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