Optonica
ST-3636 features:
FM IF AMP.
Section
FM Front-End
Circuit
FM IF Band with Selector Circuit
FM Tuning
Auto-Lock Circuit
FM Detection
Sections (Quadrature Detector Circuit)
Hi-Blend
Circuit
Low-Frequency
Amplifier Circuit
Power Supply
Circuit
Audio Muting
Circuit
FM Detector
Circuit. This unit employs "Quadrature Detector" based on newly
developed IC, which is substituted for ratio detector and Foster-Seeley's
detector that have been sp far used. The basic structure of quadrature detector
circuit is as shon.
Multipath
Detection Circuit
Multipath
Distortion. In any of electric-wave signals broadcasting including FM waves, it
would be ideal if the signals emitted by abroadcasting station were caught by a
receiver's antenne as they midway. Actually saying, however, there are
practically some obtacles (like mountains and
skyscrapers, etc.) between the transniter side and the receiver side,
which have the emitted signals undergo a phenomenon of waves reflection,
leading to that the signals become distored variously when caughtby the
receiver's antenna
A simple
exampleconcering this distortion is that in the mountainous area or large
cities full of higher buildings, the TV stes get produced images be doubled
(this called a ghost). This phenomenon is a sort of multipath distortion and it
is caused by the there is a time delay betweenthe direct waves and reflected
waves. In the case of radio sets, this is reffed to as that the reproduced
sounds contain distortions; particularlyas for stereo broadcasting signals,
since their band width is rather wider and so they are apt to be interferred by
various objects, not only the distorted sounds are produced but also the stereo
separation characteristics will suffer. These phenomena are named a multipath
distortion.
Multipath
Distortion Detection. Multipath distortion are classified into the two, that
is, phase distortion which is found out by the frequency discriminator and AM
distortion which is removed by the limiter circuit; the latter AM distortion is
actually subject to detection by the multipath detector circuit.
FM Stereo
Demodulator Section
Features of
PLL Stereo demodulator Circuit.
This set
incorporates a stereo demodulator circuit that comprises ICs with the PLL
(Phase Locked Loop) system applied. The PLL FM demodulator circuit is provided
with such characteristics as mentioned
below.
In order to
demodulate stereo composite signals, it is necessary to take a 19 kHz pilot
signal out of the stereo composite signals and to make it a 38 kHz signal. Most of the conventional methods to obtain
such a 38 kHz signal are frequency doubling ones which utilize a nonlinearity
of the elements. Compared with the conventional type, the recently developed
IC-ed demodulator provides more sufficient separation effects. However, since it also requires 2 or 3 coils
like the conventional one, if even one of them is dislocated from the initially
adjusted point due to a secular change the separation effects will be
deteriorated. Moreover there is such a contradiction that the more the
efficiencies of the coils are increased enough to withstand the outer pulse
signals like automobil ignition noises, the more the coils suffer secular
changes.
To eliminate
such disadvantages as above, PLL system is employed in the method to make a 38
kHz signal using a 19 kHz pilot signal.
Variable Air
Check Calibrator Circuit
Theis
circuit is to make appropriate the recording level in advance when recording FM
broadcast into the tape deck or equivalent.
The
circuit is reffered to as this variable
air check calibratoe circuit and it is composed of an air check oscillator
circuit, air check meter indication circuit and further a circuit by which,
when the air check/muting switch is set to 'air check on' position during FM
reception, the indication mode of the signal/air check meter will be changed
from 'signal level' to 'air check level' indication.
Specifications
FM Section
Tuning
Range: 87,6 -108 MHz
IF: 10,7 MHz
Sensitivity
(at SN 26 dB, 40 kHz deviation): 1,4 µV
Frequency
Response: 30 - 15,000 Hz +1,5 -3 dB
Image
Rejection: 110 dB (at 98 MHz)
IF
rejection: 100 dB (at 98 MHz)
Selectivity
[normal/wide]: 72 dB / 30 dB
Capture
Ratio [normal/wide]: 2,5 dB / 1,5 dB
AM
Suppression: 45 dB
Signal-to-Noise
Ratio: 65 dB (40 Hz deviation)
Distortion
[normal/wide]
Mono : 0,6% / 0,25%
Stereo: 0,8% / 0,4%
Stereo
Separation: 42 dB (1 kHz)
AM Section
Tuning
Range: 520 - 1620 kHz
IF: 455 kHz
Quieting
Sensitivity: 400 µV/m
Image
Rejection: 55 dB (at 1400 kHz)
IF
Rejection: 50 dB (at 600 kHz)
Distortion: 1,5%
Audio
Section
FM Output
Voltage
Variable : 0
- 0,55 V
Fixed : 0,35V
AM Output
Voltage:
Variable
: 0 - 0,35 V
Fixeed
: 0,2 V
Circuit: Superheterodyne system, 2-band with PLL
stereo demodulator
Featured: FM muting, FM multipath detection, variable
air check calibrator, FM auto lock, FM IF band selector circuit
Semiconductors: 28 Transistor, 36 Diode (1-zener diode); 4
ICs, 3 FET (dual gate, MOS type); 3 LED
Power
Source: AC 110/220/240V, 50/60 Hz
Power
Consumption: 24 W
Dimensions
(W x H x D): 442 x 144 x 373 mm
Weight: 7,5 kg
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