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How To Transmit Digital Signal From Headend To Subscriber Or Digital Signal Transmission

Digital Signal Transmission

Introduction Of Digital Signal Transmission

A Digital Headend provides final output from the QAM. Now the task starts here how to deliver this signal to cable tv subscriber by maintaining good quality.

There are various devices which we need to use for Digital Signal Transmission to subscriber end. These devices should be fine tuned for proper delivery of Digital Signals to our subscribers. Also time to time we need to check these devices. These devices generally deployed in the field. These whole devices works as a medium from digital headend to subscribers.

Digital Signal Transmission Architecture

Digital Signal Transmission architecture

Digital Signal Transmission Devices

These are basically four devices which we needs to deploy in the cable tv field for transmission of digital signal.

(1) Transmitters

(2) Nodes

(3) Power Supply

(4) Amplifiers

 

(1) Transmitters

catvision transmitter for cable tv equipment

QAM provides RF output which goes via the RF cable and splitters into the RF Input port of transmitter. Now transmitter provides Optical Output. Transmitter is active device.

Generally transmitters are deployed in the digital headend. These transmitters are deployed according to distance of  sending signal. If the required distance for sending signal is large, then you need to  use one more transmitter in field to send signal at large distance.

Thus by using Multiple transmitters you can cover a city. The optical output of transmitter goes into the optical input port of nodes via the fiber.

(2) Nodes

catvision node headend equipment

Nodes are deployed at LCO location. Nodes receive the signal from the transmitter as optical input. It provides us RF output. Node is Active device.

This RF output goes into the amplifiers which are deployed in the field. Multiple amplifiers can be connected with one Node. Node have tuning functions to control RF output signal level.

Node have three RF ports named as RF output port , RF Monitor port and RF supply input port. RF output port provides the RF signal , RF Monitor port is used to monitor the RF out from node and RF supply input port is used for power supply input to the node.

We need to give RF input power supply to Node to run our deployed amplifiers in field. Thus Node plays an very important role in Digital Signal Transmission.

(3) Power Supply

catvision power supply headend equipment

There are different Amphere power supply available in the market. One that shown in the figure above is 6 Amp power supply. It is active device. Power provides power as RF output port which goes as input to the Node.

These power supply are responsible for to power up the amplifiers in field.

(4) Amplifiers

sharp amplifiers headend equipment

Amplifiers are deployed after the Node in the field. It is active device.

Amplifiers have the RF input port and RF output port. Amplifiers are used to amplify the RF signal. Multiple amplifiers are connected in series. It has the tuning functions to control the RF output signal level. It provide the facility to tune the Gain and Slope.

A passive splitter is used near the amplifiers to split the signal and provides output to the subscribers home. Thus RF output of these splitters goes into the STBs as RF input.

Conclusion

Digital Signal Transmission to subscriber end is a teamwork. We need to have large team to maintain the field. If we found a problem in the field then we need to check the devices step by step from headend to field.

Above discussed 4 devices are responsible for Digital Signal Transmission into the cable tv field. The cost of transmitter is high rather than other devices.

Know More About   What Is Optical Fiber Cable Or OFC

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Comments

  1. KAMAL BERA says:

    THANKS SIR

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