APPLIED AND INDUSTRIAL ELECTRONICS ( EA): Chapter6

 CH- 6 REMOTE CONTROL                           Marks: 08 (12)

Definition: 

The control of functions of instruments from long distance, without any physical contacts is called remote control system.

Necessity/Need of remote control system: 

  1. The need of remote control arises when electronic instruments are required to be placed and operated in remote areas or in space.

  2. It is used where regular attention of human operator is not possible not convenient.

  3. Remote control system is needed in devices where we have to control the operations frequently e.g. TV receiver, DVD player, Air conditioner etc. 

  4. There are three essential components in a remote control system: transmitter, a transmission medium, and a receiver. 

  5. The position from where the functions are to be controlled is called the ground station or base station/transmitter. 

  6. The position where operations are performed is called remote station or receiver. 


Block diagram of Remote Control System:

   Working:

  1. A complete remote control system consists of a transmitter, a receiver and a feedback circuit. 

  2. The instructions are executed by the transmitter. It is known as ground station.

  3. The control signals are modulated by carrier and send to receiver by high power amplifier and transmitting antenna.

  4. Transmitter also receives the feedback signals transmitted by remote station. 

  5. The transmitted signals are received by receiver.

  6. These signals are amplified and detected by detector. Different control signals are obtained to operate relay circuits.

  7. Feedback such as operation performed or not is sent from remote station.

  8. Sometimes information like weather condition, rainfall, temperature etc also sent as feedback.

Ground Station (Transmitter)

The ground station in a remote control system performs two important functions: 

(i) To send the instructions to remote station.

(ii) To receive the feedback signals transmitted by remote station. 

Working: 

  1. The instructions to be sent to the remote station are given to the information generator either by a human operator or computer. 

  2. These instructions are always given in a digital form. Digital form makes the operation more easy and simple reducing errors. 

  3. Instructions actually consist of a series of binary bits in coded forms. To these series of bits other bits are also added to represent start, stop, channel No and error messages.

  4. To make it ready for transmission the signal processor block modulates these series of bits in such a way that the RF carrier is transmitted for Bit 1 and no carrier is transmitted for Bit 0. In other words a signal is transmitted by presence and absence of carrier wave.

  5. The feedback signals transmitted by remote station are received by the ground station and processed accordingly. 

  6. Then next required instruction sent by the ground station transmitter. 


Remote Station (Receiver) 

Fig.  Block Diagram of Remote Station (Receiver)

Working: 

  1. The signal transmitted by the ground station is intercepted by the receiving antenna of the remote station and is demodulated. 

  2. The carrier is removed and the series of bits is obtained. 

  3. The series of the bits received is taken to the signal processor where additional bits for start, stop error etc. are checked and removed, recovering the actual instruction. 

  4. It is then given to the decoder which decodes it and performs operations as required per the message. 

  5. The equipments at the remote stations are required to keep ON always as on human attendant can turn it ON or OFF. Fig shows the block diagram of a remote station in a remote control system.

  6. As it is essential for the ground station to know whether the function is done at the remote station as per order or not, feedback is required in remote control. 

  7. Sometimes some in formation like weather condition, map, and rainfall is also fetched from the remote station. And sent back to ground station.


Types of Remote Control

 (i) ON/OFF Remote Control: In this type of remote control system the equipment at a remote station can be made ON or OFF. 

For ex. Railway signal control system, Traffic signal control system    

(ii) Radio remote control: It is used to control remote vehicles like plane, car, boat etc.

(iii) Ultrasonic remote control: It is used to control telephone answering systems.

(iv) Laser remote control: It is used in guided weapons such as missiles and bombs.

(v) Mechanical remote control: It is used in handling radioactive material.

(vi) Infrared remote control: It Used to control televisions VCR, VCD, DVD, stereos and car audio system

(vii) Linear Remote Control: In this type of remote control system the working of equipment at a remote station can be controlled as per requirement. In linear remote control systems both the units, i.e. transmitter and receiver are necessary at both the places.  Due to feedback, the information required for further control and processes is received from both the places. 


Applications of Remote Control Systems

1.  Remote Control Systems in Industry

  1. In Industries, Remote manipulators are widely used to control various operations. 

  2. These are the mechanical, electromechanical or hydro-mechanical devices which enable a person to perform manual operations while separated from the site of the work. 

  3. Manipulators are often equipped with touch and vision sensors. 

  4. It is used to perform hazardous work or which is difficult or impossible to gain access to because it is blocked, too large, too small, or too far away.


2.  Remote control system for controlling spaceship/Space science: 

  1. In this remote controlling system, the transmitter is fitted on the earth while the receiver is fitted in the spaceship. 

  2. Satellite is launched in space by rocket. Then operations like 

a) Freeing of rocket 

b) Direction of satellite 

c) Fixing of orbit 

d) Forward-backward speed or revolution of satellite 

e) Left turn and right turn is controlled by remote.

  1. Each of these requires the different frequencies. 

  2. The spaceship consisting of receiver, detects the frequency and control circuits are operated depending on the transmitted frequencies. 

  3. Satellite receives, amplifies and transmits different TV programmes, mobile communication, reports, and photographs on earth station.




3.  Working of remote control system used in a Consumer product (e.g. Television).

  1. In television remote control system, the distance between the receiver and transmitter is small (10 meters). 

  2. Hence infrared signal is used to control various operations of the receiver. 

  3. The transmitter consists of power supply (or dry cell) infrared frequency signal generator, which generates different frequencies in infrared frequency range. 

  4. Each of these frequencies is designed to control a particular operation. 

  5. In a typical television brand a remote control requires (i) 10-frequencies to select channel (ii) two frequencies to increase or decrease the volume (iii) two frequencies to control color intensity and (iv) two frequencies to control the brightness of a picture. 

  6. A push button switches are provided to control these operations of front panel of the transmitter. 

  7. This signal is applied to infrared emitters (such as infrared diodes).


4.  Remote control in Weather Study for Weather Forecast: 

  1. Remote control systems are used to study atmospheric conditions such as temperature, humidity rainfall etc. 

  2. At unmanned remote stations like deep forests or high mountain peaks, the recordings are obtained at regular intervals 

  3. It is useful in weather prediction and to take necessary steps for further precautions. 

  4. For studies of floods in rivers and waves in oceans, the remote control systems are used and the positions of harbors etc are fixed. 

  5. Even necessary measures against floods can be taken.


5. Remote control in Missile launching and guidance system/Radar communication:

  1. In this system, the antenna detects the target plane (object). 

  2. It then locks in and continuously tracks the target plane. 

  3. Depending upon the position and velocity of the plane, as given by the radar, the output is fed to the launch computer. 





Use of remote control system in Military (Warfare) application

1) For surface to surface missiles

2) Surface to air missiles.

3) Protection ideas of VIPs

4) To detect enemy missiles.


Use of remote control in TV receiver:

1) ON / OFF 2) Brightness 3) Volume control 4) Channel selection 5) Colour 6) Mute

7) Searching channels

Use of remote control in VCD / DVD players: 

1) ON / OFF 2) Forward motion of disc 3) Reverse motion of disc 4) Pause 5) Play

6) Mute 7) Volume control 8) stop

Use of remote control in Air conditioning: 

1) ON / OFF 2) Temperature control 3) Fan speed control 4) Swing cool

Use of remote control in Auto car:

1) To open the locks 2) To open the doors and windows 3) To operate music system

4) To control loudness of horn.

Use of remote control in consumer equipments:

1) TV, 2) VCD, 3) DVD, 4) A/C, 5) Auto car, 6) Toys, 7) Music system

.


Questions


Marks wise Questions: 1M(2), 3M(2), 4M(1)

1. Fill in the blanks-

  1. In remote control system the position from where the functions are to be controlled

  1. is called ———— station.

  (a) Remote  (b) Ground (c) Relay  (d) None 

  1. Remote control signals are transmitted using ————— modulation.

  (a) Amplitude (b) frequency (c) Pulse code (d) Phase

  1.  In a remote control system the instructions are executed by the ------------.

  (a)) Ground station (b)) Remote station (c) Power station (d) Hill station

  1. The function of a remote control system is to control the operation of a machine at a distance -------------.

  (a)Without any connection with the machine (b) With transmission lines

  (c)None of these

  1. The --------- senses the signal and executes the mechanism to carry out an operation. 

  (a) Receiver  (b) Transmitter (c) None of these

  1. -----------is used for the adjustment in instruction code to attain highest stability of the system. 

  (a) Feedback (b) Transmission lines (c) None of these

  1. In remote control of TV and DVD, -------- waves are used.

  (a) Electromagnetic (b) Infrared (c) Sound (d) None

  1. -------- station has feedback path in remote control.

  (a) Ground station (b) Channel (c) Remote station (d) None






2. Match the following-

A B

(a) Remote control system (1) Transmitter

(b) Ground station (2) Remote control

(c) Radar [M-10] (3) Sonography

(d) Remote station (4) Space science/satellite communication

(5) Receiver

3. True or false-

  1. In TV/VCR receiver, ultrasonic remote control is used.

  2. Laser remote control is used in weapons such as bombs and missiles.

  3. Mechanical remote control is used in handling radioactive materials.

  4. It is essential for ground station to know whether the function is done at the remote station as per order or not.

  5. The instruments at remote station should be always in ON state.

  6. In TV receiver infrared sensor is used to receive instructions from remote control.


4. Answer the following-

  1. What is remote control? Explain its working principle/concept.    [O-09, 11, M- 10, 13]

  2. Explain concept of Remote Control System?       [M-11]

  3. State applications of remote control system.       [M-11, M-12]]

  4. Draw block diagram of remote control system and explain function of each block.           [O-09, M-10,O-11]

  5. Explain use of remote control in TV receiver.

  6. Explain working of transmitter /ground station with block diagram. [M-11, M-12, 13]

  7. Explain use of remote in warfare and weather studies.         [O-10, M-13]

  8. What is remote control? Define ground station and remote station.

  9. Draw block diagram of receiver /remote station in remote control system and explain its working.       [M-09, M-11, M-12, M-13]

  10. State and explain different types remote control systems and explain its working.

  11. Explain use of remote control system in satellite communication.           [M-10, O-11]]

  12. Write use of remote control in DVD.       [M-09]

  13. Explain use of remote control system in consumer products.       [M-11]

  14. Write use of remote in air conditioning machine.       [M-09]

  15. Write short note on remote control system.       [M-09]

  16. Explain use of remote control system in military application and radar communication system.         [M-09, O-11, M-13]

  17. What do you mean by remote control? State its types.         [O-09]

  18. What is the use/need of feedback in remote control system?

  19. List the applications of remote control system. Explain any one of them.       [M-12]

  20. What are the types of remote control systems? Explain in brief.       [M-12]


डॉ. आर व्ही शेजवळ ,  प्राचार्य , लाल बहादूर शास्त्री महाविद्यालय , सातारा  सहसचिव (प्रशासन ) श्री स्वामी विवेकानंद शिक्षण संस्था , कोल्हापूर...