channel separation unit includes narrow band filters each corresponding to a narrow band obtained by dividing a range of frequency fluctuations oscillated by the oscillator into a plurality of parts. 6. The wireless communication system according to claim 5, wherein the narrow band filter is set in a frequency region that is discontinuous with the frequency of another narrow band filter adjacent thereto.

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