Fact-checked by Grok 2 weeks ago

Television transmitter

A television transmitter is an electronic device or system used in broadcasting to convert baseband video and audio signals into modulated radio frequency (RF) signals, which are then amplified and radiated via an antenna to enable over-the-air reception by television sets and other devices. These transmitters form the core of television broadcast infrastructure, supporting the delivery of programming to wide geographic areas, from local communities to national audiences. The primary components of a basic television transmitter include a for voltage conversion, an to generate the RF , modulator s to combine video and audio signals with the carrier using appropriate schemes (such as for video and for audio in analog systems, or schemes like vestigial in ATSC systems for ), RF power amplifiers to boost signal strength, and an to optimize transmission to the . Synchronizing and scanning circuits ensure precise timing for , while video and audio amplifiers prepare signals for . In operation, the system transforms electrical inputs into RF currents, modulates them with content, and transmits the combined signal through a single , adhering to standards like 625-line scanning at 25 frames per second in certain systems. Television transmitters are classified by power and type, including main transmitters for regular full-power service and low-power television (LPTV) transmitters for localized coverage, which operate on VHF (channels 2-13) or UHF (channels 14-36) bands with maximum effective radiated powers () of 3 kW (VHF) or 15 kW (UHF) for digital signals. Historically analog, modern transmitters predominantly use digital modulation, representing signals as (0s and 1s) for improved efficiency, resistance to noise, and support for high-definition formats, following global transitions completed in regions like the by 2009. Digital systems enable features like multiple subchannels within a single and are evolving toward advanced standards such as for enhanced interactivity and mobile reception.

Fundamentals

Definition and Role

A television transmitter is an electronic device that generates and amplifies (RF) signals carrying video and audio content for over-the-air broadcast to receivers. It serves as the critical endpoint in the , transforming studio-originated content into a form suitable for . In the broadcast chain, the transmitter converts video signals, such as composite or component formats, and associated audio inputs into modulated RF carriers that can be radiated from an . This enables efficient one-to-many of programming to multiple receivers within a coverage area, typically over VHF or UHF bands. Experimental television broadcasts using such transmitters first occurred in the , laying the groundwork for modern systems. The key operational principle involves to encode the content onto a : analog systems employ (AM) for the video signal, often with vestigial filtering to optimize , and () for audio to provide noise resistance. Digital systems, in contrast, utilize methods like (OFDM) to transmit data streams robustly. At a high level, the transmitter's structure includes input processors for , modulators to apply the encoding, amplifiers to boost power, a combiner to integrate video and audio paths, and an for radiation. This architecture has evolved to support transitions to digital standards such as ATSC and .

Historical Evolution

The development of television transmitters began in the with mechanical scanning systems, pioneered by Scottish inventor , who demonstrated the first electromechanical television transmission in 1926 using a rotating to scan and transmit images over radio waves. These early transmitters were limited to low-resolution images, typically 30 lines, and relied on mechanical components for both scanning and modulation. A significant advancement came in 1923 when Vladimir Zworykin, working at , patented the , an camera tube that enabled all- television systems by converting optical images into electrical signals without moving parts. This paved the way for the transition from to transmitters. In 1936, the launched the world's first regular high-definition public television service from in , initially alternating between Baird's system and EMI's system using -based cameras, marking the practical implementation of transmission technology. The first commercial television broadcast occurred on April 30, 1939, at the New York World's Fair, where transmitted live images from the event using an transmitter, introducing television to a wider American audience. Following , the analog era solidified with the standardization of black-and-white television. In 1941, the () approved the () standard for 525-line monochrome transmission, enabling widespread with vacuum tube-based transmitters that dominated the industry through the and into the due to their reliability in high-power amplification. The introduction of in 1953 required modifications to these transmitters for compatible color signals; the adopted the color standard on , 1953, allowing with existing monochrome receivers while adding color subcarrier . The shift to solid-state technology in the improved efficiency and reduced maintenance, with early high-power solid-state VHF transmitters emerging around 1980, such as Pye's 15/25 kW models for the UK's network, replacing vacuum tubes with transistor amplifiers for better reliability and lower power consumption. The digital transition accelerated in the 1990s, with the Advanced Television Systems Committee (ATSC) developing the DTV standard, adopted by the FCC in 1995 for 8-VSB modulation to support high-definition broadcasting. Global analog shutdowns followed, including the U.S. full-power transition on June 12, 2009, and various European countries completing theirs in the 2010s, such as the UK's final switchover in 2012. By 2025, advancements have enabled and potential 8K resolutions alongside IP integration for enhanced interactivity and datacasting, revitalizing over-the-air broadcasting through software-updatable features.

Classifications

Analog Transmitters

Analog television transmitters employ a design that processes video and audio signals through separate modulators before amplification and transmission. The video signal is modulated using (AM) with a vestigial (VSB) to optimize efficiency within the allocated , while the audio signal uses (FM) for improved noise resistance. These separate modulators feed into dedicated amplifiers, historically relying on technology such as tetrodes for VHF applications and klystrons for UHF, with early solid-state amplifiers emerging in lower-power setups during the late . This modular ensures precise control over each signal component to meet transmission standards. Modulation specifics vary by standard but follow consistent principles. The video is positioned 1.25 MHz above the lower edge, allowing the full upper (up to 4-6 MHz ) to be transmitted while retaining only a vestigial portion of the lower (typically 0.75-1.25 MHz) to conserve . The audio is offset from the video by 4.5 MHz in systems, 5.5 MHz in most PAL variants and some variants (e.g., ), and 6.5 MHz in other variants (e.g., D/K/L), with deviation set at ±25 kHz for or ±50 kHz for PAL/ to balance audio quality and . Linear is essential throughout to prevent , particularly in the VSB video signal where non-linearities could introduce quadrature . High-power amplification in analog transmitters often utilizes vacuum tubes for VHF bands (54-216 MHz), capable of outputs up to 20-50 kW with high , or klystrons for UHF bands (470-890 MHz), achieving powers up to 100 kW through velocity modulation for efficient high-frequency operation. Common standards include (525 lines, 60 fields per second), PAL (625 lines, 50 fields), and (625 lines, 50 fields), each allocating 6 MHz channels for NTSC or 7-8 MHz for PAL/SECAM to accommodate the combined signals. These systems were widely used until the 2000s, when many countries transitioned to . Despite their reliability, analog transmitters exhibit key limitations, including high susceptibility to and , which degrade signal quality cumulatively over distance, and inefficient utilization, requiring a full 6 MHz per standard-definition service without capabilities. In contrast, systems offer greater within the same .

Digital Transmitters

Digital television transmitters represent a significant advancement over analog systems, incorporating integrated exciters that handle MPEG-2 or MPEG-4 encoding to compress video and audio data into a transport stream before modulation. These exciters typically employ 8-level vestigial sideband (8VSB) modulation for the ATSC standard in the United States or orthogonal frequency-division multiplexing (OFDM), often as coded OFDM (COFDM), for standards like DVB-T/T2 in Europe and ISDB-T in Japan. The design supports solid-state amplifiers using laterally diffused metal oxide semiconductor (LDMOS) technology, which can deliver power outputs from low kilowatts up to over 10 kW in multi-stage configurations, enabling reliable broadcast over VHF and UHF bands. Modulation schemes in digital transmitters are optimized for efficient spectrum use and error resilience, with in ATSC 1.0 providing a data rate of approximately 19.39 Mbps within a 6 MHz channel, sufficient for standard-definition (SD) or television. In contrast, OFDM variants in utilize up to 32,768 subcarriers with orders from QPSK to 256-QAM, achieving data rates from 1.7 Mbps to 45 Mbps in an 8 MHz channel, while ISDB-T employs band-segmented transmission OFDM (BST-OFDM) for similar flexible bandwidth allocation. (FEC) is integral, featuring Reed-Solomon outer coding—such as RS(207,187) in ATSC or RS(204,188) in —and inner coding like trellis (2/3 rate) for ATSC or punctured convolutional (rates 1/2 to 7/8) for , enhancing signal integrity against noise and fading. Standards like (deployed in the since the early 2020s, with over 75% of households covered as of 2025) support 6 or 8 MHz channels with enhanced OFDM for and UHD, while in and DTMB in (using single-carrier or TDS-OFDM with LDPC and BCH FEC) enable mobile TV reception and data rates up to 32 Mbps in 8 MHz for DTMB. Amplification stages in digital transmitters rely on multi-stage solid-state architectures to achieve high and , often incorporating pre-distortion () techniques that predetermine and counteract nonlinear distortions in the power amplifier, ensuring adjacent channel power ratios below -35 . Envelope tracking modulates the amplifier's supply voltage in real-time to match the signal envelope, boosting to over 50% for non-constant envelope signals like OFDM, compared to 20-30% in traditional class AB amplifiers. These features allow transmitters to handle the full power range without tube-based components, reducing maintenance and enabling compact designs for both fixed and mobile . The primary advantages of digital transmitters include superior spectrum efficiency, such as multiplexing multiple SD channels within a single 6 MHz ATSC band or delivering one HD stream, which maximizes throughput without additional bandwidth. OFDM-based systems offer inherent robustness to multipath interference and impulse noise through guard intervals and frequency diversity, improving reception in urban or mobile environments over analog counterparts. ATSC 3.0 further introduces IP over broadcast capabilities, enabling datacasting and integration with broadband for interactive services during its 2020s rollout, while overall digital architectures reduce susceptibility to interference and support advanced features like 4K delivery with lower power consumption.

Standards and Specifications

Analog System Standards

The ITU Stockholm Plan of 1961 established frequency allocations for analog television broadcasting in the VHF and UHF bands across the European Broadcasting Area, defining Band I (47–68 MHz) and Band III (174–230 MHz) for VHF television channels, while Bands IV (470–582 MHz) and V (582–960 MHz) were allocated for UHF. Channel bandwidths were set at 7 MHz for VHF in 625-line systems compatible with PAL and SECAM, and 8 MHz for UHF, with guard bands incorporated into the channel spacing to reduce adjacent-channel interference and ensure effective frequency reuse. These allocations prioritized 625-line standards (such as Systems B, G, and I) for Bands I, III, IV, and V, supporting video bandwidths of 5–6 MHz and sound carrier offsets of 5.5–6.5 MHz. In the United States, the Federal Communications Commission (FCC) regulated analog television under 47 CFR Part 73, assigning Channels 2–13 in the VHF band (54–216 MHz) and Channels 14–69 in the UHF band (470–806 MHz), each with a 6 MHz channel bandwidth suitable for the NTSC System M. The visual carrier frequency was positioned 1.25 MHz above the lower channel boundary, while the aural carrier was offset 4.5 MHz higher than the visual carrier to accommodate frequency modulation for audio. Maximum video modulation was limited to 87.5% for reference white levels to prevent overmodulation, and audio signals employed 75 μs pre-emphasis to enhance high-frequency response and improve signal-to-noise ratio. Key signal parameters for analog systems included a synchronization pulse amplitude equivalent to 40% of the peak-to-peak video signal, ensuring stable locking. frequencies were standardized at approximately 60 Hz for to align with North American power grids, while PAL systems used 50 Hz to match European 50 Hz mains frequency, reducing visible flicker in interlaced scanning. For color transmission in , the subcarrier operated at 3.58 MHz, modulated in to carry hue and information compatibly with receivers. International variations under CCIR recommendations included System B/G, widely adopted in for PAL and , utilizing 7 MHz channels in VHF Band I/III and 8 MHz in UHF Bands IV/V to support 625-line resolution with backward compatibility to monochrome broadcasts. In contrast, System M in the employed 6 MHz channels for , optimizing for narrower bandwidths while maintaining monochrome compatibility through luminance-chrominance separation. Compliance testing for analog transmitters involved measurements of (typically limited to 2% depth), (weighted exceeding 50 ), and quadrature distortion (below 1% for audio carriers) to verify . limits were enforced to protect co-channel services and ensure coverage without excessive .

Digital System Standards

transmission standards emerged in the late 1990s and early to replace analog systems, enabling more efficient use through error correction, compression, and advanced . These standards define schemes, data rates, and framing to ensure reliable delivery of and audio over terrestrial channels, with global adoption driven by regulatory mandates and international harmonization efforts. Key systems include the ATSC family in , the DVB family in and beyond, and ISDB-T in and , each optimized for regional allocations and receiver capabilities. The ATSC A/53 standard, adopted in the United States, employs modulation to transmit an transport stream at up to 19.39 Mbps within a 6 MHz . This single-carrier approach provides robust performance in fixed reception scenarios, supporting multiple standard-definition programs or one high-definition stream. For enhanced capabilities, , specified in A/322, shifts to (OFDM) with up to 57 Mbps throughput in a 6 MHz , incorporating layered division (LDM) to simultaneously serve and fixed services by layering robust signals for portables beneath higher-rate streams for viewers. In , the standard utilizes coded (COFDM) across channel bandwidths of 6, 7, or 8 MHz, enabling variable data rates up to approximately 24 Mbps depending on configuration. This multi-carrier modulation excels in multipath environments common to terrestrial broadcasting. Its successor, , boosts capacity by up to 50% over through advanced , higher-order modulation (up to 256-QAM), and support for multiple-input multiple-output () techniques, allowing enhanced throughput for ultra-high-definition content in the same bandwidth. Meanwhile, Japan's ISDB-T standard, also adopted in as ISDB-T International, features segmented transmission structure with 13 frequency segments in an 8 MHz channel (or 6 MHz variant), facilitating hierarchical modulation for simultaneous standard and high-definition services, as well as mobile reception. Regulatory frameworks have shaped the transition to these digital standards post-2000. In the US, the (FCC) mandated the end of analog broadcasting on June 12, 2009, requiring full-power stations to transmit solely in digital format to free spectrum for public safety and other uses. This shift included reallocating the 600 MHz band, with an incentive auction concluding in 2017 that repurposed 84 MHz—70 MHz for licensed and 14 MHz for unlicensed operations—generating over $19 billion while relocating TV channels to higher frequencies. Globally, Recommendation BT.1306 promotes harmonization by specifying common error-correction, framing, , and emission methods across digital terrestrial TV systems, facilitating interoperability and spectrum sharing. Core signal parameters ensure reliable transmission under varying conditions. For ATSC A/53, the is 10.76 Msps, with a field synchronization segment acting as a to mitigate multipath interference, targeting a pre-forward error correction (BER) below 10^{-4} for decoder input. Similar thresholds apply to and systems, where s (typically 1/4 to 1/32 of symbol duration) protect against echoes in urban environments. These parameters yield spectral efficiencies far surpassing analog, with ATSC 1.0 achieving approximately 3.2 bits/Hz compared to analog NTSC's 0.25 bits/Hz equivalent. As of 2025, adoption remains voluntary in the , with the FCC authorizing permissive use to encourage market-driven rollout without mandatory simulcasting requirements, focusing on consumer benefits like improved mobile reception. As of early 2025, new receivers were launched at CES to accelerate adoption, and in November 2025, the FCC extended deadlines for transition-related filings while maintaining voluntary status. This standard supports (HDR) video and immersive audio formats such as , enhancing viewing experiences while delivering spectrum efficiency gains up to 9.5 bits/Hz in optimal configurations.

Core Components

Input Processing Stage

The input processing stage of a television transmitter handles the initial reception and conditioning of video and audio signals, preparing them for subsequent upconversion to intermediate frequencies (IF) while ensuring compliance with broadcast standards such as SMPTE 170M for analog systems. This stage stabilizes signal levels, applies necessary filtering and corrections, and performs initial encoding or formatting to maintain before feeding into processes. For analog video inputs, the signal is typically received as a at 1.0 V peak-to-peak with black level negative polarity, terminated on a 75 Ω unbalanced impedance, adhering to SMPTE 170M specifications that define 140 IRE units from sync tip to peak white. Digital video inputs, such as (SDI) per SMPTE 259M or , arrive in 10-bit format, supporting standard definition rates up to 270 Mb/s. Initial processing includes low-pass filtering with a cutoff around 5 MHz for luma components to prevent , and sync insertion or extraction to align timing per levels. Analog audio inputs are balanced signals at 0 dBm (0.775 V ) on 600 Ω impedance, covering a range of 20 Hz to 15 kHz, with provisions for composite or subcarrier inputs at 75 Ω unbalanced. uses AES/EBU interfaces for uncompressed or multichannel delivery. Pre-emphasis is applied at 75 μs for U.S. standards to boost high frequencies and improve , while a 19 kHz pilot tone is inserted for identification in compatible systems. Key processing steps include (AGC) to stabilize input levels within ±0.5 dB, preventing overload or distortion from varying source amplitudes. For digital signals, and enhance , while (CRC) verifies packet integrity in transport streams. The stage culminates in IF generation, converting video to 45.75 MHz and audio to 41.25 MHz carriers for analog systems, or preparing digital streams for further handling. In analog systems, vestigial sideband (VSB) filtering shapes the lower sideband with a 0.75 MHz cutoff to optimize bandwidth efficiency while preserving low-frequency content essential for image quality. For digital systems, video undergoes or MPEG-4 encoding to compress data, followed by into 188-byte transport stream (TS) packets that integrate audio, video, and . Monitoring in this stage employs waveform monitors and vector scopes to visualize video amplitude, phase, and color balance, ensuring adherence to standards like 100 IRE luminance range. Spectrum analyzers assess audio frequency response and distortion, confirming flat response within 30 Hz to 15 kHz post-pre-emphasis. These tools enable real-time quality checks before signals proceed to modulation.

Modulation and Intermediate Stages

In analog television transmitters, the video signal is modulated using (AM) where the reference white level corresponds to 100% , ensuring maximum excursion without . To conserve while preserving image quality, vestigial (VSB) filtering is applied, retaining the full lower and a portion of the upper after standard AM or double- suppressed-carrier . For audio, frequency (FM) is employed with a peak deviation of ±25 kHz in systems, defined as 100% to balance audio fidelity and . In PAL and systems, the deviation increases to ±50 kHz to accommodate wider audio s. In digital television transmitters, video data is mapped onto quadrature amplitude modulation (QAM) constellations for cable distribution or 8-level VSB (8VSB) for terrestrial ATSC broadcasting, enabling robust single-carrier transmission within 6 MHz channels. Audio signals are compressed using Advanced Audio Coding (AAC), such as MPEG-2 AAC, before integration into the transport stream and modulation via QPSK or higher-order schemes within orthogonal frequency-division multiplexing (OFDM) subcarriers for DVB-T systems. The intermediate stages process the modulated signals at low power levels prior to amplification. These include upconversion via (IF) mixing, where a typical 44 MHz IF signal is translated to the final RF channel in the UHF band using a . The exciter unit generates a stable carrier signal, incorporating low-power and frequency translation to ensure before handover to power amplifiers. For enhanced in digital transmitters, digital predistortion techniques pre-compensate for amplifier nonlinearities by inverting characteristics in the or IF domain. Multiplexing in digital systems involves embedding Program Association Tables (PAT) and Program Map Tables (PMT) within the MPEG-2 transport stream's Program Specific Information (PSI) and Service Information (SI) to identify and route video, audio, and data components. In analog systems, intercarrier buzz—unwanted audio interference from video carrier harmonics—is suppressed through filtering in the modulation stage to prevent low-frequency hum in receivers. Frequency synthesis relies on (PLL) circuits to maintain carrier stability, achieving drift below 10 Hz in transmitters to meet stringent requirements. Subcarrier generation, such as the 4.5 MHz offset for audio relative to the video carrier, is derived from the PLL for precise intercarrier spacing.

Output Amplification Stages

The output amplification stages of a television transmitter the low-power modulated RF signal from the intermediate stages to broadcast levels, typically achieving (ERP) in the range of several kilowatts through a multi-stage chain. The chain begins with a driver stage generating 10-100 W to provide sufficient drive for the main power (PA), which scales output to 1-50 kW or higher, often using modular designs with amplifiers for and broadband capability to support multi-channel TV transmission. Contemporary systems favor solid-state amplifiers utilizing LDMOS or GaN transistors, supplied at 28-65 V, due to their compactness, reliability, and suitability for digital modulation with high peak-to-average power ratios. Tube-based options, such as klystrons for outputs exceeding 50 kW, have become rare in modern installations because of their lower efficiency with high-definition digital signals and the dominance of solid-state technology. To maintain linearity essential for digital TV standards, amplifiers operate in Class AB mode, which minimizes crossover distortion while supporting the wide dynamic range of signals like ATSC or DVB-T. Digital pre-correction (DPC), also known as digital predistortion (DPD), further enhances linearity by predistorting the input to counteract PA nonlinearities, reducing intermodulation distortion (IMD) to below -30 dBc in the spectral shoulder for compliance with emission limits. Efficiency in these stages is critical for reducing operational costs and heat dissipation, with Doherty architecture widely adopted in solid-state PAs to achieve 40-50% drain efficiency (DE) by dynamically combining carrier and peaking amplifiers, offering 15-20% improvement over traditional Class AB designs. Envelope tracking techniques modulate the PA supply voltage in with the signal , enabling up to 60% power added efficiency (PAE) in transmitters by optimizing bias for varying power levels. Following amplification, bandpass or low-pass filters are employed post-PA to attenuate harmonics and emissions, ensuring spectral mask compliance such as the ATSC template with harmonic suppression exceeding 40 dB.

Signal Integration and Output

Audio-Visual Signal Combining

In analog television transmitters, the visual and aural signals are generated separately before being combined at the (RF) stage to form the composite broadcast signal. The visual signal, amplitude-modulated with up to 80% modulation depth on its , is produced at significantly higher power than the aural signal, which is frequency-modulated and typically operates at 10-20% of the total transmitted power to maintain signal balance and minimize . This power disparity ensures the visual dominates the spectrum while the aural , offset by 4.5 MHz in systems, remains audible without overpowering the video. Two primary methods are used for combining these signals in analog systems. The conventional approach employs separate visual and aural transmitters, with their RF outputs merged using a hybrid coupler or to achieve isolation between the carriers and prevent mutual . Hybrid couplers provide balanced power division and typically introduce losses of 0.5-1 , while diplexers, tuned to the specific carrier separation, allow efficient channeling of the signals to the output with minimal . Alternatively, the intercarrier method generates a low-power composite signal by mixing the audio directly with the intermediate frequency (IF) video signal, producing a 4.5 MHz intercarrier ; a notch filter at this frequency then suppresses the unwanted tone before final and amplification, reducing hardware complexity at the cost of precise filtering requirements. To mitigate interference in the combined signal, analog transmitters incorporate group delay equalization circuits that compensate for frequency-dependent delays introduced by IF filters and vestigial sideband processing, ensuring uniform signal propagation across the video bandwidth. Aural-visual crosstalk is suppressed to below -40 dB through high-isolation combiners and filtering, preventing audio bleed into the video or vice versa, which could degrade picture quality or introduce buzz. For enhanced audio capabilities, stereo and dual-sound transmission use a 15 kHz pilot tone in the Multichannel Television Sound (MTS) system for the U.S., enabling Second Audio Program (SAP) channels for bilingual broadcasts, while the Near Instantaneous Companded Audio Multiplex (NICAM) system in and elsewhere embeds digital stereo or dual audio as metadata on a secondary , maintaining with mono receivers. In digital television transmitters, audio and video integration varies by standard and occurs digitally before RF modulation, eliminating separate RF combining. For , compressed audio (e.g., ) and video packets are interleaved via in an transport stream (TS), which is then mapped to constellations (QPSK, 16-QAM, or 64-QAM) and modulated onto an (OFDM) carrier set. For ATSC 1.0, audio (e.g., AC-3) and video () are similarly multiplexed into an TS but modulated using 8-level vestigial sideband () on a single carrier. For , audio (e.g., AC-4 or ) and video (HEVC/H.265) are packetized using IP-based protocols such as ROUTE (Real-time Object delivery over Unidirectional ) or MMT ( Media ), forming physical layer pipes (PLPs) that support layered division multiplexing; these are then modulated onto an OFDM waveform with constellations up to 4096-QAM. As of November 2025, is deployed in over 75 U.S. markets, enhancing efficiency, mobile reception, and features like and . In all cases, inherent digital error correction (e.g., Reed-Solomon or LDPC coding) provides robustness against without additional analog-style equalization.

Antenna Systems and Propagation

Antenna systems in television broadcasting are designed to efficiently radiate the combined audiovisual signal over wide areas, primarily in the VHF (very high frequency) and UHF (ultra high frequency) bands. Common types include panel arrays for UHF applications, which are directional and assembled from elementary radiators like dipoles to achieve operation and optimized patterns. Slot radiators are prevalent for VHF, offering compact designs integrated into waveguides or cylindrical structures for . For coverage, collinear arrays stack dipoles vertically, providing uniform patterns suitable for serving circular service areas. Key design parameters ensure reliable performance, with typical gains ranging from 10 to 20 dBi for VHF antennas and higher for UHF to focus energy toward the horizon. Voltage (VSWR) is maintained below 1.2:1 to minimize reflections and power loss, often achieving values as low as 1.05 in optimized systems. is generally horizontal for fixed , but is increasingly adopted in systems to improve by mitigating multipath and issues. Antennas are mounted on towers typically 300 to 2000 feet (91 to 610 meters) tall to extend line-of-sight coverage, with side-mounted configurations on tower faces for panel arrays or top-loaded designs for types to avoid clutter . protection is essential, incorporating grounding systems, arrestors, and conductive paths along the tower structure to safely dissipate strikes and prevent damage to the transmitter feedlines. Signal propagation for television transmitters relies on line-of-sight (LOS) dominance in VHF and UHF bands, where direct waves reach receivers with minimal obstruction. clearance is critical, ensuring the first —spanning about 60% of the radius—remains unobstructed to avoid losses exceeding 6 dB. signals exhibit a "," abruptly failing below threshold signal-to-noise ratios, in contrast to analog's graceful degradation where picture quality diminishes progressively. Coverage planning shapes radiation patterns to meet () limits, incorporating to direct power toward target areas while suppressing . Tools like the Longley-Rice irregular model simulate over varied landscapes, accounting for and clutter losses to predict field strengths accurately. In digital terrestrial systems such as , single-frequency networks (SFNs) enable efficient spectrum use by synchronizing multiple transmitters on one , extending coverage without in overlap zones.

Performance and Operations

Output Power and Efficiency

In television transmitters, output power for analog systems is defined as the peak power measured during the horizontal sync tip, representing the maximum power level of the synchronizing pulses to ensure reliable synchronization. For systems, output power is measured as the average power across symbols, reflecting the value of the modulated signal over time, which remains consistent regardless of content variability. (PEP) limits apply to constrain instantaneous peaks, particularly in analog visual carriers, to prevent and as per FCC regulations. Effective radiated power (ERP) quantifies the total power directed toward the coverage area and is calculated as ERP = P_t × G_a, where P_t is the transmitter output power in kW and G_a is the antenna gain in linear units (converted from ). FCC rules under 47 CFR § 73.614 limit maximum based on band and antenna (HAAT): for VHF channels 2-6, up to 100 kW in Zone I or 316 kW in Zones II/III at ≤305 m HAAT; for VHF channels 7-13, up to 316 kW across zones at the same height; and for UHF channels 14-36, up to 1,000 kW at ≤365 m HAAT, with reductions for taller antennas to control . Efficiency in television transmitters is assessed via power-added efficiency (PAE), defined as PAE = (P_RF - P_in) / P_DC × 100%, where P_RF is RF output power, P_in is RF input power, and P_DC is DC input power; this metric captures how effectively the final amplification stage converts electrical input to usable RF output. Typical PAE values range from 30% to 60% in modern solid-state designs, with digital transmitters achieving higher efficiencies (up to 55% at 9 dB back-off) through techniques like digital predistortion (DPD), which linearizes the power amplifier to reduce distortion while operating closer to saturation. Power measurements for compliance use directional couplers to sample RF output without interrupting , combined with analyzers to verify and peak/average levels at the transmitter terminals, including filters. These ensure adherence to FCC Part 73 requirements. scaling varies by application: low- translators operate at 10 W to 1 kW to extend coverage in remote areas without full infrastructure, while full-service stations use 10 kW to 100 kW for broad regional reach. systems enable 6-10 lower for equivalent coverage compared to analog due to coding gain, which improves signal robustness against noise.

Backup Systems and Reliability

Television transmitters employ redundancy setups to minimize downtime, such as hot-standby that automatically switch over to a unit in the event of a primary , ensuring seamless with switchover times typically under 1 second. Parallel power amplifier (PA) modules configured in architectures provide additional , where N modules handle normal loads and one extra module activates upon , supporting systems up to 40 kW in solid-state designs. These configurations, including dual and automated RF switching via controllers like the Multi-System Controller (MSC3), are standard in modern UHF and VHF transmitters to maintain broadcast continuity. Backup facilities extend to key components, with reserve modulators and multiplexers ready for rapid integration during faults, alongside PA spares that allow hot-swappable replacement without interrupting . Power reliability is ensured through uninterruptible power supplies () that bridge short outages, often using flywheel-based systems to handle high inrush currents from transmitter events—up to 4,000 in a 65 kW digital setup—while transitioning to diesel generators for extended blackouts. These generators, typically sized for full facility loads including HVAC and technical equipment, undergo weekly testing to achieve , with parallel units providing further in critical broadcast environments. Monitoring systems enable proactive fault detection, utilizing SNMP-based remote control interfaces for real-time oversight via web GUIs or / networks, allowing operators to track essential parameters like voltage standing wave ratio (VSWR), internal temperatures, and (). In digital transmitters, thresholds exceeding 30 dB indicate optimal , with alarms triggered for deviations in VSWR (to prevent damage) or temperature rises that could signal cooling issues. Ethernet-enabled flags for overdrive, high VSWR, and thermal excursions further support automated alerts in systems like VHF units. Reliability metrics for solid-state TV transmitters emphasize (MTBF) exceeding 10,000 hours, achieved through modular designs that isolate faults without total shutdown. Cooling systems, either forced air for lower-power setups or liquid-based with redundant pumps and auto-changeover, are critical to averting by maintaining component temperatures below operational limits, even in high-ambient environments up to 45°C. These measures enhance overall uptime, with hot-swappable PAs and power supplies minimizing (MTTR) to minutes. Maintenance protocols include annual Federal Communications Commission (FCC) proof-of-performance tests to verify signal conformance, waveform integrity, and coverage, ensuring compliance with standards like those in 47 CFR § 73.687 for full-power stations. For digital systems, routine software updates—such as firmware upgrades for modulation—address evolving standards and improve efficiency, often requiring minimal hardware changes via exciter reconfiguration. These practices, combined with periodic cooling system inspections, sustain long-term reliability in operational environments.

References

  1. [1]
    Broadcast Transmitter Systems Explained Simply - CTI
    Broadcast transmitter systems are responsible for converting audio and video signals into radio frequency (RF) signals that can be transmitted over long ...
  2. [2]
    Low Power Television Service | Federal Communications Commission
    Dec 9, 2019 · On the technical side, LPTV stations transmit on one of the standard television channels -- VHF (channels 2 through 13) or UHF (channels 14 ...
  3. [3]
    None
    ### Block Diagram Components and Operation of a Basic TV Transmitter
  4. [4]
    47 CFR 73.1665 -- Main transmitters. - eCFR
    A main transmitter is one which is used for regular program service having power ratings appropriate for the authorized operating power(s). (b) There is no ...
  5. [5]
    Difference: Analog & Digital TV Transmitter | FMUSER BROADCAST
    The analog TV transmitter uses FM modulation and AM modulation, while the digital TV transmitter uses the digital signal represented by 1 and 0.
  6. [6]
    [PDF] October 7, 2025 FCC FACT SHEET∗ Authorizing Permissive Use of ...
    Oct 7, 2025 · Background: Next Gen TV (which uses the “ATSC 3.0” or “3.0” standard) is the future of broadcast television. ATSC 3.0 promises to revitalize ...
  7. [7]
    A Practical Guide To RF In Broadcast: Transmitter & Receiver ...
    Aug 21, 2023 · Frequency modulation (FM) adds information by slightly varying the carrier signal's frequency and unaffected by atmospheric static. Analog TV ...
  8. [8]
    [PDF] Palestine Polytechnic University
    Elementary block diagram of a monochrome television transmitter. A simplified block diagram of a black and white TV receiver is shown in Fig.2. 3. The ...
  9. [9]
    16. 7.1 The Evolution of Television - Open Text WSU
    Television broadcasting began as early as 1928, when the Federal Radio Commission authorized inventor Charles Jenkins to broadcast from W3XK, an experimental ...
  10. [10]
    [PDF] Modulation Systems and Characteristics
    Modulation varies a carrier wave's characteristics with a message signal. Amplitude modulation varies the carrier's amplitude with the modulating signal.<|control11|><|separator|>
  11. [11]
    John Logie Baird's Televisor: An Early Mechanical TV - IEEE Spectrum
    Sep 16, 2024 · In 1926, the Scottish inventor John Logie Baird demonstrated an electromechanical system for transmitting moving images.
  12. [12]
    Vladimir Zworykin | 1889-1982 | RCA - Baird Television
    Zworykin invented television transmitting and receiving systems employing cathode ray tubes. He was instrumental in the practical development of television ...
  13. [13]
    Zworykin Applies for Patent on an Early Type of Television - EBSCO
    Vladimir Zworykin is often credited as a pioneering figure in the development of television, particularly for his invention of the iconoscope and kinescope ...
  14. [14]
    Opening Night: November 1936 - BBC
    The BBC's – and the world's – first regular high-definition television service started on Monday the 2nd of November 1936. A German service had begun the ...Missing: electronic | Show results with:electronic
  15. [15]
    The 1939 New York World's Fair - Early Television Museum
    RCA introduced TV at the 1939 fair, televised the opening, and displayed TRK-12s. Visitors could see themselves on TV. Other manufacturers also demonstrated ...Missing: transmitter | Show results with:transmitter
  16. [16]
    Composite video basics | TV Tech - TVTechnology
    Jan 1, 2004 · In 1941, after many experiments with television, the Federal Communications Commission approved the NTSC standard. This was a revolutionary ...
  17. [17]
    Milestones:Monochrome-Compatible Electronic Color Television ...
    Dec 3, 2024 · After RCA carried out more field tests, the NTSC forwarded this standard to the FCC in a petition on July 22, 1953. The FCC approved the ...<|control11|><|separator|>
  18. [18]
    Transmitters - Pye Story
    First produced in 1980 this 15/25kW Transmitter was supplied to the IBA (previously the ITA) to establish the new Channel 4 network. · They employed the more ...
  19. [19]
    [PDF] ATSC Digital Television Standard, Part 1
    Aug 7, 2013 · This Annex contains for historical reasons the background section that was originally published in. A/53 on 16 December 1995. A.2 HISTORICAL ...
  20. [20]
    The Switch from Analog to Digital TV - Nielsen
    On June 12, 2009, the FCC required all high-power analog US television stations to turn off their signals and move to a digital-only transmission.
  21. [21]
    Analogue terrestrial TV switch-off in the EU - briefing
    Feb 16, 2009 · Analogue terrestrial TV will be switched off between the end of 2010 and the end of 2012 in Belgium (Wallonia and Brussels capital region) ...Missing: shutdown | Show results with:shutdown<|control11|><|separator|>
  22. [22]
    [PDF] The Future of Television Initiative Report January 17, 2025
    Jan 17, 2025 · Moreover, in the most analogous prior broadcast technology transition, the nation's transition to digital television in 2009, consumers who had.
  23. [23]
    None
    ### Summary of Analog Television Transmitter Modulation (ITU-R BT.470-6)
  24. [24]
    BTS-3 — Television Broadcasting
    May 10, 2023 · The visual carrier frequency shall be nominally 1.25 MHz above the lower boundary of the channel. The aural carrier frequency shall be 4.5 ...<|control11|><|separator|>
  25. [25]
    [PDF] Transition from analogue to digital terrestrial broadcasting - ITU
    It provides an overview of digital terrestrial sound and television broadcasting technologies and system migration. The Report outlines the available options ...
  26. [26]
    [PDF] ATSC Digital Television Standard – Part 2: RF/Transmission System ...
    Dec 15, 2011 · Incoming data is randomized and then encoded using Reed-Solomon (RS) coding for forward error correction (FEC), one-sixth-Data-. Field ...Missing: OFDM DVB- T2 ISDB-
  27. [27]
    [PDF] Framing structure, channel coding and modulation for digital ... - DVB
    DVB BlueBook A012. 35. Table 16: Number of Reed-Solomon packets per OFDM super-frame for all combinations of code rates and modulation forms. Code rate. QPSK.Missing: 8VSB ATSC ISDB- Trellis
  28. [28]
    Ultra-Wideband Doherty Amplifier for Digital TV Transmitters
    Jun 14, 2017 · Predistortion is used almost exclusively in the broadcast transmitter market. Design goals typically achieve ‐35 dBc shoulders at a 4.3 MHz ...
  29. [29]
    [PDF] DTMB-A, latest International Telecommunication Union Standard ...
    Standard from China. (DTMB: Digital Television/Terrestrial. Multimedia ... DTMB Payload Data Rate for 6/8 MHz. FEC Rate. 0.4. 0.6. 0.8. BW. 6MHz. 8MHz. 6MHz.
  30. [30]
    [PDF] Frame structure channel coding and modulation for a second ... - DVB
    A Future Extension Frame may carry data in way unknown to a DVB-T2 receiver addressing the current standard version. A receiver addressing the current ...
  31. [31]
    [PDF] DTV transmitter power efficiency - EBU tech
    This article discusses various issues relating to the power efficiency of digital TV transmitters, and describes how Envelope Tracking technology could make a.
  32. [32]
    [PDF] Realizing the Full Benefits of ATSC 3.0 Broadcasts in the U.S.
    ATSC 3.0 redefines broadcasting, integrating advanced IP-based technologies and reliable, robust ... o As of January 2025, there were approximately 437 ATSC 3.0 ...Missing: 8K | Show results with:8K
  33. [33]
    [PDF] Stockholm, 1961 - ITU
    ... television standards for Bands IV and V are designated in the Plans ... plan for apportionment of frequency channels for broadcasting stations in the band 645-.Missing: NTSC PAL SECAM
  34. [34]
    Code of Federal Regulations Title 47. Telecommunication 47 CFR ...
    (2) The visual carrier frequency shall be nominally 1.25 MHz above the lower boundary of the channel. (3) The aural center frequency shall be 4.5 MHz higher ...Missing: analog offset pre- emphasis
  35. [35]
    [PDF] NTSC-M Color Television Specifications - The AM Stereo Tech Zone™
    Unless otherwise specified, the transmission system requirements are defined for 75µs pre-emphasis. (which is matched to that in the main channel in the case of ...<|separator|>
  36. [36]
    [PDF] standard and procedures for video level measurement - FM Systems
    Of that, 40 IRE units constitute the amplitude of the sync pulse as measured from the “Back Porch”, and 100 IRE units constitute maximum brightness, also as ...
  37. [37]
    NTSC Television Broadcasting System - Telecomponents
    In March 1941, the committee issued a technical standard for black-and-white television that built upon a 1936 recommendation made by the Radio Manufacturers ...
  38. [38]
    Analog TV Broadcast Systems - Stjarnhimlen.se
    On a 7 MHz channel, max luminance bandwidth becomes 4.6 Mhz and max chrominance bandwidth 1.2 MHz. On PAL, max luminance bandwitth is 3.8 MHz. Eurocrypt is a ...
  39. [39]
    [PDF] Measuring Hum on a QAM Digital Carrier - VIAVI Solutions
    Hum is often caused by poor filtering in an amplifier's power supply. In an analog TV signal, hum causes horizontal lighter/darker bands in the picture. In ...Missing: noise quadrature
  40. [40]
    Cable Television Technical and Operational Requirements
    Oct 9, 2012 · That correlated well with the approximately 1,000 µV/m leakage field strength at 750 MHz versus the approximately 10 µV/m leakage field strength ...
  41. [41]
    BT.1306 : Error-correction, data framing, modulation and ... - ITU
    Sep 22, 2023 · BT.1306-2 (07/05), Error-correction, data framing, modulation and emission methods for digital terrestrial television broadcasting, SupersededMissing: harmonization | Show results with:harmonization
  42. [42]
    [PDF] A/53: ATSC Digital Television Standard, Parts 1-6, 2007
    This Annex contains for historical reasons the background section that was originally published in A/53 on 16 December 1995. 2. HISTORICAL BACKGROUND. The ...
  43. [43]
    [PDF] A/322. "Physical Layer Protocol" - ATSC Standard
    ATSC also develops digital television implementation strategies and supports educational activities on ATSC standards. ATSC was formed in 1983 by the member ...
  44. [44]
    [PDF] transmission system for digital terrestrial television broadcasting
    The ARIB standard is a technical requirement for digital terrestrial television broadcasting, established by the Association of Radio Industries and Businesses.Missing: Brazil | Show results with:Brazil
  45. [45]
    Digital Television - Federal Communications Commission
    Aug 9, 2016 · Since June 13, 2009, full-power television stations nationwide have been required to broadcast exclusively in a digital format. The switch from ...Missing: mandate | Show results with:mandate
  46. [46]
    600 MHz Band - Federal Communications Commission
    Aug 11, 2022 · The incentive auction bidding closed on March 30, 2017, repurposing 84 megahertz of low band spectrum for both licensed use and unlicensed use.Missing: reallocation | Show results with:reallocation
  47. [47]
    [PDF] Guide to the Use of the ATSC Digital Television Standard, including ...
    In co-channel cases, DTV interference into analog TV appears noise-like. The pilot carrier is low on the Nyquist slope of the IF filter in the analog receiver, ...
  48. [48]
    Guide to Standard HD Digital Video Measurements - Tektronix
    NTSC, PAL, and SECAM video transmitters are amplitude-modulated with sync tip at peak power and video white level plus chroma extending towards minimum power.
  49. [49]
    BETS-4 — Technical Standards and Requirements for Television ...
    This document covers the transmitting equipment proper: namely from the video and audio input terminals or the RF input terminal to the output terminals ...
  50. [50]
    [PDF] TM-100 Technalogix - FCC Report
    Combined IF Input/ Output – 45.75 MHz visual carrier and 41.25 MHz audio carrier intermediate frequency signal loop. Audio Input/ Ouput Loop – Available for ...
  51. [51]
    [PDF] The Vestigial Sideband and Other Tribulations
    The lower sidebands, between roughly 0.5 and 1.0 MHz below the visual carrier, are susceptible to phase errors at both the VSB filter in the transmitter (or ...
  52. [52]
    [PDF] Technical Realisation of Digital TV Transmitter Systems - ITU
    Advantages of the SFN: * Frequency efficiency. - the DVB-T system use the SFN: one frequency for several programs. (current situation: each program has ...Missing: COFDM 8VSB solid-<|separator|>
  53. [53]
    [PDF] Measuring and Evaluating Video Signals in the Headend
    You will need a waveform monitor (vector scope required for measuring differential phase) and a good demodulator. Many measurements can be made with an.<|control11|><|separator|>
  54. [54]
    [PDF] INTERFERENCE PROTECTION CRITERIA Phase 1
    With positive modulation, the sync pulse tips are held at the zero-modulation level, whilst peak white is 100% and black level around 30%. With negative.
  55. [55]
    [PDF] Linear Modulation Techniques - UCCS Faculty Sites
    Assuming an ideal lowpass filter, the only requirement is that the cutoff frequency be greater than W and less than 2fc.
  56. [56]
    [PDF] September 8, 2022 FCC FACT SHEET* Amendment of Part 73 of the ...
    Sep 8, 2022 · (c) A Class A TV station must meet the offset carrier frequency and frequency tolerance provisions of § 73.1545 of this part. [Reserved]. (d) ...
  57. [57]
    [PDF] SM.851-1 - Sharing between the broadcasting service and the fixed ...
    The maximum deviation of the wanted FM sound carrier is assumed to be 50 kHz. Corrections should be made for other deviations. 2.3.2. Digital sound systems.
  58. [58]
    [PDF] DTV REPORT ON COFDM AND 8-VSB PERFORMANCE
    Sep 30, 1999 · The Sinclair demonstrations used a COFDM system based upon the European Terrestrial Digital. Video Broadcasting (DVB-T) standard using equipment ...
  59. [59]
    Digital Television Terrestrial Broadcasting Primer - Embedded
    Oct 2, 2001 · Digital Television Terrestrial Broadcasting Primer. Digital ... DVB, and MPEG-AAC for ISDB.However, these audio standards use a ...
  60. [60]
    [PDF] Federal Communications Commission FCC 04-220
    A TV translator station is a low power television broadcast station that receives the signal of a television station and simultaneously retransmits it on ...
  61. [61]
    https://www.embedded.com/digital-television-terrestrial-broadcasting-primer/
  62. [62]
    [PDF] RECOMMENDATION ITU-R BT.1300-3 - Service multiplex, transport ...
    ITU-R recommends that digital television systems employ the MPEG-2 TS syntax for the packetization and multiplexing of video, audio, and data signals for ...
  63. [63]
    Monitoring in a digital video environment | TV Tech - TVTechnology
    Apr 1, 2003 · This display indicates transmitter overload and intercarrier buzz due to the illegal signal coming from the character generator. Michael Robin, ...
  64. [64]
    [PDF] Transmission Measurement and Compliance for Digital Television
    The frequency tolerance of the DTV transmitters should be ±10 Hz. 5.1.6.2. Co ... signal 5.082138 MHz above the visual carrier frequency of any analog TV.Missing: PLL | Show results with:PLL
  65. [65]
    Real-World Results: Transistors vs. Tubes at UHF - TVTechnology.com
    Apr 21, 2014 · Solid-state amplifiers won the battle at VHF before the DTV transition started. The Harris Platinum transmitter, with its drawers of amplifiers, ...
  66. [66]
    [PDF] Ampleon's UWD for TV Transmitters White Paper
    As such, this demonstrator offers. 15 - 20 % more efficiency [9], [10] than the currently used wideband class-AB power amplifiers in today's broadcast.
  67. [67]
    LDMOS versus GaN RF Power Amplifier Comparison Based ... - MDPI
    Nov 1, 2019 · This paper analyzes the differences between the laterally diffused MOSFET (LDMOS) and gallium nitride (GaN) power amplifiers, in terms of their nonlinearity ...
  68. [68]
    IOT: an old dream, now come true - Bext – Broadcast Equipment
    The class A nature of the Klystron makes it very energy inefficient when amplifying a signal with low duty cycle like HDTV one.
  69. [69]
    Transmitter power efficiency | TV Tech - TVTechnology
    Nov 1, 2009 · Envelope tracking is based on modulating the supply voltage of the final RF stage power transistor in sync with the transmitted RF power ...Missing: PAE | Show results with:PAE
  70. [70]
    What is Digital Pre-Distortion? - everything RF
    Oct 14, 2020 · Digital Pre-Distortion (DPD) is a technique to increase linearity or compensate for non-linearity in power amplifiers.
  71. [71]
    https://www.tvtechnology.com/miscellaneous/transmitter-power-efficiency
  72. [72]
    Doherty Amplifiers Push Efficiency | TV Tech - TVTechnology.com
    Jun 25, 2015 · Doherty amplification can result in up to a 14-percent efficiency improvement over more traditional amplification when driven by digital signals.
  73. [73]
    Broadcast RF Filters - MCI Broadcast - Waveguide & Coaxial Filters
    The MCI Harmonic Filter is designed to suppress the second and third harmonics generated by the transmitter. Achieving values greater than 40dB at these ...
  74. [74]
    [PDF] Very-Sharp Filter Enhanced Compensation in ATSC 1.0 & ATSC 3.0
    The paper discusses adjacent channel filtering/combining, RF mask filters, and pre-correction techniques for very-sharp tuned filters in ATSC 1.0 and 3.0.
  75. [75]
    [PDF] Television Antenna Principles - The Society of Broadcast Engineers
    The nomenclature typically used in rating the antenna is “peak of sync TV power + 20 percent (or 10 percent) aural.” The equivalent heating. (average) power ...
  76. [76]
    [PDF] Federal Communications Commission § 73.682 - GovInfo
    (1) The width of the television broadcast chan- nel shall be 6 MHz. (2) The visual carrier frequency shall be nominally 1.25 MHz above the lower boundary of the ...Missing: offset emphasis
  77. [77]
    [PDF] FOR SPA Volume I1 hnical Report Phase I/
    The power levels required by an AM TV transmitter were considered to range from 0.15 to. 7.7 kilowatts. A primary power and power conditioner size advantage ...
  78. [78]
    Combining digital and analog TV signals - TVTechnology.com
    Feb 1, 2003 · The most common way to correct group delay for the two analog systems (PAL and NTSC) is to introduce a pre-distorted signal into the transmitter ...
  79. [79]
    Encoder's Spare Channel Embeds Whole-House Stereo Audio in ...
    Note that the BTSC spectrum incorporates a pilot signal at 15.734 kHz, which is the same frequency as the NTSC video horizontal sync, 1H = fH sync.Missing: 15 NICAM
  80. [80]
    [PDF] Transmission of two or more sound programmes or information ... - ITU
    Regarding interference from the digital signal into the analogue sound channel, results from over-air tests and supplementary laboratory measurements show that ...
  81. [81]
    None
    Summary of each segment:
  82. [82]
    [PDF] Benefits of Circular Polarization for Mobile Services | Dielectric
    Circular polarization provides margin improvement, reducing signal variability, with 5dB average improvement over linear polarization, and 16.9dB over VHF for ...
  83. [83]
    [PDF] Tall Television Towers - Civil Engineering Practice Journal
    Tall television towers, in heights of 1000 feet or over, were almost non-existent just a few years ago. As television began to come of age.Missing: 300-2000 lightning protection
  84. [84]
    [PDF] Lightning Protection for Communications Facilities
    Feb 14, 2011 · Its 500-foot antenna tower (shown in the photo to the right) is a perfect lightning rod, attracting numerous strikes in a typical summer. One ...
  85. [85]
    [PDF] REPORT ITU-R BT.2137 Coverage prediction methods and ...
    These propagation models used terrain data (approx 90 m resolution) by default and clutter data (approximately 500 m resolution) when specified. A summary of ...
  86. [86]
    [PDF] tr 029 - dvb-t2 single frequency networks and spectrum ... - EBU tech
    2.6.4 Determination of planning parameters. In order to achieve an intended coverage objective by means of an SFN the system and planning parameters must be ...
  87. [87]
    RF Power to the People: Measuring DTV Signals - TVTechnology
    Aug 16, 2005 · The power of an analog signal is always measured as peak power, which is the power level reached while transmitting the synchronizing pulses.
  88. [88]
    https://www.bscesjournal.org/wp-content/uploads/Vol-44-No-4-04.pdf
  89. [89]
    http://www.nab.org/xert/scitech/pdfs/rd021411.pdf
  90. [90]
    Power Added Efficiency (PAE) Calculator Explained - Pasternack Blog
    Dec 1, 2022 · From the equation it is clear that PAE metric is simply a ratio of the difference between the input and output power and the DC supply power, ...
  91. [91]
    Digital Doherty Amplifier With Enhanced Efficiency and Extended ...
    Aug 5, 2025 · Measurements show power added efficiency (PAE) of 69% at 42.9 dBm saturation output power, PAE of 55% at 9-dB PBO, and gain of 12 dB. We ...
  92. [92]
    https://www.tvtechnology.com/opinions/rf-power-to-the-people-measuring-dtv-signals
  93. [93]
    [PDF] TTU1000FA FCC letter
    Apr 30, 2001 · Amplitude Modulation Noise [73.687(b)(5)]. Test Equipment Setup ... An RC network was used with the RMS voltmeter to roll off noise above 15kHz.<|separator|>
  94. [94]
    Low-power transmitters | TV Tech - TVTechnology
    Dec 1, 2007 · BEXT's Lex100 has a power output of 1W to 1kW, with its next largest model ranging from 250W to 10kW. Many of the larger low-power transmitters ...
  95. [95]
    [PDF] R&S Tx9 Transmitter System Operating Manual - FCC Report
    The automatic exciter switchover function enables a faulty exciter to be automatically switched over to a functional standby exciter. In the "Exciter Automatic" ...
  96. [96]
    [PDF] MAXIVA™ ULXTE WITH POWERSMART® PLUS - GatesAir
    Built on GatesAir's groundbreaking PowerSmart® Plus architecture, Maxiva ULXTE offers today's digital broadcaster the most compact, energy-efficient solutions.Missing: standby switchover
  97. [97]
    [PDF] Integrated Flywheel Based Uninterruptible Power Supply (UPS ...
    This paper will review television transmitters, their sensitivity to certain power disturbances and the application of integrated flywheel UPS systems on ...Missing: diesel | Show results with:diesel
  98. [98]
    Emergency power systems | TV Tech - TVTechnology
    Oct 1, 2003 · Just about every news or entertainment broadcast facility requires a backup generator system. Today, such a system must be highly reliable ...Missing: transmitter | Show results with:transmitter
  99. [99]
    TV Monitor and Remote Control
    They provide real-time site information, like transmitter function, antenna VSWR, auxiliary power generation, night-time and tower lighting, temperature, ...Missing: MER | Show results with:MER
  100. [100]
    https://fcc.report/FCC-ID/HFLTMU925/2323678.pdf
  101. [101]
    Tube transmitters vs Solid State transmitters - Engineering Radio
    Aug 15, 2011 · Tube transmitters are more rugged and will take more abuse than a solid-state unit. Things like heat, lightning, EMP, and mismatched antenna won't phase a well ...
  102. [102]
    [PDF] Air Cooled versus Liquid Cooled Transmitters 2018
    Feb 9, 2018 · Typically the vacuum amplifier was in the majority of cases cooled with liquid and the transistorized amplifier cooled by forced air. As the ...Missing: runaway | Show results with:runaway
  103. [103]
    Establishing Rules for Full Power Television and Class A Television ...
    Feb 29, 2024 · ... television broadcast stations be made via LMS with the FCC. ... The results of either the partial proof of performance or the moment method proof ...
  104. [104]
    ATSC 3.0: Transmitter and Monitoring - GatesAir
    As you move to ATSC 3.0, the transmitter will, at the very least, need a software update to transition to the new modulation. Depending on your coverage ...Missing: firmware | Show results with:firmware
  105. [105]
    Maintaining Liquid-cooled Transmitters - Radio World
    Jul 3, 2024 · Some of these transmitters used an open-loop cooling design with fountains and cooling ponds for water that had been heated by the transmitter.Missing: MTBF runaway