Learn how to distribute eight HDMI sources to 48 TVs over coax using the Thor Broadcast Thunder-8 HDMI-to-RF modulator, an RF amplifier and a splitter network, with practical guidance on signal levels, cable losses and TV tuner compatibility.
A commercial television distribution system does not require an HDMI cable, IP decoder or set-top box at every television. By using an HDMI to RF modulator, multiple HDMI video sources can be converted into digital ATSC or QAM television channels and distributed throughout a building using standard 75-ohm coaxial cable.
This application example explains how the Thor Broadcast HDMI RF modulation platform can distribute eight HDMI sources to approximately 48 televisions in a two-story commercial facility.
Table of Contents
The example installation requires:
Possible HDMI sources include cable receivers, satellite receivers, digital signage players, media players, computers and other compatible HDMI devices.
For this installation, the recommended RF distribution topology is:
8 HDMI Sources → Thunder-8 HDMI RF Modulator → RF Distribution Amplifier → 1×2 RF Splitter → Two 1×24 RF Splitters → 48 Coax Runs → 48 TVs
This architecture creates a centralized television headend while allowing all 48 TVs to receive the same group of digital television channels.
The Thor Broadcast H-THUNDER-8 HDMI RF Modulator accepts up to eight HDMI video sources and converts them into digital television channels for distribution over coaxial cable.
Instead of installing separate HDMI receivers behind dozens of televisions, the modulated RF channels are delivered directly to compatible TV tuners.
This makes an HDMI-to-RF system particularly useful for commercial installations where the same group of video sources needs to be available on many displays.
In this application, every television has an individual home-run coaxial cable returning to the main equipment room.
Because the largest distribution splitter required for this design provides 24 outputs, the RF signal can first be divided using a 1×2 splitter. Each output then feeds a separate 1×24 rack-mount splitter.
1 RF Input → 1×2 Splitter → 2 × 1×24 Splitters → 48 RF Outputs
Each of the 48 outputs connects to an individual television through its dedicated coaxial cable.
Large passive RF distribution networks introduce signal loss. Every splitter, connector and length of coaxial cable reduces the RF level.
For a system feeding approximately 48 televisions, particularly where cable runs approach 300 feet, an RF distribution amplifier can provide additional RF margin to compensate for splitter and cable losses.
The RF link budget should include:
When an RF amplifier is installed after the HDMI modulator, the modulator output must be adjusted to remain within the amplifier's specified RF input range.
For example, if the selected amplifier accepts approximately 0 to +10 dBmV, the modulator output should be attenuated appropriately before entering the amplifier.
Excessive RF input can overload an amplifier and degrade modulation quality, MER and overall digital television reception.
A home-run topology is ideal when every television already has its own coaxial cable returning to the headend.
For larger buildings, hotels, schools, apartment complexes and multi-floor facilities, RF taps or cascaded splitters can sometimes reduce the total amount of coaxial cable required.
The best RF distribution architecture depends on the number of televisions, cable lengths, building layout, available RF level and required signal level at each TV.
Cable and satellite set-top boxes can be used as HDMI sources for the Thunder HDMI RF modulator.
For maximum stability, configure each source for a fixed HDMI output resolution, such as 1080p or 1080i, instead of using Auto Resolution.
A fixed resolution helps prevent unnecessary HDMI format changes and HDMI renegotiation between the source and encoder.
After the HDMI signals have been converted into ATSC or QAM channels, the televisions receive the programming through their standard coaxial RF inputs.
During installation, compatible televisions perform a normal digital channel scan. The channels generated by the RF modulator then appear as regular television channels.
For example, eight HDMI sources can be assigned to eight digital television channels. Users can then select the desired source using the television's normal channel controls.
One of the major advantages of RF modulation is that a separate decoder is generally not required behind every compatible television.
The television's integrated ATSC or QAM tuner receives the RF channels directly.
For installations containing dozens or hundreds of TVs, this can simplify installation, wiring, power requirements, equipment management and maintenance.
HDMI-to-coax television distribution is commonly used in:
A typical system can include:
Final equipment selection and RF levels should be based on actual cable lengths, coax type, operating frequencies and passive distribution losses.
Use an HDMI-to-RF modulator to convert HDMI sources into ATSC or QAM television channels. The resulting RF channels can then be distributed through standard 75-ohm coax using amplifiers, splitters or taps.
An 8-channel HDMI RF modulator can feed an appropriately designed RF distribution network. One configuration uses an RF amplifier followed by a 1×2 splitter and two 1×24 splitters, providing 48 individual coaxial outputs.
Normally, a separate receiver is not required when the televisions contain compatible ATSC or QAM tuners. Each television receives the generated RF channels through its standard coaxial input.
Yes. Once HDMI has been encoded and converted to RF, the television signal can travel substantial distances over suitable coaxial cable. Maximum distance depends on cable attenuation, operating frequency, splitter losses and available RF signal level.
It depends on the RF link budget. With large splitters and long coaxial runs, an amplifier is often used to compensate for distribution losses. The amplifier should be selected and adjusted according to the required RF level at each television.
In many installations, existing 75-ohm coaxial cable can be reused, provided the cable, splitters, connectors and other passive components support the required RF frequency range and are in suitable condition.
Yes. Compatible cable and satellite receivers can provide HDMI signals to the modulator. Setting each receiver to a fixed HDMI resolution such as 1080p or 1080i is recommended for stable operation.
HDMI over coax using RF modulation creates standard digital television channels that compatible TVs can tune directly. HDMI over IP transports video over an Ethernet network and commonly requires compatible receiving or decoding equipment at each display.
Thor Broadcast can assist with designing HDMI-to-RF and coaxial television distribution systems ranging from a few displays to large commercial installations with dozens or hundreds of televisions.
For system design assistance, provide:
Contact Thor Broadcast for HDMI to RF system design assistance and a quotation.
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