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公开(公告)号：JPH0590959A
公开(公告)日：1993-04-09
申请号：JP25073191
申请日：1991-09-30
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
Abstract: PURPOSE:To obtain a carrier recovery circuit providing sure locking even at a required narrow band needing the circuit operated at a very low C/N condition such as mobile body satellite communication. CONSTITUTION:This circuit is provided with a 1st limiter 10 setting an amplitude of a complex signal sample string to 1, a 1st complex multiplier 11 connecting to an output of the 1st limiter, a 1st phase frequency divider 12 connecting to an output of the 1st complex multiplier 11, a 2nd complex multiplier 13, a 2nd limiter 20 and a 1 sample delay device 14 being components of a feedback loop of the 2nd complex multiplier 13, a 2nd phase frequency divider 15 connecting to an output of the 2nd limiter 20, a 3rd limiter connecting to the 3rd complex multiplier 13 multiplying an output of the 1st phase frequency divider 12 and an output of the 2nd phase frequency divider 15, and a 4th complex multiplier 17 using a 1 sample delay device 19 as a component of a feedback loop.
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公开(公告)号：JPH0583314A
公开(公告)日：1993-04-02
申请号：JP23996991
申请日：1991-09-19
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
IPC: H04L27/227 , H04L27/00 , H04L27/22 , H04L27/233
Abstract: PURPOSE:To realize the demodulation circuit suitable for burst operation. CONSTITUTION:A reception signal is subject to quasi-synchronization detection, the result is A/D-converted and demodulated by a digital signal processing. An output of an A/D converter is multiplied by (m) (m is a modulation phase number) and its output is inputted to a 1st tank circuit 11 tuned to 0Hz. On the other hand, an output frequency of a multiplier 7 is shifted in the positive and negative direction by a clock frequency with a complex local clock signal whose frequency is almost equal to a modulation clock frequency and the result is respectively inputted to 2nd and 3rd tank circuits 12,13. Outputs of the 2nd and 3rd tank circuits 12,13 are multiplied respectively by a coefficient (w) and its complex conjugation value, the result is added to an output of the 1st tank circuit and the sum is divided by 1/m to obtain a recovered carrier and it is used for synchronization detection. Thus, burst operation is surely implemented under a low C/N condition.
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公开(公告)号：JPH04315317A
公开(公告)日：1992-11-06
申请号：JP8269791
申请日：1991-04-15
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
Abstract: PURPOSE:To obtain a frequency synthesizer with less phase noise in which the frequency is set in a small step frequency unit. CONSTITUTION:The frequency synthesizer composed of a reference phase generating section A outputting a digital signal while delaying its input by one sample, applying binary sum between the output and a numeral given externally and using it output as the above-mentioned input, and a phase synchronization section B comparing the phase of an output frequency-dividing the output of a voltage controlled oscillator 7 with the phase of the digital output and controlling a voltage controlled oscillator by using the result and obtaining a desired sinusoidal wave from the voltage controlled oscillator 7 implements the frequency division of the output of the voltage controlled oscillator 7 by binary frequency division and implements phase comparison by binary sum. An accurate and small sized mobile object communication equipment is realized by employing a conventional voltage controlled oscillator 7.
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公开(公告)号：JPH04160843A
公开(公告)日：1992-06-04
申请号：JP28575190
申请日：1990-10-25
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
IPC: H04L27/227 , H03L7/099 , H04L7/00 , H04L7/02 , H04L7/027 , H04L7/033 , H04L27/00 , H04L27/22 , H04L27/233
Abstract: PURPOSE:To implement carrier recovery and sample timing recovery independently by reading a weight coefficient from a memory storing coefficients in advance based on timing error information, calculating an FIR filter output and outputting the result externally as a demodulation data. CONSTITUTION:The circuit is provided with a quasi-synchronization detection circuit 2, an A/D converter 3, an M-power complex multiplier 4, digital filter groups 8-10, complex arithmetic circuits 16, 14, an interpolation clock generating circuit 15, a delay device 19, a complex multiplier 6, an interpolation channel filter 18 and a weight coefficient memory 17. Then the interpolation channel filter 18 receiving an output of the weight coefficient memory 17 and outputs the result as a demodulation data. Thus, the carrier recovery and sample timing recovery are implemented independently and burst operation is quickly attained.
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公开(公告)号：JPH03284003A
公开(公告)日：1991-12-13
申请号：JP8546190
申请日：1990-03-30
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
Abstract: PURPOSE:To realize high S/N characteristic by forming a transmission signal with constant amplitude by synthesizing the output of two modulation multipliers at a transmission side, and outputting a signal from the phases of the output of two demodulation multipliers from a reception side to suppress a carrier. CONSTITUTION:The modulation multiplier 2a forms a signal in which a carrier signal is multiplied by a value B of constant level, and inputs it to a synthesizer 5, and obtains the output s'(t). An original sound signal is modulated with a deep modulation factor, and the modulation spectrum of the transmission signal shows the one in which the carrier is suppressed as shown in figure. At a reception side device, a reproducing carrier signal is multiplied by a reception signal r(t) by the demodulation multiplier 11. A demodulation signal d(t) is outputted from a conversion table 12 by receiving the output of the demodulation multiplier 9 and that of the multiplier 11. In other words, a ratio of low frequency component of the output of the multiplier 9 to that of the multiplier 11 is set in advance at the table 12, therefore, the signal d(t) can be immediately obtained. A signal to be modulated includes remarkable amount of distortion components due to the deep modulation factor, however, the distortion component can be eliminated at the table 12, and the original audio signal without generating the distortion can be demodulated and reproduced, which enables an S/N to be improved to the one multiplied by (A/B).
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Patent Agency Ranking
公开(公告)号：JPH03270422A
公开(公告)日：1991-12-02
申请号：JP7098390
申请日：1990-03-20
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
Abstract: PURPOSE:To enable high-performance communication and high-accuracy position measurement by transmitting a received position measuring signal from a geostationary satellite at exactly synchronous timing at the time of GPS(Global Positioning System) standard. CONSTITUTION:GPS satellites (3-1)-(3-6) mount highly stable atomic oscillators and hold the common GPS standard time with high accuracy and synchronously with the GPS standard time, the respective GPS satellites (3-1)-(3-6) transmit the position measuring signals. Functions are added to respective traveling objects so as to directly receive the position measuring signals from the GPS satellites (3-1)-(3-6). Further, in a base station, a means is added to receive the position measuring signals from the GPS satellites, and a means is added to broadcast the received position measuring signals from the geostationary satellites at the timing exactly matched with the GPS standard time together with the track information of the satellites. Consequently, the equivalent same effect can be obtained as the case of increasing the GPS satellites (3-1)-(3-6). Thus, bidirectional communication can be executed through geostationary satellites (4-1) and (4-2) between the base station and each mobile object, and the position measurement can be executed with high accuracy.
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公开(公告)号：JPH0193241A
公开(公告)日：1989-04-12
申请号：JP25108987
申请日：1987-10-05
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
IPC: H04L27/22 , H04L27/227
Abstract: PURPOSE:To attain a fast and sure acquisition of synchronism operation by realizing a demodulation circuit in a base band zone based on an inverse modulation tank limiter method. CONSTITUTION:An input digital modulation signal Vi(t) is supplied commonly to mixers 3a and 3b, and a local oscillator 1 generates a local signal VL(t) with a frequency almost equivalent to that of the carrier of the Vi(t), and supplies it to the mixer 3a and a phase shifter 2. The phase shifter 2 performs phase shift of pi/2 on the phase of the VL(t), and supplies it to the mixer 3b. The Vi(t) is frequency-converted to a complex modulation signal Wi(t) in the base band zone. At this time, the mixer 3a forms a real part signal and the mixer 3b forms an imaginary part signal. At a base band limiter circuit, an amplitude stabilizing processing is performed on a signal C(t), and it is supplied to a complex multiplier 6 as a reproducing carrier WL(t). In such a way, it is possible to always attain synchronization, and to perform the fast acquisition operation.
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公开(公告)号：JPS6488270A
公开(公告)日：1989-04-03
申请号：JP24628687
申请日：1987-09-30
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
Abstract: PURPOSE:To enable the execution of tracking by a very simple circuit construction, by receiving beacon waves of a plurality of geostationary satellites by means of one antenna. CONSTITUTION:A moving body 2 is equipped basically with an antenna device 3 comprising one antenna 3a and a control means to drive and control this antenna, a beacon power detector 6 detecting the power of a beacon signal delivered by a geostationary satellite 1-1 out of the outputs of a down converter 5, a beacon power detector 7 detecting the power of a beacon signal delivered by a geostationary satellite 1-3 out of said outputs, and a comparator 8 receiving the outputs of the two detectors 6 and 7 and delivering to the device 3a control signal for making the device control the direction of the antenna 3a. The powers of the respective beacon signals of the satellites 1-1 and 1-3 received by the antenna 3a are measured by the detectors 6 and 7 respectively, the results of measurement are compared with each other by the comparator 8, and a directional error of the antenna 3a is detected therefrom. Based on the result of detection, the antenna 3a is controlled so that it be directed to a geostationary satellite 1-2.
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公开(公告)号：JPS6465474A
公开(公告)日：1989-03-10
申请号：JP22158987
申请日：1987-09-04
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
Abstract: PURPOSE:To enable sound volume communication and data communication by inserting a pilot signal into one frequency channel and sending it back by a normal single carrier per channel-frequency division multiple access system. CONSTITUTION:When the need for position measurement is generated on the side of a moving body 20, the moving body 20 sends a request for the position measurement to a base station 30 and a moving terminal 20-7 varies and sets the contents of commands (a) and (b). Then a signal received over a pilot channel ChP is passed to the communication frequency channel of its station and sent back to the base station 30. The base station receives it by base station antennas 3-1 and 3-2 and a base station terminal 30-11 detects the signal of the frequency channel and supplies it to a position measurement arithmetic part 30-10. The arithmetic part 30-10 calculates the distances between the moving body 20 and communication satellites 1-1 and 1-2 from the time difference between two outputs of the terminals 30-11 and the transmission timing of the pilot signal to determine the position of the moving body 20 by a trigonometric measuring method, and sends the result to the terminal 30-11; and the position measurement result is sent to the moving body 20 and inputted to a terminal 20-7.
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公开(公告)号：JPS6465472A
公开(公告)日：1989-03-10
申请号：JP22158887
申请日：1987-09-04
Applicant: NEC CORP
Inventor： ICHIYOSHI OSAMU
Abstract: PURPOSE:To measure the position of an optional number of moving bodies instantaneously by utilizing M(M>=3) stationary satellites and using M kinds of frequencies for position measurement. CONSTITUTION:A base station 4 sends out three kinds of sent signals generated by a base station transmission and reception processing part 44 to high-frequency parts 42a-42c through modulation and demodulation parts 43a-43C at a common repetitive period. The high-frequency parts 42a-42c convert them into high-frequency signals of different prescribed frequencies to excite high- directivity antennas 41a-41c are sent out to the stationary satellites 1-3, and the signal repeated by the satellites 1-3 are sent to an optional moving body in broadcasting mode. Then the moving body 5 receives the radio waves from the satellites 1-3 by its antenna 51 and inputs them to a moving body reception processing part 55 through a high frequency part 52, a branching filter part 53, and demodulation parts 54a-54c. Then the processing part 55 extracts time information, etc., from the three regenerated signals, detects their mutual propagation time differences, and specifies the position by a trigonometric measuring method.
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