technical knowledge

Navigate throughout this section to find explanations and definitions for a wide range of specialized terms, making it easier for both beginners and professionals to gain a deep understanding of the topic.

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4G is the short name for fourth-generation wireless, the stage of broadband mobile communications that supersedes 3G (third-generation wireless) and is the predecessor of 5G (fifth-generation wireless). It can be deployed in the upper portion of the spectrum of the UHF band, in the 700 MHz band, close to where OTA signals are broadcasted, so depending on the reception scenario, 4G could be an interefering signal for the OTA signals, whether impairing or destroying them.
5G is the short name of the fifth generation wireless and It has been designed with an extended capacity to enable next-generation user experiences, empower new deployment models and deliver new services. 5G can be deployed in the 600 MHz band, very close to OTA signals, so depending on the reception scenario, it could be an interefering signal for the OTA signals, whether impairing or destroying them.
Device which boost TV signals for incresing their strength. Amplifiers can encompass one or more bands (VHF, UHF). Normally amplifiers are classified in the market according mainly to input configurations, bands to be amplified, gain and output level.
Also referred as booster, the amplifier is a device which is used to increase signal strength.
ATSC 3.0 / NextGen
ATSC 3.0, also known as NextGen TV, is the latest version of the Advanced Television Systems Committee (ATSC) digital television standard used in North America. It is an upgrade to the previous ATSC 1.0 standard and is designed to provide broadcasters with a more flexible, efficient, and interactive television broadcasting system. Some of the key features of ATSC 3.0 include: higher quality video and audio, more efficient broadcasting, interactive features and mobile viewing.
Attenuation is commonly measured in decibels (dB) and refers to the reduction of the amplitude, power, or strength of a signal as it travels through a medium or component. Attenuation can have both desirable and undesirable effects on electronic systems. In some cases, attenuating a signal can help reduce noise or interference, improve signal quality, or prevent damage to sensitive components. However, excessive attenuation can also cause signal degradation, resulting in a loss of signal strength, distortion, or other issues that can affect the performance of the system.
Word that comes from the arabic "al sumut" or "all directions". When pointing an antenna, azimut is the direction to point at in the horizontal plane refered to 0º (true north). Thus 90º points at east, 180 points at south and 270º points at west.
Amount of spectrum which is used. In case of a TV station, the Bandwith is 6 MHz.
Maximum angle around the receiving direction of an antenna when signal strength is maximized.
Cable Loss
Maximum angle around the receiving direction of an antenna when signal strength is maximized.
Channels 14-36
Portion of the spectrum between 470 and 608 MHz where the channels 14 to 36 are broadcasted.
Channels 2-6
Portion of the spectrum between 54 and 88 MHz where the channels 2 to 6 are broadcasted.
Channels 7-13
Portion of the spectrum between 174 and 216 MHz where the channels 7 to 13 are broadcasted.
Coaxial cable
Coaxial cables are used since the 30's to carry TV signals and they are formed by two cables sharing the same axis separated by an isolation plastic layer. The inner cable carries the information while the outer cable makes the shielding or protection against interference. The specs of the inner cable determine the signal strength losses. On the other hand, the better the shielding, the less prone the cable is to pick interference that can destroy the wanted TV signals.
Converter box
Device installed outside the TV set which receives the off-air signals and converts them to A/V signals to input a TV set or a screen without TV tuner. In the early stages of analog and DTV simulcasting, converter boxes were used to receive DTV signals in old analog NTSC TV sets. Today, converter boxes can be used to receive ATSC 3.0 broadcastings in TVs without this specification.
dBA is a unit of measurement for sound levels, which takes into account the sensitivity of the human ear to different frequencies. It is used to measure the loudness of sounds, and is commonly used in industrial noise monitoring, environmental noise assessment, and workplace safety. The "a" stands for "A-weighting," which is a type of frequency weighting that is applied to sound level measurements.
dBd is a unit of measurement for the gain of an antenna, particularly in the context of radio and telecommunications. dBd is a measure of an antenna's directional gain compared to a standard dipole antenna, which is a type of antenna that is commonly used as a reference for comparison. An antenna with a higher dBd value provides better directional gain, meaning it can receive and transmit signals more effectively in a particular direction.
dBi is a unit of measurement for the gain of an antenna, particularly in the context of radio and telecommunications. dBi is a measure of an antenna's directional gain compared to an isotropic antenna, which is a hypothetical antenna that radiates equally in all directions. An antenna with a higher dBi value provides better overall gain, meaning it can receive and transmit signals more effectively in all directions.
dBm is a unit of measurement for power in a communication system. It measures the amount of power in decibels (dB) relative to one milliwatt (mW). In a communication system, dBm is often used to express the strength of a signal, which can be important for determining the range and quality of a wireless connection. A signal with a higher dBm value has more power and is stronger, which generally means it can be received over a greater distance or with less interference. For example, if the power level of a signal is 1 milliwatt, it would be expressed as 0 dBm. If the power level is increased to 10 milliwatts, it would be expressed as 10 dBm. Conversely, if the power level is decreased to 0.1 milliwatts, it would be expressed as -10 dB.
dBμV is a unit of measurement for the voltage level of an electrical signal in a communication system. It measures the level of voltage in decibels (dB) relative to one microvolt (μV). In a communication system, dBμV is often used to express the strength of a signal that is being transmitted or received. For example, if the voltage level of a signal is 1 microvolt, it would be expressed as 0 dBμV. If the voltage level is increased to 10 microvolts, it would be expressed as 20 dBμV, because the ratio of the two voltages is 10:1, or 20 dB.
To convert between dBμV and dBmV, you need to know the impedance of the circuit. Considering an antenna scenario (75 ohm), the conversion factor is approximately 112, so you might use the formula: dBμV = dBmV +112.
DC Ground
0 volts potential reference of a system.
Measurement unit of power of a conducted signal referred to a given level in a logarithmic scale.
The dipole is the part of the antenna that concentrates the electromagnetic waves that are propagated in free space. The dipole antenna includes two conductive elements, like wires and rods, where the feeder is at the center and the two receiving sections of the antenna are on either side, hence the name di(two)-pole. The dipole is taylored so the length of the conductive elements is half of the highest wavelength (λ/2, where λ equals speed of light in vacuum divided by frequency) at the frequency of operation.
When refered to an antenna, the one which is able to focus the maximum received signal strength in one direction within its main lobe, whose angle is normally called beamwidth. The narrower the beamwidth, the higher the directivity and gain. On the other side the stricter the pointing has to be in order to maximize received signal strength.
DTV stands for Digital Television. It is a type of television broadcasting that uses digital signals instead of old analog NTSC signals to transmit audio and video information. Digital television offers several advantages over traditional analog television, including higher picture and sound quality, as well as the ability to transmit additional programming and interactive features through the same signal.
FM Antenna
Antenna designed specifically for the reception of FM radio signals. FM stands for frequency modulation, which is a method of encoding information on a radio wave by varying the frequency of the wave. An FM antenna is typically a dipole antenna, which consists of two conductive elements of equal length and thickness that are separated by a small gap. The dipole antenna is oriented vertically for reception of FM signals, as FM radio signals are vertically polarized.
Electromagnetic signals are propagated as waves in free space. The number of waves that pass a fixed place in a given amount of time is the frequency of the wave and it is expressed in Hertz (waves per second) or multiples of Hertz (1 million is referred as Megahertz and 1 billion is referred as GigaHertz).
Front-To-Back Ratio
Portion of signal that an antenna receives from its back, the opposite side of the direction where the antenna receives its maximum signal strength. The higher the Front-to-Back Ratio, the better. This means that the antenna can avoid interference from signals coming from behind, emitted on the same channels.
Ratio of signal strength which is boosted by an amplifier. Gain is measured in dB which expresses ouput signal minus input signal.
Gigahertz (GHz)
Measurement unit of frequency, in units of Hertz multiplied by a billion.
GPS stands for Global Positioning System. It is a satellite-based navigation system that provides location and time information in all weather conditions and at all times, anywhere on or near the Earth. The system consists of a network of satellites in orbit around the Earth, ground control stations, and GPS receivers that are used by users to determine their precise location, velocity, and time.
HDTV stands for High-Definition Television. It refers to a digital television broadcasting system that provides higher resolution than traditional analog or standard-definition television (SDTV) broadcasts. HDTV offers a picture resolution of at least 720 pixels vertically and 1,280 pixels horizontally, resulting in a much sharper and more detailed image than that provided by SDTV. Additionally, HDTV broadcasts typically offer high-quality surround sound audio.
Hertz (Hz)
Measurement unit of frequency, expressing the number of cycles per second a wave does.
High VHF
Portion of the VHF band between 174 and 216 MHz, or channels 7-13.
The measure of the opposition to the flow of electric current in the antenna. It is the combination of the resistance (due to the losses in the antenna) and the reactance (due to the capacitance and inductance of the antenna), and its unit is the ohm (symbol: Ω).
When an antenna is operating, it is important that its impedance is matched to the impedance of the transmission line or the receiver to which it is connected. If the impedance is not matched, it can result in signal reflection, which can cause a reduction in signal strength and overall performance of the antenna system. For TV broadcasting reception, the most commonly used impedance is 75 ohms.
Signal (unwanted) which is added or combined with the wanted signal impairing or even destroying it.
Lightning Protector
Device that is inserted in the coaxial cable after the antenna to divert to earth the possible atmospheric surges that may destroy the reception chain.
Line of Sight
Line of sight means that the broadcasting tower is visible for the antenna. Usually it is also referred as free space receiving conditions. The theory says that free space receiving conditions are achieved if the first Fresnel ellipsoid is free of obstacles, which is a function of the distance between trasmitter and receiver, the height of the transmitter and receiver antennas and the frequency of the station.
Portion of the VHF band between 54 and 88 MHz, or channels 2-6.
LTE stands for Long Term Evolution, and is associated with the 4G and 5G wireless communications standard designed to provide higher speeds than the 3G networks for mobile devices, such as smartphones, tablets, and wireless hotspots.
Megahertz (MHz)
Measurement unit of frequency, in units of Hertz multiplied by a million.
Mile range
The range, expressed in miles, denotes how far from the TV transmitter the antenna can receive clear signals. Antenna range is more a marketing term than a fully technical parameter. It gives some indication of the ability to receive high power transmissions from towers with direct line of sight from the antenna set at a defined height above ground (equal to rooftop mounting) and with certain power radiated. At long distances the height of the transmitter has to be sufficient to overcome the curvature of the Earth.
If these conditions are not met, extra losses have to be added that reduce this practical range.
Outdoor antennas perform better because normally they have higher gains and are installed at the rooftop, closer to meet free space conditions.
Multipath interference
Portion of the receiving signal which, after a reflection in a wall or difracted by woods or obstacles, is added to the wanted signal, causing its fading. In the time of analog TV, multipath interference was refered as ghost signal. In DTV multipath interference adds noise to the wanted signal and may destroy it.
Unwanted signal that is randomly added to the TV signal and impairs it and, should its amount be high enough, may destroy it.
When referred to an antena, the one which is able to receive signal in all directions (round the clock). Due to its design, the gain of an omnidirectional antenna is typically lower compared to directional antennas, which focus the signal in a specific direction.
Over the Air, of broadcast, in contrast to cabled distribution. It refers to the transmission of signals through the airwaves without the need for cables or wires.
In the context of antennas or electronics, a passive device is one that does not require an external power source to operate (so, it is not active). Instead, it realies on the electrical energy present in the circuit in whch it is connected, or on the electromagnetic waves surrounding the environment in the case of antenna, to perform its intended funcion.
In the context of antenna reception, polarization refers to the orientation of the electric field of an electromagnetic wave with respect to the earth's surface. It is the direction in which the electric field vectors of the electromagnetic wave oscillate as the wave propagates through space. For example, a vertically polarized antenna has its electric field oriented vertically, while a horizontally polarized antenna has its electric field oriented horizontally. Circularly polarized antennas have their electric field rotating in a circular pattern. The polarization of the antenna must be matched with the polarization of the transmitted signal for optimal reception. In general, for terrestrial broadcast transmissions, the most common polarizations used are vertical and horizontal.
RF Channels
Portion of 6 MHz of the frequency spectrum where a station broadcasts the audio and video signals.
Rotator / Rotor
An antenna rotator (or antenna rotor) is a device used to change the orientation, within the horizontal plane, of a directional antenna. Most antenna rotators have two parts, the rotator unit and the controller. The controller is normally placed near the equipment which the antenna is connected to, while the rotator is mounted on the antenna mast directly below the antenna. Rotators are commonly used in amateur radio and military communications installations. They are also used with TV and FM antennas, where stations are available from multiple directions, as the cost of a rotator is often significantly less than that of installing a second antenna to receive stations from multiple directions.
Device that divides the strength of the signals to feed more users or tuners. They are refered as 1:N, where N is the number of outputs. The more the outputs, the more the losses and hence the less the output signal strength in the outputs.
Broadcasting Tower, usually placed in high elevation to overcome the curvature of the earth and maximize its coverage where the Stations are transmitted to the users in a point to multipoint broadcast.
Device in the television or converter box which converts the RF input signals to A/V signals.
Ultra High Frequency. After Repack, the off-air signals in UHF are constrained between frequencies 470 MHz and 698 MHz or channels 14-36.
Very High Frequency. Frequencies between 54 and 88 MHz and 174-216 MHz or channels 2-6 and 7-13.
Consult the terms VHF and UHF separately. If a product specifies VHF / UHF, it indicates that the product is capable of operating on both frequency bands.
Virtual Channels
An assigned channel number that allows TV stations to preserve their original channel identification before the conversion to digital broadcasting. It consists of the familiar channel number that viewers are accustomed to (e.g., 3, 7) followed by a period and a second number (e.g., 3.1, 7.1), indicating the new RF broadcast channel for their digital signal. This enables viewers to find their desired programs using the same channel numbers they are familiar with, despite changes in the current broadcasting frequencies.
The wavelength (λ) is the distance between two peak points of a wave. It is inversely proportional to the frequency, and is calculated in relation to the speed of light in vacuum (c) as follows: λ= c/f.