1. Telemetry Principles Prepared by J N KOTHARI I.C.DEPARTMENT
A.V.P.T.I. RAJKOT

2. Telemetry Principles Outlines: Telemetry system overview
Functional block diagram
Telemetry classification
Pneumatic telemetry
Current telemetry
Pulse telemetry
Frequency spectrum for various application

3. Telemetry definition:
Telemetry may be defined as measurement at a distance.
Telemetry is the process by which the measured quantities such
as temperature, level, pressure, flow, displacement, velocity, acceleration
etc. are transmitted to a convenient remote location, in a form, suitable
for displaying, recording, actuating a process etc
Dr. H.K. VERMA ,SHARDA UNIVERSITY

4. Short Range Radio Telemetry
Why Telemetry used:
Distant location of the measurand: Telemetry uses electrical communication for transmitting electrical signal representing the value of the measurand from the location of the measurand to the location of the user.
(b) Inaccessibility of measurand: In such a situation, the electrical output of the transducer (or sensor) sensing the measurand, or that of the associated signal conditioner, cannot be accessed by conventional method of connecting wires. Therefore, the electrical output is converted to a radio wave, which is then transmitted to the user’s location. This type of telemetry is called Radio Telemetry. If this radio telemetry is meant for covering only a short distance as the user is not physically far off from the measurand, then it is called
Short Range Radio Telemetry
Dr. H.K. VERMA ,SHARDA UNIVERSITY

5. Block diagram of Telemetry system:
Dr. H.K. VERMA ,SHARDA UNIVERSITY

6. Transducer or Sensor: Converts the physical variable to be telemetered
Signal Conditioner-1: Converts the electrical output of the transducer (or sensor) into an electrical signal compatible with the next element, i.e. the transmitter.
Transmitter: Its purpose is to transmit the information signal (a signal containing
Information coming from the signal conditioner-1 using a suitable carrier signal to the receiving end
Signal Transmission Medium: It is the medium or link that connects the sending or
transmitting end to the receiving end,
Receiver: Its purpose is to receive the signal(s) coming from the transmitter via the signal transmission medium and recover the information from the same
Signal Conditioner-2: Processes the receiver outputs necessary to make it suitable to drive the given end device
End Device: The element is so called because it appears at the end of the system. Depending on the purpose of the telemetry in the given situation .
Dr. H.K. VERMA ,SHARDA UNIVERSITY

7. Types of Signal Transmission Media
Copper Wires
A pair of copper wires (or conductors) provides a closed-circuit path for the flow of an
electrical signal from the transmitter to the receiver of the telemetry system
Radio Link
The space between transmitting and receiving antennas of the transmitter and receiver,
respectively, provides a radio link between the two ends of the telemetry system by allowing the propagation of radio waves (high frequency electromagnetic waves) generated by the
transmitting antenna through it.
Optical- Fibre Link
An optical fibre, acting as a waveguide for the optical beam (in infra-red wavelength band)
generated by the transmitter, delivers the same to the receiver. It acts as an optical-signal
transmission link between the transmitter and receiver of the telemetry system
Dr. H.K. VERMA ,SHARDA UNIVERSITY

8. Telemetry system classification: 1)Base on mode of signal: 1)Hydraulic
2)Pneumatic
3)Electric
4)Pulse
2)Base on mode of modulation
1)AC
1)Amplitude modulation
2)Frequency modulation
2)DC
1)Direct current
2)Direct voltage
3)Pulse
1)Pulse Amplitude Modulation
2)Pulse width modulation
3)Pulse Position modulation
4)Pulse code modulation
Dr. H.K. VERMA ,SHARDA UNIVERSITY

9. 3)Base on information signal 1)Analog 1)Amplitude modulation
2)Frequency modulation
3)Pulse Amplitude Modulation
4)Pulse width modulation
5)Pulse Position modulation
2)Digital
1) Pulse code modulation
4)Base on channel
1)Single channel
2)Double channel
1)Time Division multiplexing
2)Frequency Division Multiplexing
5)Base on transmission media
1)Wired
2)fiber optic
3)Radio
Dr. H.K. VERMA ,SHARDA UNIVERSITY

10. Pneumatic Telemetry
compressed air is used to communicate the values of measured quantity from one location to the other location.
There are four bellows elements A and B transmitting with stroke lever & the interface disc d.C & D form the receiving & display block along link.
The two blocks are connected by pneumatic lines. with the float rising or falling ,the push rod moves up pressing bellows element B or expanding it so pressure increase in line 1 or 2 expanding element D or C at the receiving end
Book:Telemetry Principles by D. Patranabis

11. CURRENT TELEMETRY: In this telemetry pressure sensed by bourdon tube.
That connected to potentiometer
That covert the signal into electrical signal
Electrical signal can be read by multimeter
Industrial Instrumentation by S.K.Singh

12. PULSE TELEMETRY:1)ANALOG PULSE TELEMETRY
Various channel connected for signal
Commutator commutates the signal with sampling interval
Decommutator decode the signal according to destination

13. 2)DIGITAL PULSE TELEMETRY
In this telemetry different signal come into commutator
Encoder encodes the signal
Receiver receive the signal
Bit synchronizer convert the signal into form of bits.
Frame synchronizer convert the bit into frame.
The signal go to different channel

14. THANK YOU