Terrestrial TV Amplification: Systems and Components
Terrestrial Television Amplification Systems
The Amplification Process
A distribution amplifier generates the power required to distribute the signal between all users on a network, mitigating signal losses that occur on their way from the antenna to the TV.
Modifications Required in the Amplification Process
Attenuator
An attenuator is an element that produces signal attenuation. They can be fixed or adjustable. The attenuation is constant throughout the band of the TV/SAT.
Equalizer
An equalizer attenuates high frequencies and low frequencies to different depths, attempting to equalize frequency signals.
Bandpass Filter
A bandpass filter allows signals within a given band to pass through.
Filter Rejects or Trap
A filter rejects or trap attenuates a particular frequency band.
Characteristics of Extenders
Gain
Gain determines the difference in level between input and output and is expressed in dB.
Gain Control
Output level adjustment is necessary and is made using a gain control method. There are two types:
- Manual Gain Control: Accomplished with an attenuator located at the amplifier input or intermediate stages. This control is called margin control and is expressed in dB.
- Automatic Gain Control: Uses a feedback control system regulating the input signal level fluctuations. This is called margin control automatic control and is expressed in dB.
Noise Figure
Expressed in dB, the levels typically hover between 5 and 10 dB. This parameter affects the C/N (carrier/noise) ratio.
Output Voltage
Distortion of the signal due to the saturation effect of the expander.
Bandwidth
Frequency range of the amplifying device, expressed in MHz.
Amplifier Types
There are several types of amplifiers:
- Broadband amplifier
- Narrowband amplifier
Broadband Amplifier
Amplifies all channels of one or more bands without being endowed with any specific type of output filter.
They can be classified as:
Central Line
Input amplifiers are equipped with independent attenuator band filters per band EQ controls used in distribution networks where signals can be any band should be amplified and reach of a single line.
Mast Broadband Amplifiers
Equipped with several inputs which connect directly signals from the antennas are installed on the mast itself catchment system the power of these amplifiers is generally low so that its expansion is limited to individual installations of the few shots placed on the RITS.
Central Multi Head Band
Broadband amplifiers are several entries for each band normally these are often used in small community facilities where exclusive power is not needed and the channels are separated by more power than RITS and placed on the mast.
All internally broadband magnifiers have filters that separate the bands and allow independent control. We can differentiate between:
Expanders Expansion
Joint internal amplification of this kind of facility consists of a single amp for all bands. Several bands amplified.
Separate Amplifier
This type of amplifier has internal amplifiers as many bands. More commonly, used amplifier stages covering entire bands.
The inter-modulation is the emergence of replicas of certain channels in the rest of the band.
Band Amplifiers
Narrow independently treat the channels present in a facility.
Depending on the number of channels that amplify these amplifiers are:
Channel Mono Amplifiers
They are amplifiers whose bandwidth is a television station are but few active filters whose frequency is not ideal so this amplifies not only the tight channel but also those located adjacent where the influence will depend on your level and characteristics of rejection the amplifier.
Multichannel Amplifier
The emergence of multiple and frequent digital signals provided adjacent channels either analog or digital multi –
Amplification Headers Terrestrial TV Systems
There are two types of individual or collective.