Application Example - Industrial CCTV System Over Multimode Fiber

System Overview

In many industrial environments such as plants, factories, or large facilities, cameras may be located hundreds of feet away from the monitoring location. Running new coax cables for each camera can be expensive and time-consuming, especially if fiber infrastructure already exists between buildings or control rooms.

A practical solution is to use a TVI over Fiber transmitter and receiver kit, which allows multiple HD analog cameras to be transported over a single fiber optic link.

In this example, we will explain how to transmit:

• 8 HD-TVI cameras

• PTZ control signals using RS-485

• Over an existing multimode fiber cable

System Architecture

Main Components

1. 8 HD-TVI Cameras (PTZ capable)

2. 8-Channel TVI Fiber Transmitter

3. Fiber Optic Cable (Multimode or Single Mode)

4. 8-Channel TVI Fiber Receiver

5. DVR / Control System

6. RS-485 PTZ Controller

How Video Transmission Works

Step 1 – Cameras send TVI signal

Each camera outputs a TVI video signal over coax.

Example formats:

• 720p

• 1080p

• HD-TVI analog signal

These signals connect to the 8 BNC inputs on the fiber transmitter.

Step 2 – Fiber transmitter converts video to optical signal

The transmitter performs optical multiplexing:

• All 8 camera signals are combined into one optical stream.

• The signal is converted into laser light.

This optical signal is then transmitted through a single fiber strand.

Step 3 – Fiber carries the signal

The signal travels through the existing fiber cable.

Typical distances:

• Multimode fiber: hundreds of meters to several kilometers

• Single mode fiber: up to tens of kilometers

In this example:

• Distance = ~500 ft

• Multimode fiber = works well for short runs

Step 4 – Receiver converts optical back to video

At the monitoring location:

The fiber receiver converts the optical signal back into 8 coax TVI outputs.

Each output connects to:

• DVR

• Video matrix

• Encoder

• Monitor system

PTZ Control Using RS-485

Many CCTV PTZ cameras use RS-485 serial communication for control.

Examples of PTZ commands:

• Pan left/right

• Tilt up/down

• Zoom

• Presets

How RS-485 Return Data Works Over Fiber

The fiber system includes a return data channel.

This means:

Control signals can travel from the control room back to the cameras.

Signal direction

Why Only One RS-485 Port Is Needed

The fiber unit provides one RS-485 interface, even though there are 8 cameras. This works because RS-485 is a multi-drop bus. Multiple devices share the same communication line.

RS-485 Addressing Explained

Each PTZ camera has a unique address (ID).

Example configuration:

When the controller sends a command:

Example command:

Camera Address: 003
Command: PAN LEFT

Only Camera 3 will respond.

All other cameras ignore the command.

RS-485 Wiring (Daisy Chain / Cascade)

Since there is only one RS-485 output, the control signal is daisy-chained between cameras.

Example wiring:

Fiber Receiver RS485
        │
        │
   Camera 1
        │
        │
   Camera 2
        │
        │
   Camera 3
        │
        │
   Camera 4
        │
        │
   Camera 5
        │
        │
   Camera 6
        │
        │
   Camera 7
        │
        │
   Camera 8

Each camera taps into the same RS-485 pair.

Why This Works

RS-485 was designed specifically for:

• Industrial environments

• Long cable runs

• Multiple devices on one bus

Typical capacity:

• Up to 32 devices on one RS-485 line

Therefore 8 PTZ cameras is very easy to support.

Advantages of This Fiber Solution

Uses existing fiber infrastructure

No need to run new coax cables.

Long distance transmission

Fiber supports much longer distances than coax.

No video compression

TVI video remains real-time and low latency.

PTZ control supported

RS-485 return channel allows full PTZ functionality.

Reduced cabling

Only one fiber cable instead of 8 coax runs.

Example Real-World Deployment

Industrial plant monitoring system:

• 8 PTZ cameras installed around a facility

• Cameras located 500 ft from control room

• Existing multimode fiber between buildings

Solution:

8 PTZ Cameras
     │
     │ coax
     │
8CH TVI Fiber Transmitter
     │
     │ fiber optic cable
     │
8CH TVI Fiber Receiver
     │
     │ coax outputs
     │
DVR / Monitoring Station
     │
     │ RS485 control
     │
PTZ Controller

Operators can now:

• View all cameras

• Control PTZ movement

• Use presets and zoom

All through the single fiber connection.

Important Note About Multimode Fiber

Modern fiber transmitters typically use laser optics designed for single-mode fiber.

They can still work on multimode fiber for short distances, but:

Possible issues include:

• Signal dispersion

• Higher attenuation

• Sensitivity to tight fiber bends

For 500 ft runs, multimode generally works well.

Final Result

Using an 8-channel TVI over fiber system with RS-485 return, it is possible to transmit:

• 8 HD analog cameras

• PTZ control commands

• Over one fiber link

While still allowing individual camera control through RS-485 addressing.

Application Diagram - 8 Cameras Over Fiber

      CAMERA LOCATION / FIELD AREA

  PTZ1   PTZ2   PTZ3   PTZ4   PTZ5   PTZ6   PTZ7   PTZ8
   │      │      │      │      │      │      │      │
   │      │      │      │      │      │      │      │
   └────────────── COAX TVI VIDEO ────────────────┘
                          │
                          │
        ┌───────────────────────────────────────┐
        │  F-8HD-1D-TVI-TX                       │
        │  8 Channel TVI Fiber Transmitter      │
        │                                       │
        │  8x BNC Video Inputs                  │
        │  RS-485 PTZ Data                      │
        │  Fiber Optic Output                   │
        └───────────────┬───────────────────────┘
                        │
                        │
                SINGLE FIBER LINK
            (Single Mode or Multimode)
                        │
                        │
        ┌───────────────┴───────────────────────┐
        │  F-8HD-1D-TVI-RX                       │
        │  8 Channel TVI Fiber Receiver         │
        │                                       │
        │  Fiber Input                          │
        │  8x BNC Video Outputs                 │
        │  RS-485 PTZ Control                   │
        └───────────────┬───────────────────────┘
                        │
                        │

                DVR / CONTROL ROOM

   CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8 → DVR Recorder
                        │
                        │
                  PTZ Controller
                        │
                      RS-485