JPH0229039A - Pilot signal elimination circuit - Google Patents
Pilot signal elimination circuitInfo
- Publication number
- JPH0229039A JPH0229039A JP3654889A JP3654889A JPH0229039A JP H0229039 A JPH0229039 A JP H0229039A JP 3654889 A JP3654889 A JP 3654889A JP 3654889 A JP3654889 A JP 3654889A JP H0229039 A JPH0229039 A JP H0229039A
- Authority
- JP
- Japan
- Prior art keywords
- pilot signal
- level
- output
- input
- variable gain
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000008030 elimination Effects 0.000 title abstract 2
- 238000003379 elimination reaction Methods 0.000 title abstract 2
- 238000001514 detection method Methods 0.000 claims abstract description 26
- 230000003321 amplification Effects 0.000 claims abstract description 5
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 5
- 238000010586 diagram Methods 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 241000723353 Chrysanthemum Species 0.000 description 1
- 235000007516 Chrysanthemum Nutrition 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
Landscapes
- Stereo-Broadcasting Methods (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、ＦＭステレオ復調器におけるパイロット信号
除去システムに関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pilot signal cancellation system in an FM stereo demodulator.
一般的なＦＭ （Ｆｒｅｑｕｅｎｃｙ Ｍｏｄｕｌａｔ
ｉｏｎ）ステレオ放送においては、１９ＫＨ’ｚの正弦
波のパイロット信号が存在する。パイロット信号は、Ｐ
ＬＬ （Ｐｈａｓｅ Ｌｏｃｋｅｄ Ｌｏｏｐ）におい
て重要な働きをするが入力信号に含まれているので、単
に復調すると復調器出力にも出てくる為、聴感上問題と
がる。そこで、この１９ＫＨｚのパイロット信号の除去
が必要である。従来の１９ＫＨｚのパイロット信号の除
去システムを第３図に示す。システムハは、三角波変換
器１６．可変利得増幅器１８、加算器２０．パイロット
信号レベル検波回路２２より構成される。ステレオ信号
は端子２３より入力され加算器２０を経て出力２４に出
力される。実際には、前記加算器２０においてパイロッ
ト信号の位相と１８０逆位相の三角波と（正弦波）のパ
イロット信号の加算が行われ、パイロット信号の除去を
行うものである。前述した逆位相の三角波については、
ＰＬＬでのパイロット信号と９０゛位相差のある方形波
を使用し、三角波変換器１６により方形波を三角波に変
換し、通常三角波変換器１６に設けられた容量（図示せ
ず）の充放電により三角波に変換する為、三角波変換器
１６の入力端子１５に入力される方形波と三角波変換器
１６の出力における三角波との関係は第４図の（ａ）、
（ｂ）となり、方形波の位相と比べて三角波はさらに
９０°の位相差が生じパイロット信号と１８０°位相差
となる。三角波変換器出力は、可変利得増幅器１８に接
続されており可変利得増幅器１８の増幅率は、ステレオ
信号入力端子２３に接続されているパイロット信号レベ
ル検波回路２２により制御され、入力端子２３のパイロ
ット信号レベルに応じた三角形が加算器の出力端子であ
る１９に出力され加算器に入力され、ステレオ信号と加
算され、パイロット信号と加算される為、常に入力端子
１９のパイロット信号レベルに応じた除去を可能とした
システムである。General FM (Frequency Modulat
ion) In stereo broadcasting, there is a 19 KHz sine wave pilot signal. The pilot signal is P
Although it plays an important role in the LL (Phase Locked Loop), it is included in the input signal, so if it is simply demodulated, it will also appear in the output of the demodulator, causing problems in terms of hearing. Therefore, it is necessary to remove this 19 KHz pilot signal. A conventional 19 KHz pilot signal cancellation system is shown in FIG. System C includes a triangular wave converter 16. Variable gain amplifier 18, adder 20. It is composed of a pilot signal level detection circuit 22. A stereo signal is input from a terminal 23, passes through an adder 20, and is output to an output 24. In reality, the adder 20 adds a triangular wave (sine wave) pilot signal having a phase 180 opposite to that of the pilot signal, and removes the pilot signal. Regarding the anti-phase triangular wave mentioned above,
A square wave with a phase difference of 90 degrees from the pilot signal in the PLL is used, and the square wave is converted into a triangle wave by the triangular wave converter 16. Normally, by charging and discharging a capacitor (not shown) provided in the triangular wave converter 16, In order to convert into a triangular wave, the relationship between the square wave input to the input terminal 15 of the triangular wave converter 16 and the triangular wave output from the triangular wave converter 16 is as shown in (a) in FIG.
(b), the triangular wave has a phase difference of 90° compared to the phase of the square wave, resulting in a 180° phase difference with the pilot signal. The triangular wave converter output is connected to a variable gain amplifier 18, and the amplification factor of the variable gain amplifier 18 is controlled by a pilot signal level detection circuit 22 connected to a stereo signal input terminal 23, and the pilot signal at the input terminal 23 is controlled by a pilot signal level detection circuit 22 connected to a stereo signal input terminal 23. Since a triangle corresponding to the level is outputted to the output terminal 19 of the adder, inputted to the adder, added to the stereo signal, and added to the pilot signal, removal is always performed according to the level of the pilot signal at the input terminal 19. This is a system that makes it possible.
しかしながら、前述した従来のパイロット除去システム
においては、パイロット信号レベル検波回路２２の利得
等のバラツキにより加算器における三角波の加算率もバ
ラツキを生ずる。その為前述した従来のパイロット除去
システムを使用する場合、バラツキを調整する必要があ
る。また、従来のパイロット除去システムを集積回路化
した場合バラツキを調整する端子と外付素子（通常ボリ
ューム）が必要となる。However, in the conventional pilot removal system described above, variations in the gain of the pilot signal level detection circuit 22 cause variations in the addition rate of the triangular wave in the adder. Therefore, when using the conventional pilot removal system described above, it is necessary to adjust for variations. Furthermore, when a conventional pilot removal system is integrated into an integrated circuit, a terminal and an external element (usually a volume) are required to adjust variations.
本発明によるパイコツト信号除去回路は、三角波変換器
の出力が可変利得増幅器の入力に接続され、前記可変利
得増幅器の出力が２入力加算器の１つの入力と接続され
、さらに第１のレベル検波回路の入力に接続され、前記
２入力加算器の他の入力が第２のレベル検波回路の入力
と共通で入力端子とし、前記第１のレベル検波回路の出
力と前記第２のレベル検波の出力はレベル比較器の比較
−端子にそれぞれが接続され、前記レベル比較器の出力
が前記可変利得増幅器の増幅率制御端子に接続され、前
記２入力加算器の出力を出力端子としている。In the piezoelectric signal removal circuit according to the present invention, the output of the triangular wave converter is connected to the input of a variable gain amplifier, the output of the variable gain amplifier is connected to one input of a two-input adder, and further includes a first level detection circuit. , the other input of the two-input adder is a common input terminal with the input of the second level detection circuit, and the output of the first level detection circuit and the output of the second level detection circuit are Each is connected to a comparison terminal of a level comparator, the output of the level comparator is connected to an amplification control terminal of the variable gain amplifier, and the output of the two-input adder is used as an output terminal.
次に本発明のシステム図を第１図に示す。システムは、
三角波変換器２．可変利得増幅器６．三角波レベル検波
回路１１．パイロット信号レベル検波回路１２．比較器
１０．加算器８より構成される。ステレオ信号は、端子
１３より入力され加算器８を経て出力１４に出力される
。本発明回路においては、加算器８においてパイロット
信号と逆位相の三角波とパイロットの加算が行われ、パ
イロット信号の除去を行うものである。パイロット信号
と逆位相の三角波については、従来例と同様ＰＬＬでの
パイロット信号と９０゛位相差のある方形波を使用する
。端子１に入力された方形波は、三角波変換器２により
三角波に変換される。Next, a system diagram of the present invention is shown in FIG. the system,
Triangular wave converter 2. Variable gain amplifier6. Triangular wave level detection circuit 11. Pilot signal level detection circuit 12. Comparator 10. It consists of an adder 8. The stereo signal is input from the terminal 13, passes through the adder 8, and is output to the output 14. In the circuit of the present invention, the adder 8 adds a triangular wave having an opposite phase to the pilot signal and removes the pilot signal. As for the triangular wave having a phase opposite to that of the pilot signal, a square wave having a phase difference of 90° from the pilot signal in the PLL is used as in the conventional example. A square wave input to terminal 1 is converted into a triangular wave by triangular wave converter 2 .
三角波変換は容量の充放電により行う為、三角波変換器
２の入力端子１と出力端子２における関係は、第２図の
（ａ）、 （ｂ）となり、方形波の位相と比べて三角波
は、さらに９０°の位相差が生じパイロット信号と１８
０°位相差となる。三角波変換器２の出力は、可変利得
増幅器６に接続されている。可変利得増幅器６の増幅率
は、可変利得増幅器６出力の三角波のレベルと、ステレ
オ信号と入力端子である端子１３のパイロット信号のレ
ベルとの差により制御し、入力端子１３のパイロット信
号レベルと常に同レベルの三角波が可変利得増幅器６の
出カニ７に出る・ようにする。そのために、可変利得増
幅器の出力に三角波レベル検波回路１１が接続され、入
力端子１３にパイロット信号レベル検波回路１２が接続
されておりさらに前記三角波レベル検波回路１１とパイ
ロット信号レベル検波回路１２とのＤＣレベル差をとる
比較器１０が接続されている。以上のことにより２入力
加算器８におけるパイロット信号とパイロット信号除去
用の三角波との関係は、逆位相で同レベルとなり出力端
子１４におけるステレオ信号にはパイロット信号成分が
除去されたものが出力される。集積回路に用いた場合、
三角波レベル検波回路１１とパイロット信号レベル検波
回路１２は互いに同様なバラツキを生じる為、比較器１
０の出力では、各々のレベル検波器のバラツキは除いて
考えれば良い。Since the triangular wave conversion is performed by charging and discharging the capacitor, the relationship between the input terminal 1 and the output terminal 2 of the triangular wave converter 2 is as shown in (a) and (b) in Fig. 2, and compared to the phase of the square wave, the triangular wave is Furthermore, a phase difference of 90° occurs and the pilot signal and 18
The phase difference is 0°. The output of the triangular wave converter 2 is connected to a variable gain amplifier 6. The amplification factor of the variable gain amplifier 6 is controlled by the difference between the level of the triangular wave output from the variable gain amplifier 6 and the level of the pilot signal at the stereo signal and the input terminal 13, and is always equal to the pilot signal level at the input terminal 13. A triangular wave of the same level is outputted to the output 7 of the variable gain amplifier 6. For this purpose, a triangular wave level detection circuit 11 is connected to the output of the variable gain amplifier, a pilot signal level detection circuit 12 is connected to the input terminal 13, and a DC voltage between the triangular wave level detection circuit 11 and the pilot signal level detection circuit 12 is connected. A comparator 10 that takes a level difference is connected. As a result of the above, the relationship between the pilot signal in the two-input adder 8 and the triangular wave for pilot signal removal is in opposite phases and at the same level, and the stereo signal at the output terminal 14 is output with the pilot signal component removed. . When used in integrated circuits,
Since the triangular wave level detection circuit 11 and the pilot signal level detection circuit 12 produce similar variations, the comparator 1
In the case of an output of 0, it is sufficient to consider excluding variations in each level detector.
さらに三角波変換器２と可変利得増幅器６との間にパイ
ロット除去を大きくする為の三角波から正弦波への変換
回路を挿入しても本発明の効果は同様に得られる。Further, even if a triangular wave to sine wave conversion circuit is inserted between the triangular wave converter 2 and the variable gain amplifier 6 to increase pilot rejection, the same effect of the present invention can be obtained.
第５図に本発明の他の実施例を示す。本実施例は、第１
図のシステムに波形整形器２４及びバ。FIG. 5 shows another embodiment of the invention. In this example, the first
The system shown in the figure includes a waveform shaper 24 and a bar.
ノアアンプ２５．疑似ｓｉｎ波変換器２７を追加したも
のであり、構成回路の一例を第７図に示す。Noah amp 25. A pseudo sine wave converter 27 is added, and an example of the configuration circuit is shown in FIG.
波形整形器２４はトランジスターＴｒｙ（以下トランジ
スターは省略）、Ｔｒｚ、抵抗Ｒ１〜Ｒ４゜定電流源工
、からなる差動増幅器で入力端子１からのパイロット信
号と９０°位相差のある方形波の整形を行に三角波変換
器２に入力される。三角波変換器２は、第７図に示すよ
うにＴｒ３＋Ｔｒ４＋容量Ｃ１定電流源Ｉ２．Ｉｓによ
り成り容量Ｃ及び定電流源Ｉ２．Ｉ３により波形整形器
２４かの方形波を充放電により三角波に変換する（第６
図端子３０波形参照）。三角波変換器２の出力は、Ｔｒ
ｓ〜Ｔ ｒ ｓ ＋定電流源Ｉ４．Ｉｓから成るバッフ
ァアンプ２５により、疑似ｓｉｎ波変換器２７の入力イ
ンピーダンスの影響を受けない様にしており、疑似ｓｉ
ｎ波変換器２７は、抵抗Ｒ５〜Ｒ７、Ｔ ｒ ９゜Ｔｒ
、。、定電流源ｒｅ、Ｉｔから差動の入出力特性により
三角波からｓｉｎ波に変換され（第６図端子２６の波形
参照）可変利得増幅器６に入力される。The waveform shaper 24 is a differential amplifier consisting of a transistor Try (the transistor is omitted hereafter), Trz, and a constant current source with resistors R1 to R4, and shapes a square wave with a 90° phase difference from the pilot signal from the input terminal 1. is input to the triangular wave converter 2 in rows. As shown in FIG. 7, the triangular wave converter 2 includes Tr3+Tr4+capacitance C1 constant current source I2. Is, the capacitance C and the constant current source I2. I3 converts the square wave of the waveform shaper 24 into a triangular wave by charging and discharging (6th
(Refer to the waveform of terminal 30 in the figure). The output of the triangular wave converter 2 is Tr
s~T r s + constant current source I4. The buffer amplifier 25 consisting of Is prevents it from being affected by the input impedance of the pseudo sine wave converter 27.
The n-wave converter 27 includes resistors R5 to R7, Tr 9°Tr
,. , constant current sources re and It are converted from triangular waves to sine waves by differential input/output characteristics (see waveforms at terminals 26 in FIG. 6) and input to the variable gain amplifier 6.
加算器以後については、第１図で説明した内容と同じで
あり、第５図のシステムにおいては、２入力加算器８に
おけるパイロット信号とパイロット信号除去用疑似ｓｉ
ｎ波の関係は逆位相で同レベルとなり端子１４には疑似
ｓｉｎ波で除去されたステレオ信号が出力され、第１図
のシステムにおける三角波での除去よりも効率がよい。The contents after the adder are the same as those explained in FIG. 1, and in the system shown in FIG.
The relationship between the n waves is that they have opposite phases and the same level, and a stereo signal removed by a pseudo sine wave is outputted to the terminal 14, which is more efficient than the removal by a triangular wave in the system of FIG.
以上説明したように本発明におけるパイロット信号除去
システムにおいては、除去用信号である三角波とパイロ
ット信号の信号レベルが常に同レベルになる為、パイロ
ット信号を完全に除去し、従来回路においての、三角波
の加算率の調整も必要無くなり、セット上における調整
工数の削除が可能となる。さらに集積回路化した場合調
整端子の削減、さらにパイロット信号除去率が高くかく
安定に維持、継続可能となる。さらに、三角波変換器２
と可変利得増幅器６との間に三角波から正弦波への変換
回路を挿入することによりパイロット除去率の増大及び
レベル検波回路１１，１２がまったく同じ回路を使用で
きる利点もある。As explained above, in the pilot signal removal system of the present invention, the signal level of the triangular wave, which is the removal signal, and the pilot signal are always at the same level, so the pilot signal is completely removed. There is no need to adjust the addition rate, and adjustment man-hours on the set can be eliminated. Furthermore, when it is integrated into an integrated circuit, the number of adjustment terminals can be reduced and the pilot signal rejection rate is high, making it possible to maintain stability and continue. Furthermore, the triangular wave converter 2
By inserting a triangular wave to sine wave conversion circuit between the variable gain amplifier 6 and the variable gain amplifier 6, there is an advantage that the pilot rejection rate can be increased and that the level detection circuits 11 and 12 can use exactly the same circuit.
角波変換器、３，１７・・・・・・三角波変換器出力端
子、６．１８・・・・・・可変利得増幅器、７，１９・
・・・・・可変利得増幅器出力端子、８，２０・・・・
・・加算器、９゜２１・・・・・・可変利得増幅器制御
端子、１０・・・・・・比較器、１１，１２．２２・・
・・・・レベル検波回路、１３゜２３・・・・・・ステ
レオ信号入力端子、１４．２４・・・・・・出力端子、
２４・・・・・・波形整形器、２７・・・・・・疑似ｓ
ｉｎ波変換器、２５・・・・・・バッファアンプ。Angular wave converter, 3, 17... Triangular wave converter output terminal, 6.18... Variable gain amplifier, 7, 19...
...Variable gain amplifier output terminal, 8, 20...
...Adder, 9゜21...Variable gain amplifier control terminal, 10...Comparator, 11, 12.22...
... Level detection circuit, 13゜23 ... Stereo signal input terminal, 14.24 ... Output terminal,
24... Waveform shaper, 27... Pseudo s
In-wave converter, 25...buffer amplifier.
代理人 弁理士 内 原 晋Agent: Patent Attorney Susumu Uchihara
第１図は本発明の一実施例のシステム図、第２図は第１
図における実施例の信号波形図、第３図は従来例のシス
テム図、第４図は従来例の波形図、第５図は本発明の他
の実施例のシステム図、第６図は第５図における実施例
の信号波形図、第７図は第５図における実施例の具体的
な回路図である。
１．１５・・・・・・方形波入力端子、２，１６・・・
・・・三菊
Ｚ
図
第
図Fig. 1 is a system diagram of one embodiment of the present invention, and Fig. 2 is a system diagram of an embodiment of the present invention.
3 is a system diagram of a conventional example, FIG. 4 is a waveform diagram of a conventional example, FIG. 5 is a system diagram of another embodiment of the present invention, and FIG. 6 is a system diagram of a conventional example. FIG. 7 is a signal waveform diagram of the embodiment shown in the figure, and FIG. 7 is a specific circuit diagram of the embodiment shown in FIG. 1.15... Square wave input terminal, 2,16...
...Three chrysanthemums Z diagram
Claims (1)
可変利得増幅器の出力が２入力加算器の１つの入力と接
続され、さらに、第１のレベル検波回路の入力に接続さ
れ、２入力加算器の他の入力が第２のレベル検波回路の
入力と共通でパイロット信号除去システムの入力端子と
し、前記第１のレベル検波回路の出力と前記第２のレベ
ル検波の出力はレベル比較器の比較端子にそれぞれ接続
され、前記レベル比較器の出力が前記可変利得増幅器の
増幅率制御端子に接続され、前記２入力加算の出力をパ
イロット信号除去システムの出力端子とすることを特徴
とするパイロット信号除去回路。The output of the triangular wave converter is supplied to a variable gain amplifier, and the output of the variable gain amplifier is connected to one input of a two-input adder, which is further connected to the input of a first level detection circuit, and the output of the variable gain amplifier is connected to one input of a two-input adder. The other input is common to the input of the second level detection circuit and serves as an input terminal of the pilot signal removal system, and the output of the first level detection circuit and the output of the second level detection are the comparison terminals of the level comparator. a pilot signal removal circuit, wherein the output of the level comparator is connected to an amplification factor control terminal of the variable gain amplifier, and the output of the two-input addition is used as an output terminal of a pilot signal removal system. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1036548A JP2711343B2 (en) | 1988-04-25 | 1989-02-15 | Pilot signal removal circuit |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63-103286 | 1988-04-25 | ||
| JP10328688 | 1988-04-25 | ||
| JP1036548A JP2711343B2 (en) | 1988-04-25 | 1989-02-15 | Pilot signal removal circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0229039A true JPH0229039A (en) | 1990-01-31 |
| JP2711343B2 JP2711343B2 (en) | 1998-02-10 |
Family
ID=26375610
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1036548A Expired - Fee Related JP2711343B2 (en) | 1988-04-25 | 1989-02-15 | Pilot signal removal circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2711343B2 (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5487101A (en) * | 1977-12-23 | 1979-07-11 | Hitachi Ltd | Adjusting circuit for electronic circuit |
| JPS5853805A (en) * | 1981-09-25 | 1983-03-30 | Matsushita Electric Ind Co Ltd | Inductance adjustment method and inductor |
| JPS5871742A (en) * | 1981-10-26 | 1983-04-28 | Matsushita Electric Ind Co Ltd | Canceling circuit of pilot signal |
| JPS6041337A (en) * | 1984-06-22 | 1985-03-05 | Pioneer Electronic Corp | Pilot signal eliminating circuit of fm stereo receiver |
| JPS6058725A (en) * | 1983-09-09 | 1985-04-04 | Sanyo Electric Co Ltd | Harmonic eliminating circuit |
-
1989
- 1989-02-15 JP JP1036548A patent/JP2711343B2/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5487101A (en) * | 1977-12-23 | 1979-07-11 | Hitachi Ltd | Adjusting circuit for electronic circuit |
| JPS5853805A (en) * | 1981-09-25 | 1983-03-30 | Matsushita Electric Ind Co Ltd | Inductance adjustment method and inductor |
| JPS5871742A (en) * | 1981-10-26 | 1983-04-28 | Matsushita Electric Ind Co Ltd | Canceling circuit of pilot signal |
| JPS6058725A (en) * | 1983-09-09 | 1985-04-04 | Sanyo Electric Co Ltd | Harmonic eliminating circuit |
| JPS6041337A (en) * | 1984-06-22 | 1985-03-05 | Pioneer Electronic Corp | Pilot signal eliminating circuit of fm stereo receiver |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2711343B2 (en) | 1998-02-10 |
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