telemetry types, frequency,position and multiplexing in telemetry
TRANSCRIPT
1. FREQUENCY TELEMETRY
2. POSITION TELEMETRY 3. MULTIPLEXING IN TELEMETRY
TELEMETRY
PREPARED BY
1. SAGHEER AHMED 12-03 2. HARIS KHAN 12-39
DEPARTMENT OF ELECTRONICS SEMISTER VI
INTRODUCTION• IN MODERN INSTRUMENTATION SYSTEM COMPONENTS OF
THE SYSTEM ARE LOCATED AT A DISTANCE.
• IT IS NESSESARY TO TRANSMIT MEAURED DATA.
• TELEMETRY IS THE SCIENCE OF MEAURING DATA AT A DISTANCE.
• USED IN COMMERCIAL, INDUSTRIAL, MILTARY AND SPACE OPERATIONS.
• TELEMETRY INVOLVES THE CONVERSION OF MEAURED DATA INTO REPRESENTATIVE SIGNAL .
• ON THE BASIS OF ELECTRICAL SIGNAL IT CAN BE CLASSIFIED INTO DIFFERENT TYPES SUCH AS VOLTAGE, CURRENT, POSITION AND FREQUENCY TELEMETRY.
• HERE WE DISCUSS POSITION, FREQUENCY AND MULTIPLEXING IN TELEMETRY.
FREQUENCY TELEMETRY
• MEAURED MAGNITUDES ARE REPRESENTED BY AN ALTRNATING CURRENT OR VOLTAGE OF VARYING FREQUENCY.
• SMALL VARIABLE CAPISTOR IS MECHANICALLY ATTACHED TO THE SHAFT OF INSTRUMENT.
• THIS CAPISTOR IS ELECTRICALLY ATTACHED TO THE OSCILATOR CIRCUIT
• OUTPUT FREQUENCY VARIES ACCORDING TO THE INSTRUMENT READING.
VARIBLE CAPISTORS
INTERNAL STRUCTURE OF VARIABLE CAPISTOR
VARYING AREA VARYING DISTANCE BETWEEN PLATES
PRESSURE SENSING INSTRUMENT
• THE VARYING FREQUENCY IS TRASMITTED TO RECEIVING END OVER ACHANNEL.
• CHANNEL CAN BE WIRES OR WIRELESS MEDIA.• AT RECEIVER END THIS VARYING FREQUENCY
OPERATES A DIRECT READING FREQUENCY METER CALIBRATED IN THE UNITS OF QUANTITY MEAURED AT TRANSMITTED END.
• BUT NOW A DAYS INCOMING FREQUENCY CONTROL THE MAGNITUDE OF PROPORTIONAL DIRECT CURRENT OR VOLTAGE.
APPLICATIONS
• REMOTE PRESSURE READING• FUEL OIL MONITORING• LPG TANK MONITORING• WATOR LEVEL MONITORING• REMOTE METER READING• REMOTE SPEED READING
POSITION TELEMETRY
• TRANSMITTING INSTUMENT ADJUST THE RELATION BETWEEN THE SIGNAL IN CORRESPONDING TO THE MEAUREMENT.
• RECEIVING INSTRUNENT CONVERT THESE SIGNAL INTO DISPLACEMENT.
• MECHANICAL PART REPRESENT THESE MEAUREMENTS.
• OPERATION IS BASED UPON COMPARISON OF TWO OR MORE ELECTRICAL MAGNITUDES.
• REQUIRE ATLEAST THREE CONDUCTORS BETWEEN TRANSMITTING AND RECEIVING UNITS.
MULTIPLEXING IN TELEMETRY SYSTEMS
• TRANSMISSION OF TWO OR MORE MESSAGES AT THE SAME TIME OVER SINGLE CHANNEL
• MORE THAN ONE MEAUREMENTS OVER SINGLE CHANNEL.
• COST, SPACE AND WEIGHT INCREASE BY USING SEPARATE WIRES.
• WE DO NOT REQUIRE SEPARATE WIRE FOR EACH MEAURAND IN MULTIPLEXING.
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Multiplexing
• Two or more simultaneous transmissions on a single circuit.– Transparent to end user.
• Multiplexing costs less.
EEG ACQUISITION SYSTEM
• IN MULTIPLEXING CHANNELIS SHARED BETWEEN THE VARIOUS QUANTITIES EITHER BY TIME DIVISION BASIS OR FREQUENCY DIVISION BASES.
• TWO METHODS OF MULTIPLEXING.
• TIME DIVISION MULTIPLEXING (TDM)• FREQUENCY DIVISION MULTIPLEXING (FDM)
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Assignment of non-overlapping frequency ranges to each “user” or signal on a medium. Thus, all signals are transmitted at the same time, each using different frequencies.
A multiplexor accepts inputs and assigns frequencies to each device.
The multiplexor is attached to a high-speed communications line.
A corresponding multiplexor, or demultiplexor, is on the end of the high-speed line and separates the multiplexed signals.
Frequency Division Multiplexing
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COMPUTER NETWORKS CONNECTED THROUGH ONE CHANNEL USING FDM
THE END