JP2000224075A - Spread spectrum communications equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs and to improve receiving sensitivity and signal delay characteristic by modulating an output of a 2nd analog modulator into a spread spectrum signal, transmitting it as the high frequency signal of a 2nd frequency, receiving a high frequency signal of a 1st frequency, performing inverse diffusion of the received signal and performing analog demodulation of its output. SOLUTION: An FM modulator 10 modulates information inputted to a slave unit 1 by an FM modulation system. A diffuser 6 further modulates the signal with a PN code generated by a PN code generator 8 of a transmitting side and defines it as a spread spectrum signal. Furthermore, an RF transmitting part 4 performs high frequency conversion and amplification of it and the signal is emitted from an antenna 13 through a filter 2. Meanwhile, a signal transmitted from the slave unit 1 is received by the antenna 29 of a master unit 15, amplified by an RF receiving part 19 through a filter 17, and converted into an IF frequency. The signal from the part 19 is multiplied by the PN code generated by a PN code generator 23 of a receiving side in an inverse diffuser 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication apparatus comprising a pair of a slave unit and a master unit which are connected to each other wirelessly using a spread spectrum communication system and capable of full-duplex communication.

[0002]

2. Description of the Related Art In recent years, Federal Communication Commissi
on (FCC) to use Industrial Scien for spread spectrum
Since the opening of the Tific and Medical (ISM) Band, products using this system have appeared in various communication equipment fields, including cordless telephones. The spread spectrum method is characterized by excellent sentimentality and privacy. Also, by using this system, transmission with a larger output than in the case of the conventional analog communication system is approved by the FCC, which is advantageous in terms of communication distance. On the other hand, products using this system are generally based on digital communication systems, and are more complex and expensive than products using conventional analog communication systems.

[0003] Hereinafter, a conventional spread spectrum communication apparatus will be described with reference to the drawings. FIG. 2 is a configuration diagram of an example of a conventional spread spectrum communication apparatus for performing full-duplex voice communication.
And a master unit 45 capable of wireless full-duplex communication with the slave unit 31 by radio.

The slave unit 31 includes, as constituent elements, an encoding circuit 42 for digitally encoding an audio signal, a time-division processing circuit 41 for controlling time-division confidential communication, and a modulation for transmitting an information signal to a high frequency. A primary modulator 38, a PN code generator 36 and a spreader 34 for generating a spread spectrum signal, an RF transmitter 32 for converting a modulated signal to a high frequency and amplifying the signal, and an antenna for transmitting or receiving the signal. An antenna switch 44 connected to the circuit, an antenna 43 for transmitting and receiving a high-frequency signal, an RF receiving unit 33 for amplifying a received high-frequency signal and converting it to an IF, and returning the received spread spectrum signal to an original narrow-band signal PN code generation circuit 37, despreader 35 and synchronization circuit 40, and demodulator 39 for demodulating the narrowband modulated signal obtained by despreader 35. It is made.

[0005] On the other hand, the master unit 45 is exactly the same component as the saw 31.

The operation of a conventional front-duplex spread-spectrum communication device having the above-described components will be described. In the time-division compound communication system, the communication is performed while the dark 31 and the master unit 45 alternately switch between transmission and reception. Explaining the timing of transmission from the slave unit 31, the dark 3
The information input to 1 is first digitally encoded by an encoding circuit 42. Next, the timing to be transmitted is controlled by the time division processing circuit 41, and the data is transmitted at high speed. This data is digitally modulated by the primary modulator 38. 1
The signal modulated by the next modulator 38 is further modulated by a spreader 345 with a PN code generated by a PN code generator 36 to become a spread spectrum signal. Further, the signal is converted and amplified to a high frequency by the RF transmission unit 32, and passes through the antenna changeover switch 44 connected on the transmitter side.
Radiated from 3. On the other hand, the signal transmitted from the dark 31 is received by the antenna 57 of
And is converted to an IF frequency. RF receiver 47
Are multiplied by the despreader 49 with the PN code generated by the PN code generator 51. At this time, the original narrowband signal is output from the despreader 49 by the synchronization circuit 54 to the timing of the PN code generator 51. The narrow band signal obtained by the despreader 49 is demodulated to the original digital data by the demodulator 53, returned to the audio signal by the time division processing circuit 55 and the encoding circuit 56, and becomes an information output. On the other hand, information input from master unit 45 to master unit 45 is output by slave unit 31.

[0007]

As described above, the conventional spread spectrum communication apparatus requires complicated digital processing such as an encoding circuit and a time division processing circuit, and has a large scale compared to the conventional analog communication system.・ High cost. In general, the demodulator of the digital modulation method has a higher required signal-to-noise ratio at the reception limit of the weak telecommunications than the analog demodulator of the narrow band FM. In the case of the same transmission power, the reach limit becomes shorter. Further, the encoding circuit and the time-division processing circuit cause information delay. Due to the information delay, for example, side sounds of a cordless telephone are felt as a very unnatural echo feeling, which is not preferable.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a spread spectrum communication apparatus which has a reduced reception cost and a signal reception characteristic equivalent to analog communication.

[0009]

In order to solve the above-mentioned conventional problems, the present invention uses two widely separated frequencies,
In addition to the frequency division duplex system, the information modulation is a spread spectrum communication device using the same system as the analog communication system. According to the present invention, the information modulation uses the same system as the analog communication system, so that the encoding circuit and the time division processing circuit can be eliminated. This can reduce the circuit scale,
This makes it possible to reduce the size and to reduce the manufacturing cost. In addition, communication with no information delay due to digitization can be performed while ensuring anti-interference and confidentiality of the spread spectrum communication system.

[0010] Furthermore, by using two ISM bands for transmission and reception, such as the 900 MHz band and the 2.4 GHz band, a sufficient number of communication channels can be obtained within the designed ISM band. Since the duplexer required for separation of the components can have a simple configuration, the cost can be reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a pair of a slave unit and a master unit which are connected to each other wirelessly by using a spread spectrum communication system.
A first analog modulator for modulating information, a first spreader for modulating an output of the first analog modulator into a spread spectrum signal, and a first spreader for outputting an output from the first spreader.
A first transmitter for transmitting as a high-frequency signal of a frequency of the first, a first receiving unit for receiving a high-frequency signal of a second frequency sufficiently separated from the frequency transmitted by the first transmitter,
A first despreader for despreading the signal received by the first receiving unit; and a first analog demodulator for analogly demodulating an output of the first despreader, wherein the master unit A second analog modulator for modulating information, a second spreader for modulating an output of the second analog modulator into a spread spectrum signal, and an output from the second spreader A second transmitter for transmitting as a high-frequency signal of frequency 2;
A second receiving unit that receives a high-frequency signal of a first frequency;
A second despreader for despreading the signal received by the second receiving unit; and a second analog demodulator for analog demodulating an output of the second despreader. In addition, according to the invention described in claim 2, in the invention described in claim 1, the first frequency used by the first transmitting unit and the second receiving unit is in a 900 MHz band.
Any one of the 2.4 GHz band and the 5.7 GHz band is used, and the second frequency used by the second transmitting unit and the first receiving unit is 900 MHz band, 2.4.
It is characterized in that, of any of the frequency bands of the GHz band and the 5.7 GHz band, the frequency of the frequency band to which the first frequency band does not belong is used. By adopting the same method as described above, the encoding circuit and the time division processing circuit can be eliminated. As a result, the circuit scale can be reduced, so that the size can be reduced and the manufacturing cost can be reduced. in addition,
It has the effect that communication with no information delay due to digitization can be performed while ensuring the anti-interference and confidentiality of the spread spectrum communication system.

[0012] The invention described in claim 3 of the present invention relates to claim 1
Alternatively, in the invention according to claim 2, the first frequency used by the first transmission unit and the second reception unit is a second frequency used by the second transmission unit and the first reception unit. It is characterized in that a frequency lower than the frequency is used. In general, reception consumes more power than transmission, and the lower the frequency, the lower the power consumption. By lowering the transmission frequency from the slave unit as in the invention of claim 3, it is possible to reduce the power consumption and extend the communicable time more than when the configuration is reversed. Having.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the frequency used for communication is the Federal Communication Commission (FC).
C) by using a frequency band approved for spread spectrum communication.
This has the effect that a sufficient number of communication channels can be obtained even within the limited ISM band restricted by the FCC. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram of a spread spectrum communication apparatus according to Embodiment 1 of the present invention.

The spread spectrum communication apparatus comprises a main unit 14 as a main component and a main unit 14 capable of wireless full-duplex communication with a handset. The slave unit 1 includes, as constituent elements, an FM modulator 10 for performing primary modulation for putting an information signal on a high frequency, a PN code generating circuit 8 and a spreader 6 for generating a nest-pectrum signal spread signal, 900 MHz band RF transmitter 4 for converting the modulated signal to a high frequency and amplifying it
A 900 MHz antenna 13 for transmitting a 900 MHz band signal, and a 900 MHz filter 2 and 2.4 GH for separating transmission and reception and performing frequency division duplex communication.
1. z-filter 3 for receiving 2.4 GHz band signal
A 4 GHz antenna 14, an RF receiving unit 5 for amplifying a received high-frequency signal and converting it to an IF, a PN code generating circuit 9, a despreader 7, and a synchronizing circuit for returning the received spread spectrum signal to the original narrow band signal 12 and an FM demodulator 11 for demodulating the narrow band FM modulated signal obtained by the despreader 7
The base unit 15 includes, as constituent elements, an FM modulator 24 for performing primary modulation for putting an information signal on a high frequency, and a PN code generation circuit 2 for generating a spread spectrum signal.
2 and a spreader 20, a 2.4 GHz band RF transmission unit 18 for converting and amplifying the modulated signal to a high frequency, and 2.4 GHz
a 2.4 GHz antenna 27 for transmitting a signal in the z band, and a 9 for separating frequency and duplex transmission by separating transmission and reception.
00 MHz filter 17 and 2.4 GHz filter 16
And a 900 MHz antenna 28 for receiving a 900 MHz band signal, an RF receiver 19 for amplifying a received high frequency signal and converting it to an IF, and a PN code generation for returning the received spread spectrum signal to an original narrow band signal. It has a configuration including a circuit 23, a despreader 21 and a synchronization circuit 26, and an FM demodulator 25 for demodulating the narrow-band FM modulated signal obtained by the despreader 21.

A feature of the first embodiment of the present invention is that the slave unit 1 and the master unit 15 use two ISM bands, which are greatly separated from each other, 900 MHz and 2.4 GHz, for transmission and reception, respectively. , Full-duplex communication, an FM modulator and a demodulator similar to the analog communication system, and a digital composite circuit and a time-division processing circuit are eliminated.

The full-duplex communication operation of the spread spectrum communication apparatus configured as described above will be described below.

The information input to the slave unit 1 is transmitted to the FM modulator 1
By 0, modulation is performed in the same FM modulation scheme as in a conventional analog system. This signal is further modulated by the spreader 6 with the PN code generated by the PN code generator 8 to become a spread spectrum signal. Further, 900
It is converted and amplified to a high frequency of MHz, and radiated from a 900 MHz antenna 13 through a 900 MHz filter 2. On the other hand, the signal transmitted from handset 1
900 MHz received by the 0 MHz antenna 28
The signal is amplified by the RF receiver 19 through the filter 17 and
Converted to frequency. The signal from the RF receiver 19 is P
The PN code generated by the N code generator 23 and the despreader 21
Multiplied by At this time, the timing of the PN code generator 23 is controlled by the synchronizing circuit 26 and is synchronized with the spread spectrum signal input from the RF receiver 19, so that the original narrow band FM modulated signal is output by the despreader 21. . The narrow-band FM modulated signal obtained by the despreader 21 is converted back to an audio signal by the demodulator 25 and becomes an information output. The information input to the base unit 15 operates in a completely opposite manner to the above description using radio waves of 2.4 GHz, and
Output.

In the spread spectrum communication, since the content frequency in one communication channel is large, when it is necessary to use a plurality of communication channels in a limited band, the number of communication channels can be secured by the code division multiplexing method. Done. However, in applications such as cordless telephones using the ISM band, there are many opportunities to work with multiple systems that are not controlled by each other.
It is difficult to solve the perspective problem. Therefore, in such an application, the occupied frequency bandwidth is made relatively small, frequency division multiplexing is performed, and full-duplex communication is performed using time division duplexing, so that all ISM bands are used. A method for securing the number of communication channels is generally used. Here, the time division duplex system is based on a digital communication system. If pre-duplex communication using the frequency division duplex method is performed in the ISM band in order to adopt the analog communication signal system, two frequencies are required for transmission and reception, and transmission and reception can be completely separated by a duplex difference. Necessary
Only a small frequency range at both ends of the ISM band can be used,
In the spread spectrum communication system which originally has a large occupied bandwidth, the number of usable channels is extremely limited, which makes it impractical. In addition, if a large transmission output is to be output in order to increase the communication distance, the duplexer becomes expensive on the scale of the title.

In the present invention, 900 MHz and 2.4 GHz
The two ISM bands that are widely separated from each other are used for transmission and reception, and frequency division duplexing is performed.
A sufficient number of communication channels can be obtained using the full band. In addition, since the frequencies are far apart, the duplex difference can be relatively small and inexpensive.

According to the above-mentioned method, front-duplex spread spectrum communication based on the analog communication system is limited to I
It can be used in SM, and by eliminating digital coding circuits and time-division processing circuits, it is possible to realize communication with good reception sensitivity and no information delay, and also to reduce costs.

Even if the primary modulation is analog FM, spread spectrum modulation is performed after that, as in the conventional system. Therefore, excellent anti-interference and confidentiality and large output, which are characteristics of the spread spectrum system, are obtained. A long communication distance by transmission is also maintained.

Note that a communication device using a 5.7 GHz band other than the 900 MHz band and the 2.4 GHz band can of course be considered. However, at present, at 5.7 GHz, components to be used are more expensive than 900 MHz and 2.4 GHz. In addition, as the frequency increases, the propagation loss increases, and it is necessary to transmit with a larger output in order to obtain the same communication distance range, resulting in an increase in current consumption. Therefore, 900 MHz as in the first embodiment is used.
The combination of the band and the 2.4 GHz band is most advantageous in terms of cost reduction and current consumption reduction.

Further, 2.4 GHz also has a large propagation loss for 900 MHz, and it is necessary to transmit with an output larger than 900 MHz. Although the combination of 2.4 GHz and 900 MHz is possible, assuming that the slave unit is driven by a battery such as a portable terminal and the master unit is driven by using a commercial power supply, the power consumption of the slave unit is taken into consideration. Embodiment 1
It is more practical to use 900 MHz, that is, a low frequency on the transmitting side of the slave unit as described above.

As described above, according to the first embodiment, the characteristics of the spread spectrum system such as excellent anti-interference and confidentiality and a long communication distance due to high-power transmission, and a sufficient number of communication channels are maintained. A spread spectrum communication apparatus with good reception sensitivity, no information delay, and reduced cost can be provided.

As is apparent from the above description, 900M
In order to perform full-duplex communication by frequency division duplexing, which uses two ISM bands for the transmission and reception in the Hz band and the 2.4 GHz band, analog FM modulation can be used for primary modulation.
Cost reduction compared to conventional digital time division duplex
This has the effect of improving reception sensitivity and eliminating information delay.

[0027]

According to the present invention, a spread-spectrum communication device using the same system as the analog communication system in addition to the frequency division duplex system using two widely separated frequencies. According to the present invention, the information modulation uses the same system as the analog communication system, so that the encoding circuit and the time division processing circuit can be eliminated. As a result, the circuit scale can be reduced, so that the size can be reduced and the manufacturing cost can be reduced. In addition, after ensuring the anti-interference and confidentiality of the spread spectrum communication system,
Communication without information delay due to digitization can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a spread spectrum communication apparatus according to Embodiment 2 of the present invention.

FIG. 2 is a configuration diagram of a conventional spread spectrum communication apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 slave unit 2 900 MHz filter 3 2.4 GHz filter 4 RF transmitter 5 RF receiver 6 spreader 7 despreader 8 transmitter PN code generator 9 receiver PN code generator 10 FM modulator 11 FM demodulator 13 900 MHz Antenna 14 2.4 GHz antenna 15 Base unit 16 2.4 GHz antenna 17 900 MHz antenna 18 RF transmitting unit 19 RF receiving unit 20 Spreader 21 Despreader 22 Transmitting PN code generator 23 Receiving PN code generator 24 FM modulator 25 FM demodulator 26 Synchronous circuit 27 2.4 GHz antenna 28 900 MHz antenna

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Yoshinaga 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. Ritchie Sawyer United States Utah American Fork East Utah Valley Drive 772 (72) Inventor Dave And Reuse Utah American Fork East Utah Valley Drive 772 (72) Inventor Fail Bunker U.S. 772 F term (reference) 5K022 EE01 EE02 EE11 EE21 EE31

Claims (4)

[Claims] The present invention comprises a pair of a slave unit and a master unit which are connected to each other wirelessly using a spread spectrum communication system, wherein the slave unit includes a first analog modulator for modulating information and the second analog modulator. A first spreader for modulating an output of the first analog modulator into a spread spectrum signal, a first transmitter for transmitting an output from the first spreader as a high frequency signal of a first frequency, A first receiving unit for receiving a high-frequency signal of a second frequency sufficiently separated from a frequency transmitted by the first transmitter, and a first inverse unit for despreading the signal received by the first receiving unit A spreader; and a first analog demodulator for analogly demodulating an output of the first despreader, wherein the master unit includes a second analog modulator for information modulation, and a second analog modulator for information modulation. A second spreader for modulating the output of the analog modulator into a spread spectrum signal; A second transmitter for transmitting an output from the second spreader as a high-frequency signal of a second frequency, a second receiving unit for receiving a high-frequency signal of the first frequency, and the second receiving unit. A spread spectrum communication apparatus, comprising: a second despreader for despreading a signal received by the unit; and a second analog demodulator for analogly demodulating an output of the second despreader. 2. The first frequency used by the first transmitting unit and the second receiving unit is 900 MHz band and 2.4 GHz.
Any one of the z band and the 5.7 GHz band is used, and the second frequency used by the second transmitting unit and the first receiving unit is 900 MHz band, 2.4 GHz band,
2. The spread spectrum communication apparatus according to claim 1, wherein a frequency of a frequency band to which the first frequency band does not belong is used in any one of the 5.7 GHz frequency bands. 3. The first frequency used by the first transmitting unit and the second receiving unit is lower than the second frequency used by the second transmitting unit and the first receiving unit. 3. The spread spectrum communication apparatus according to claim 1, wherein 4. The frequency used for communication is Federal Communic
4. The spread spectrum communication apparatus according to claim 1, wherein the communication is performed using a frequency band approved for spread spectrum communication by the National Commission.