AU7319498A - Synthesization diversity receiving system capable of preventing degradation of reception sensitivity - Google Patents

Description

S F Ref: 423352

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECtFICA_'ON FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: NEC Corporation 7-I, Shiba Minato-ku Tokyo

JAPAN

Nozomu Watanabe Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Synthesization Diversity Receiving System Capable of Preventing Degradation of Reception Sensitivity O t

O

invention Title: The following statement is a full description of this invention, including the best method of performing it known to me/us:- SYNTHESIZATION DIVERSITY RECEIVING SYSTEM

CAPABLE

OF PREVENTING DEGRADATION OF RECEPTION

SENSITIVITY

Background of the Invention The present invention relates to a synthesization diversity receiving system, and more particularly to a synthesization diversity 10 receiving system which is used for a wireless apparatus of mobile communlicationl.

Fig. I is a block diagram which shows a conventional synthesization diversity receiving system. In this figure, 2-system signals which are received by two independent antennas 1-1 and 1-2 are converted into IF signals 4-1 and 4-2 which are signals at the middle frequency band, by receiving sections 2-1 and 2-2, respectively- Also, at the same time, the receiving sections 2- I and 2-2 output reception electric field strength detection signals 3-1 and 3-2 which indicate the electric field strength of the received signals. Further, phase detection is performed to the IF signals 4-1 and 4-2 in phase detecting sections 5-1 and 5-2 and the results are outputted as phase information signals 6-1 2 and 6-2.

A Weighting and synthesizing section 9 is composed of weighting sections 9a-1 and 9a-2 and a phase synthesizing sections 9c. First, the weighting sections 9a-1 and 9a-2 weight the respective phase information signals 6-1 and 6-2 based on the reception electric field strength detection signals 3-1 and 3-2, respectively. The 2-system weighted phase information signals are supplied to the phase synthesizing sections 9c and is synthesized therein. The synthesizing result is supplied to a demodulating section 11 as a synthesized phase information signal 10. The demodulation section 11 performs demodulation based on this synthesized phase information signal 10 and outputs a demodulation data 12 as the result of the demodulation. That is, the weighting when the 2-system reception signals are synthesized is determined in accordance with the reception levels, and the weighted signals are synthesized. This technique is described in, for example, Japanese Laid Open Patent Disclosure (JP-A-Heisei 7-202775).

In the conventional synthesization diversity receiving system, a noise level of a receiver is detected as the reception electric field strength level even when any failure occurs 3 in the antenna so that any reception signal can not be received at all from the antenna. Because the weighting and synthesizing operations are performed to the detected noise level in the abnormal state and the reception signal from the antenna system in the normal state, there is a problem in that reception sensitivity has been extremely degraded. This is because the reception signal of the system in which the antenna is in the abnormal state is also handled as the weighting and synthesizing object.

In addition to the above reference, an automobile antenna diagnosing apparatus is disclosed in Japanese Laid Open Patent Disclosure (JP-A-Heisei 8-162829). In this reference, the automobile antenna diagnosing apparatus is composed of an antenna failure diagnosis control circuit which includes counting means for counting the number of selection times of each of I 20 antennas 31 and 32 and determining means for Soutputting a failure signal when the number of selection times of each of the antennas 31 and 32 counted by said counting means is smaller than the predetermined number of selection times, and failure displaying means for performing a failure display in response to the failure signal.

In Japanese Examined Patent Application S- 4 (Jp-A-Showa 57-28983), is disclosed a diversity Sapparatus, which is composed of diversity means of a time divisional communication system, for switching input connection to introduce to a receiving unit one of inputs from a plurality of antennas which indicates the maximum signal power for providing a stable input level and a time divisional signal selecting unit for detecting the arrival of a time divisional signal to the apparatus. The operation of switching the input connection is inhibited for a period during which the time divisional signal selecting unit selects detects the time divisional signal to the apparatus.

In Japanese Laid Open Patent Disclosure (JP-A-Heisei 6-276166), an antenna failure detecting apparatus is described. In this reference, reception electric field strength levels of reception signal received by antennas of a diversity wireless apparatus are continuously monitored by receiving units 11 and 12 in units of predetermined time periods so that peak values of the reception electric field strength levels can be detected by peak detecting units 41 and 42, respectively. The detected peak values are compared by a comparing unit 2. When the difference is more than a predetermined value,

B*

-4 (JP-A-Showa 57-28983). is disclosed a diversity 1apparatus, which is composed of diversity means of a time divisional communication system, for switching input connection to introduce to a receiving unit one of inputs from a plurality of antennas which indicates the maximum signal power for providing a stable input level and a time divisional signal selecting unit for detecting the arrival of a time divisional signal to the apparatus. The operation of switching the input connection is inhibited for a period during which the time divisional signal selecting unit selects detects the time divisional signal to the apparatus.

In Japanese Laid Open Patent Disclosure (JP-A-Heisei 6-276166), an antenna failure detecting apparatus is described. In this reference, reception electric field strength levels of reception signal received by antennas of a diversity wireless apparatus are continuously monitored by receiving units 11 and 12 in units of predetermined time periods so that peak values of the reception electric field strength levels can be detected by peak detecting units 41 and 42, respectively. The detected peak values are compared by a comparing unit 2. When the difference is more than a predetermined value, 5 ji the antenna through which the signal of the lower one of the reception electric field strength levels is received is determined to be in the failure state.

In Japanese Laid Open Patent Disclosure (Jp-A-Heisei 1-200729), a space diversity receiving apparatus is described in which a switch circuit is unnecessary for disconnecting an antenna in the failure state. In this 10 reference, the space diversity receiving apparatus is composed of first and second antennas, a local oscillator, a phase shifter for variably shifting the phase of an output from the local oscillator, an amplifier for compensating an insertion loss of the phase shifter, and a first frequency converter for mixing a signal received by the first antenna and the output of the local oscillator to produce a first intermediate frequency signal, a second frequency converter for mixing a signal received by the second antenna and the output of the local oscillator through the phase shifter and the amplifier to produce a second intermediate frequency signal, the first and second intermediate frequency signals being synthesized into a reception signal, and a control unit for controlling the phase of the phase shifter. When 6 the phase control of the phase shifter by the control unit is not performed correctly, a decay amount in the phase shifter is increased. At the same time, at least one of the amplifier and the second frequency converter is set to a nonoperation state to decay the level of the intermediate frequency signal outputted from the second frequency converter lower than a predetermined level.

1 0 In Japanese Laid Open Patent Disclosure (JP-A-Showa 64-55923), a space diversity receiving apparatus is described in which a unit failure is distinguished from a transmission channel failure. In this reference, the space diversity receiving apparatus is composed of a control unit for detecting an in-band amplitude variance of a signal obtained by synthesizing a S. reception signal by a main antenna and a signal received by an auxiliary antenna and phase- 20 shifted by a phase shifted to control the phase shift operation of the phase shifter such that the in-band amplitude variance is set to 0. The space diversity receiving apparatus is further composed of an inverse phase synthesizing unit for synthesi-ing the reception signals by the main antenna and the auxiliary antenna in an inverse phase and a detecting circuit for 7 detecting a small periodic level change of the phase shifter which appears at the output of the inverse phase synthesizing unit. The failure of any unit of the space diversity receiving circuit is distinguished from the transmission channel failure based on the output of the detecting circuit.

In Japanese Laid Open Patent Disclosure (JP-A-Showa 64-60027), an antenna switching 10 system is described. In this reference, a wireless communication apparatus includes a main antenna and an auxiliary antenna. A reflection wave detecting circuit is provided on a transmission path from the main antenna to detect a reflection wave of a transmission output to the main antenna. When an amount of reflection wave detected by the reflection wave detecting circuit is more than a predetermined value, a transmission antenna is switched from the main antenna to the auxiliary antenna.

Summary of the Invention The present invention is accomplished to solve the above problems. Therefore, an object of the present invention is to provide a synthesization diversity receiving system in which the degradation of reception characteristic 8 when an antenna is in the abnormal failure state can be suppressed to the minimum.

Another object of the present invention is to provide a synthesization diversity receiving system in which the reduction of a base station service area can be suppressed to the minimum to maintain service quality when the antenna is in an abnormal failure state.

In order to achieve an aspect of the present invention, a synthesization diversity receiving system includes a first receiving section, a first antenna state detecting section, a second receiving section, a second antenna state detecting section, a first vector signal generating section, a first vector signal generating section and a synthesizing section.

The first receiving section includes a first antenna, and generates a first reception electric field strength signal and first phase signal for a signal received by the first antenna. The first antenna state detecting section detects whether the first antenna is in an abnormal state, to generate a first abnormal state detection signal.

The second receiving section includes a second antenna, and generates a second reception electric field strength signal and second phase signal for a signal received by the second 9 antenna. The second antenna state detecting section detects whether the second antenna is in the abnormal state, to generate a second abnormal state detection signal. The first vector signal generating section generates a first vecto.signal from the first reception electric tield strength signal and the first phase signal, and inhibits the generation of the first vector signal in response to the first abnormal state 1 0 detection signal. The second vector signal generating section generates a second vector signal from the second reception electric field strength signal and the second phase signal, and inhibits the generation of the second vector signal in response to the second abnormal state detection signal. The synthesizing section synthesizes the first vector signal and the Ssecond vector signal into a synthetic reception signal.

The first vector signal generating section may include a first multiplying section for multiplying the first phase signal based on the first reception electric field strength signal to generate the first vector signal, and a first switching section for passing the first vector signal to the synthesizing section and for inhibiting the passing of the first vector signal b-a" WO m -slraarra~l-~ ~aaa- ~L LLOWI~BJ 10 in response to the first abnormal state detection signal. Also, the second vector signal generating section may include a second multiplying section for multiplying the second phase signal based on the second reception electric field strength signal to generate the second vector signal, and a second switching section for passing the second vector signal to the synthesizing section and for inhibiting the passing of the second vector 10 signal in response to the second abnormal state detection signal.

Also, the first vector signal generating section may include a first multiplying section for multiplying the first reception electric field strength signal by the first abnormal state Sdetection signal, and the second multiplying section for multiplying the first phase signal by the multiplying result of the first multiplying section. Here, the first abnormal state detection signal is 0 when it is detected that the first antenna is in the abnormal state, and 1, otherwise. Also, the second vector signal generating section may include a third multiplying section for multiplying the second reception electric field strength signal by the second abnormal state detection signal, and the fourth multiplying section for multiplying the Tr~n .1111Ini.ii11.1n-.. N 11 phase signal by the multiplying result of the second multiplying section. Here, the second abnormal state detection signal is 0 when it is detected that the second antenna is in the abnormal state, and 1. otherwise- Instead, the first vector signal generating section may include a first weighting section for weighting the first phase signal based on the first reception electric field strength signal to generate the first vector signal, and a first connection control section for disconnecting the first weighting section from the synthesizing section in response to the first abnormal state detection signal. Also, the second vector signal generating section may include a second weighting section for weighting the second phase signal based on the second reception electric field i:.

i strength signal to generate the second vector signal, and a second connection control section I 20 for disconnecting the second weighting section from the synthesizing section, in response to the second abnormal state detection signal.

Otherwise, the first vector signal generating section may include a first weighting section for weighting the first phase signal based on the first reception electric field strength signal to generate the first vector r 12 signal, and a first invalidating section for invalidating the weighting operation of the first weighting section in response to the first abnormal state detection signal. Also, the second vector signal generating section may include a second weighting section for weighting the second phase signal based on the second reception electric field strength signal to generate the second vector signal, and a second invalidating 10 section for invalidating the weighting operation of the second weighting section in response to the second abnormal state detection signal.

In order to achieve another aspect of the present invention, a method of producing a reception signal in a synthesization diversity receiving system, includes the steps of: generating a vector signal for a signal received by each of a plurality of antennas; detecting whether each of the plurality of antennas is in an abnormal state, to generate an abnormal state detection signal; and a synthesizing section for synthesizing the vector signals for the plurality of antennas other than the vector signals for the antennas designated in accordance with the abnormal state detection signals, into a synthetic reception signal.

PBb~ aa .1 *riii" i« a 13 As described above, the synthesization diversity receiving system of the present invention removes the signal which is received from the antenna in the failure state system from the weighting and synthesizing object.

Brief Description of the Drawings Fig. 1 is a block diagram of a conventional synthesization diversity system; 0 Fig. 2 is a block diagram illustrating a synthesization diversity system according to a first embodiment of the present invention; Fig. 3 is a diagram illustrating the weighting and synthesizing operation in the first embodiment of the present invention; and Fig. 4 is a block diagram illustrating the structure of the synthesization diversity system according to the second embodiment of the present invention.

Description of the preferred Embodiments The synthesization diversity system of the present invention will be described below in detail with reference to the attached drawings.

Fig. 2 is a block diagram illustrating the synthesization diversity system according to the first embodiment of the present invention- *iy C ^raRI BF 111,.. i. -"..i'iIiiiii''' 14 Referring to Fig. 2, the structure of the synthesization diversity system according to the first embodiment of the present invention will be described in detail.

The synthesization diversity system in the first embodiment is composed of first and second reception systems, a weighting and synthesizing section 9. and a demodulating section 11. The first reception system is composed of an antenna S 10 1-1, a receiving section 2-1, a phase detecting section 5-1 and an antenna abnormal state detecting section 7-1. The second reception *::system is composed of an antenna 1-2, a receiving section 2-2, a phase detecting section 5-2 and an antenna abnormal state detecting section 7-2. The weighting and synthesizing section 9 is composed of a weighting section 9a-1 and a switch section 9b-1, which are both for the first reception system, a weighting section 9a-2 and a switch section 9b-2 which are both for the second reception system, and a phase synthesizing section 9c.

Referring to Fig. 2, a signal which is received by the antenna 1-1 is converted into an IF signal 4-1 by the receiving section 2-1 and is subjected to the detection of a reception electric field strength level. The detected a TOi a«8 spvs~~ras~a--- ~l.,-~.lazl~r;rrn~;hlrC~ ~i-~~ITIFIYrrY^-- ~-LI~YI.YI -~IXYU~UI(V~C C"U" M~-U 15 reception electric field strength level is outputted as a reception electric field strength detection signal 3-1. The IF signal 4-1 is supplied to the phase detecting section 5-1, and a phase detection is performed there. Then, the detection result is outputted as a phase information signal 6-1. Also, an antenna abnormal state detecting section 7-1 is provided at one end of the antenna to detect the abnormal state 10 of the antenna 1-1 and outputs an antenna abnormal state detection signal 8-1 to inform existence or non-existence of the abnormal state of the antenna 1-1.

Also, a signal which is received by the 15 antenna 1-2 is converted into an IF signal 4-2 by the receiving section 2-1 and is subjected to the detection of a reception electric field strength level. The detected reception electric field strength level is outputted as a reception electric field strength detection signal 3-2. The f IF signal 4-2 is supplied to the phase detecting section 5-2, and a phase detection is performed there- Then, the detection result is outputted as a phase information signal 6-2. Also, an antenna abnormal state detecting section 7-2 is provided at one end of the antenna to detect the abnormal state of the antenna 1-2 and outputs an antenna 16 abnormal state detection signal 8-2 to inform existence or non-existence of the abnormal state of the antenna 1-1.

The weighting sections 9a-i and 9b--1 weight the phase information signals 6-1 and 6-2 in accordance with the reception electric field strength detection signals 3-1 and 3-2, respectively. The weighted phase information signals are supplied to the phase synthesizing section 9c through the switch sections 9b-1 and 9b-2, which are turned on or off in accordance with the antenna abnormal state detection signals 8-1 and 8-2, respectively. The phase synthesizing section 9c synthesizes the weighted phase information signals to output the synthesization result to the demodulating section 11 as a synthesized reception signal 10. The demodulating section 11 performs the demodulating operation based on the supplied synthesized reception signal 10 and outputs the demodulation data 12 which is the demodulation result.

In the above structure, there are two reception systems. However, the present invention is not limited to two reception systems but can be applied to an apparatus having more than 2 reception systems.

Next, the operation of the synthesization 17 diversity system according to the first embodiment of the present invention will be described below.

Generally, the signals which are received by the respective antennas 1-1 and 1-2 are supplied to the receiving sections 2-1 and 2-2, respectively. The signals which are received by the respective receiving sections 2-1 and 2-2 are converted into the IF signals 4-1 and 4-2, after 10 an analog-to-digital conversion is performed. At the same time, the electric field strength levels of the reception signal are detected. The detected signal levels are supplied to the weighting and synthesizing section 9 as the 15 reception electric field strength detection signals 3-1 and 3-2, respectively.

On the other hand, the IF signals 4-1 and F4-2 are delay-detected in the phase detecting sections 5-1 and 5-2, and are outputted as the phase information signals 6-1 and 6-2, which indicate the states of the phase changes of the IF signals 4-1 and 4-2, respectively.

The weighting and synthesizing operation will be explained with reference to Fig. 3 in addition to Fig. 2.

The weighting section 9a-1 weights the phase information signal 6-1 in accordance with m--i~iiiii-iinirmii..iininrnrn^ «a S-18-

I

4- the reception electric field strength detection signal 3-1- That is, the weighting section Sa-i multiplies the phase information signal 6-1 by the reception electric field strength detection signal 3-1. Through the weighting or multiplying operation, a vector signal is generated from the phase information signal 6-1 and the reception electric field strength detection signal 3-1.

In Fig. 3, it is assumed for the vector signal of the first reception system that a quantity of phase change indicated by the phase information signal 6-1 is 01 and the weighting coefficient by the reception electric field strength detection signal 3-1 is 3. Also, in the second reception system, the weighting operation is performed in the same way as in the weighting section 9a-2. In the second reception system, it is assumed for the vector signal that a quantity of phase change indicated by the phase information signal 6-2 is 02 and the weighting coefficient for the reception electric field strength detection signal 3-2 is The signals after the weighting operations are shown by two vectors in Fig. 3. These weighted signals are supplied to the switch sections 9b-1 and 9b-2, respectively. When the antennas 1-1 and 1-2 are in the normal state, the i '4 ~-L~aaEIl-- ~gap~ae(L~swaer~s rc~eap ~l~aaaaar~r~sas~ 19 switch sections 9b-l and 9b-2 are set to the on state by the antenna abnormal state detection signals 8-1 and 8-2, respectively. As a result, the weighted phase information signals from the first and second reception systems are synthesized by the phase synthesizing section 9c.

A signal having an angle of 6 indicated by the vector obtained by synthesizing two vectors shown in Fig. 3 is the synthesized phase information 10 signal 10 which is the output from the phase synthesizing section 9c.

Next, the case where the antenna abnormal state occurs will be explained.

It is supposed that the antenna 1-2 is damaged. In this case, the receiving section 2-2 performs the level detection to a noise component of the receiving section 2-2 as a reception signal. The detected noise level is supplied to the weighting section 9a-2 as the reception electric field strength detection signal 3-2.

Also, the phase information signal 6-2 indicates the phase information as the result of that the noise component is detected, and is supplied to the weighting section 9a-2. The weighting operation is performed based on the reception electric field strength detection signal 3-2. The antenna abnormal state detecting section 7-2 r ,aip ni. i i 1, n r i.i 11.11 im 11-i~i .1111,1. .i iiw C 20 detects the abnormal state of the antenna 1-2 and informs that the antenna 1-2 is in an abnormal state, to the switch section 9b-2 by the antenna abnormal state detection signal 8-2. The switch section 9b-2 receives this signal to switch to the off state. Thus, the phase information of the second reception system is not supplied to the phase synthesizing section 9c. In other words.

the phase information of the second reception system is disconnected from the synthesizing operation. As a result of this, only the weighted phase information of the first antenna system in the normal state is supplied to the demodulating section 11 through the phase synthesizing section 9c and is demodulated.

Next. the synthesization diversity receiving system according to the second embodiment of the present invention will be described.

Fig. 4 is a block diagram illustrating the structure of the synthesization diversity receiving system according to the second embodiment of the present invention. As shown in Fig. 4. the synthesization diversity receiving system in the second embodiment is different from that of the first embodiment in that multiplying sections 13-1 and 13-2 are provided between the ~~PP*Mfe ~I ~f_ 21 reception electric field strength detection signals 3-1 and 3-2 and the weighting sections 9a-1 and 9a-2, respectively. The reception electric field strength detection signals 3-1 and 3-2 of the respective reception systems and the antenna abnormal state detection signals 8-1 and 8-2 are supplied to the multiplying sections 13-1 and 13-2. respectively. The antenna abnormal state detection signal 8-1 or 8-2 is 1 when the antenna 1-1 or 1-2 is in the normal state and is 0 when the antenna 1-1 or 1-2 is in the abnormal failure state. The multiplying sections 13-1 and 13-2 multiply the reception electric field strength detection signals 3-1 and 3-2 by the S: 15 antenna abnormal state detection signals 8-1 and 8-2, and supply the multiplying result to the weighting sections 9a-l and 9a-2, respectively.

Since the reception electric field strength detection signal is multiplied by 0 when the antenna is in the abnormal state, the weighting coefficient in the weighting section is 0. In other words, the multiplying sections 13-1 and 13-2 invalidate the weighting sections 9a-1 and 9a-2. As a result, the phase information is not synthesized in the phase synthesizing section 9c, and is not used for the demodulation. On the other hand, when the antennL is in the normal I.C 11 i I 111111 l~-r~--.p--Uaa~ODI~L~LIIIIP 22 state, since the reception electric field strength detection signal is multiplied by 1, the normal synthesizing operation is performed.

The effect of the present invention is in that the degradation of the reception sensitivity in case of antenna failure can be suppressed to the minimum. This is because when the antenna failure occurs, the phase information obtained from the reception system in the abnormal state 10 is removed from the weighting and synthesizing object. As a result, information of noise is not synthesized and only the original signal information which has been received from the reception system is synthesized and demodulated.

i t i Z_

Claims (9)

1. A synthesization diversity receiving system comprising: a first receiving section including a first antenna, for generating a first reception electric field strength signal and first phase signal for a signal received by said first antenna; a first antenna state detecting section for detecting whether said first antenna is in an i" 10 abnormal state, to generate a first abnormal state detection signal; ~a second receiving section including a second antenna, for generating a second reception electric field strength signal and second phase signal for a signal received by said second antenna; a second antenna state detecting section for detecting whether said second antenna is in the abnormal state, to generate a second abnormal state detection signal; a first vector signal generating section for generating a first vector signal from said first reception electric field strength signal and said first phase signal, and for inhibiting the generation of said first vector signal in response to said first abnormal state detection -24- signal; a second vector signal generating section for generating a second vector signal from said second reception electric field strength signal and said second phase signal, and for inhibiting the generation of said second vector signal in response to said second abnormal state detection signal; and a synthesizing section for synthesizing said first vector signal and said second vector signal into a synthetic reception signal.

2. A synthesization diversity receiving system according to claim 1, wherein said first vector signal generating section comprises: a first multiplying section for multiplying said first phase signal based on said first reception electric field strength signal to generate said first vector signal; and a first switching section for passing said first vector signal to said synthesizing section and for inhibiting the passing of said first vector signal in response to said first abnormal state detection signal, and i wherein said second vector signal T generating section comprises: a second multiplying section for multiplying said second phase signal based on said second reception electric field strength signal to generate said second vector signal; and a second switching section for passing said second vector signal to said synthesizing section and for inhibiting the passing of said second vector signal in response to said second abnormal state detection signal.

3. A synthesization diversity receiving system according to claim 1, wherein said first vector signal generating section comprises: a first multiplying section for multiplying said first reception electric field strength signal by said first abnormal state detection signal, said first abnormal state detection signal is 0 when it is detected that said first antenna is in the abnormal state, and I, otherwise; and said second multiplying section for multiplying said first phase signal by the multiplying result of said first multiplying section, and wherein said second vector signal generating section comprises: a third multiplying section for multiplying said second reception electric field strength S26- signal by said second abnormal state detection signal, said second abnormal state detection signal is 0 when it is detected that said second antenna is in the abnormal state, and 1, otherwise; and said fourth multiplying section for multiplying said phase signal by the multiplying result of said second multiplying section.

4. A synthesization diversity receiving system according to claim 1i, wherein said first vector signal generating section comprises: a first weighting section for weighting said first phase signal based on said first reception electric field strength signal to generate said first vector signal; and S. a first connection control section for disconnecting said first weighting section from said synthesizing section in response to said first abnormal state detection signal, and wherein said second vector signal generating section comprises: a second weighting section for weighting said second phase signal based on said second reception electric field strength signal to generate said second vector signal; and a second connection control section for -27- disconnecting said seccnd weighting section from said synthesizing section, in response to said second abnormal state detection signal. A synthesization diversity receiving system according to claim 1, wherein said first vector signal generating section comprises: a first weighting section for weighting S.

5 said first phase signal based on said first reception electric field strength signal to generate said first vector signal; and a first invalidating section for invalidating the weighting operation of said first weighting section in response to said first Sabnormal state detection signal, and wherein said second vector signal generating section comprises: a second weighting section for weighting said second phase signal based on said second reception electric field strength signal to generate said second vector signal; and a second invalidating section for invalidating the weighting operation of said second weighting section in response to said second abnormal state detection signal.

6. A method of producing a reception signal in 28 a synthesization diversity receiving system, comprising the steps of: generating a vector signal for a signal received by each of a plurality of antennas; detecting whether each of said plurality of antennas is in an abnormal state, to generate an abnormal state detection signal; and a synthesizing section for synthesizing 10 said vector signals for said plurality of antennas other than said vector signals for said antennas designated in accordance with said abnormal state detection signals, into a synthetic reception signal.

7. A method according to claim 6, wherein said step of generating a vector signal includes: generating a reception electric field strength signal and phase signal for the signal received by each of said plurality of antennas; multiplying said phase signal based on said reception electric field strength signal for each of said plurality of antennas to generate said vector signal; and inhibiting the generation of said vector signal in response to each of said abnormal state detection signal. 29

8. A method according to claim 6, wherein said step of generating a vector signal includes: generating a reception electric field strength signal and phase signal for the signal received by each of said plurality of antennas; and multiplying said reception electric field strength signal by said abnormal state detection signal for each of said plurality of antennas, said abnormal state detection signal is 0 when it is detected that said antenna is in the abnormal state, and i, otherwise.

9. A method according to claim 6, wherein said step of generating a vector signal includes: generating a reception electric field strength signal and phase signal for the signal received by each of said plurality of antennas; and weighting said phase signal by said reception electric field strength signal for each of said plurality of antennas to generate said vector signal, arnd wherein said synthesizing step includes: disconnecting said weighted phase signal from said synthesizing operation in response to said corresponding abnormal state detection signal. A method according to claim 6, wherein said step of generating a vector signal includes: generating a reception electric field strength signal and phase signal for the signal received by each of said plurality of antennas; weighting said phase signal by said reception electric field strength signal for each of said plurality of antennas to generate said vector signal, and invalidating the weighting operation in response to said corresponding to abnormal state detection signal. 1. A synthesization diversity receiving system substantially as herein described with reference to Figs 2 and 3 or Fig 4. 5 12. A method of producing a reception signal substantially as herein described with reference to Figs 2 and 3 or Fig 4. DATED this Nineteenth Day of June 1998 NEC Corporation Patent Attorneys for the Applicant SPRUSON FERGUSON