75Ω Bias Tee for CATV Repeaters

75Ω Bias Tee for CATV Repeaters

Tecdia’s Bias-Ts not only help repeat a clear picture, but can also be used to enable using the transmission cable to supply electrical power to displays in places where a power supply is hard to come by.

We all enjoy and learn from television as a part of our daily lives, and when the sound and picture are not crisp and clear, the pleasure of watching TV is significantly reduced. A common problem exists in locations with poor wireless reception and where cable transmissions lack a sufficient boost.
This tutorial shows how using Bias-Tees can not only help the installation of cable transmission repeaters in places where power supplies are hard to come by but also help maintain a clear picture.

The Challenge:

Installation of repeaters for cable TV transmission used to be limited by location

In order for cable TV viewers to receive clear audio and picture in their homes, signal transmission lines are set up with equipment called repeaters at points along the transmission route to boost the signal. The repeaters are installed roughly every 10 km and serve the purpose of amplifying the sound and picture signals sent from the cable television station and filtering electrical signal “noise” in order to bring viewers a TV signal that hasn’t been degraded.

Because these repeaters operate 24/7, they need a continuous supply of power. Connecting to a power source can be a problem depending on the location of the cable route. If access to power lines is a problem, power supply units may need to be set up for them. To do this those putting in the equipment needed to go through the burdensome process of special construction permits and fees for the installation on a power supply. In some places where it is difficult or too expensive to provide an external power supply, such as mountainous regions, the installation of repeaters may be abandoned.

The Solution:

Use of Tecdia’s high current wideband Bias-Tees to enable power to be supplied via the TV relay cable.
Since the cable used for picture transmission has an intrinsic impedance of 75 Ω, we needed a Bias-Tee that had connectors and circuit capability to match that impedance. Using these Bias-Tees would allow a supply of power to be transmitted through the cable itself along with the TV signals, solving the problem of power for repeaters as well as the burden of costs and paperwork that go with getting the access.
Tecdia already had a lineup of Bias-Ts with an intrinsic impedance of 75 Ω which were being used by TV set-top box manufacturers to test their products, as well as for other TV signal transmission applications. Capitalizing on this product technology was a natural way to go.
Tecdia’s microwave technology division has a long history, and our microwave engineers with high current wideband Bias-Tees expertise have designed and guided the production of best in class products used worldwide by laboratories. In addition to our wide and varied lineup of Bias-Tee products, we can also customize them to suit the most detailed demands of our clients. We like to think that Tecdia’s focus when working with our clients is to address their specific problems rather than simply selling our existing products. That “extra step” is a deciding factor in the client’s decision to implement our solution.
Example of providing a power source from the cable television facility to a repeater using a Tecdia bias-T

Example of providing a power source from the cable television facility to a repeater using a Tecdia bias-T

A Tecdia bias-T with an intrinsic impedance of 75Ω (TBT-2M20C-F shown)

Tecdia bias-T with an intrinsic impedance of 75Ω (TBT-2M20C-F shown)

A Tecdia bias-T with an intrinsic impedance of 75Ω (data for TBT-2M20C-F)

A Tecdia bias-T with an intrinsic impedance of 75Ω (data for TBT-2M20C-F)

The Result:

Tecdia’s Bias-T solution is helping bring cable TV to more viewers in places with limited access to power sources for cable signal repeaters. Service providers have another option to power their equipment that can expedite installations, lower costs, and enhance transmission quality.

Client Information

【Client Industries】Cable TV equipment manufacturing (USA)
【Business Description】Manufacturing and installation of cable TV repeaters