The Essentials About TV Frequencies

The Essentials About TV Frequencies

The primary function of a TV antenna is to capture the energy (electromagnetic frequencies) of radio waves adequately. That induces a signal current transmitted, which in turn travel to the lead wires.

A majority of TV antennas are specifically designed to detect the very same signal at several points which are called elements. That combines the signal currents, thereby amplifying your signal strength.

Tv Antenna With Amplifier

The length and number of these factors, their precise thickness and the spacing between them are dependent on the wavelength of the specific frequency the TV antenna is made to detect and capture.

When the initial TV broadcasts hit our airwaves way back in the 1920’s, analog technology was used to transmit all TV shows and news programs. However, in late 1996, an innovative, new technology was introduced that revolutionized signal transmission technology. It is called the digital signal. Now, the FCC mandates all televisions to have a digital tuner.

 On June 12, 2009, there was a significant transition to digital TV from the analog TV in the U.S. This drastically changed how consumers receive signals and watch TV. It also had a massive impact on the type of televisions that were available for purchase.

There was a surge in demand for digital TVs. While a majority of television transmission transitioned to digital from analog, you will still find some consumers who are again watching the news and entertainment programs on their analog TV stations.

Difference Between Digital And Analog Signals

The primary difference between digital and analog is the method of transmission and broadcasting to your TV from the source. Video and audio signals are transmitted over the airwaves by analog television in a way quite similar to radio signals.

All TV stations have one frequency over which they broadcast their analog TV signals. Users often recognize the frequencies as different channel numbers on their TVs.

Similar to a radio signal, analog television signals could experience frequency interference. That may lead to snow, static, or ghosting on a TV channel. That can be a real nuisance. Also, it could also trigger fluctuations in brightness, color, or sound quality. And just like radio signals, typically analog TV transmission tends to decline as the distance from the source increases.

On the other hand, transmitting digital TV signals involve "data packets"; where the data is compressed. This information, similar to a computer or DVD player, uses a combination of 0’s and 1’s.As the data uses the code, in most cases, digital signals don’t suffer from the same type of signal loss or interference that analog signals do.

Illustration Of Analog Vs Digital Signal

That implies that users can enjoy a consistent and excellent picture with top-notch audio without experiencing any snow or static.

Moreover, digital television signals are a more efficient technology. That is because a digital transmission needs considerably less bandwidth than analog signals. Actually, according to research, five or more digital TV channels often utilize the same bandwidth as one analog TV channel.

That is why a TV station can broadcast more TV channels, including many high definition channels, over similar airwaves, which gives users a lot of programming variety and better quality at the same time.

Another notable difference between analog and digital signals is that digital signals have the unique ability to broadcast your programming in an authentic high definition widescreen (in the 16:9 format).  It allows users to enjoy top quality programming in the convenience of their home. In contrast, the transmissions of analog signals have a 4:3 ratio and have poor quality.

UHF Vs. VHF

Before the advent of digital broadcast TV, local channels from 2 to 13 were usually broadcast in very high frequency (VHF), while TV channels from 14 onwards went out in the ultra-high frequency (UHF). However, nowadays, digital TV is mostly broadcast in UHF band.VHF, in contrast, is used today mainly for marine-band radio and FM radio.

Due to the vastly different characteristics of these two frequency bands, there is a significant difference between the most suitable designs for VHF and UHF antennas.  The VHF band has a frequency range of about 50 MHz to 220 MHz, while the frequency of the UHF band ranges from about 420 MHz to 1.3 GHz.

There is a dramatic variation in these wavelengths; for example, a VHF signal of 55 MHz has a wavelength of about six meters in length. On the other hand, a UHF signal with a frequency of 450 MHz has a much shorter wavelength of only 70 cm.

The shorter wavelength of ultra high-frequency TV signals let them pass more quickly and efficiently through various obstructions. UHF TV signals also bounce off the ionosphere, which allows them to travel beyond the transmitting tower’s horizon.

Illustration Of UHF vs VHF Signal

As very high-frequency wavelengths are quite long, a majority of VHF TV antennas need more extended elements. But, the higher efficiency of VHF TV frequencies to induce current often implies that fewer components are required.

As a result, the boom or rod to which these are typically attached could be much shorter in length, which is usually the case with ultra-high frequency antennas. For example, a suitable antenna for a frequency of 145 MHz will need twelve elements, ranging from 34 ¾ inches to 41 1/8 inches in length, often arrayed on seventeen-foot booms.

In contrast, ultra high-frequency wavelengths tend to be much shorter compared to their VHF counterparts. That is why their elements tend to be much shorter. Moreover, a UHF TV antenna needs more components to deliver a suitable amount of signal amplification.

For instance, a UHF TV antenna optimized for about 430 MHz will require 33 elements arrayed on a boom with a length of 24 ½ feet. However, these factors will measure only 10 11/16 inches to 13 11/16 inches in diameter.

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