JP2006261813A - Receiving method in moving object and receiver - Google Patents

Receiving method in moving object and receiver Download PDF

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Publication number
JP2006261813A
JP2006261813A JP2005073541A JP2005073541A JP2006261813A JP 2006261813 A JP2006261813 A JP 2006261813A JP 2005073541 A JP2005073541 A JP 2005073541A JP 2005073541 A JP2005073541 A JP 2005073541A JP 2006261813 A JP2006261813 A JP 2006261813A
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gt
sb
antennas
antenna
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JP2005073541A
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Japanese (ja)
Inventor
Tomoyasu Harada
Kenji Ito
Noburo Ito
Katsushi Mita
勝史 三田
修朗 伊藤
健二 伊藤
知育 原田
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Toyota Central Res & Dev Lab Inc
株式会社豊田中央研究所
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Abstract

<P>PROBLEM TO BE SOLVED: To compensate the Doppler shift of a plurality of arriving waves in a receiver for a moving object. <P>SOLUTION: Two antennas are fixed on a moving object so that a line connecting the antennas is parallel to a moving direction of the object, and a signal to be received by a fixed pseudo antenna virtually fixed in a space is calculated by synthesis from received waves of the antennas. If it is assumed that the fixed pseudo antenna is formed at a position of a distance x<SB>0</SB>from an antenna A<SB>F</SB>which is a previously set position between antennas A<SB>F</SB>and A<SB>B</SB>, a relative position I(t) of the fixed pseudo antenna with respect to the moving object is x<SB>0</SB>+∫v(t)dt for a velocity v(t). A reception signal S<SB>S</SB>in the fixed pseudo antenna at the relative position I(t) is obtained by S<SB>S</SB>=[äd-I(t)}S<SB>F</SB>+I(t)S<SB>B</SB>]/d from a reception signal S<SB>F</SB>of the antenna A<SB>F</SB>at a position 0 and a reception signal S<SB>B</SB>of the antenna A<SB>B</SB>at a position d. Thus, a signal in which the Doppler shift of a reception signal generated from the velocity of the moving object is compensated can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a receiving method and a receiving apparatus in a moving body. INDUSTRIAL APPLICABILITY The present invention is effective as a receiving method and a receiving apparatus in a mobile body in a receiving environment that receives one or more delayed waves in addition to a direct wave.

In mobile reception, Doppler frequency deviation (hereinafter simply referred to as Doppler shift) occurs. In the case where only the direct wave is mobilely received, it is possible to compensate for the Doppler frequency deviation and demodulate normally by providing the local transmission circuit with an automatic frequency adjustment function.
Shiomi Masaru, "Wave Summit Course Digital Broadcasting", Ohmsha, 1998, p. 144

  Now, in the reception environment that receives one or more delayed waves in addition to the direct wave, it is possible to receive a plurality of received waves with different Doppler shifts. The bit error rate is degraded.

  The inventors of the present invention diligently studied diversity reception in a mobile receiver and conceived that compensation of Doppler shift is easily performed from signals received by two antennas, thereby completing the present invention.

  In order to solve the above-mentioned problem, according to the means described in claim 1, it is a reception method used for a moving body, and is provided so that a line connecting them is parallel to the main moving direction of the moving body. The signal to be received by the pseudo fixed antenna between the two antennas and virtually fixed in space is synthesized from the received signals of the two antennas fixed to the mobile body and moving together with the mobile body. By calculating and demodulating from the combined signal, demodulation with compensated Doppler frequency shift is performed.

  According to a second aspect of the present invention, a plurality of pseudo fixed antennas are formed between two antennas, and after demodulating them, demodulation is performed. According to the third aspect of the present invention, there are provided a plurality of sets of two antennas for forming a pseudo fixed antenna, and demodulation is performed after diversity combining of the formed pseudo fixed antenna is performed. Features.

  According to a fourth aspect of the present invention, an OFDM modulated signal having a guard interval is received, and the position of the pseudo fixed antenna can be changed for each symbol.

  According to the means described in claim 5, the receiving device is used for a moving body, and is fixed to the moving body provided such that a line connecting them is parallel to the main moving direction of the moving body. From the two antennas that move with the moving body and the signals of the two antennas, a signal to be received by the pseudo-fixed antenna between the two antennas and virtually fixed in space is calculated by synthesis And demodulating the output signal from the pseudo-fixed antenna forming unit so as to compensate for the Doppler frequency shift.

When the straight line connecting the two antennas is fixed to the moving body in parallel with the moving direction of the moving body, the received waves of those antennas are received by the pseudo fixed antenna virtually fixed in space. The power signal can be calculated by synthesis. Thereby, it is possible to obtain a signal that compensates for the Doppler shift of the received signal caused by the speed of the moving body. That is, FIG. A and FIG. Like B, the two antennas A F and A B moving with the moving body of the velocity v cause a Doppler shift when receiving the high frequency RF. However, the reception signal at the pseudo fixed antenna A I can be calculated from the reception signals of the two antennas A F and A B based on the time t and the speed v. It is also possible to calculate a signal to be received by combining a plurality of pseudo fixed antennas between two antennas. This will be described below using mathematical expressions.

Two antennas are arranged so that the straight line connecting them is parallel to the main moving direction of the moving body, the received signal of the antenna A F on the moving direction side of the moving body is S F , and the received signal of the antenna A B on the opposite side Let the signal be S B. Also, a signal of frequency f is received from the front of the moving body, the speed of light is c, the imaginary unit is j, and the time is t. Also, let d be the distance between the two antennas A F and A B. Hereinafter, the mathematical expression is expanded in a complex display.

First, when the moving body is stopped, representing the S F and S B as the following equation (1-1) of formula (1-2). It is assumed that signals having the same waveform other than the phase difference due to the distance d arrive at the two antennas.

Moving body and starts moving at a velocity v toward the arrival direction of the received wave, S F and S B is the following equations (2-1) and (2-2).

Now, the position of the antenna on the moving direction side when t = 0 is virtually fixed to form a pseudo fixed antenna. The line segment connecting the antenna A F and the antenna A B at time t vt: points obtained by internally dividing by (d-vt) is the position of the pseudo-fixed antenna. So are two signals, and S B of the formula (2-1) S F and formula (2-2), vt: (d -vt) signal S S of points obtained by internally dividing the following formula ( Interpolation can be performed as in 3). fv / c is the Doppler shift.

Here, when the inside of the second curly bracket on the last side of the equation (3) is transformed, the following equation (4) is obtained.

Substituting equation (4) into equation (3) yields equation (5).

Equation (5) matches equation (1). That is, the moving body, when moving at speed v towards the direction of arrival of the received wave, the received signal S B of the received signal S F and the antenna A B of the two antennas A F disposed spaced distance d Is weighted average with 1- (vt / d) and vt / d, a received signal of the pseudo virtual antenna virtually fixed at the position of the antenna AF at time t = 0 is obtained, and the Doppler shift is compensated. Can do.

It can be easily understood that this can be set at an arbitrary position between the antennas A F and A B at time t = 0. In fact, 1-k- (vt / d ) and k + (vt / d) Weighted Averaging, the signal for the position near kd from antenna A F antenna A B-side at time t = 0 and the position of the pseudo-virtual antenna Aexp2πfj {t− (kd / c)} can be obtained. It should be noted that the present invention is effective as long as the approximation of the first side and the final side of Equation (4) is established. In this sense, the present invention is established not only for the internal dividing point but also for the external dividing point.

When the arrival direction of the received wave is different from the moving direction of the moving body, each of the vector from the moving body to the transmission point (or the final reflection point) and the moving direction vector is θ, and v If d and d are all replaced by v cos θ and d cos θ, the same holds true. Note that ω D = 2πfv cos θ / c. At this time, it is assumed that the distance from the moving body to the transmission point (or the final reflection point) is sufficiently far, and the same waveform except for the phase difference arrives at the antennas A F and A B at the same angle θ.

  Then, since the Doppler shift caused by the speed of the moving body can be compensated for the received waves from all directions, the present invention can detect the Doppler shift caused by the speed of the moving body for each delayed wave no matter how many delayed waves arrive. Compensation is possible (claims 1 and 5).

  If the distance between the two antennas is such that the approximation of the above formula (4) is established, a plurality of pseudo fixed antennas can be formed between the two antennas. By combining these with diversity, it is possible to obtain a combined signal with high directivity and more emphasized desired wave. In addition, since the signals of the two pseudo fixed antennas can be obtained from the two antennas fixed to the moving body, the antenna is effectively used (claim 2).

  Also, by providing a plurality of sets of two antennas and diversity combining the received waves of a plurality of pseudo-fixed antennas, it is possible to obtain a composite signal with high directivity and more enhanced desired waves (claims) Item 3).

  When receiving an OFDM signal having a guard interval, the position of the pseudo-fixed antenna is switched during the guard interval so that the pseudo-fixed antenna is always placed between the antennas fixed to the two moving bodies that move together with the moving body. (Claim 4).

  FIG. 2 is an oscilloscope diagram showing changes in amplitude when the present invention is applied. FIG. A shows a waveform when a high frequency of 503 MHz is received by a fixed antenna. FIG. B shows the waveform of the received wave when a high frequency of 503 MHz arrives at the antenna moving at 108 km / h from the front and rear. FIG. In B, it can be seen that a Doppler shift of ± 50 Hz occurs in the high frequency of 503 MHz, and a distort of about 100 Hz occurs. In this state, for example, a digital modulation signal having a symbol length of about 1 ms cannot be correctly demodulated. FIG. C shows a signal waveform when the present invention is applied and the formation position of the pseudo fixed antenna is updated for each symbol length of about 1 ms. According to the present invention, it can be understood that the amplitude can be constant in each symbol.

  When the received wave is a product of the intermediate frequency band and the carrier high frequency, the present invention may be applied to the received wave in the intermediate frequency band except for the high frequency. Further, at that time, it is convenient to perform processing with a digital signal. However, ωd / c in Equation (4) is a phase difference between the two antennas at the high frequency. In the case where a plurality of pseudo-fixed antennas are formed between two antennas, the antenna interval d is preferably 0.2 to 0.4 wavelengths of high frequency. If the wavelength exceeds 0.4, the estimation accuracy of the pseudo fixed antenna is deteriorated. If the wavelength is less than 0.2, it is difficult to form a plurality of pseudo fixed antennas between the antennas, and it is difficult to select the positions of the pseudo fixed antennas shown below. The local oscillator circuit is not an automatic frequency adjustment type. When using an auto gain controller (AGC), it is necessary to make sure that the amplification factor is not different between at least two antennas forming a pseudo fixed antenna.

  When receiving an OFDM signal having a guard interval and switching the position of the pseudo fixed antenna, it is desirable not to change the position of the pseudo fixed antenna during the effective symbol length. The position of the pseudo fixed antenna may be changed in the moving direction of the moving body for each effective symbol length.

  There is a method in which the position of the pseudo fixed antenna is changed in the moving direction of the moving body for each effective symbol length, and the relative position of the pseudo fixed antenna with respect to the moving body at the start of the effective symbol is made constant. Very small (null) cases can occur. Therefore, it is desirable to use a method for avoiding null as follows. In either case, a plurality of pseudo-fixed antennas between the antennas are assumed, the average amplitude of the received signal is calculated, and one of the pseudo-fixed antennas is selected.

  The first method of avoiding nulls is to eliminate the update position candidates of the pseudo fixed antenna, and determine the update position from the remaining candidates by eliminating the calculated average amplitude of the received signal that has not reached the predetermined threshold. To do. In this case, the position of the pseudo fixed antenna may not be updated. Even in such a case, it is desirable that the position of the pseudo fixed antenna does not go out between the two antennas fixed to the moving body.

  The second method for avoiding null is to select the update position of the pseudo-fixed antenna that has the maximum average amplitude of the received signal and determine it as the update position. In this case, the frequency with which the position of the pseudo fixed antenna is updated is reduced. Even in such a case, it is desirable that the position of the pseudo-fixed antenna does not go out between the two antennas fixed to the moving body. Further, when forming a plurality of pseudo-fixed antennas, select each of the two preset ranges, or select the second from the candidates that are more than the set distance away from the update position candidate with the maximum amplitude. There are methods such as selecting update position candidates.

FIG. 3 is a block diagram showing the configuration of the mobile receiver 100, which is a specific embodiment of the present invention. The mobile receiver 100 includes two antennas A F and A B , multipliers (down converters) 20F and 20B, variable analog amplifiers 30F and 30B, analog / digital converters (corresponding to them). A / D) 40F and 40B, a local oscillator 10, an auto gain controller (AGC) 30, a quasi-fixed antenna forming unit 110, an orthogonal demodulating unit 51, and a signal processing unit in the subsequent stage (not shown). The two antennas A F and A B are spaced so that the straight line connecting them is parallel to the moving direction of the moving body. The antenna A F on the front side of the moving body, placing the antenna A B behind the antenna A F.

The signal processing in the mobile receiver 100 is as follows. A high frequency of, for example, a 500 MHz band received by the antenna AF is multiplied by a sine wave generated by the local oscillator 10 in a multiplier (down converter) 20F and converted into an intermediate frequency signal (IF). This is amplified by the variable analog amplifier 30F controlled by the AGC 30 and converted into a digital signal by the A / D 40F and input to the pseudo fixed antenna forming unit 110. Received signal just as the antenna A B is also input to the pseudo fixed antenna forming part 110.

The pseudo fixed antenna forming unit 110 generates a reception signal at the pseudo fixed antenna as follows. From the symbol timing, a reception signal of a pseudo fixed antenna having a length of one symbol is generated. At this time, 0 the position of the antenna A F, the position of the antenna A B d Distant at t = 0, a predetermined position between the antennas A F and A B, from the antenna A F of the distance x 0 If the pseudo fixed antenna is formed at the position, the relative position I (t) of the pseudo fixed antenna with respect to the moving body is x 0 + ∫v (t) dt with respect to the speed v (t). The integration is from t = 0 to t = t. Thus, the received signal S S in pseudo fixed antenna relative position I (t), from the received signal S B of the antenna A B of the received signal S F and the position d of the antenna A F position 0, S S = [{ d−I (t)} S F + I (t) S B ] / d. This signal is output to the quadrature demodulator 51 to obtain a digital complex signal and perform subsequent signal processing.

The pseudo fixed antenna forming unit 110 forms a pseudo fixed antenna from the preset position x 0 between the antennas A F and A B for one symbol length at t = 0, and the same at the next symbol timing. The pseudo fixed antenna is formed at the updated position. The following modifications may be used.

FIG. 4 is a block diagram showing a configuration of a mobile receiver 200, which is another specific example of the present invention. The mobile receiver 200 includes two antennas A F and A B , multipliers (down converters) 20F and 20B, variable analog amplifiers 30F and 30B, analog / digital converters (corresponding to them). A / D) 40F and 40B, local oscillator 10, auto gain controller (AGC) 30, pseudo fixed antenna forming unit 120, quadrature demodulating unit 52, diversity combining unit 700, and signal processing unit in the subsequent stage (not shown) Become. The two antennas A F and A B are spaced so that the straight line connecting them is parallel to the moving direction of the moving body. The antenna A F on the front side of the moving body, placing the antenna A B behind the antenna A F.

The pseudo fixed antenna forming unit 120 of the mobile receiver 200 of FIG. 4 is essentially the same as the pseudo fixed antenna forming unit 110 of the mobile receiver 100 of FIG. 3 except that it forms two pseudo fixed antennas. Has equivalent functions. The two pseudo fixed antennas are formed between the antennas A F and A B so that they are always at different positions. In the mobile receiver 200 of FIG. 4, since the reception signals at the two pseudo fixed antennas are output, the quadrature demodulation unit 52 obtains two digital complex signals and performs diversity combining. The configuration of the diversity combining unit 700 can select any of selection diversity, equal gain combining, and maximum ratio combining. It is more preferable to perform a complex correlation operation with the synthesized signal to align the phase of the signal.

FIG. 5 is a block diagram showing a configuration of a mobile receiver 300, which is another specific example of the present invention. The mobile receiver 300 performs diversity combining for two mobile receivers 200 in FIG. The mobile receiver 300 includes two antennas A 1F and A 1B , multipliers (down converters) 21 F and 21 B, variable analog amplifiers 31 F and 31 B, and analog / digital converters (corresponding to them). A / D) 41F and 41B, local oscillator 11, auto gain controller (AGC) 31, pseudo fixed antenna forming unit 121, two antennas A 2F and A 2B provided in the same manner, and corresponding to them Multipliers (down converters) 22F and 22B, variable analog amplifiers 32F and 32B, analog / digital converters (A / D) 42F and 42B, a local oscillator 12, an auto gain controller (AGC) 32, a pseudo A fixed antenna forming portion 122 is included. Further, it includes an orthogonal demodulator 54, a weighting factor calculator 70, complex multipliers 71, 72, 73 and 74, and an adder 80. The two antennas A 1F and A 1B are spaced so that the distance between them is d, and the straight line connecting them is parallel to the moving direction of the moving body. The antenna A 1F is disposed on the front side of the moving body, and the antenna A 1B is disposed on the rear side of the antenna A 1F . Exactly the same, the two antennas A 2F and A 2B are spaced so that the distance between them is d, and the straight line connecting them is parallel to the moving direction of the moving body. The antenna A 2F is disposed on the front side of the moving body, and the antenna A 2B is disposed on the rear side of the antenna A 2F . The relative positions of the antennas A 1F and A 1B and the antennas A 2F and A 2B are arbitrary. For example, the antennas A 1F and A 1B may be arranged on the left side of the moving body, and the antennas A 2F and A 2B may be arranged on the right side. . At this time, the antenna A 1F and the antenna A 2F are preferably placed at a distance longer than one wavelength of the high frequency.

  The mobile receiver 200 in FIG. 4 is diversity combining using two pseudo fixed antennas, whereas the mobile receiver 300 in FIG. 5 is a receiver that performs diversity combining using four pseudo fixed antennas. It is. The weight coefficient calculator 70 performs complex correlation calculation processing on the output of the adder 80 and the four outputs of the orthogonal demodulator 54 to determine complex weights. The adder 80 adds the real part and the imaginary part of the four complex multipliers 71 to 74, respectively, and outputs a complex signal to the subsequent signal processing part.

  FIG. 6 is a block diagram showing a configuration of a mobile receiver 400, which is another specific example of the present invention. The mobile receiver 400 performs band division diversity combining as shown in Japanese Patent Application Laid-Open No. 2004-221808 on the mobile receiver 300 of FIG. The mobile receiver 400 of FIG. 6 is provided with four band division filters 61, 62, 63 and 64 in the subsequent stage of the orthogonal demodulator 54 of the mobile receiver 300 of FIG. It is divided into three bands of Low, Mid, and High-Band. Diversity combining in each of the three bands substantially corresponds to that of mobile receiver 300 in FIG. 5, and in FIG. 6, weighting factor calculator 70 and complex multipliers 71 to 71 that are the diversity combining unit in FIG. 5. 74 and an adder 80, a weight coefficient calculator 70L, a set of complex multipliers 71L to 74L and an adder 80L, a set of weight coefficient calculator 70M, a complex multiplier 71M to 74M and an adder 80M, a weight coefficient calculation Three sets of a set of a multiplier 70H and complex multipliers 71H to 74H and an adder 80H are provided, and these are further added by an adder 90. In the mobile receiver 400 of FIG. 6, complex correlation calculation for calculating a weighting coefficient is executed using the output of the adder 90.

  In the mobile receiver 400 of FIG. 6, the output of the adder 90 is used for the complex correlation calculation for calculating the weighting coefficient. However, as in JP-A-2004-221808, the adders 80L and 80M are used. , 80H may be used in weighting factor calculators 70L, 70M, 70H, respectively, to perform diversity combining, and combined with one of the outputs of adders 80L, 80M, 80H for phase matching. For the combination, it is preferable to calculate a phase coefficient that is a complex number from a complex correlation calculation between one of the outputs of the adders 80L, 80M, and 80H and the other output.

[Modification]
In each of the embodiments described above, the start position of the pseudo fixed antenna is set to a preset position between the two antennas and updated for each symbol. However, the start position candidate of the pseudo fixed antenna is set between the two antennas. It is good also as a structure which sets multiple and selects based on the amplitude of the synthetic | combination signal in the said position. In this case, since the calculation time for the selection is required, it is preferable to apply to an OFDM receiver having a guard interval.

  The present invention is preferably applied to a receiving apparatus provided in a mobile body for receiving terrestrial digital television broadcasting.

The conceptual diagram which shows the outline | summary of this invention. It is an oscilloscope figure which shows the effect of this invention, FIG. A is a received wave at a fixed antenna, FIG. B is the sum of two received waves with Doppler shifts from the front and rear of the moving body, respectively. C is the same as FIG. A synthesized wave obtained by applying the present invention to the received wave of B. The block diagram which shows the structure of the receiver 100 for mobile bodies which is one specific Example of this invention. The block diagram which shows the structure of the receiver 100 for mobile bodies which is one specific Example of this invention. The block diagram which shows the structure of the receiver 100 for mobile bodies which is one specific Example of this invention. The block diagram which shows the structure of the receiver 100 for mobile bodies which is one specific Example of this invention.

Explanation of symbols

100, 200, 300, 400: Mobile receivers A F , A B , A 1F , A 1B , A 2F , A 2B : Antennas 10, 11, 12: Local oscillators 20F, 20B, 21F, 21B, 22F, 22B: Multiplier 30, 31, 32: Auto gain controller (AGC)
30F, 30B, 31F, 31B, 32F, 32B: Variable analog amplifier 40F, 40B, 41F, 41B, 42F, 42B: Analog / digital converter (A / D)
51, 52, 54: Quadrature demodulator 61, 62, 63, 64: Band division filter (3 bands)
70, 70L, 70M, 70H: Weight coefficient calculators 71, 72, 73, 74, 71L, 72L, 73L, 74L, 71M, 72M, 73M, 74M, 71H, 72H, 73H, 74H: Complex multipliers 80L, 80M , 80H, 90: Adder 110, 120, 121, 122: Pseudo fixed antenna forming unit

Claims (5)

  1. A reception method used for a mobile object,
    From the received signals of the two antennas, which are fixed to the moving body and moved together with the moving body, so that the line connecting them is parallel to the main moving direction of the moving body,
    Compensation of Doppler frequency shift by calculating a signal to be received by a pseudo-fixed antenna virtually fixed in space between the two antennas and performing demodulation from the combined signal A receiving method in a moving body, characterized by performing demodulation.
  2. 2. The receiving method according to claim 1, wherein a plurality of the pseudo fixed antennas are formed between the two antennas, and the demodulating is performed after combining the diversity.
  3. 3. The method according to claim 1, wherein a plurality of sets of two antennas for forming the pseudo-fixed antenna are provided, and demodulation is performed after diversity combining of the formed pseudo-fixed antenna is performed. The receiving method in the described moving body.
  4. 4. The reception method according to claim 1, wherein an OFDM modulation signal having a guard interval is received, and the position of the pseudo fixed antenna can be changed for each symbol. 5. .
  5. A receiving device used for a mobile object,
    Two antennas, which are fixed to the moving body and move together with the moving body, so that a line connecting them is parallel to the main moving direction of the moving body;
    A pseudo-fixed antenna forming unit that calculates a signal to be received by a pseudo-fixed antenna between the two antennas and virtually fixed in space from the signals of the two antennas; A receiving apparatus for a moving body, wherein demodulation is performed with demodulation of a Doppler frequency shift compensated by demodulating an output signal of the pseudo-fixed antenna forming unit.
JP2005073541A 2005-03-15 2005-03-15 Receiving method in moving object and receiver Pending JP2006261813A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160174241A1 (en) * 2014-12-16 2016-06-16 New Jersey Institute Of Technology Radio over fiber antenna extender systems and methods for high speed trains

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001211134A (en) * 2000-01-25 2001-08-03 Toyota Central Res & Dev Lab Inc Adaptive reception device
JP2002051095A (en) * 2000-08-01 2002-02-15 Mitsubishi Electric Corp Fading compensator
JP2004112216A (en) * 2002-09-17 2004-04-08 Alps Electric Co Ltd Ofdm receiver
WO2005022777A1 (en) * 2003-09-03 2005-03-10 Koninklijke Philips Electronics N.V. Virtual-antenna receiver

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001211134A (en) * 2000-01-25 2001-08-03 Toyota Central Res & Dev Lab Inc Adaptive reception device
JP2002051095A (en) * 2000-08-01 2002-02-15 Mitsubishi Electric Corp Fading compensator
JP2004112216A (en) * 2002-09-17 2004-04-08 Alps Electric Co Ltd Ofdm receiver
WO2005022777A1 (en) * 2003-09-03 2005-03-10 Koninklijke Philips Electronics N.V. Virtual-antenna receiver

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160174241A1 (en) * 2014-12-16 2016-06-16 New Jersey Institute Of Technology Radio over fiber antenna extender systems and methods for high speed trains
US10292058B2 (en) * 2014-12-16 2019-05-14 New Jersey Institute Of Technology Radio over fiber antenna extender systems and methods for high speed trains

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