1. CH-6 CABLE TV

2. Cable TV Master antenna TV (MATV) CATV system is a cable sys.
CCTV Closed circuit TV

3. Master antenna TV (MATV)

4. Antenna-
Numbers of antennas are located on roof top, depending on direction of telecast.
Antennas are placed such that all stations are received simultaneously.
Antenna o/p is fed into 4 way hybrid.

5. 4 way hybrid –
Provide impedance matching to avoid standing waves.
O/p of 4 way hybrid is fed to distribution amplifier amplifies the level to prevent losses.

6. O/p is fed to splitters through coaxial line.
The o/p of splitters is convey to the pt. of delivery via coaxial line.

7. need of terminating resistance in MATV.
Max power is transfer if load impedance is equal to source impedance.
If load impedance is not equal to source impedance standing wave pattern is generated.
As terminating resistance in MATV is 75ohm, if source impedance is equal to terminating impedance, none of the signals are reflected
But if terminating impedance is not equal source impedance signal are reflected back forming a “GHOST IMAGE” in the TV screen.
The viewer will view a shadow image the picture in his screen.

8. CATV
community antenna (CATV) television

9. community antenna (CATV) television
The CATV system is a cable system which distributes good quality television signal to a very large number of receivers throughout an entire community.
Means a common receiver antenna for the community.

10. This signal received by common antenna
This signal received by common antenna. than distributed to large number of houses through network of co-axial cable.
This concept is valid to huge buildings having hundreds of apartment thus eliminate the need of each house to have its own dish antenna on roof top.

11. Cable signal Distribution

13. Cable TV distribution system is a co-axial cable network
Combiner -
It is a broad band amplifier
This amplifier feed trunk amplifier on cable line.
Trunk & Distribution amplifier-
Distribute signal
Attenuate the signal.

14. Splitter
It is a directional couplers
Network divide signal power equally in all branch
Match impedance to keep minimum losses
The signal distribute from splitter to tap-off point done through co-axial cable.

15. Cable TV network

16. Many converter is design to enable the subscriber communicate with the cable station.
Long distance link-
Distribute signal to over subscribers over 75 channels
Reduces cable losses
Long distance require super trunk, fiber optics cable.

17. Two way application
Down –stream signals from Head end to each subscriber.
Up-stream signals towards head end communication.
Application- subscriber billing, change program, market survey etc.

18. Simple CCTV system
CLOSED CIRCUIT TELEVISION

19. It is system which ckt is closed & all elements are directly connected.
In CCTV video output from TV camera is fed directly by co-axial or a low power wireless link to special type of TV
A TV monitor or video monitor is an ordinary TV Rx. without RF-IF stages.
It is very useful in education, industry business.

20. Movable Camera
Many fixed camera used to convert into movable platform.
This plat form controlled by remote.
Cameras may be used indoor & outdoor.

21. Block diagram of CCTV

22. Video monitor reproduces the picture directly from composite video signal.
It does not contains any RF & IF stage
Better reproduction, it does not have any audio reproduction
Video input from camera is given to video amplifier,

23. Loop –
several camera are used for monitoring scenes at different locations.
They are looped
Sync separator separate sync pulses.
Application – at cricket ,football stadiums, traffic monitoring on road.

24. dB Meter
Principle:
The logarithmic term is applied to an electronic voltmeter when the current or voltage produced in the indicating instrument by an applied voltage is proportional to the logarithm of applied voltage
Such a characteristics leads to a linear decibel scale for the indicating instruments
finds many applications in electronics.
The reading on the meter scale is calibrated in decibels and hence the instrument is called a dB voltmeter or simply dB meter.

25. Working:
The RF signal to be measured is connected to the input of high impedance input circuit through a RF connector, whose input impedance is 75 Ω.
The range selector switch selects the band and range of its frequencies to be tuned.

26. The logarithmic amplifier is connected to the differential amplified whose signal output.
Deflects the dB scale in the dB meter. To obtain logarithmic characteristics, the meter use a diode in feedback loop of an op-amp.
dB is the unit for losses and gains.

27. DTH Direct to home television
DTH is defined as the reception of satellite programming with a personal dish in an individual home.
DTH does not need the local cable operator & puts the broadcast directly in the consumer TV.

29. DTH service is in which large no of channels are digitalised compressed from high power satellite & these program can be directly received at home.
DTH operate on KU band (11.7GHz to GHz) band from satellite

30. Encoder- convert audio ,video signal into the digital format
Multiplexer – mixing of these signals.
At user end, there is Dish Antenna & Set-top box to decode and view no of channel.

31. DTH differ from cable –
Signal transmitted from satellite to dish antenna directly.
Broadcast directly to user.
DTH is Superior than Cable
Better quality of picture
Cable signal is analog, DTH is digital.
Enhance picture effect
DTH provides interactive TV Programmes such as movie on demand, Internet access, Games, .
Provide service to Tata Sky, Dish TV.