UHF, VHF & TV Broadcast Frequencies

Yes. An ATSC RF modulator can convert a video source into a digital television channel that can be distributed over the same coaxial cable network used for Over the Air television signals.

For example, the Channel Master ATSC HD Modulator CM-1050 converts an HDMI video source into an ATSC 1.0 digital RF channel. The generated channel can then be scanned and received by televisions and set top boxes equipped with compatible ATSC tuners.

This can be useful for distributing content from a DVR, security camera system, computer, digital signage system, satellite receiver, or other HDMI source to multiple televisions over an existing coaxial network.

The most important part of configuring a modulator is selecting an unused RF channel. Do not assume that a channel number displayed on your television is the station's RF channel. A local station displaying virtual channel 5.1, for example, could actually be transmitting on RF channel 25. Before assigning the modulator to RF channel 25, verify that no local broadcast station is already using that RF frequency at your location.

The Channel Master CM-1050 allows the installer to configure both the RF channel used to physically transmit the signal and the virtual channel number displayed by the television. It also includes an RF pass through input so the generated channel can be combined with signals from an Over the Air antenna system.

For example, if RF channel 24 is unused in your area, the modulator can transmit within the channel 24 allocation of 530 to 536 MHz, centered at approximately 533 MHz. The virtual channel displayed on the televisions can then be configured separately.

After adding the modulated channel, televisions and ATSC receivers connected to the coaxial network generally need to perform a channel scan so the new digital channel is added to their channel lists.

The RF channel is the actual radio frequency channel used by a television station to transmit its signal. The virtual channel is the channel number displayed to viewers on the television or Stream+.

For example, a station may display as channel 5.1 while physically transmitting on a different RF channel. This is normal for digital television and is managed through information included in the broadcast signal.

Each television RF channel occupies a 6 MHz wide frequency range. The center frequency is the midpoint of that 6 MHz channel.

For modern digital television, the old analog picture carrier and sound carrier frequencies are generally not useful when planning an ATSC system. For RF measurements, frequency planning, and equipment such as RF modulators, it is more useful to understand the complete 6 MHz channel allocation and its center frequency.

Following the FCC spectrum repack, the current United States television broadcast spectrum extends through RF channel 36, which occupies 602 to 608 MHz. 

Over the Air television in the United States currently uses three primary frequency ranges, Low VHF, High VHF and UHF.

Low VHF includes RF channels 2 through 6. Channels 2 through 4 occupy 54 to 72 MHz, and channels 5 and 6 occupy 76 to 88 MHz. High VHF includes RF channels 7 through 13 and occupies 174 to 216 MHz. UHF television currently includes RF channels 14 through 36 and occupies 470 to 608 MHz.

These frequency differences are important because radio waves behave differently as frequency changes, and antennas must be physically designed to receive the wavelengths associated with the frequencies being used.

Lower frequency VHF signals have longer wavelengths. They can propagate well over distance and around some terrain and obstructions, but efficient long range reception requires physically larger antenna elements. Low VHF is also more susceptible to certain types of electrical and environmental noise.

High VHF uses shorter wavelengths than Low VHF and allows smaller antenna elements while still providing favorable propagation characteristics.

UHF uses much shorter wavelengths, which allows antennas to use considerably smaller elements. UHF is now the most commonly used portion of the television broadcast spectrum in the United States. Following the FCC spectrum repack, UHF television broadcasting ends at RF channel 36, or 608 MHz.

Because most television markets today primarily use UHF channels, along with some High VHF channels, many consumers do not need a very large antenna specifically optimized for weak, long distance Low VHF reception.

However, if your market includes an important Low VHF station and the predicted signal at your location is weak, antenna design becomes particularly important. Channel Master full range antennas such as the CM-3018, CM-3020, CM-5018 and CM-5020 incorporate large elements designed to provide improved reception across Low VHF, High VHF and UHF frequencies.

If a Low VHF signal is predicted to be strong or good at your location, a very large long range antenna may not be necessary simply because the station broadcasts on Low VHF. A high quality medium size antenna with Low VHF capability, such as the Channel Master Pro-Model CM-1776, may provide sufficient reception.

The best approach is to identify the actual RF channels and predicted signal strengths at your address before selecting an antenna.