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发表于 2024-4-30 17:11:55
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山水T-7 收音头自动搜索原理翻译
（by高老庄2024年4月30日）
2. OPERATIONS OF MOTOR DRIVE SERVO LOCK SYSTEM
The tuner T-7 adopts a motor drive servo lock system. Therefore, it is possible to perform a stable tuning operation based on automatic follow-up control, even when the tuned frequency fluctuates for some reason or other.
The operations of the automatic search tuning by the motor drive
servo lock system will be described below simply.
(T-7 See Block Diagram)
2.伺服电机调谐系统的原理
调谐器T-7采用了一套伺服电机调谐系统。因此，即使当调谐频率由于手动或其他原因发生漂移时，也可以基于自动跟随控制稳定于锁定的电台。
下面将简单地描述这套由伺服电机驱动的自动搜索调谐系统。
（请参照T-7方框图）
Automatic search operation
When depressing once the up-search key fsw 1 and down-search key fsw 2, the servo motor begins to rotate and therefore the dial tuning mechanism operates to move the variable tuning condenser.
自动搜索开始
当按下向上搜索键fsw1和向下搜索键fsw 2一次时，伺服电机开始转动，通过拉线带动刻度盘指针和可变电容开始自动调谐操作。
Automatic search stop operation
When the tuner is set to a desired broadcasting station, the search circuit changes to a cut-off state by the IF signal and therefore the servo motor stops rotating, so that the operation of the dial tuning mechanism stops temporarily.
自动搜索停止
当调谐器检测到广播信号时，会产生IF信号，IF信号将搜索调谐电路变为截止状态，同时伺服电机停止转动，调谐机构暂停动作。
Servo lock operation
When the tuner has been set to a desired broadcasting station, the servo motor actuates the dial tuning mechanism so that the optimum tuning point can be obtained by using the AFC voltage gene.rated by detecting the IF signal.
电台锁定
当调谐器检测到广播信号时，调谐电路通过检测IF信号产生AFC压差信号，伺服电机根据压差信号驱动调谐机构进行微调，获得最佳调谐点。
2-1. Automatic search tuning operation in FM receiving
When depressing once the up-search key fswl, a minus trigger pulse signal is inputted to the terminal No. 13 of the flip-flop cir.cuit (up/down) fIC2a.
Accordingly, the terminal No. 11 of the flip-flop circuit flC2a changes to H level in potential. After having been inversed through the inverter fIC3 to L level in potential, the pulse signal is applied to the level comparator fIC1b through the transistor fQ4.
(Since a minus trigger pulse signal is also applied to the flip-flop circuit (search on/off) fIC2b, the terminal No. 3 of the flip-flop fIC2b changes to H level in potential to turn on the transistor fQ4.)
As a result, the output terminal No. 1 of the level comparator
fICIb changes to a plus voltage.
Therefore, a plus voltage +B is supplied to the servo motor to rotate it counterclockwise, so that the variable tuning condenser is rotated.
2-1. 调频接收中的自动搜索调谐操作
当按下一次向上搜索键fsw1时，一个负触发脉冲信号被输入到触发器电路（向上/向下）fIC2a的输入端13，触发器电路flC2a的输出端11的电位变为H电平。在已经通过反相器fIC3被反相到L电平后，脉冲信号通过晶体管fQ4被施加到电平比较器fIC1b。（注：即电机驱动比较器输入端2）
由于负触发脉冲信号也被施加到触发器电路（搜索开始/停止）fIC2b输入端1，触发器fIC2b的输出端3的电位变为H电平，加到fQ4基极以使晶体管导通。
结果是，电平比较器fICIb的输出端1 变为正电压，fQ8导通，正电压+B加至伺服电机以使其逆时针旋转，带动可调电容转动。
When the tuner is set to a desired broadcasting station by the operation of the dial tuning mechanism by the servo motor, the FM muting signal from the terminal No. 12 of the IF amplifier/quadrature detector dIC1 changes from H level to L level in potential.
In addition, the signal 2 from the terminal No. 10 of the signal
indicator driver slC1, changes to H level in potential.
When the above-mentioned FM muting signal and signal 2 are inputted to the search stop section made up of the transistors fQS, fQ6, fQ7 and the inverter fIC3f,the transistor fQ7 is turned off, and the terminal No. 6 of the inverter fiC3f changes from H level to L level in potential.
As a result, a minus trigger pulse is inputted to the terminal No. 6 of the flip-flop circuit (search on/off) fIC2b, and therefore the terminal No. 3 of the flip-flop circuit fIC2b changes to L level in potential to turn off the transistor fQ4.
Accordingly, no servo motor control voltage is inputted from the flip-flop circuit (up/down) fIC2a to the level comparator fiC1b,so that the search operation of the dial tuning mechanism is stopped.
电机驱动调谐机构接收到电台信号时，来自IF放大器/正交检测器dIC1的引脚12的FM静音信号的从H电平变为L电平（LA1231的引脚12即静音输出）。
同时，信号强度指示驱动器slC1的引脚10变为H电平，即信号②变高。（LA1231的13脚的信号电平输出至信号强度指示驱动器LB1416，LB1416的10脚接第二个指示灯sLD8,即有信号时sLD8会点亮，信号②即signal ②变高）。
当上述FM静音信号（L）和信号②（H）被输入到由晶体管fQS、fQ6、fQ7和反相器fIC3f组成的搜索停止部分时，晶体管fQ7截止，反相器fIC3f的输出端6的电位从H电平变为L电平，L电平被输入到触发器电路（搜索开始/停止）fIC2b的输入端子No.6，触发器电路fIC1b的输出端子No.3的电位变为L电平以截止晶体管fQ4。
fQ4截止后，就没有控制电压从触发器电路（向上/向下）fIC2a输入到电平比较器fIC1b，伺服电机从而停止调谐机构的搜索。
After the tuner has been set to a desired broadcasting station,the AFC voltage from the terminal No. 7 of the IF amplifier/quadrature detector dIC1 is inputted to the level comparator fIC1b.
This AFC voltage becomes higher than the reference AFC volt.age when the tuner is set to a frequency higher than a desired tuning point, and lower than the reference AFC valtage when set to a frequency lower than a desired tuning point. Therefore, the relationship between AFC voltage and received frequency has characteristics shown by a S-curve graphical representation.Whenever the turner is set to a frequency apart from a desired tuning point, a plus voltage +B or a minus voltage -B is necessarily applied to the servo motor to rotate it clockwise or counterclockwise.
When the tuner is set correctly to the optimum tuning point,since the AFC voltage coincides with the reference voltage, the voltage between the two input terminals of the level comparator fICIbbecomes zero and therefore the servo motor stops rotating.
电机驱动调谐机构接收到电台信号时，来IF放大器/正交检测器dIC1的引脚7的AFC电压（AFC signal）被输入到电平比较器fIC1b。
当调谐器被设置为高于所需调谐点的频率时，该AFC电压变得高于AFC参考电压（由LA1231外围电路产生的信号⑤），而当被设置为低于所需调谐点时将低于AFC参考电压。因此，AFC电压和接收频率之间的关系具有由S曲线图形表示所示的特性。因此，只要当前频率与所需调谐点不同，或高或低比较器都将翻转，向伺服电机施加正电压+B或负电压-B，使其顺时针或逆时针旋转。
当调谐器被正确地设置到最佳调谐点时，由于AFC电压与参考电压一致，电平比较器fICIbbe的两个输入端子之间的电压变为零，此时伺服电机停止旋转。
2-2. Automatic search tuning operation in AM receiving
Almost the same automatic search tuning operation is carried out in AM receiving or in FM receiving. In AM receiving, however, the search stop operation is carried out by using only the signal 2.
After the tuner has been set to a desired AM broadcasting station,the IF signal from the terminal No. 9 of the AM-IF amplifier elC1 is FM-detected by the detector made up of the transisior fQl,transformer coils fT1 and fT2 and diodes fD12 and fD13 and next inputted to the level comparator fIC1b.
This AFC voltage actuates the servo motor for dial tuning operation,so that the received frequency can be set to the optimum tuning point in the same way as in FM receiving.
2-2. AM 接收中的自动搜索调谐
在AM接收自动搜索调谐与FM接收几乎相同的自动搜索调谐，但在AM接收中，仅通过使用信号2来执行停止搜索。
在调谐器已经被设置到期望的AM广播电台之后，来自AM-IF放大器elC1的引脚的IF信号被由晶体管fQ1、变压器线圈fT1和fT2以及二极管fD12和fD13组成的频率调制检测器（此处还没搞懂），产生AFC信号，输入到电平比较器fIC1b。
该AFC电压驱动伺服电机进行调谐操作，从而可以以与FM接收相同的方式将接收的频率设置为最佳调谐点。
2-3. Search operation by touch sensor and stop of
servo lock operation
When touching the tuning knob with the hand, hum noise is pro duced from the knob. By utilizing this hum noise, the search operation and the servo lock operation can be stopped. After having been amplified by the amplifier fIC1a, the hum noise is detected by the detectors fD1 and fD2 into a H-level voltage. This H-level signal is passed through the diode fD14 and applied to the terminal No. 7 of the automatic search stop circuit fIC3f to stop the search operation.Also, since this H-level signal is applied to the bases of the transistors fQ2 and fQ3 to turn them on, no AFC signal is inputted to the level comparator fICIb, and therefore the servo lock operation stops.
(In the case of AM receiving, this H-level signal changes the AM-IF waveform shaper fIC3b into a cut-off state to prevent the AFC voltage from being generated.)
Therefore, the automatic tuning operation changes to the manual tuning operation whenever the hand is brought into contact with the tuning knob。
2-3. 通过触摸传感器进行搜索和停止伺服锁定操作
当用手触摸调谐旋钮时，旋钮会产生感生电压。通过利用这种感生电压，可以停止搜索操作和伺服锁定操作。感生电压被放大器fIC1a放大之后，被检测器fD1和fD2检测为H电平（即图中Auto Tune Stop Signal）。该H电平信号通过二极管fD1并施加到自动搜索停止电路fIC3f的端子7以停止搜索操作。此外，由于该H电平信号被施加到晶体管fQ2和fQ3的基极以使它们导通，所以没有AFC电压信号被输入到电平比较器fICIb，因此伺服锁定操作停止（此时比较器输入端被短接，电平一致）。
在AM接收的情况下，该H电平信号将AM-IF波形整形器fIC3b改变为截止状态，以防止AFC电压的产生。
因此，每当手与调谐旋钮接触时，自动调谐操作就变为手动调谐操作。 |
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