JP2008252632A - Transmitter and radio transmission system - Google Patents

Transmitter and radio transmission system Download PDF

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JP2008252632A
JP2008252632A JP2007092553A JP2007092553A JP2008252632A JP 2008252632 A JP2008252632 A JP 2008252632A JP 2007092553 A JP2007092553 A JP 2007092553A JP 2007092553 A JP2007092553 A JP 2007092553A JP 2008252632 A JP2008252632 A JP 2008252632A
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signal
transmission
level
pilot signal
pilot
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Kenji Suzuki
賢治 鈴木
Takashi Arakawa
孝 荒川
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Maspro Denkoh Corp
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Maspro Denkoh Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To prevent the original transmission signal from being decoded by the level difference, between the transmission signal and a pilot signal on a receiver side in a transmitter for up-converting the signal imparted to the pilot signal, to the transmission signal and transmitting from a transmitting antenna. <P>SOLUTION: A transmitter 4 up-converts IF signal to transmission signal of microwave band and radio transmits from a transmitting antenna, after adding the pilot signal to IF signal of terrestrial digital television broadcast in a mixer 24. When the level difference between IF signal and pilot signal is large, each signal can be fully separated on the receiver side and IF signal can be decoded. So the transmitter 4 is provided with a signal level detecting section 20 for detecting input level of IF signal, and a signal level control section 22 for controlling attenuation amount of a variable attenuator 16 so that the level difference between IF signal and pilot signal input in the mixer 24 lies within an allowable range, based on the detection result. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、伝送信号にパイロット信号を付与した信号を周波数変換（アップコンバート）することにより送信信号を生成する送信装置、及び、この送信装置を備えた無線伝送システムに関する。   The present invention relates to a transmission apparatus that generates a transmission signal by frequency-converting (up-converting) a signal obtained by adding a pilot signal to a transmission signal, and a radio transmission system including the transmission apparatus.

従来、テレビ放送等の放送信号を遠隔地まで伝送する際には、伝送信号（一般に中間周波信号）をマイクロ波帯（若しくはミリ波帯）に周波数変換（アップコンバート）して送信アンテナから無線送信させる送信装置と、この送信装置からの送信信号を受信アンテナを介して受信し、その受信信号を周波数変換（ダウンコンバート）することにより元の伝送信号を復元する受信装置とが使用される。   Conventionally, when transmitting a broadcast signal such as a television broadcast to a remote location, the transmission signal (generally an intermediate frequency signal) is frequency-converted (up-converted) to a microwave band (or millimeter wave band) and transmitted wirelessly from a transmitting antenna. And a receiving device that receives a transmission signal from the transmitting device via a receiving antenna and performs frequency conversion (down-conversion) on the received signal to restore the original transmission signal.

また、この種の無線伝送システムでは、送信装置にて生成される送信信号は、送信装置側で伝送信号をアップコンバートするのに用いた高周波信号の位相雑音や周波数漂動の影響を受けることから、受信装置側で受信信号を単にダウンコンバートしたのでは、元の伝送信号を正確に復元することができない、といった問題があった。   In this type of wireless transmission system, the transmission signal generated by the transmission device is affected by phase noise and frequency drift of the high-frequency signal used to upconvert the transmission signal on the transmission device side. There is a problem that the original transmission signal cannot be accurately restored if the received signal is simply down-converted on the receiving device side.

そこで、この種の無線伝送システムにおいては、送信装置側では、伝送信号に一定周波数のパイロット信号を付与し、そのパイロット信号を付与した伝送信号をアップコンバートすることにより、送信信号を生成し、受信装置側では、その送信信号を受信してダウンコンバートした受信信号からパイロット信号を抽出し、その抽出したパイロット信号を用いて、元の伝送信号を復元する、といったことも提案されている（例えば、特許文献１、２等参照）。   Therefore, in this type of wireless transmission system, on the transmitting device side, a transmission signal is generated by receiving a pilot signal having a constant frequency, and up-converting the transmission signal to which the pilot signal is added. On the device side, it has also been proposed that a pilot signal is extracted from a reception signal that is down-converted by receiving the transmission signal, and the original transmission signal is restored using the extracted pilot signal (for example, (See Patent Documents 1 and 2).

つまり、この提案の無線伝送システムにおいては、送信装置からの送信信号は、アップコンバートに用いた高周波信号の位相雑音や周波数漂動の影響を受けるものの、その変動成分は、受信装置側で受信信号をダウンコンバートすることにより得られる伝送信号にもパイロット信号にも含まれることから、受信装置側では、ダウンコンバート後のパイロット信号を用いて、ダウンコンバート用の高周波信号若しくはダウンコンバート後の伝送信号を補正することで、変動成分を含まない元の伝送信号を復元するようにしているのである。
特開２０００−１５１５５３号公報 特開２００４−２３５７５８号公報 In other words, in this proposed wireless transmission system, the transmission signal from the transmission device is affected by the phase noise and frequency drift of the high-frequency signal used for up-conversion, but the fluctuation component is received by the reception device side. Therefore, the reception device side uses the pilot signal after down-conversion to convert the high-frequency signal for down-conversion or the transmission signal after down-conversion. By correcting, the original transmission signal that does not include the fluctuation component is restored.
JP 2000-151553 A JP 2004-235758 A

ところで、上記提案の無線伝送システムにおいて、受信装置側でダウンコンバート後の受信信号の中からパイロット信号を抽出する際には、受信信号をパイロット信号と伝送信号とに分離するフィルタが使用されるが、このフィルタにてパイロット信号と伝送信号とを分離する際に、これら各信号にレベル差があると、これら各信号を充分分離できず、各信号が互いに影響しあって、元の伝送信号を正確に復元することができなくなる、といった問題があった。   By the way, in the proposed radio transmission system, when a pilot signal is extracted from the down-converted received signal on the receiving device side, a filter that separates the received signal into a pilot signal and a transmitted signal is used. When the pilot signal and the transmission signal are separated by this filter, if there is a level difference between these signals, these signals cannot be sufficiently separated, and each signal affects each other, and the original transmission signal is changed. There was a problem that it could not be restored accurately.

つまり、伝送信号に付与されるパイロット信号の周波数は、伝送信号に極めて近い周波数に設定されることから、これら各信号にレベル差があると、各信号をフィルタにて分離しても、レベルの低い信号（パイロット信号又は伝送信号）の経路にはレベルの高い信号（伝送信号又はパイロット信号）が漏れだし、その信号純度が低下して、最終的に元の伝
送信号を正確に復元することができなくなるのである。 In other words, since the frequency of the pilot signal given to the transmission signal is set to a frequency very close to the transmission signal, if there is a level difference between these signals, even if each signal is separated by a filter, A high-level signal (transmission signal or pilot signal) leaks into the path of the low signal (pilot signal or transmission signal), and the signal purity is lowered, and finally the original transmission signal can be accurately restored. It will not be possible.

本発明は、こうした問題に鑑みなされたものであり、伝送信号にパイロット信号を付与した信号をアップコンバートすることにより送信信号を生成する送信装置において、アップコンバート前の伝送信号とパイロット信号とのレベル差を抑えることで、受信装置側でそのレベル差により元の伝送信号を復元できなくなるのを防止することを目的とする。   The present invention has been made in view of such problems, and in a transmission apparatus that generates a transmission signal by up-converting a signal obtained by adding a pilot signal to a transmission signal, levels of the transmission signal and the pilot signal before the up-conversion By suppressing the difference, an object is to prevent the receiving apparatus from being unable to restore the original transmission signal due to the level difference.

かかる目的を達成するためになされた請求項１に記載の発明は、伝送信号とほぼ同じ周波数帯で一定周波数のパイロット信号を発生するパイロット信号発生手段と、前記伝送信号に前記パイロット信号発生手段からのパイロット信号を付与するパイロット信号付与手段と、該パイロット信号付与手段にてパイロット信号が付与された伝送信号を、該伝送信号よりも周波数が高い送信信号に周波数変換する周波数変換手段とを備えた送信装置において、前記パイロット信号付与手段への前記伝送信号の入力レベルを調整可能な第１レベル調整手段と、該第１レベル調整手段にてレベル調整される前の前記伝送信号の信号レベルを検出する信号レベル検出手段と、該信号レベル検出手段にて検出された信号レベルに基づき、前記第１レベル調整手段による信号レベル調整量を制御することにより、前記パイロット信号付与手段に入力される伝送信号とパイロット信号とのレベル差を許容範囲内に抑える第１制御手段とを設けたことを特徴とする。   In order to achieve this object, the invention according to claim 1 is characterized in that a pilot signal generating means for generating a pilot signal having a constant frequency in substantially the same frequency band as that of the transmission signal, and the transmission signal from the pilot signal generating means. Pilot signal providing means for providing a pilot signal of the above and a frequency conversion means for converting the frequency of the transmission signal provided with the pilot signal by the pilot signal providing means to a transmission signal having a frequency higher than that of the transmission signal. In the transmission apparatus, a first level adjusting means capable of adjusting an input level of the transmission signal to the pilot signal providing means, and detecting a signal level of the transmission signal before the level is adjusted by the first level adjusting means And a first level adjusting means based on the signal level detected by the signal level detecting means. Controlling a signal level adjustment amount of the, characterized in that the level difference between the transmission signal and the pilot signal inputted to the pilot signal applying means is provided and a first control means for suppressing within the allowable range.

また、請求項２に記載の発明は、伝送信号とほぼ同じ周波数帯で一定周波数のパイロット信号を発生するパイロット信号発生手段と、前記伝送信号に前記パイロット信号発生手段からのパイロット信号を付与するパイロット信号付与手段と、該パイロット信号付与手段にてパイロット信号が付与された伝送信号を、該伝送信号よりも周波数が高い送信信号に周波数変換する周波数変換手段とを備えた送信装置において、前記パイロット信号付与手段への前記パイロット信号の入力レベルを調整可能な第２レベル調整手段と、前記伝送信号の信号レベルを検出する信号レベル検出手段と、該信号レベル検出手段にて検出された信号レベルに基づき、前記第２レベル調整手段による信号レベル調整量を制御することにより、前記パイロット信号付与手段に入力される伝送信号とパイロット信号とのレベル差を許容範囲内に抑える第２制御手段とを設けたことを特徴とする。   According to a second aspect of the present invention, there is provided a pilot signal generating means for generating a pilot signal having a constant frequency in substantially the same frequency band as that of the transmission signal, and a pilot for giving a pilot signal from the pilot signal generating means to the transmission signal. In the transmission apparatus comprising: a signal providing unit; and a frequency conversion unit configured to frequency-convert the transmission signal to which the pilot signal is added by the pilot signal providing unit into a transmission signal having a frequency higher than that of the transmission signal. A second level adjusting means capable of adjusting an input level of the pilot signal to the assigning means; a signal level detecting means for detecting a signal level of the transmission signal; and a signal level detected by the signal level detecting means. , By controlling the signal level adjustment amount by the second level adjustment means, Characterized in that a second control means for suppressing the level difference between the transmission signal and the pilot signal input to the means within the allowable range.

また更に、請求項３に記載の発明は、伝送信号にパイロット信号を付与すると共に、該パイロット信号を付与した伝送信号を、該伝送信号よりも周波数が高い送信信号に周波数変換することにより送信信号を生成し、該送信信号を送信アンテナを介して無線送信する送信装置と、前記送信装置からの送信信号を受信アンテナを介して受信し、該受信信号を、該受信信号よりも周波数が低い信号に周波数変換すると共に、該周波数変換後の受信信号から前記パイロット信号を抽出し、該パイロット信号に基づき、前記送信装置側で周波数変換される前の元の伝送信号を復元する受信装置とを備えた無線伝送システムにおいて、前記送信装置として、請求項１又は請求項２に記載の送信装置を備えたことを特徴とする。   Furthermore, the invention according to claim 3 provides a transmission signal by adding a pilot signal to the transmission signal and frequency-converting the transmission signal to which the pilot signal is added into a transmission signal having a higher frequency than the transmission signal. A transmission device that wirelessly transmits the transmission signal via a transmission antenna, a transmission signal from the transmission device is received via a reception antenna, and the reception signal is a signal having a frequency lower than that of the reception signal. And a receiving device that extracts the pilot signal from the frequency-converted received signal and restores the original transmission signal before the frequency conversion on the transmitting device side based on the pilot signal. In the wireless transmission system, the transmission device according to claim 1 or 2 is provided as the transmission device.

上記のように本発明（請求項１及び請求項２）の送信装置においては、パイロット信号付与手段が、送信対象となる伝送信号にパイロット信号発生手段からのパイロット信号を付与し、周波数変換手段が、そのパイロット信号が付与された伝送信号を周波数変換（アップコンバート）することにより送信信号を生成する。   As described above, in the transmission apparatus of the present invention (Claim 1 and Claim 2), the pilot signal applying means applies the pilot signal from the pilot signal generating means to the transmission signal to be transmitted, and the frequency converting means Then, a transmission signal is generated by frequency-converting (up-converting) the transmission signal provided with the pilot signal.

そして、請求項１に記載の送信装置においては、パイロット信号付与手段への伝送信号の入力レベルを調整可能な第１レベル調整手段が設けられており、信号レベル検出手段が、第１レベル調整手段にてレベル調整される前の伝送信号の信号レベルを検出し、第１制
御手段が、その検出された信号レベルに基づき、第１レベル調整手段による信号レベル調整量を制御することにより、パイロット信号付与手段に入力される伝送信号とパイロット信号とのレベル差を許容範囲内に抑える。 In the transmission device according to claim 1, the first level adjusting means capable of adjusting the input level of the transmission signal to the pilot signal providing means is provided, and the signal level detecting means is the first level adjusting means. The first control means detects the signal level of the transmission signal before the level is adjusted at the first level, and the first control means controls the signal level adjustment amount by the first level adjustment means based on the detected signal level. The level difference between the transmission signal input to the assigning means and the pilot signal is suppressed within an allowable range.

また、請求項２に記載の送信装置においては、パイロット信号付与手段へのパイロット信号の入力レベルを調整可能な第２レベル調整手段が設けられており、信号レベル検出手段が、伝送信号の信号レベルを検出し、第２制御手段が、その検出された信号レベルに基づき、第２レベル調整手段による信号レベル調整量を制御することにより、パイロット信号付与手段に入力される伝送信号とパイロット信号とのレベル差を許容範囲内に抑える。   Further, in the transmission device according to claim 2, the second level adjusting means capable of adjusting the input level of the pilot signal to the pilot signal providing means is provided, and the signal level detecting means is a signal level of the transmission signal. And the second control means controls the signal level adjustment amount by the second level adjustment means based on the detected signal level, so that the transmission signal and the pilot signal input to the pilot signal giving means are controlled. Keep the level difference within an acceptable range.

このため、請求項１及び請求項２に記載の送信装置によれば、この送信装置からの送信信号を受信する受信装置側で受信信号を周波数変換することにより得られる伝送信号とパイロット信号とのレベル差が大きくなるのを防止し、受信装置側で、パイロット信号を用いて伝送信号を復元する際に、これら各信号を充分分離できずに、元の伝送信号を復元できなくなるのを防止することができる。   For this reason, according to the transmission device according to claim 1 and claim 2, between the transmission signal and the pilot signal obtained by frequency-converting the reception signal on the reception device side that receives the transmission signal from the transmission device. Prevents the level difference from becoming large, and prevents the original transmission signal from being restored without sufficiently separating these signals when restoring the transmission signal using the pilot signal on the receiving device side. be able to.

また特に、請求項１に記載の送信装置においては、パイロット信号付与手段への伝送信号の入力レベルを調整するに当たって、一般的なＡＧＣ回路のように、レベル調整後の伝送信号の信号レベルを検出するのではなく、レベル調整前の伝送信号の信号レベルを検出する。   In particular, in the transmission apparatus according to claim 1, when adjusting the input level of the transmission signal to the pilot signal applying means, the signal level of the transmission signal after level adjustment is detected as in a general AGC circuit. Instead, the signal level of the transmission signal before level adjustment is detected.

このため、レベル調整のために伝送信号を増幅した際に生じる歪成分の影響を受けることなく、伝送信号の信号レベルを正確に検出することができ、延いては、パイロット信号付与手段へ入力される伝送信号とパイロット信号とのレベル差をより正確に制御することが可能となる。   Therefore, it is possible to accurately detect the signal level of the transmission signal without being affected by distortion components generated when the transmission signal is amplified for level adjustment, and as a result, input to the pilot signal applying means. Therefore, the level difference between the transmission signal and the pilot signal can be controlled more accurately.

また、請求項２に記載の送信装置においては、伝送信号の信号レベルに応じて、変調されていないパイロット信号一波の信号レベルを調整するので、そのレベル調整によって歪成分が生成されることがない。よって、送信信号の信号純度を高め、受信装置側で伝送信号をより良好に復元させることができる。   Further, in the transmission apparatus according to claim 2, since the signal level of one unmodulated pilot signal is adjusted according to the signal level of the transmission signal, a distortion component may be generated by the level adjustment. Absent. Therefore, the signal purity of the transmission signal can be increased, and the transmission signal can be restored more favorably on the receiving device side.

次に、請求項３に記載の無線伝送システムにおいては、上述した従来装置と同様、送信装置側では、パイロット信号を付与した伝送信号を周波数変換（アップコンバート）することにより送信信号を生成して、送信アンテナから送信し、受信装置側では、この送信信号を受信アンテナを介して受信し、その受信信号を周波数変換（ダウンコンバート）すると共に、そのダウンコンバート後の受信信号からパイロット信号を抽出し、そのパイロット信号に基づき元の伝送信号を復元するが、送信装置には、上述した本発明（請求項１又は請求項２）の送信装置が使用される。   Next, in the wireless transmission system according to claim 3, like the conventional apparatus described above, the transmission apparatus generates a transmission signal by frequency-converting (up-converting) the transmission signal to which the pilot signal is added. Then, the signal is transmitted from the transmitting antenna, and the receiving device receives the transmitted signal via the receiving antenna, converts the frequency of the received signal (down-conversion), and extracts the pilot signal from the received signal after the down-conversion. The original transmission signal is restored based on the pilot signal, and the transmission device of the present invention (claim 1 or claim 2) is used as the transmission device.

このため、本発明の無線伝送システムによれば、送信装置からの送信信号に含まれる伝送信号とパイロット信号とのレベル差を許容範囲内に抑えて、受信装置側で、そのレベル差によりこれら各信号を充分分離できず、元の伝送信号を復元できなくなるのを防止することができる。   For this reason, according to the wireless transmission system of the present invention, the level difference between the transmission signal and the pilot signal included in the transmission signal from the transmission device is suppressed within an allowable range, and the reception device side determines each of these levels by the level difference. It is possible to prevent the signals from being sufficiently separated and the original transmission signal from being restored.

以下に、本発明の一実施形態を図面と共に説明する。
図１は、本発明が適用された実施形態の無線伝送システム全体の構成を表すブロック図である。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the overall configuration of a wireless transmission system according to an embodiment to which the present invention is applied.

図１に示すように、本実施形態の無線伝送システムは、放送局（若しくは中継局）にて生成（若しくは復元）された地上デジタル放送用テレビ放送信号の中間周波信号（例えば、中心周波数が３７．１５ＭＨｚの信号：以下、ＩＦ信号ともいう）を、無線伝送用のマイクロ波帯（例えば７ＧＨｚ帯）に周波数変換（アップコンバート）し、そのアップコンバート後の信号（つまり送信信号）を送信アンテナ２から無線送信させる送信装置４と、この送信装置４からの送信信号を受信アンテナ６で受信し、その受信信号を周波数変換（ダウンコンバート）することにより、送信装置４側でアップコンバートする前の元の伝送信号（ＩＦ信号）を復元し、その復元したＩＦ信号を端末側伝送装置へ出力する受信装置８とから構成されている。   As shown in FIG. 1, the wireless transmission system according to the present embodiment has an intermediate frequency signal (for example, a center frequency of 37) of a terrestrial digital broadcast television broadcast signal generated (or restored) by a broadcast station (or relay station). .15 MHz signal (hereinafter also referred to as IF signal) is frequency-converted (up-converted) into a microwave band for radio transmission (for example, 7 GHz band), and the signal after the up-conversion (that is, the transmission signal) is transmitted to the transmission antenna 2. Transmitting apparatus 4 to transmit wirelessly, and a transmission signal from the transmitting apparatus 4 is received by the receiving antenna 6, and the received signal is subjected to frequency conversion (down-conversion), so that the original before the up-conversion on the transmitting apparatus 4 side. And a receiving device 8 that outputs the restored IF signal to the terminal-side transmission device.

なお、端末側伝送装置は、受信装置８から入力された伝送信号（ＩＦ信号）をＵＨＦ帯のテレビ放送信号に変換して、受信端末装置へ無線又は有線にて配信するものである。
また、送信装置４は、図２の点線内に記載されているように、伝送信号であるＩＦ信号に対して、ＩＦ信号とほぼ同じ周波数帯で一定周波数のパイロット信号（具体的にはＩＦ信号の中心周波数よりも４ＭＨｚだけ周波数が低い３３．１５ＭＨｚの信号）を付与し、そのパイロット信号を付与した伝送信号（ＩＦ信号＋パイロット信号）をマイクロ波帯にアップコンバートすることにより、送信信号を生成するよう構成されており、受信装置８は、その送信信号を受信してダウンコンバートした受信信号からパイロット信号を抽出し、その抽出したパイロット信号を用いて、ダウンコンバート用の高周波信号若しくはダウンコンバート後の伝送信号（ＩＦ信号）を補正することで、送信装置４にてアップコンバートされる前の元の伝送信号を復元するように構成されている。 The terminal-side transmission device converts a transmission signal (IF signal) input from the receiving device 8 into a UHF band television broadcast signal and distributes the signal to the receiving terminal device wirelessly or by wire.
Further, as described in the dotted line in FIG. 2, the transmission device 4 is configured to generate a pilot signal (specifically, an IF signal) with a constant frequency in substantially the same frequency band as that of the IF signal. (3.15 MHz signal, which is 4 MHz lower than the center frequency), and the transmission signal (IF signal + pilot signal) to which the pilot signal has been added is up-converted to a microwave band to generate a transmission signal The receiving device 8 receives the transmission signal, extracts a pilot signal from the down-converted reception signal, and uses the extracted pilot signal to perform a down-conversion high-frequency signal or after down-conversion The original transmission signal before being up-converted by the transmitter 4 is corrected by correcting the transmission signal (IF signal) of It is configured to source.

これら各装置４、８のうち、受信装置８は、上述した特許文献１、２等に開示されたものと同様に構成できることから、ここでは詳細な説明を省略し、次に、本発明にかかわる主要部である送信装置４の構成について説明する。   Among these devices 4 and 8, the receiving device 8 can be configured in the same manner as that disclosed in the above-mentioned Patent Documents 1 and 2, etc., so detailed description thereof will be omitted here, and then it will be related to the present invention. A configuration of the transmission device 4 which is a main part will be described.

図２に示すように、送信装置４には、伝送信号であるＩＦ信号を同軸ケーブル等を介して入力するための入力端子１２と、この入力端子１２に入力されたＩＦ信号を増幅する増幅回路１８と、この増幅回路１８にて増幅されたＩＦ信号に、パイロット信号発生用の発振器２６から出力されたパイロット信号を付与する混合器２４と、この混合器２４にてパイロット信号が付与されたＩＦ信号を選択的に通過させるバンドパスフィルタ（ＢＰＦ）２８と、このＢＰＦ２８を通過した伝送信号（ＩＦ信号＋パイロット信号）と、周波数変換用の高周波信号を発生する発振器３２からの出力（７ＧＨｚ帯の高周波信号）とを混合することで、伝送信号（ＩＦ信号＋パイロット信号）をマイクロ波帯に周波数変換（アップコンバート）する混合器３０と、この混合器３０にてアップコンバートされた伝送信号（ＩＦ信号＋パイロット信号）を選択的に通過させるバンドパスフィルタ（ＢＰＦ）３４と、このＢＰＦ３４を通過した伝送信号（ＩＦ信号＋パイロット信号）を増幅する増幅回路３６と、この増幅回路３６にて増幅された伝送信号（ＩＦ信号＋パイロット信号）を同軸ケーブル等を介して端末側伝送装置へ出力するための出力端子３８と、が設けられている。   As shown in FIG. 2, the transmission device 4 includes an input terminal 12 for inputting an IF signal as a transmission signal via a coaxial cable or the like, and an amplification circuit for amplifying the IF signal input to the input terminal 12. 18, a mixer 24 for adding a pilot signal output from an oscillator 26 for generating a pilot signal to the IF signal amplified by the amplifier circuit 18, and an IF to which the pilot signal is added by the mixer 24 A band-pass filter (BPF) 28 that selectively passes a signal, a transmission signal (IF signal + pilot signal) that has passed through the BPF 28, and an output (7 GHz band output) from an oscillator 32 that generates a high-frequency signal for frequency conversion. The high frequency signal) is mixed and the transmission signal (IF signal + pilot signal) is frequency-converted (up-converted) into a microwave band. The band-pass filter (BPF) 34 that selectively passes the transmission signal (IF signal + pilot signal) up-converted by the mixer 30 and the transmission signal (IF signal + pilot signal) that has passed through the BPF 34 An amplifying circuit 36 for amplifying and an output terminal 38 for outputting the transmission signal (IF signal + pilot signal) amplified by the amplifying circuit 36 to the terminal-side transmission device via a coaxial cable or the like are provided. Yes.

また、送信装置４の入力端子１２から増幅回路１８に至るＩＦ信号の入力経路上には、入力端子１２側から順に、入力端子１２に入力されたＩＦ信号の一部を分岐させる分岐器１４と、可変減衰器１６とが設けられており、分岐器１４にて分岐されたＩＦ信号は、その信号レベルを検出する信号レベル検出部２０に入力される。   Further, on the input path of the IF signal from the input terminal 12 of the transmission device 4 to the amplifier circuit 18, a branching device 14 for branching a part of the IF signal input to the input terminal 12 in order from the input terminal 12 side; A variable attenuator 16 is provided, and the IF signal branched by the branching unit 14 is input to a signal level detection unit 20 that detects the signal level.

ここで、可変減衰器１６は、例えば、順方向に流れる電流量に応じて抵抗値が変化するＰＩＮダイオード用いて構成されており、このＰＩＮダイオードに印加される駆動電圧を制御することにより、ＩＦ信号の減衰量を調整できるようになっている。   Here, the variable attenuator 16 is configured by using, for example, a PIN diode whose resistance value changes in accordance with the amount of current flowing in the forward direction. By controlling the drive voltage applied to the PIN diode, the variable attenuator 16 The amount of signal attenuation can be adjusted.

また、信号レベル検出部２０は、例えば、ＩＦ信号を包絡線検波して、その検波電圧をＩＦ信号の信号レベルとして出力する検波回路にて構成されており、この信号レベル検出部２０からの検出信号は、信号レベル制御部２２に入力される。   The signal level detection unit 20 includes, for example, a detection circuit that detects an envelope of the IF signal and outputs the detection voltage as a signal level of the IF signal. Detection from the signal level detection unit 20 The signal is input to the signal level control unit 22.

この信号レベル制御部２２は、例えば、ＩＦ信号の信号レベルに応じて変化する駆動電圧を生成し、これを可変減衰器１６のＰＩＮダイオードに印加することで、可変減衰器１６の減衰量を、ＩＦ信号の信号レベルに応じて制御するように構成されている。   The signal level control unit 22 generates, for example, a drive voltage that changes according to the signal level of the IF signal, and applies this to the PIN diode of the variable attenuator 16, thereby reducing the attenuation amount of the variable attenuator 16. Control is performed according to the signal level of the IF signal.

つまり、この信号レベル制御部２２は、信号レベル検出部２０からの入力信号（レベル検出信号）に応じて、ＩＦ信号の信号レベルが高い場合には、可変減衰器１６の減衰量が大きく、ＩＦ信号の信号レベルが低い場合には、可変減衰器１６の減衰量が小さくなるよう、可変減衰器１６の駆動電圧を生成することで、混合器２４に入力されるＩＦ信号が、混合器２４に入力されるパイロット信号とほぼ同じ信号レベルとなるように、可変減衰器１６の減衰量を制御する。   That is, when the signal level of the IF signal is high according to the input signal (level detection signal) from the signal level detection unit 20, the signal level control unit 22 increases the attenuation amount of the variable attenuator 16, and When the signal level of the signal is low, the IF signal input to the mixer 24 is supplied to the mixer 24 by generating the drive voltage of the variable attenuator 16 so that the attenuation amount of the variable attenuator 16 becomes small. The attenuation amount of the variable attenuator 16 is controlled so that the signal level is substantially the same as the input pilot signal.

従って、本実施形態の送信装置４によれば、混合器２４にて混合されるＩＦ信号とパイロット信号とのレベル差を許容範囲（例えば１ｄＢ）内に抑えて、受信装置８側で受信信号をダウンコンバートすることにより得られる伝送信号とパイロット信号とのレベル差が大きくなるのを防止することができる。   Therefore, according to the transmission device 4 of the present embodiment, the level difference between the IF signal mixed by the mixer 24 and the pilot signal is suppressed within an allowable range (for example, 1 dB), and the reception signal is received on the reception device 8 side. It is possible to prevent an increase in level difference between the transmission signal obtained by down-conversion and the pilot signal.

このため、本実施形態の送信装置４によれば、受信装置８側で、パイロット信号を用いてＩＦ信号を復元する際に、ダウンコンバート後の受信信号からこれら各信号を充分分離できずに、ＩＦ信号を復元できなくなるのを防止することができる。   Therefore, according to the transmission device 4 of the present embodiment, when the IF signal is restored using the pilot signal on the reception device 8 side, these signals cannot be sufficiently separated from the received signal after down-conversion. It is possible to prevent the IF signal from being restored.

また、本実施形態の送信装置４においては、混合器２４へのＩＦ信号の入力レベルを調整するに当たって、一般的なＡＧＣ回路のように、レベル調整後のＩＦ信号の信号レベルを検出するのではなく、レベル調整前のＩＦ信号の信号レベルを検出することから、レベル調整のためにＩＦ信号を増幅した際に生じる歪成分の影響を受けることなく、ＩＦ信号の信号レベルを正確に検出することができる。よって、本実施形態の送信装置４によれば、混合器２４にて混合される前のＩＦ信号とパイロット信号とのレベル差をより確実に抑制することができる。   Further, in the transmission device 4 of this embodiment, when adjusting the input level of the IF signal to the mixer 24, the signal level of the IF signal after level adjustment is not detected as in a general AGC circuit. In addition, since the signal level of the IF signal before level adjustment is detected, the signal level of the IF signal can be accurately detected without being affected by distortion components generated when the IF signal is amplified for level adjustment. Can do. Therefore, according to the transmission device 4 of the present embodiment, the level difference between the IF signal before being mixed by the mixer 24 and the pilot signal can be more reliably suppressed.

なお、本実施形態においては、発振器２６が本発明のパイロット信号発生手段に相当し、混合器２４が本発明のパイロット信号付与手段に相当し、発振器３２及び混合器３０が本発明の周波数変換手段に相当し、可変減衰器１６が本発明の第１レベル調整手段に相当し、信号レベル検出部２０が本発明の信号レベル検出手段に相当し、信号レベル制御部２２が本発明の第１制御手段に相当する。   In this embodiment, the oscillator 26 corresponds to the pilot signal generating means of the present invention, the mixer 24 corresponds to the pilot signal applying means of the present invention, and the oscillator 32 and the mixer 30 are the frequency converting means of the present invention. The variable attenuator 16 corresponds to the first level adjustment means of the present invention, the signal level detection unit 20 corresponds to the signal level detection means of the present invention, and the signal level control unit 22 corresponds to the first control of the present invention. Corresponds to means.

以上、本発明の一実施形態について説明したが、本発明は、上記実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲内にて種々の態様をとることができる。
例えば、上記実施形態では、入力端子１２から増幅回路１８に至るＩＦ信号の入力経路上に可変減衰器１６を設け、この可変減衰器１６の減衰量を調整することにより、混合器２４に入力されるＩＦ信号とパイロット信号とのレベル差を許容範囲内に抑えるものとして説明したが、図３に示すように、発振器２６から混合器２４へのパイロット信号の入力経路上に可変減衰器４０を設け、信号レベル制御部４２が、この可変減衰器４０の減衰量を調整することで、混合器２４に入力されるＩＦ信号とパイロット信号とのレベル差を許容範囲内に抑えようにしてもよい。 As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken in the range which does not deviate from the summary of this invention.
For example, in the above embodiment, the variable attenuator 16 is provided on the input path of the IF signal from the input terminal 12 to the amplifier circuit 18, and the attenuation amount of the variable attenuator 16 is adjusted so that the signal is input to the mixer 24. As described in FIG. 3, a variable attenuator 40 is provided on the pilot signal input path from the oscillator 26 to the mixer 24 as shown in FIG. The signal level control unit 42 may adjust the attenuation amount of the variable attenuator 40 to suppress the level difference between the IF signal input to the mixer 24 and the pilot signal within an allowable range.

なお、この場合、信号レベル制御部４２は、信号レベル検出部２０からの入力信号（レベル検出信号）に応じて、ＩＦ信号の信号レベルが高い場合には可変減衰器１６の減衰量が小さくなり、ＩＦ信号の信号レベルが低い場合には可変減衰器１６の減衰量が大きくなるよう、可変減衰器４０の減衰量を制御することで、混合器２４に入力されるパイロット信号の信号レベルを調整するように構成すればよい。   In this case, the signal level control unit 42 reduces the attenuation amount of the variable attenuator 16 when the signal level of the IF signal is high according to the input signal (level detection signal) from the signal level detection unit 20. The signal level of the pilot signal input to the mixer 24 is adjusted by controlling the attenuation amount of the variable attenuator 40 so that the attenuation amount of the variable attenuator 16 increases when the signal level of the IF signal is low. What is necessary is just to comprise so.

また、上記実施形態では、地上デジタル放送のテレビ放送信号をマイクロ波を使って無線伝送するシステムについて説明したが、本発明は、送信装置が伝送信号をアップコンバートして無線伝送するシステムであれば、どのようなシステムであっても適用できる。   In the above embodiment, a system for wirelessly transmitting a terrestrial digital broadcast television broadcast signal using microwaves has been described. However, the present invention is a system in which a transmission device upconverts a transmission signal and wirelessly transmits the signal. Any system can be applied.

実施例の無線伝送システム全体の構成を表す構成図である。It is a block diagram showing the structure of the whole radio | wireless transmission system of an Example. 送信装置の構成を表すブロック図である。It is a block diagram showing the structure of a transmitter. 送信装置の他の構成例を表すブロック図である。It is a block diagram showing the other structural example of a transmitter.

符号の説明Explanation of symbols

２…送信アンテナ、４…送信装置、６…受信アンテナ、８…受信装置、１２…入力端子、１４…分岐器、１６…可変減衰器、１８…増幅回路、２０…信号レベル検出部、２２…信号レベル制御部、２４…混合器、２６…発振器、２８…ＢＰＦ（バンドパスフィルタ）、３０…混合器、３２…発振器、３４…ＢＰＦ（バンドパスフィルタ）、３６…増幅回路、３８…出力端子、４０…可変減衰器、４２…信号レベル制御部。   DESCRIPTION OF SYMBOLS 2 ... Transmitting antenna, 4 ... Transmitting device, 6 ... Receiving antenna, 8 ... Receiving device, 12 ... Input terminal, 14 ... Branching device, 16 ... Variable attenuator, 18 ... Amplifying circuit, 20 ... Signal level detection part, 22 ... Signal level control unit, 24 ... mixer, 26 ... oscillator, 28 ... BPF (bandpass filter), 30 ... mixer, 32 ... oscillator, 34 ... BPF (bandpass filter), 36 ... amplifier circuit, 38 ... output terminal , 40 ... variable attenuator, 42 ... signal level control unit.

Claims (3)

伝送信号とほぼ同じ周波数帯で一定周波数のパイロット信号を発生するパイロット信号発生手段と、
前記伝送信号に前記パイロット信号発生手段からのパイロット信号を付与するパイロット信号付与手段と、
該パイロット信号付与手段にてパイロット信号が付与された伝送信号を、該伝送信号よりも周波数が高い送信信号に周波数変換する周波数変換手段と、
を備えた送信装置において、
前記パイロット信号付与手段への前記伝送信号の入力レベルを調整可能な第１レベル調整手段と、
該第１レベル調整手段にてレベル調整される前の前記伝送信号の信号レベルを検出する信号レベル検出手段と、
該信号レベル検出手段にて検出された信号レベルに基づき、前記第１レベル調整手段による信号レベル調整量を制御することにより、前記パイロット信号付与手段に入力される伝送信号とパイロット信号とのレベル差を許容範囲内に抑える第１制御手段と、
を設けたことを特徴とする送信装置。 Pilot signal generating means for generating a pilot signal of a constant frequency in substantially the same frequency band as the transmission signal;
Pilot signal giving means for giving a pilot signal from the pilot signal generating means to the transmission signal;
A frequency conversion means for frequency-converting the transmission signal to which the pilot signal is assigned by the pilot signal giving means to a transmission signal having a frequency higher than that of the transmission signal;
In a transmission device comprising:
First level adjusting means capable of adjusting an input level of the transmission signal to the pilot signal applying means;
Signal level detection means for detecting the signal level of the transmission signal before being level-adjusted by the first level adjustment means;
Based on the signal level detected by the signal level detection means, the level difference between the transmission signal input to the pilot signal providing means and the pilot signal is controlled by controlling the signal level adjustment amount by the first level adjustment means. First control means for keeping the value within an allowable range;
A transmission apparatus characterized by comprising: 伝送信号とほぼ同じ周波数帯で一定周波数のパイロット信号を発生するパイロット信号発生手段と、
前記伝送信号に前記パイロット信号発生手段からのパイロット信号を付与するパイロット信号付与手段と、
該パイロット信号付与手段にてパイロット信号が付与された伝送信号を、該伝送信号よりも周波数が高い送信信号に周波数変換する周波数変換手段と、
を備えた送信装置において、
前記パイロット信号付与手段への前記パイロット信号の入力レベルを調整可能な第２レベル調整手段と、
前記伝送信号の信号レベルを検出する信号レベル検出手段と、
該信号レベル検出手段にて検出された信号レベルに基づき、前記第２レベル調整手段による信号レベル調整量を制御することにより、前記パイロット信号付与手段に入力される伝送信号とパイロット信号とのレベル差を許容範囲内に抑える第２制御手段と、
を設けたことを特徴とする送信装置。 Pilot signal generating means for generating a pilot signal of a constant frequency in substantially the same frequency band as the transmission signal;
Pilot signal giving means for giving a pilot signal from the pilot signal generating means to the transmission signal;
A frequency conversion means for frequency-converting the transmission signal to which the pilot signal is assigned by the pilot signal giving means to a transmission signal having a frequency higher than that of the transmission signal;
In a transmission device comprising:
Second level adjusting means capable of adjusting the input level of the pilot signal to the pilot signal applying means;
Signal level detection means for detecting the signal level of the transmission signal;
Based on the signal level detected by the signal level detecting means, the level difference between the transmission signal input to the pilot signal providing means and the pilot signal is controlled by controlling the signal level adjustment amount by the second level adjusting means. Second control means for keeping the value within an allowable range;
A transmission apparatus characterized by comprising: 伝送信号にパイロット信号を付与すると共に、該パイロット信号を付与した伝送信号を、該伝送信号よりも周波数が高い送信信号に周波数変換することにより送信信号を生成し、該送信信号を送信アンテナを介して無線送信する送信装置と、
前記送信装置からの送信信号を受信アンテナを介して受信し、該受信信号を、該受信信号よりも周波数が低い信号に周波数変換すると共に、該周波数変換後の受信信号から前記パイロット信号を抽出し、該パイロット信号に基づき、前記送信装置側で周波数変換される前の元の伝送信号を復元する受信装置と、
を備えた無線伝送システムにおいて、
前記送信装置として、請求項１又は請求項２に記載の送信装置を備えたことを特徴とする無線伝送システム。 A transmission signal is generated by adding a pilot signal to the transmission signal and frequency-converting the transmission signal to which the pilot signal is added into a transmission signal having a frequency higher than that of the transmission signal, and transmitting the transmission signal via a transmission antenna. A transmission device for wireless transmission,
A transmission signal from the transmission device is received via a reception antenna, the reception signal is frequency-converted to a signal having a frequency lower than that of the reception signal, and the pilot signal is extracted from the reception signal after the frequency conversion. A receiving device that restores an original transmission signal before frequency conversion on the transmitting device side based on the pilot signal;
In a wireless transmission system with
A wireless transmission system comprising the transmission device according to claim 1 or 2 as the transmission device.
JP2007092553A 2007-03-30 2007-03-30 Transmitter and radio transmission system Pending JP2008252632A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013026719A (en) * 2011-07-19 2013-02-04 Toyota Motor Corp Collation system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004235758A (en) * 2003-01-28 2004-08-19 Nippon Hoso Kyokai <Nhk> Millimeter wave transmission/reception system, millimeter wave transmitter, millimeter wave receiver and satellite broadcast receiving antenna
JP2006060767A (en) * 2004-07-23 2006-03-02 Sharp Corp Radio receiving device, radio communication system and electronic apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004235758A (en) * 2003-01-28 2004-08-19 Nippon Hoso Kyokai <Nhk> Millimeter wave transmission/reception system, millimeter wave transmitter, millimeter wave receiver and satellite broadcast receiving antenna
JP2006060767A (en) * 2004-07-23 2006-03-02 Sharp Corp Radio receiving device, radio communication system and electronic apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013026719A (en) * 2011-07-19 2013-02-04 Toyota Motor Corp Collation system

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