Longwave 198kHz

Longwave 198kHz
Name	198 kHz
Band	Longwave
Frequency	198 kHz
Wavelength	1515 m
Mode	AM, DRM
Typical power	100 kW–2 MW
Users	Broadcasting, time signals, navigation

Longwave 198kHz is a specific frequency within the longwave radio band used for amplitude modulation broadcasting, digital radio, and specialized services. It sits among allocations utilized by national broadcasters, maritime authorities, and experimental services across Europe, North Africa, and parts of Asia, and is notable for groundwave propagation over long distances. The frequency has been associated with high-power transmitters, landmark antennas, and regulatory coordination under international treaties.

Overview and Characteristics of 198 kHz

198 kHz lies in the longwave radio portion of the radio spectrum and is characterized by long wavelengths allowing reliable ground wave propagation, particularly over sea and flat terrain. Propagation at 198 kHz is influenced by ionosphere conditions, sunspot cycle, and seasonal diurnal variation, which together affect signal-to-noise ratio and reach to distant coastal regions. Typical services on 198 kHz have used high effective radiated power from transmitters such as those operated by national broadcasters like BBC, Radio France, Deutsche Welle, and Radio Nederland Wereldomroep prior to its closure. Technical implementations include amplitude modulation (AM) and digital modes such as Digital Radio Mondiale (DRM), which provide tradeoffs among coverage, audio quality, and spectral efficiency.

Historical Development and Key Transmitters

Use of 198 kHz expanded during the 20th century with continental broadcasters establishing longwave chains; notable milestones involve transmitters built by entities like TDF (Télédiffusion de France), Fernmeldeanstalt, and state organizations in Soviet Union era infrastructure. Landmark sites that have been associated with frequencies around 198 kHz include major installations in Allouis, Nauen, Droitwich, and Rostov-on-Don, each reflecting developments in antenna engineering by firms such as Marconi Company, Siemens, and Racal. Cold War era coordination affected assignments, drawing in agencies like North Atlantic Treaty Organization technical committees and bilateral agreements between countries such as France and United Kingdom. Transition to digital and post-Cold War restructuring led to transmitter upgrades and in some cases decommissioning, influenced by broadcasters such as BBC World Service, Radio Luxembourg, and Radio Monte Carlo.

International Usage and Regulatory Framework

Allocations around 198 kHz are governed by international agreements under the International Telecommunication Union (ITU) and regional bodies like the European Conference of Postal and Telecommunications Administrations (CEPT). National administrations, including Ofcom, Agence nationale des fréquences, and counterparts in Germany and Russia, implement ITU Radio Regulations and coordinate cross-border assignments to limit co-channel interference and ensure compliance with emission masks. Historical treaties such as the Radio Regulations of the ITU and regional planning conferences shaped bandplans that affected broadcasters like Radio Télévision Luxembourg and public services in Belgium, Netherlands, and Spain.

Technical Applications and Coverage Patterns

At 198 kHz, transmitters employ mast radiators, umbrella antennas, and ground radial systems engineered by companies like Broadcast Electronics and Thales. Coverage patterns exploit ground conductivity and antenna height to provide primary service areas extending hundreds of kilometers; maritime coverage similarly benefits coastal propagation to serve ports associated with organizations such as the International Maritime Organization and national coastguards. Power levels historically ranged from tens of kilowatts to megawatt-scale facilities used by broadcasters including Radio France Internationale and state services in Czech Republic and Poland. DRM experiments at longwave frequencies explored improved spectral efficiency and emergency broadcasting resilience, involving research institutions like Fraunhofer Society and universities such as University of Oxford and Technical University of Munich.

Interference, Reception Challenges, and Mitigation

Reception on 198 kHz faces challenges from atmospheric noise, industrial interference from installations operated by companies like Siemens and ABB, and urban electromagnetic pollution near cities such as London, Paris, and Berlin. Cross-border interference incidents have prompted coordination among regulators including Ofcom, BNetzA, and ANFR to implement technical measures like frequency offsetting, directional antenna patterns, and power adjustments. Mitigation techniques used by broadcasters and receivers include bandpass filtering, adaptive noise cancellation developed in labs at Nokia Bell Labs and Fraunhofer IIS, and improved site siting informed by studies from organizations like International Association of Broadcasting Manufacturers.

Notable Stations and Programming on 198 kHz

Historically, prominent stations associated with nearby longwave assignments included national services and cultural broadcasters such as BBC Radio 4, France Inter, Deutschlandfunk, Radio Luxembourg, and RTÉ Radio 1, each offering news, drama, and cultural programming that targeted both domestic and international audiences. Time and navigation services and experimental broadcasts have involved scientific institutions like National Physical Laboratory and Russian Academy of Sciences for propagation research. Programming strategies on longwave were often coordinated with public institutions including British Broadcasting Corporation and Radio France to provide nationwide continuity services, disaster information, and ceremonial broadcasts tied to events like Bastille Day and Remembrance Day.

Category:Longwave radio