Providing A TV Signal

I am often asked how I am able to watch a tv station on an old style analog TV now that the TV stations have switched over to ditital broadcasting. Most people understand the old style TV sets, that used to receive analog, over-the-air signals, can no longer receive the new Digital over-the-air television broadcasts. The answer is; I had to build my own, in house system to receive Digital over-the-air television signals, and convert them back into "old style" analog TV channels. In essence, I have a small, in house, television station. It's similar to systems used in motels which provide a signal to the TV sets in the motel rooms. I call my in house TV station "WBOB".

The first step is to receive the Digital over-the-air signals, which are broadcast on the standard UHF frequencies. The Digital signals are picked up by a small UHF antenna mounted on the ceiling of my television display room.

UHF Receiving Antenna

The Digital signals which are picked up by the antenna, are sent on a co-axial cable to an amplified cable splitter box. The splitter box provides a signal to the input of 4 Magnavox Digital Converter boxes. The 4 converter boxes are tuned to 4 different Digital TV stations in the Milwaukee area. I usually tune the Digital Converter boxes to channels 4, 6, 10, and 12. Each Digital Converter box sends its output signal (composite video, and audio) to its own dedicated Holland HM55 modulator.

There are 4 Holland modulators. One for each Digital converter box. The Holland Modulators convert the video and audio signals from the Magnavox Converter into a corresponding old style analog RF TV Channel. IE: Digital Channel 4 is converted to Analog VHF Channel 4 and so on. The RF signal outputs of the 4 moduators are sent into a Holland "combiner", which combines the 4 analog RF signals from the modulators, and outputs the signals onto one co-axial antenna cable. That cable is routed to an amplified splitter which has multiple outputs. The splitter has many antenna cables attached to it which provide a seperate antenna signal to each of the TV sets. This is similar to the way an appliance store provides signals to the many TV sets it has on display in the showroom.

Amplified Splitter

In addition, I have a DVD player connected to WBOB and a corresponding 5th Holland Modulator broadcasting on VHF Channel 8. So if i want to watch a DVD I place the DVD in the player and tune to the TV set to channel 8 so I can watch what ever is playing on the DVD player.

In the end I have 5 "old style" analog VHF tv channels (4, 6, 8, 10, 12) that can be tuned by each TV set connected to the WBOB system

The system works very well. I can attach as many TV sets to WBOB as I want. In addition I can tune the Digital Converter Boxes to any Digital Channel. So basically I can watch what ever is being broadcast over-the-air. I can watch 4 different tv channels and play a DVD all at the same time on different TV sets.

This is a block diagram of how the components in WBOB are connected.

Front view of WBOB. From top down:Top unit is Holland combiner. 2nd thru 6th units are Holland HM55 modulators. Below the modulators sits the 4 Magnavox Digital Converter boxes. On the bottom is the Daewoo DVD Player.

Rear view of WBOB showing the interconnect cabling.