JPS62294316A - Am radio receiver - Google Patents
Am radio receiverInfo
- Publication number
- JPS62294316A JPS62294316A JP11509586A JP11509586A JPS62294316A JP S62294316 A JPS62294316 A JP S62294316A JP 11509586 A JP11509586 A JP 11509586A JP 11509586 A JP11509586 A JP 11509586A JP S62294316 A JPS62294316 A JP S62294316A
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- signal
- agc
- sensitivity
- search
- 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
- 230000035945 sensitivity Effects 0.000 claims abstract description 15
- 230000005684 electric field Effects 0.000 abstract description 12
- 238000010586 diagram Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000013016 damping Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Landscapes
- Channel Selection Circuits, Automatic Tuning Circuits (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Abstract
Description
【発明の詳細な説明】
3、発明の詳細な説明
(イ)産業上の利用分野
本発明は、オートサーチ機能を有するとともに広帯域R
F AGC回路を備えるAMラジオ受信機の改良に係
り、特にオートサーチ動作時における誤停止を防止した
AMラジオ受信機に関する。Detailed Description of the Invention 3. Detailed Description of the Invention (a) Industrial Application Field The present invention has an auto search function and a broadband R
The present invention relates to an improvement of an AM radio receiver equipped with an AGC circuit, and particularly relates to an AM radio receiver that prevents erroneous stoppage during auto-search operation.
(ロ)従来の技術
実開昭58−116314号公報に開示された如く、広
帯域RF AGC回路を備えるAMラジオ受信機が知
られている。前記AMラジオ受信機は、第2図に示す如
く、アンテナ(1)に受信されたRF倍信号増幅するF
E T (2)と、該FET(2)のドレインにカス
ケード接続きれたA G C+−ランジスタ(3)と、
該AGCl−ランジスタ(3)のミニ2レクタに接続さ
れた同調コイル(4)及び可変容量ダイオードを含むR
F同調回路(5)と、前記同調コイル(4)と負荷抵抗
(6〉との接続点に得られる増幅されたRF倍信号用い
て利得制御を行なう為のAGC信号を発生するAGC駆
動回路(7)とを備えるものである。しかして、アンテ
ナ(1)に受信されるRF倍信号電界強度が小の場合に
は、AGC駆動回路(7)の出力AGCt圧が高くなり
、AGCトランジスタ(3)の導通度が増大し、前記R
F倍信号電界強度が犬の場合には、AGC駆動回路(7
)の出力AGC電圧が低くなり、アンデーナダンピング
回路がオンしてFET(2)の入力制限を行なうととも
に、AGCトランジスタ(3)の導通度が低下するので
、安定なAGC動作を行なわせることが出来る。また、
RF倍信号電界強度を示す信号としては、同調コイル(
4)と負荷抵抗(6)との接読点に発生する帯域制限を
受けない信号が用いられるので、前記AGC動作は広帯
域となる。(b) Prior Art As disclosed in Japanese Unexamined Utility Model Publication No. 58-116314, an AM radio receiver equipped with a wideband RF AGC circuit is known. The AM radio receiver, as shown in FIG.
E T (2), an A G C+- transistor (3) cascade-connected to the drain of the FET (2),
R including a tuning coil (4) and a variable capacitance diode connected to the mini-2 rector of the AGCl-transistor (3).
An AGC drive circuit (5) that generates an AGC signal for gain control using an amplified RF multiplied signal obtained at the connection point between the F tuning circuit (5) and the tuning coil (4) and the load resistor (6). 7).However, when the RF multiplied signal electric field strength received by the antenna (1) is small, the output AGCt pressure of the AGC drive circuit (7) becomes high, and the AGC transistor (3) ) increases, and the conductivity of R
When the F-fold signal electric field strength is dog, the AGC drive circuit (7
) becomes low, the antenna damping circuit turns on and limits the input of FET (2), and the conductivity of AGC transistor (3) decreases, making it difficult to perform stable AGC operation. I can do it. Also,
As a signal indicating the RF multiplied signal electric field strength, the tuning coil (
4) and the load resistor (6), which is not subjected to band limitation, is used, so the AGC operation is performed over a wide band.
ところで、強電界局の近傍に存在する弱電界局の信号を
受信する為には、広帯域RF AGC回路の感度を低下
させる必要がある。前記広帯域RF AGC回路の感度
を低下許せ、AGC動作の開始レベルを混信が発生する
直前まで遅らせると、前記弱電界局からの信号を明瞭に
受信出来る為、通常のAMラジオ受信機においては、前
記広帯域RFAGC回路の感度をある程度低く押さえて
いる。By the way, in order to receive a signal from a weak electric field station located near a strong electric field station, it is necessary to reduce the sensitivity of the wideband RF AGC circuit. If the sensitivity of the broadband RF AGC circuit is allowed to decrease and the start level of AGC operation is delayed until just before interference occurs, the signal from the weak electric field station can be clearly received. The sensitivity of the broadband RFAGC circuit is kept low to some extent.
(ハ)発明が解決しようとする問題点
しかしながら、広帯域RF AGC回路の感度を低下さ
せると、相互変調特性が悪化するという別の問題が生じ
る。すなわち、アンテナ(1)に接続されたFET(2
)は、入力信号周波数の2倍の高調波を発生し易く、か
つRF同調回路(5〉に用いられている可変容量ダイオ
ードが周波数混合効果を有する為、異なる周波数の2つ
の信号がアンテナ(1)に印加されると、各々の周波数
の和及び差の周波数を有する信号や入力信号周波数の2
倍の周波数と各々の周波数との和及び差の周波数を有す
る信号が発生する。例えば、周波数fl及びf、の2つ
の局の信号がアンテナ(1)に受信された場合、rI+
rx、t、−r、、2 f’l+ r*、2fIf’s
等の様々な周波数を有する信号が発生する。(C) Problems to be Solved by the Invention However, when the sensitivity of the wideband RF AGC circuit is reduced, another problem arises: the intermodulation characteristics deteriorate. That is, FET (2) connected to antenna (1)
) tends to generate harmonics twice the input signal frequency, and the variable capacitance diode used in the RF tuning circuit (5) has a frequency mixing effect, so two signals with different frequencies are transmitted to the antenna (1). ), the signal having the sum and difference frequencies of each frequency or two of the input signal frequencies
A signal having a frequency that is the sum and difference of the double frequency and each frequency is generated. For example, if signals from two stations with frequencies fl and f are received by antenna (1), then rI+
rx, t, -r,, 2 f'l+ r*, 2fIf's
Signals having various frequencies are generated.
そして、例えば2 f’、−f、という信号が受信帯域
内に入ると、低感度の広帯域RF AGC回路を有する
AMラジオ受信機においてオートサーチを行なわせた場
合、本来局の無い2 f、−f’!という周波数でオー
トサーチが停止するという誤動作を生じる。For example, when a signal 2 f', -f enters the reception band, if an AM radio receiver with a low-sensitivity wideband RF AGC circuit performs an auto search, the signal 2 f', -f, which originally does not have a station, will be detected. f'! This causes a malfunction in which the auto search stops at this frequency.
(ニ)問題点を解決するための手段
本発明は、上述の点に鑑み成されたもので、オートサー
チの誤停止を防止する為、オートサーチ開始を知らせる
信号に応じて、広帯域RF AGC回路の感度を上昇さ
せる手段を設けた点を特徴とする。(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned points, and in order to prevent erroneous termination of auto search, a wideband RF AGC circuit is installed in response to a signal notifying the start of auto search. It is characterized by providing means for increasing the sensitivity of the sensor.
(*)作用
本発明に依れば、通常の受信時における広帯域RF
AGC回路の感度を低く押さえ、弱電界局を良好に受信
することが出来る。また、オートサーチ時には、広帯域
RFAGC回路の感度を」−4′C!せ、オートサーチ
の誤停止を防止出来る。(*) Effect According to the present invention, wideband RF during normal reception
It is possible to keep the sensitivity of the AGC circuit low and receive weak electric field stations well. Also, during auto search, the sensitivity of the wideband RFAGC circuit is set to -4'C! This prevents automatic search from stopping erroneously.
(へ)実施例
第1図は、本発明の一実施例を示す回路図で、(8)は
オートサーチ時にRF同調回路(5)の可変合液ダイオ
ードの容量を可変させるオートサーチ信号を発生ずると
ともに、AMラジオ受信機がオートサーチ動作中である
ことを示す制御信号を発生ずるオートサーチ回路、(9
)は該オートサーチ回路(8)からの制御信号に応じて
切換えられ、同調コイル(4)と負荷抵抗(6)との接
続点に得られる増幅きれたRF倍信号第1もしくは第2
出力端子に発生するスイッチ回路、(lO)は該スイッ
チ回路(9)の第1出力端子に発生するRF倍信号第1
の利得GIで増幅する第1増幅回路、(11)は該スイ
ッチ回路(9)の第2出力端子に発生ずるRF倍信号第
1の利得よりも小なる第2の利得G2で増幅する第2増
幅回路、及び(12)は前記第1もしくは第2増幅回路
(10)もしくは(11)の出力信号に応じたAGC信
号をAGC)ランジスタ(3)のベースに印加するAG
C駆動回路である。尚、第1図において第2図と同一の
回路素子には同一の符号を付し、説明を省略する。(f) Embodiment Figure 1 is a circuit diagram showing an embodiment of the present invention, and (8) is an auto search signal that generates an auto search signal that varies the capacity of the variable mixer diode of the RF tuning circuit (5) during auto search. an auto search circuit (9) which generates a control signal indicating that the AM radio receiver is in the auto search operation;
) is switched according to the control signal from the auto search circuit (8), and the amplified RF multiplied signal obtained at the connection point between the tuning coil (4) and the load resistor (6) is switched to the first or second amplified RF signal.
The switch circuit generated at the output terminal, (lO) is the first RF multiplied signal generated at the first output terminal of the switch circuit (9).
A first amplifier circuit (11) amplifies the RF multiplied signal generated at the second output terminal of the switch circuit (9) with a second gain G2 that is smaller than the first gain. an amplifier circuit, and (12) an AG that applies an AGC signal according to the output signal of the first or second amplifier circuit (10) or (11) to the base of the AGC transistor (3);
This is a C drive circuit. In FIG. 1, circuit elements that are the same as those in FIG. 2 are designated by the same reference numerals, and explanations thereof will be omitted.
いま、AMラジオ受信機をオートサーチ状態にしたとす
ると、オートサーチ回路(8)から制御信号が発生し、
スイッチ回路(9)を第1の状態に切換える。すると、
同調コイル(4)と負荷抵抗(6)との接続点に発生し
たRF倍信号、前記スイッチ回路(9)を介して第1増
幅回路(10)に印加きれ、利得G、で増幅された後A
GC駆動回路(12)に印加される。従って、広帯域R
F AGC回路の感度が上昇し、相互変調により発生ず
る不要信号が十分に抑圧され、前記不要信号周波数にお
けるオートサーチの誤停止が藺止される。そして、オー
トサーチにより希望局が受信されると、オートサーチ回
路(8)からの制御信号が無くなり、スイッチ回路(9
)が第2の状態に切換わる。その場合、前記制御信号は
、例えばオートサーチ釦(図示せ4”)の抑圧に応して
セットされ、ストップ信号に応じてリセットされるブリ
ップフロップ回路をオートサーチ回路(8〉中に設けて
おけは、簡単に発生さけることが出来る。Now, if we put the AM radio receiver into the auto search state, a control signal is generated from the auto search circuit (8),
Switch the switch circuit (9) to the first state. Then,
The RF multiplied signal generated at the connection point between the tuning coil (4) and the load resistor (6) is applied to the first amplifier circuit (10) via the switch circuit (9), and is amplified with a gain of G. A
It is applied to the GC drive circuit (12). Therefore, wideband R
The sensitivity of the FAGC circuit increases, unnecessary signals generated by intermodulation are sufficiently suppressed, and erroneous termination of auto search at the unnecessary signal frequency is prevented. When the desired station is received by auto search, the control signal from the auto search circuit (8) disappears and the switch circuit (9
) switches to the second state. In that case, the control signal may be set in the auto-search circuit (8), for example, by providing a flip-flop circuit that is set in response to the suppression of the auto-search button (4'' shown in the figure) and reset in response to the stop signal. can be easily avoided from occurring.
また、通常の受信状態においては、オー1・゛す一チ状
態を示す制御信号が存在しないから、スイッチ回路(9
)は第2の状態を維持し、同調コイル(4)と負荷抵抗
(6)との接続点に得られるRF倍信号、スイッチ回路
(9)を介して第2増幅回路(11)に印加され、利得
G、で増幅された後AGC駆動回路(12)に印加され
る。従って、広帯域RF AGC回路の感度が低下し、
強電界局近傍の弱電界局を良好に受信することが111
来る。In addition, in the normal reception state, there is no control signal indicating the 1/2 state, so the switch circuit (9
) maintains the second state, and the RF multiplied signal obtained at the connection point between the tuning coil (4) and the load resistor (6) is applied to the second amplifier circuit (11) via the switch circuit (9). , gain G, and then applied to the AGC drive circuit (12). Therefore, the sensitivity of the wideband RF AGC circuit decreases,
Good reception of weak electric field stations near strong electric field stations is 111
come.
第3図は、第1図のスイッチ回路(9)、第1及び第2
増幅回路(10)及び(11)の具体回路例を示すもの
で、制御端子(13)にオートサーチ中を示ず制御信号
1H」が印加されると、第1トランジスタ(14)がオ
ンし、第2トランジスタ(15)がオフする。その為、
差動増幅回路(↓9)の利得は、第1抵抗(17)の値
に応じて定まる値G、となり、入力端)(18)に印加
されるRF倍信号、前記差動増幅回路(功)において利
得G1で増幅され、出力l・ランジスタ(19)のエミ
ッタから第1図のAGC駆動回路(12)に印加される
。また、通常の受信状態においては、制御信号r H、
が印加されないので、第11−ランジスタ(14)がオ
フ、第2トランジスタ(15)がオンとなり、差動増幅
回路(功)の利得は第1及び第2抵抗(17)及び(2
0)で決まる値G、(ただしG、>(、)となる。その
為、入力端子(18)に印加されるRF倍信号、前記差
動増幅回路(Vりにおいて利得G、で増幅され、出力ト
ランジスタ(19〉のエミッタからAGC駆動回路(1
2)に印加される。それ故、第1抵抗(17)の値をF
ET(2)及びRF同調回路(5)で相互変調が発生し
ない様に設定し、第1及び第2抵抗(17)及び(20
)の並列抵抗値をFET(2)で混変調が発生しない様
に設定4れは、オートサーチの誤停止1−を防11−シ
得るとともに、弱電界局の良好な受信を達成出来る。Figure 3 shows the switch circuit (9) of Figure 1, the first and second
This shows a specific circuit example of the amplifier circuits (10) and (11). When the control signal 1H is applied to the control terminal (13) without indicating that auto-search is in progress, the first transistor (14) is turned on. The second transistor (15) is turned off. For that reason,
The gain of the differential amplifier circuit (↓9) is a value G determined according to the value of the first resistor (17), and the RF multiplied signal applied to the input terminal (18), the differential amplifier circuit (effective ) is amplified with a gain G1 and applied to the AGC drive circuit (12) in FIG. 1 from the emitter of the output l transistor (19). In addition, in the normal reception state, the control signal r H,
is not applied, the eleventh transistor (14) is turned off and the second transistor (15) is turned on, and the gain of the differential amplifier circuit is equal to the first and second resistors (17) and (2).
0) is determined by the value G, (where G>(,). Therefore, the RF multiplied signal applied to the input terminal (18) is amplified by the differential amplifier circuit (gain G at V), From the emitter of the output transistor (19) to the AGC drive circuit (1
2) is applied. Therefore, the value of the first resistor (17) is F
The ET (2) and the RF tuning circuit (5) are set so that no intermodulation occurs, and the first and second resistors (17) and (20
) is set so that cross-modulation does not occur in the FET (2), it is possible to prevent erroneous termination of auto search and achieve good reception of weak electric field stations.
第4凶は、本発明の別の実施例を示−艶回路図で、負荷
抵抗を第1及び第2負荷抵抗(21〉及び(22)に分
割し、該第1及び第2負荷抵抗(21)及び(22)の
接続点を交流的に接地する制御トランジスタ(23)を
設け、該制御トランジスタ(23)のベースにオートサ
ーチ中にr H、となる制御信号を印加する様にした点
を特徴とする。第4図の場合、オートサーチ中は制御ト
ランジスタ(23)がオフになる為、負荷抵抗値は第1
及び第2負荷抵抗(21)及び(22)の直列抵抗値と
なり、AGC駆動回路(24)に印加されるRF倍信号
レベルが犬となり、広帯域RF AGC回路の感度を
上昇きせることが出来る。また、通常受信時は制御トラ
ンジスタ(23)がオンし、第1及び第2負荷抵抗(2
1)及び(22)の接続点が交流的に接地され、第2負
荷抵抗(22)のみが負荷抵抗として作用するので、広
帯域RF AGC回路の感度を低下させることが出来る
。The fourth example is a circuit diagram showing another embodiment of the present invention, in which the load resistance is divided into a first and second load resistance (21> and (22)), and the first and second load resistance ( A control transistor (23) is provided that connects the connection point of 21) and (22) to ground in an alternating current manner, and a control signal that becomes rH during auto search is applied to the base of the control transistor (23). In the case of Fig. 4, the control transistor (23) is turned off during auto search, so the load resistance value is the first
and the series resistance value of the second load resistors (21) and (22), and the RF multiplied signal level applied to the AGC drive circuit (24) becomes a dog, making it possible to increase the sensitivity of the wideband RF AGC circuit. Also, during normal reception, the control transistor (23) is turned on, and the first and second load resistors (23) are turned on.
Since the connection point of 1) and (22) is AC grounded and only the second load resistor (22) acts as a load resistor, the sensitivity of the broadband RF AGC circuit can be reduced.
(ト)発明の効果
以上述べた如く、本発明に依れば、広帯域RFAGC回
路の感度を、オートサーチ動作中は高く、通常受信時は
低く設定することが出来るので、相互変調及び混変調を
抑圧することが出来、オー1−サーチの誤停止I−を防
止出来るとともに、弱電界局の良好な受信を達成するこ
とが出来る。(g) Effects of the Invention As described above, according to the present invention, the sensitivity of the wideband RFAGC circuit can be set high during auto-search operation and low during normal reception, thereby reducing intermodulation and cross-modulation. This makes it possible to prevent the erroneous stop of the O1 search and achieve good reception of weak electric field stations.
第1図は、本発明の一実施例を示す回路図、第2図は従
来の広帯域RF AGC回路を有するAMラジオ受信機
を示す回路図、第3図は第1図の具体回路例を示す回路
図、及び第4図は本発明の別の実施例を示す回路図であ
る。
(2)・・・FET、 (3)・・・AGCl〜ラン
ジスク、(8)・・・オートサーチ回路、(9)・・・
スイッチ回路、(10)・・・第1増幅回路、 (11
)・・・第2増幅回路、(12)・・・AGC駆動回路
。
出願人 玉洋電機株式会社外1名
代理人 弁理士 西野東嗣 外1名
第3rs
第4図FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing an AM radio receiver having a conventional wideband RF AGC circuit, and FIG. 3 is a specific example of the circuit shown in FIG. The circuit diagram and FIG. 4 are circuit diagrams showing another embodiment of the present invention. (2)...FET, (3)...AGCl~Randisk, (8)...auto search circuit, (9)...
Switch circuit, (10)...first amplifier circuit, (11
)...Second amplifier circuit, (12)...AGC drive circuit. Applicant Tamayo Denki Co., Ltd. and one other agent Patent attorney Higashi Nishino and one other person No. 3rd rs Figure 4
Claims (1)
RFAGC回路を備えるAMラジオ受信機において、前
記オートサーチ動作を行なわせる為の信号に応じて、前
記広帯域RFAGC回路の感度を上昇させる為の手段を
設けたことを特徴とするAMラジオ受信機。(1) In an AM radio receiver capable of performing an auto-search operation and equipped with a wideband RFAGC circuit, means is provided for increasing the sensitivity of the wideband RFAGC circuit in response to a signal for performing the auto-search operation. An AM radio receiver characterized by:
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11509586A JPS62294316A (en) | 1986-05-20 | 1986-05-20 | Am radio receiver |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11509586A JPS62294316A (en) | 1986-05-20 | 1986-05-20 | Am radio receiver |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS62294316A true JPS62294316A (en) | 1987-12-21 |
JPH0410245B2 JPH0410245B2 (en) | 1992-02-24 |
Family
ID=14654082
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11509586A Granted JPS62294316A (en) | 1986-05-20 | 1986-05-20 | Am radio receiver |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS62294316A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0428170A2 (en) * | 1989-11-15 | 1991-05-22 | Sanyo Electric Co., Ltd. | Radio receiver comprising automatic gain controlling function |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS54118101A (en) * | 1978-03-07 | 1979-09-13 | Nec Corp | Automatic tuning receiver |
-
1986
- 1986-05-20 JP JP11509586A patent/JPS62294316A/en active Granted
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS54118101A (en) * | 1978-03-07 | 1979-09-13 | Nec Corp | Automatic tuning receiver |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0428170A2 (en) * | 1989-11-15 | 1991-05-22 | Sanyo Electric Co., Ltd. | Radio receiver comprising automatic gain controlling function |
US5321851A (en) * | 1989-11-15 | 1994-06-14 | Sanyo Electric Co., Ltd. | Radio receiver comprising automatic gain controlling function |
Also Published As
Publication number | Publication date |
---|---|
JPH0410245B2 (en) | 1992-02-24 |
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EXPY | Cancellation because of completion of term |