Curriculum
Details
Sample
Activities
SIP358C
FM Stereo Multiplex Transmitter
SCOPE OF THE STUDY
A high-technology FM Stereo Multiplex Transmitter designed to teach and demonstrate
the principles of multiplexing two signals on a single RF carrier. The transmitted signal
is in the range of 88-108 MHz. The nominal transmitter frequency is 107 MHz.
The FM Stereo Multiplex Transmitter is similar in operation to a commercial
transmitter, with a pilot tone, (L+R) and (L-R) signals. The Trainer also serves as an FM
sweep generator. The reactance (veractor) modulator is provided with either two audio
tones (1 KHz and 400 Hz) or an external stereo signal.
The composite signal output includes fully adjustable signals of (L+R), (L-R), (L), (R),
and a 19 KHz pilot signal.
The center operating frequency of 10.7 MHz is phase-locked loop controlled against a 4 MHz crystal oscillator. The frequency stabilizing circuitry uses binary ripple dividers and phase comparators. The RF frequency is multiplied up to 107 MHz with wide band commercial deviation. The two audio tones (1 KHz and 400 Hz) are also crystal controlled from the same 4 MHz crystal oscillator.
When used with an FM receiver, the transmitter's oscillator can be swept at 60 Hz in order to study the detector circuit tuning of the receiver. The FM Stereo Receiver (SIP328) is a companion to the transmitter, or any FM receiver can be used.
The transmitter suppresses the 38 KHz signal and transmits a 19 KHz pilot tone. Two frequency synthesizers are incorporated into the system design.
The transmitter has a variety of test points which are used by the student to observe the various signals and voltages present throughout the system.
COURSE TIME: 50 hours
FEATURES
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Broadcast RF Output in the 88-108 MHz Range |
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Commercial-Type Multiplex Stereo with Standard Pre-emphasis (L+R) (L-R) (+19KHz) |
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Crystal-Stabilized Phase-Locked Loop RF Oscillator, 10.7 MHz |
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Used as Transmitter or RF Sweep Generator |
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Standard Commercial Audio Deviation Capability |
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Radiated Power Less than 100 mW |
EXPERIMENTAL TOPICS: The FM Transmitter
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Introduction to the FM Transmitter
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Transmitter Circuitry--RF Section
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RF Multipliers
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Frequency Deviation by Multipliers
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Frequency Deviation Modulation Index
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Toroidal-Core Transformers
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Pulse-Counter AFC System
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Frequency-Lock AFC System
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Digital Phase-Locked System
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Experimental Digital AFC
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The Crystal-Controlled Section
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The RF Oscillator Signal
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Sine Wave Generation of 1 KHz, 400 Hz, 38 KHz
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Square Wave Generation of 19 KHz
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Developing Stereo Signals
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Adding and Subtracting Audio Signals
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The Experimental Transmitter Encoder Section
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The Receiver Decoder Section
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The Deviation Display Monitor
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The Deviation Modulation Display
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The Ten-Segment Display
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The Sweep Generator
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FM Detectors
EQUIPMENT
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SIP358. FM Stereo Multiplex Transmitter Panel |
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SIP358M. Laboratory Manual |
SPECIFICATIONS
The FM Stereo Multiplex Transmitter (Generator) includes state-of-the-art devices, and techniques for producing multiplexed signals on an FM carrier. The Panel design contains a variety of test points and malfunction switches to enable the student to learn troubleshooting of an AM transmitter and/or stereo multiplex generator instrument.
The power output of the transmitter is less than 100 mW, thus enabling several transmitters and receivers to be operated in the laboratory with a minimum of interference.
Level indicators for modulation are incorporated into the design, and the student is able to determine the degree of frequency deviation from the modulating signal.
The transmitter is designed to function with the Science Instruments Power Supply Base (S300PSB) or the Master Builder (S300B).