公开(公告)号：JPS6488272A

公开(公告)日：1989-04-03

申请号：JP24628487

申请日：1987-09-30

Applicant: NEC CORP

Inventor： ICHIYOSHI OSAMU

IPC: G01S5/10 ,  G01S5/06

Abstract: PURPOSE:To enable the execution of rapid measurement in addition to bidirectional communications without increasing a circuit scale, by adopting SCPC (single-channel per carrier) - FDMA (frequency division multiplexing connection) and by using a simple digital modulator-demodulator. CONSTITUTION:Three geostationary satellites are employed in a moving-body satellite communication system of an SCPC-FDMA method. Frequency-divided and multiplexed communication signals from a plurality of mobile stations are passed from three high directivity antennas 32a-32c through FDM reception means comprising low noise amplifiers 33a-33c, down converters 34a-34c and data demodulators 1a-1c, respectively, and turn to be three sets of reproduced data and reproduced clocks for each communication frequency channel. While one set of reproduced data and reproduced clock are sent as a reception signal to a reception processing system, the three sets of reproduced data and reproduced clocks are sent out to a timing difference detecting circuit 2, wherein time differences between these signals are detected and position-measurement signals for calculating the position of the mobile stations are formed thereby.

公开(公告)号：JPS6466582A

公开(公告)日：1989-03-13

申请号：JP22487687

申请日：1987-09-08

Applicant: NEC CORP

Inventor： ICHIYOSHI OSAMU

IPC: G01S5/10 ,  G01S1/30 ,  G01S13/32 ,  G01S13/38 ,  H04B7/15

Abstract: PURPOSE:To enhance measuring accuracy, by receiving the output from a modulation means by (M) receiving antennae to separate the same and demodulating and regenerating transmission data, a clock and a sub-carrier wave to calculate the signal propagating time difference between (M) radio transmission lines. CONSTITUTION:A transmission part consists of the first sub-carrier wave generator 23, a main carrier wave generator 27 and a mixer 28. The generator 23 generates the first sub-carrier wave to give the same to a modulator 24. The digitally modulates the first sub-carrier wave on the basis of transmission data and forms a modulation signal to apply the same to one input of the mixer 28. The main carrier wave generator 27 generates a main carrier wave to apply the same to the other input of the mixer 28. As a result, the amplitude of the main carrier wave is modulated on the basis of the output signal of the modulator 24 by the mixer 28. In a receiving part, main carrier wave regenerating circuits 36-a, 36-b and mixers 37-a, 37-b are provided and the regenerated first sub-carrier wave is applied to a receiving signal processing circuit 38 from demodulators 33-a, 33-b in addition to a regenerated data and a regenerated clock. In the circuit 38, the outputs of the demodulators 33-a, 33-b are compared to determine a time difference of a bit unit.

公开(公告)号：JPS6451837A

公开(公告)日：1989-02-28

申请号：JP20976487

申请日：1987-08-24

Applicant: NEC CORP

Inventor： ICHIYOSHI OSAMU

IPC: H04J1/00 ,  H04B7/14 ,  H04J13/00

Abstract: PURPOSE:To attain effective utilization of a frequency and to suppress the disturbance with a satellite line and a ground line of an adjacent satellite by using the FDM communication system and the CDM communication system in common as the communication system between small sized earth stations. CONSTITUTION:The FDM(frequency division multiplex) communication system and the CDW(code division multiplex) communication system are used in common as the communication system between small sized earth stations. The reception system of the station used in common consists of a receiver 21 including a low noise amplifier and a down-converter for example, an FDM reception section provided with a channel selection filter 22 and an FDM demodulator 23, a comb-line filter bank 24, and a CDM reception section provided with a matching filter 25 and a CDM demodulator 26. Thus, the low frequency utilization efficiency being a defect of the CDM communication system is compensated and the spread spectrum is applied in the CDM communication system by utilizing the entire operating band width, then the desired processing gain is obtained and the disturbance with the satellite line of the adjacent satellite or a ground line is suppressed.

公开(公告)号：JPS6430343A

公开(公告)日：1989-02-01

申请号：JP18737587

申请日：1987-07-27

Applicant: NEC CORP

Inventor： ICHIYOSHI OSAMU

IPC: H04K1/04

Abstract: PURPOSE:To dispense with a filter group and to simplify a circuit constitution by selecting the one side of two single-sideband SSB signal spectra in a reflected image relation at a transmitting side corresponding to the code polarity of a pseudo-random signal and obtaining a secret call by means of the SSB signal in which a frequency relation is inverted. CONSTITUTION:At the transmitting side, by selecting, corresponding to the code polarity of the pseudo-random signal, the one side of the two SSG signal spectra in the reflected image relation, the secret call is obtained by the SSB signal in which the frequency relation is inverted, and at a receiving side, a prototype sound signal spectrum is restored by the pseudo-random signal in which a code synchronizing is established in a pilot signal. Thus, the filter group to conventionally increase a circuit scale can be made unnecessary, the circuit scale can be widely reduced and the circuit constitution can be made simple. Since the system is not one to divide the spectra, the problem of waveform deterioration does not exists, and the quality of a restoring voice can be improved.

公开(公告)号：JPS6430318A

公开(公告)日：1989-02-01

申请号：JP18469787

申请日：1987-07-25

Applicant: NEC CORP

Inventor： ICHIYOSHI OSAMU

IPC: H03H11/04 ,  H03H19/00

Abstract: PURPOSE:To vary a band in a wide range by using a variable capacitor capable of generating an element value which is the multiple of reciprocal of an arbitrary integer of a basic value at a special range by the ON and OFF control of a switch and making variable a band with a digital control from an external part. CONSTITUTION:By using a variable capacitor 13 to be able to the arbitrary reverse integer-fold element value of a basic value in the 1-1/(2 ) range by the ON the and OFF control of a switch, a band is made variable by the digital control from an external part. Thus, a variable band filter having an arbitrary integer-fold band of a basic band width can be realized in the 1-2 -fold wide range by the digital control of an (n) bit, a non-linear distortion does not occur even due to a large amplitude action and the temperature or the change with the passage of time can be stabilized.

公开(公告)号：JPS6424620A

公开(公告)日：1989-01-26

申请号：JP18173587

申请日：1987-07-21

Applicant: NEC CORP

Inventor： ICHIYOSHI OSAMU

IPC: H03H17/06 ,  H03H17/02

Abstract: PURPOSE:To form a substantially stable digital chirp filter by providing a 1st stage FIR sub filter, plural sets of 2nd stage FIR sub filters, plural multipliers multiplying a prescribed complex coefficient, a delay device and an adder. CONSTITUTION:The titled filter is constituted by employing mainly the 1st stage sub filter 1' used in common, and plural sets of 2nd stage sub filters 1'', 1'', 1'' being specific sub filters. Moreover, the basic filter 25 is of a specific form of filter. Then the 1st stage sub filter 1, is the FIR filter whose odd number order is zero and an M/2-tap filter whose basic delay is used as M-sample. Moreover, the 2nd stage sub filter 1'' is a FIR filter whose even order number is zero and M/2-1 tap filter without the order of 2m. Since the sub filter is constituted of the FIR filter capable of responding in a definite time, the substantially stable digital chirp filter is formed.

公开(公告)号：JPS63276927A

公开(公告)日：1988-11-15

申请号：JP9856287

申请日：1987-04-23

Applicant: NEC CORP

Inventor： ICHIYOSHI OSAMU

IPC: H04B7/15 ,  H04B7/185 ,  H04B7/204 ,  H04J3/00

Abstract: PURPOSE:To prevent the interruption between channels due to clock phase error of a channel by providing a trans-multiplexer branching circuit, a signal insertion/demodulation circuit and a time multiplex circuit in reproducing a signal on a satellite. CONSTITUTION:A satellite 9 applies processing to a signal subject to SCPC digital modulation and FDM multiplex from plural earth stations 10 as described below. The trans-multiplexer type branching circuit 4 applies the FDM demultiplex based on a TDM clock. Then a signal interpolation/demodulation circuit 5 calculates the signal interpolation of a TDM clock timing depending on the phase difference between FDM and TDM clocks, applies data reproduction therewith, averages and detects the phase error between the transmission clock and the TDM of each earth station from the reproduced data and gives the result. A time multiplex circuit 6 applies time division multiplex to a demodulation signal of each channel from the circuit 5 and modulates a common carrier on the satellite at a modulation circuit 7 by using the signal and the result is sent. Consequently, the production of interference between channels is prevented and safe communication is attained.

公开(公告)号：JPS63212232A

公开(公告)日：1988-09-05

申请号：JP4608787

申请日：1987-02-28

Applicant: NEC CORP ,  NIPPON TELEGRAPH & TELEPHONE

Inventor： ICHIYOSHI OSAMU ,  KAWAMURA HIROTSUGU ,  KORI TAKEJI ,  MORIKURA MASAHIRO

IPC: H04J1/05 ,  H04J3/00

Abstract: PURPOSE:To reduce remarkably the fluctuation of a timewise position of an output signal by varying a clock frequency of a clock oscillator so as to match a chirp rate of a chirp signal and a chirp rate of a chirp filter thereby interfer ence between channels. CONSTITUTION:Chirp signal generating sections 4, 5 and a control section com prising a counter 24 and a clock oscillator 10 are provided. In varying the clock frequency of the clock oscillator 10, chirp signals 2, 3 are expanded/ contracted on the time axis to change the chirp rate by the clock frequency. As a result, the chirp rate of the chirp signals 2, 3 and the chirp rate of the chirp filter 14 are matched, the reduction in the peak of the output signal of the chirp filter is prevented to eliminate the interference between channels. Moreover, the carrier frequency of the chirp signals 2, 3 is adjusted to compen sate for various characteristics of the chirp filter against temperature change or secular change, then the timewise fluctuation of the output signal of the chirp filter is reduced considerably.

公开(公告)号：JPS6360638A

公开(公告)日：1988-03-16

申请号：JP20265586

申请日：1986-08-30

Applicant: NEC CORP

Inventor： ICHIYOSHI OSAMU

IPC: H04J11/00

Abstract: PURPOSE:To obtain a stable demodulation circuit even for a modulation signal having a large multi-level by providing n-set of 1st branching devices, interference wave cancelling circuits and 2nd branching devices corresponding to n-set of analog base band signal outputs being demodulator outputs so as to process the signals. CONSTITUTION:An m-value (M=2 ) of multi-value modulation signal is inputted to a demodulator 1 having a synchronism detection function and a clock recovery function and n-set of analog base band signals are outputted from the demodulator 1. The n-set of output signals from the demodulator 1 are inputted to n-set of branch devices 2-1-2-n. A 1st output among the outputs of the branching devices 2-1-2-n is inputted to a desired wave input terminal X of corresponding interference wave cancelling circuits 3-1-3-n and a 2nd-n-th outputs are inputted to interference wave input terminals Y1-Yn-1 of the (n-1) sets of the interference wave cancelling circuits except the corresponding circuits 3-1-3-n. The output of the circuits 3-1-3-n is inputted respectively corresponding n-branching devices 4-1-4-n. The output of them is outputted externally and the 2nd-n-th outputs are inputted to an interference wave reference signal input terminal of the interference wave cancelling circuit other than the corresponding cancelling circuit to cancel the mutual interference.

公开(公告)号：JPS58186250A

公开(公告)日：1983-10-31

申请号：JP6805782

申请日：1982-04-24

Applicant: Nec Corp

Inventor： ICHIYOSHI OSAMU

IPC: H04L27/227

CPC classification number: H04L27/227

Abstract: PURPOSE:To reproduce a CW signal with high SN ratio surely even under a low C/N condition, by controlling the frequency and the band width of a band pass filter. CONSTITUTION:An AFC is formed with a closed loop comprising a band pass filter BPF 11, a limiter 12, a pi/2 phase shifter 13, a mixer 16, a low pass filter LPF 17 and a DC amplifier 18, and an AQC is formed with the said AFC circuit, square detectors 14, 19, LPFs 15, 20, a differential voltage detector 21 and a DC amplifer 22. If the initial frequency error exists, since the Q of the BPF 11 is decreased with the AQC operation, an output V18 of the DC amplifier 18 is increased and omegae is reduced with the operation of the AFC. Simultaneously, the Q of the BPF 11 is increased with the AQC loop, resulting the increment of the gain of AFC loop and the further decrease of omegae and the control of the BPF 11 is established rapidly. In this state, the detection of the CW signal is executed (omegae=omegai-omegao, where omegai= angular frequency of intermediate frequency, omegao= tuning angular frequency of BPF 11).

Abstract translation: 目的：通过控制带通滤波器的频率和带宽，即使在低C / N条件下，也可以确保高SN比的CW信号。 构成：AFC形成有闭环，包括带通滤波器BPF 11，限幅器12，pi / 2移相器13，混频器16，低通滤波器LPF 17和DC放大器18，AQC是 由所述AFC电路，方波检测器14,19，LPF 15,20，差分电压检测器21和DC放大器22形成。如果存在初始频率误差，由于BPF 11的Q随着AQC操作而减小， DC放大器18的输出V18增加，并且随着AFC的操作而减少了ωarg。 同时，随着AQC循环，BPF 11的Q增加，导致AFC循环的增益增加，并且ωF的进一步减少和BPF 11的控制被迅速建立。 在这种状态下，执行CW信号的检测（omega = omegai-omegao，其中omegai =中频角频率，ωgao= BPF11的调谐角频率）。