JP2008271452A - Receiving antenna direction adjusting method, and fpu transmitting/receiving device employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an FPU (field pick-up unit) transmitting/receiving device which is capable of adjusting the direction of a receiving antenna by performing CN estimation of an input signal of a noise level or lower. <P>SOLUTION: A signal input from an antenna is converted into an intermediate frequency by a frequency change section 21 and converted into a baseband by a quadrature demodulation section 22. The signal converted into the baseband is subjected to FFT processing by an FFT section 23 and then subjected to demodulation processing by a demodulation section 25 by a pilot signal calculated at a pilot demodulation section 24. A demodulation error calculation section 26 averages input demodulated data to determine a fixed pattern, specifies a transmitter 1, and computes a demodulation error. A direction adjustment auxiliary signal calculation section 27 calculates the auxiliary signal for adjusting the direction of a receiving antenna 20 on the basis of the input level of a receiver 2 detected by an input level detection section 28 and the demodulation error. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a receiving antenna direction adjusting method and an FPU transmitting / receiving apparatus using the same, and more particularly to a receiving antenna direction adjusting method in a transmitting / receiving apparatus using an OFDM (Orthogonal Frequency Division Multiplexing) scheme.

  The above-described OFDM method is employed as a transmission method of an FPU (Field Pick-up Unit) transmission / reception device that wirelessly transmits video at a relay site to a broadcasting station, and is used for fixed wireless relay and mobile wireless relay.

  In the conventional method for adjusting the direction of the receiving antenna, a method is adopted in which the received electric field level is detected by a detector on the receiving side, the direction in which the received electric field level is maximized is searched, and the direction of the antenna is adjusted.

  However, when the received electric field level is lowered, the received signal is buried in noise, and accurate detection is difficult. In other words, at the initial stage of the direction adjustment of the receiving antenna, the received electric field level is very low, so even if the received signal has reached even a little, the received signal buried in noise cannot be captured, and the direction adjustment is done by groping Must be performed (see, for example, Patent Document 1).

  On the other hand, since digital transmission is adopted for material transmission in broadcasting stations, operation with an electric field near the noise level of the receiver is possible. In the case of a line in which only a level about several dB higher than the noise level is input after adjusting the direction of the receiving antenna, it is assumed that the received signal is lower than the noise level of the receiver at the time of initial supplementation at the start of operation.

JP 2006-086855 A

  Therefore, in the conventional method of adjusting the direction of the receiving antenna, in the case of the electric field tracking method, the change in the region below the noise level of the received signal cannot be expressed, and therefore the direction of the receiving antenna cannot be adjusted. There is.

  Accordingly, an object of the present invention is to solve the above-described problems, perform CN (Carrier to Noise ratio) estimation of an input signal below a noise level, and adjust the direction of the receiving antenna. A method and an FPU transmitting / receiving apparatus using the method are provided.

A receiving antenna direction adjusting method according to the present invention is a receiving antenna direction adjusting method used for an FPU (Field Pick-up Unit) transmitter / receiver of an OFDM (Orthogonal Frequency Division Multiplexing) system,
On the receiving side of the FPU transmission / reception apparatus, a process of estimating a received CN (Carrier to Noise ratio) from a reception constellation, and a process of outputting an auxiliary signal for adjusting the direction of the receiving antenna based on the estimation result Running.

Another receiving antenna direction adjusting method according to the present invention is a receiving antenna direction adjusting method used for an FPU (Field Pick-up Unit) transmitter / receiver of an OFDM (Orthogonal Frequency Division Multiplexing) system,
On the receiving side of the FPU transceiver, an input level detection process for detecting an input level of an input signal, a pilot signal demodulation process for demodulating a pilot signal from the input signal, and a basis of the demodulated pilot signal A demodulating process for demodulating the input signal, a transmitting side specifying process for determining a transmitting side by performing an averaging process on the demodulated demodulated data to determine a transmitting side specific pattern, and Based on a demodulation error calculation process for calculating a demodulation error for an ideal demodulation point based on a determination result, an input level detected in the input level detection process, and a demodulation error calculated in the demodulation error calculation process A direction adjustment auxiliary signal calculation process for calculating an auxiliary signal for direction adjustment of the receiving antenna is executed.

An FPU transmitter / receiver according to the present invention is an OFDM (Orthogonal Frequency Division Multiplexing) FPU (Field Pick-up Unit) transmitter / receiver,
The receiving side includes means for estimating a received CN (Carrier to Noise ratio) from the received constellation and means for outputting an auxiliary signal for adjusting the direction of the receiving antenna based on the estimation result.

Another FPU transmission / reception apparatus according to the present invention is an OFDM (Orthogonal Frequency Division Multiplexing) FPU (Field Pick-up Unit) transmission / reception apparatus,
On the receiving side, input level detecting means for detecting an input level of the input signal, pilot signal demodulating means for demodulating a pilot signal from the input signal, and the input based on the demodulated pilot signal Demodulating means for demodulating the signal, transmitting side specifying means for determining the transmission side by performing averaging processing on the demodulated demodulated data to determine the transmitting side, and based on the determination result Demodulation error calculation means for calculating a demodulation error for an ideal demodulation point, direction adjustment of the receiving antenna based on the input level detected by the input level detection means and the demodulation error calculated by the demodulation error calculation means Direction adjusting auxiliary signal calculating means for calculating auxiliary signals for

  In other words, the receiving antenna direction adjustment method of the present invention is based on an OFDM (Orthogonal Frequency Division Multiplexing) FPU (Field Pick-up Unit) transmitter / receiver that receives CN (Carrier to Noise Ratio) from a received constellation. ) Is output, an auxiliary signal for adjusting the direction of the receiving antenna in a low electric field such that the received power is equal to or lower than the noise level of the receiver is output.

  Also, the receiving antenna direction adjustment method of the present invention is such that an OFDM FPU transmission / reception apparatus transmits a symbol having a predetermined pattern on the transmitting side, and thereby determines the transmitter on the receiving side based on the pattern. It is characterized by doing.

  More specifically, in the receiving antenna direction adjustment method of the present invention, in the OFDM FPU transceiver apparatus, on the transmission side, the transmission path coded data, the pilot signal generated by the pilot signal generator, and the fixed A pattern unique to each transmission side generated by the generation pattern generator is multiplexed and transmitted to the antenna.

  In the receiving antenna direction adjusting method according to the present invention, on the receiving side, a signal input from an antenna is demodulated by a demodulating unit using a pilot signal calculated by a pilot demodulating unit. The demodulated data demodulated by the demodulating unit is averaged by the demodulation error calculating unit, the transmission side specific pattern is determined, the transmitting side is specified, and the demodulation error is calculated. On the receiving side, based on the receiving side input level detected by the input level detecting unit and the demodulation error calculated by the demodulation error calculating unit, the direction adjustment auxiliary signal calculating unit is used to adjust the direction of the receiving antenna. An auxiliary signal is calculated.

  In the demodulation error calculation unit, the demodulated data demodulated by the demodulation unit is subjected to averaging processing in units of OFDM symbols in the averaging unit, and a fixed pattern determination unit determines a unique pattern on the transmission side. Accordingly, in the receiving antenna direction adjustment method of the present invention, CN (Carrier to Noise ratio) is performed by performing an averaging process on a symbol-by-symbol basis using the fact that symbols having a transmission-side specific pattern are transmitted from the transmission side. ) Is 0 dB or less, it is possible to extract a transmission-specific pattern.

  In the demodulation error calculation unit, a fixed pattern generation unit generates a unique pattern on the transmission side based on the determination result of the fixed pattern determination unit, and the coordinate conversion unit demodulates the demodulated signal in the demodulation unit. Coordinate conversion is performed based on the data and the transmission side specific pattern generated by the fixed pattern generation unit, and the reception constellation is collected at one point. Further, in the demodulation error calculation unit, the demodulation error calculation unit calculates an error vector from the ideal demodulation point, and estimates the CN of the input signal on the reception side. Thus, in the receiving antenna direction adjustment method of the present invention, it is possible to calculate a CN of 0 dB or less by aggregating the reception constellation at one point in the coordinate conversion unit.

  On the other hand, in the receiving antenna direction adjustment method of the present invention, video transmission is performed by calculating a demodulation error of a pilot signal demodulated by a pilot demodulating unit without transmitting a predetermined symbol on the transmitting side. However, CN estimation below the noise level is possible.

  As described above, according to the receiving antenna direction adjustment method of the present invention, it is possible to perform CN estimation of an input signal having a noise level or lower, and it is possible to determine the transmission side even for an input signal having a noise level or lower.

  The present invention is configured and operated as described above, so that it is possible to perform CN estimation of an input signal having a noise level or less and to adjust the direction of the receiving antenna.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of communication by an FPU (Field Pick-up Unit) transmitter / receiver of an OFDM (Orthogonal Frequency Division Multiplexing) system according to an embodiment of the present invention. In FIG. 1, FPU transmission / reception apparatuses A and B according to an embodiment of the present invention are composed of transmitters 1a and 1b and receivers 2a and 2b, respectively.

  Although FIG. 1 shows communication between the FPU transmitting / receiving apparatuses A and B including the transmitters 1a and 1b and the receivers 2a and 2b, the processing described later also applies when only one of the transmitters or only the receivers is used. However, the present invention is not limited to this. The transmitters 1a and 1b have the same configuration and operation, and the receivers 2a and 2b have the same configuration and operation. In the following description, communication from the transmitter 1a to the receiver 2b will be described as a transmitter 1 and a receiver 2, respectively.

  FIG. 2 is a block diagram showing a configuration example of a transmitter of the FPU transmission / reception apparatus according to an embodiment of the present invention. In FIG. 2, the transmitter 1 includes a transmission antenna 10, a transmission path encoding unit 11, a pilot signal generator 12, a fixed pattern generator 13, a framing unit 14, and an IFFT (Inverse Fast Fourier Transform). (Fourier transform) unit 15, quadrature modulation unit 16, and frequency conversion unit 17.

  FIG. 3 is a block diagram showing a configuration example of a receiver of the FPU transmitting / receiving apparatus according to one embodiment of the present invention. In FIG. 3, the receiver 2 includes a reception antenna 20, a frequency conversion unit 21, an orthogonal demodulation unit 22, an FFT (Fast Fourier Transform) unit 23, a pilot demodulation unit 24, a demodulation unit 25, , A demodulation error calculation unit 26, a direction adjustment auxiliary signal calculation unit 27, and an input level detection unit 28.

  The circuit operation of the FPU transmitting / receiving apparatus according to an embodiment of the present invention will be described with reference to FIGS. First, the circuit operation of the transmitter 1 will be described with reference to FIG.

  The transmission path encoding unit 11 performs processing such as error correction. The framing unit 14 multiplexes the transmission path encoded data, the pilot signal generated by the pilot signal generator 12, and the pattern unique to each transmitter generated by the fixed generation pattern generator 13.

  The data after framing by the framing unit 14 is subjected to IFFT processing by the IFFT unit 15, then orthogonally modulated by the orthogonal modulation unit 16 and converted to an intermediate frequency, and then RF (Radio Frequency) by the frequency conversion unit 17. After being converted to frequency, it is transmitted to the antenna.

  Next, the circuit operation of the receiver 2 will be described with reference to FIG. A signal input from the antenna is converted to an intermediate frequency by the frequency changing unit 21 and converted to a baseband by the orthogonal demodulating unit 22. The pilot demodulator 24 demodulates the pilot signal from the input signal. The signal converted to baseband by the orthogonal demodulator 22 is subjected to FFT processing by the FFT unit 23, and then demodulated by the demodulator 25 using the pilot signal demodulated by the pilot demodulator 24.

  The demodulation error calculator 26 averages the demodulated data input from the demodulator 25 to determine the transmitter-specific pattern, identifies the transmitter 1, and calculates the demodulation error for the ideal demodulation point. Do. The direction adjustment auxiliary signal calculation unit 27 adjusts the direction of the receiving antenna 20 based on the input level of the receiver 2 detected by the input level detection unit 28 and the demodulation error calculated by the demodulation error calculation unit 26. Calculate the auxiliary signal.

  4 is a block diagram showing a configuration example of the demodulation error calculation unit 26 in FIG. 3, FIG. 5 is a flowchart showing the operation of the demodulation error calculation unit 26 in FIG. 4, and FIG. 6 is a coordinate conversion unit 264 in FIG. FIG. The operation of the demodulation error calculator 26 will be described with reference to FIGS.

  In FIG. 4, the demodulation error calculation unit 26 includes an averaging unit 261, a fixed pattern determination unit 262, a fixed pattern generation unit 263, a coordinate conversion unit 264, and a demodulation error calculation unit 265.

  The demodulated data input from the demodulating unit 25 is subjected to averaging processing in units of OFDM symbols in the averaging unit 261 (step S1 in FIG. 5), and the fixed pattern determining unit 262 determines a transmitter-specific pattern. (Step S2 in FIG. 5).

  In this embodiment, by utilizing the fact that a transmitter-specific pattern symbol is transmitted from the transmitter 1 side and performing an averaging process in symbol units, CN (Carrier to Noise ratio) is 0 dB or less. However, it is possible to extract a transmitter-specific pattern.

  In this case, since the pattern unique to the transmitter is a fixed pattern with a symbol period, an averaging process with a signal delayed by one symbol is possible. The longer the averaging processing time is, the longer noise components are averaged and their values approach 0, so that correct signal components can be extracted, and synchronization can be achieved even when CN is 0 dB or less. It becomes.

  The fixed pattern generation unit 263 generates a transmitter-specific pattern based on the determination result (specific result of the transmitter 1) of the fixed pattern determination unit 262 (step S3 in FIG. 5). The coordinate conversion unit 264 performs coordinate conversion based on the demodulated data input from the demodulation unit 25 and the transmitter-specific pattern generated by the fixed pattern generation unit 263, and performs reception constellation as shown in FIG. The data are collected at one point (step S4 in FIG. 5).

  Here, the waveform of the received signal superimposed on the time axis is an eye pattern, but the I signal of the PSK (Phase Shift Keying) signal is added to the horizontal axis of the oscilloscope, and the Q signal is added to the vertical axis. When accumulation of level fluctuations is displayed, signals are collected and displayed in a specific part (see FIG. 6). What is displayed in this way is called a constellation.

  The demodulation error calculation unit 265 calculates an error vector from the ideal demodulation point (in this case, the error vector is calculated only with the ideal point on the right side of FIG. 6), and estimates the CN of the input signal of the receiver 2 (FIG. 5). Step S5). Since the noise level increases in proportion to the magnitude of the error vector, the magnitude of the error vector and the CN value have a 1: 1 relationship. Therefore, the demodulation error calculation unit 265 estimates the CN of the input signal of the receiver 2 based on the magnitude of the error vector.

  As described above, in the present embodiment, it is possible to calculate a CN of 0 dB or less by consolidating the reception constellation into one point by the coordinate conversion unit 264.

  Further, even if the transmitter 1 does not transmit a symbol having a predetermined pattern specific to the transmitter, by calculating the demodulation error of the pilot signal demodulated by the pilot demodulation unit 24, while performing video transmission, CN estimation below the noise level is possible.

  As described above, in this embodiment, the coordinate conversion unit 264 performs coordinate conversion, so that a more accurate error vector can be calculated. Therefore, CN estimation of an input signal having a noise level or less can be performed. An effect is obtained.

  Further, in this embodiment, the averaging unit 261 performs an averaging process in units of OFDM symbols so that a transmitter-specific pattern transmitted from the transmitter 1 can be demodulated even with an input signal having a noise level or less. Therefore, the effect that the transmitter 1 can be discriminated even with an input signal having a noise level or less is obtained.

It is a block diagram which shows the example of communication of the FPU transmission / reception apparatus of the OFDM system by one Example of this invention. It is a block diagram which shows the structural example of the transmitter of FPU transmission / reception apparatus by one Example of this invention. It is a block diagram which shows the structural example of the receiver of FPU transmission / reception apparatus by one Example of this invention. It is a block diagram which shows the structural example of the demodulation error calculation part of FIG. 5 is a flowchart showing an operation of a demodulation error calculation unit in FIG. It is a figure which shows the input-output signal of the coordinate transformation part of FIG.

Explanation of symbols

1, 1a, 1b Transmitter 2, 2a, 2b Receiver
10 Transmitting antenna
11 Transmission path encoding unit
12 Pilot signal generator
13 Fixed pattern generator
14 Framing part
15 IFFT section
16 Direct modulation unit
17 Frequency converter
21 Frequency converter
22 Quadrature demodulator
23 FFT section
24 Pilot demodulator
25 Demodulator
26 Demodulation error calculator
27 Direction adjustment signal calculator
28 Input level detector
261 Averaging part
262 Fixed pattern determination unit
263 Fixed pattern generator
H.264 coordinate converter
265 Demodulation error calculator
A, B OFDM FPU transceiver

Claims (10)

A receiving antenna direction adjustment method for use in an OFDM (Orthogonal Frequency Division Multiplexing) FPU (Field Pick-up Unit) transceiver device,
On the receiving side of the FPU transmission / reception apparatus, a process of estimating a received CN (Carrier to Noise ratio) from a reception constellation, and a process of outputting an auxiliary signal for adjusting the direction of the receiving antenna based on the estimation result A method for adjusting a direction of a receiving antenna, which is performed.   The receiving antenna direction according to claim 1, wherein the receiving side of the FPU transmitting / receiving apparatus executes a process of determining the transmitting side based on a symbol of a predetermined pattern transmitted from the transmitting side. Adjustment method. A receiving antenna direction adjustment method for use in an OFDM (Orthogonal Frequency Division Multiplexing) FPU (Field Pick-up Unit) transceiver device,
On the receiving side of the FPU transceiver, an input level detection process for detecting an input level of an input signal, a pilot signal demodulation process for demodulating a pilot signal from the input signal, and a basis of the demodulated pilot signal A demodulating process for demodulating the input signal, a transmitting side specifying process for determining a transmitting side by performing an averaging process on the demodulated demodulated data to determine a transmitting side specific pattern, and Based on a demodulation error calculation process for calculating a demodulation error for an ideal demodulation point based on a determination result, an input level detected in the input level detection process, and a demodulation error calculated in the demodulation error calculation process A direction adjustment auxiliary signal calculation process for calculating an auxiliary signal for direction adjustment of the reception antenna is performed. On the transmission side of the FPU transmission / reception apparatus, a coding process for coding transmission data, a pilot signal generated by the transmission line coded data, a pilot signal generator, and a fixed generation pattern generator Transmission processing that multiplexes and transmits the transmission-specific pattern generated by
The receiving antenna direction according to claim 3, wherein, in the transmitting side specifying process, an averaging process is performed on the demodulated data in units of OFDM symbols, and the pattern is determined based on the averaging process result. Adjustment method.   On the receiving side of the FPU transmission / reception apparatus, coordinate conversion is performed based on a pattern generation process that generates the pattern based on the determination result of the transmission side specifying process, and the demodulated data and the pattern generated in the pattern generation process. To convert the received constellation into one point and calculate an error vector for the ideal demodulation point based on the received constellation to estimate the CN (Carrier to Noise ratio) of the input signal 5. The receiving antenna direction adjustment method according to claim 4, wherein the processing is executed. An OFDM (Orthogonal Frequency Division Multiplexing) FPU (Field Pick-up Unit) transceiver device,
The reception side includes means for estimating a received CN (Carrier to Noise ratio) from the reception constellation, and means for outputting an auxiliary signal for adjusting the direction of the reception antenna based on the estimation result. FPU transmission / reception device.   7. The FPU transmission / reception apparatus according to claim 6, further comprising means for determining the transmission side on the reception side based on a predetermined pattern of symbols transmitted from the transmission side. An OFDM (Orthogonal Frequency Division Multiplexing) FPU (Field Pick-up Unit) transceiver device,
On the receiving side, input level detecting means for detecting an input level of the input signal, pilot signal demodulating means for demodulating a pilot signal from the input signal, and the input based on the demodulated pilot signal Demodulating means for demodulating the signal, transmitting side specifying means for determining the transmission side by performing averaging processing on the demodulated demodulated data to determine the transmitting side, and based on the determination result Demodulation error calculation means for calculating a demodulation error for an ideal demodulation point, direction adjustment of the receiving antenna based on the input level detected by the input level detection means and the demodulation error calculated by the demodulation error calculation means A directional adjustment auxiliary signal calculating means for calculating an auxiliary signal for the FPU. On the transmitting side, encoding means for encoding transmission path data, transmission path encoded data, a pilot signal generated by a pilot signal generator, and a transmission generated by a fixed generation pattern generator A transmission means for multiplexing and transmitting the side-specific pattern,
9. The FPU transmitting / receiving apparatus according to claim 8, wherein the transmitting side specifying means performs an averaging process on the demodulated data in units of OFDM symbols, and determines the pattern based on the averaging process result. .   On the receiving side, the pattern generating means for generating the pattern based on the determination result of the transmitting side specifying means, and receiving by performing coordinate conversion based on the demodulated data and the pattern generated by the pattern generating means. A coordinate conversion unit that aggregates the constellation into one point; and a unit that calculates an error vector for an ideal demodulation point based on the received constellation and estimates a CN (Carrier to Noise ratio) of the input signal. The FPU transmitting / receiving apparatus according to claim 9.

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