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CHU (radio station)
Encyclopedia
CHU is the call sign
of a shortwave
time signal
radio
station operated by the Institute for National Measurement Standards of the National Research Council of Canada
.
in Ottawa, Ontario, Canada
, with a call sign
of VE9OB. In 1938 the call was changed to CHU. The station continued to be operated by the Observatory until 1970, when its operation was transferred to the Institute for National Measurement Standards.
s. The CHU time signal and radio frequencies are derived from atomic clock
s.
CHU will acknowledge
listeners' reception reports.
A similar time signal
from the National Research Council is used by CBC
radio services daily at noon ET on Radio-Canada's Première Chaîne, and 1pm ET on CBC Radio One
.
signals on 3330 and 14670 kHz, and a 10 kW signal on 7850 kHz. The signal is amplitude modulated
, with the lower sideband
suppressed (emission type
H3E). The same information is carried on all three frequencies simultaneously including announcements every minute, alternating between English and French.
The CHU transmitter is located near Barrhaven, Ontario
, 15 km southwest of Ottawa's central business district.
The systems feeding the transmitters are duplicated for reliability, and have both battery and generator protection. The generator can also supply the transmitters. The announcements are made using digitally recorded voices. Individual vertical dipole antenna
s are used for each frequency.
CHU has long been licensed as "fixed service" within the band allocations of the International Telecommunications Union.
CHU's 10 kW signal has been transmitted on 7850 kHz since January 1, 2009. Before then, the signal was transmitted on 7335 kHz, harmonically related to their 14670 KHz frequency. The frequency change was necessary due to an ITU HF global reallocation conference where the frequency region around 7300 kHz was turned over to different users.
The digital time code sends 10 characters at 300 bits per second using 8N2 asynchronous serial communication. This follows the Bell 103 standard, a 2225 Hz tone to represent a mark (1 bit) and 2025 Hz tone for a space (0 bit). Immediately after the 10 ms tick, a mark tone is sent until 133.3̅ ms, then 110 data bits, ending at precisely 500 ms. The final stop bit is extended by 10 ms of mark tone to ensure it is detected reliably, and the final 490 ms of the second are silent. The time of day (day of year through second) is transmitted twice during each second from 32 to 39. During second 31, additional information (year, DUT1, daylight saving time, and leap second warning bits) is transmitted.
CHU quite often cannot be received in Western Canada
on any of its broadcast frequencies, as it universally uses lower transmitter powers than WWV.
Propagation conditions, lower transmitter power coupled with the typical two ionospheric hops distances from Ottawa result in relatively weak time signals for Western Canada. Electrical interference can further aggravate reception difficulty in suburban areas in the West. CHU can be practically unusable in most of Western Canada, as well as Nunavut
and the Northwest Territories
, for significant stretches of time.
Subject to limitations of their own, WWV and WWVH
are the fallback in Western Canada as far as getting reliable time signals via shortwave is concerned. In the High Arctic, however, both the US shortwave time stations and CHU become essentially unreliable or unusable.
Unlike the US, Canada has no longwave time signals dissemination option. Technically WWVB
is the only option for reliable time signals during solar storms in the Western Arctic, based on WWVB's published pattern maps. If WWVB is not available, those who need precision time transfer may be able to use GPS time transfer
instead.
Call sign
In broadcasting and radio communications, a call sign is a unique designation for a transmitting station. In North America they are used as names for broadcasting stations...
of a shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
time signal
Time signal
A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.-Audible and visible time signals:...
radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
station operated by the Institute for National Measurement Standards of the National Research Council of Canada
National Research Council of Canada
The National Research Council is an agency of the Government of Canada which conducts scientific research and development.- History :...
.
History
The station was started in 1929 by the Dominion ObservatoryDominion Observatory
The Dominion Observatory was an astronomical observatory in Ottawa, Canada that operated from 1902 to 1970. The Observatory was also an institution within the Canadian Federal Government. The observatory grew out of the Department of the Interior's need for the precise coordinates and timekeeping...
in Ottawa, Ontario, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, with a call sign
Call sign
In broadcasting and radio communications, a call sign is a unique designation for a transmitting station. In North America they are used as names for broadcasting stations...
of VE9OB. In 1938 the call was changed to CHU. The station continued to be operated by the Observatory until 1970, when its operation was transferred to the Institute for National Measurement Standards.
Broadcast format
CHU's signal is used for continuous dissemination of official Canadian government time signalTime signal
A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.-Audible and visible time signals:...
s. The CHU time signal and radio frequencies are derived from atomic clock
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
s.
CHU will acknowledge
QSL
QSL is one of the Q codes used in radiocommunication and radio broadcasting. A Q code message can stand for a statement or a question . In this case, QSL? means "do you confirm receipt of my transmission?" while QSL means "I confirm receipt of your transmission". Some also take it to mean "Query...
listeners' reception reports.
A similar time signal
National Research Council Time Signal
The National Research Council Time Signal is Canada's longest running but shortest radio programme. Heard every day since November 5, 1939 , shortly before 13:00 Eastern Time across the CBC Radio One network, it lasts between 15 and 45 seconds, ending exactly at 13:00...
from the National Research Council is used by CBC
Canadian Broadcasting Corporation
The Canadian Broadcasting Corporation, commonly known as CBC and officially as CBC/Radio-Canada, is a Canadian crown corporation that serves as the national public radio and television broadcaster...
radio services daily at noon ET on Radio-Canada's Première Chaîne, and 1pm ET on CBC Radio One
CBC Radio One
CBC Radio One is the English language news and information radio network of the publicly-owned Canadian Broadcasting Corporation. It is commercial free and offers both local and national programming...
.
Transmission system
CHU transmits 3 kWKw
kw or KW may refer to:* Kuwait, ISO 3166-1 country code** .kw, the country code top level domain for Kuwait* Kilowatt* Self-ionization of water Kw* Cornish language's ISO 639 code* Kitchener–Waterloo, Ontario, Canada...
signals on 3330 and 14670 kHz, and a 10 kW signal on 7850 kHz. The signal is amplitude modulated
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
, with the lower sideband
Sideband
In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier...
suppressed (emission type
Types of radio emissions
The International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its bandwidth, method of modulation, nature of the modulating signal, and type of information transmitted on the carrier...
H3E). The same information is carried on all three frequencies simultaneously including announcements every minute, alternating between English and French.
The CHU transmitter is located near Barrhaven, Ontario
Barrhaven, Ontario
Barrhaven is a rapidly growing suburban neighbourhood in the southwest of the urban area of the city of Ottawa, Ontario, Canada, about southwest of downtown Ottawa. Prior to amalgamation with Ottawa in 2001, Barrhaven was part of the City of Nepean. Its population as of the Canada 2006 Census was...
, 15 km southwest of Ottawa's central business district.
The systems feeding the transmitters are duplicated for reliability, and have both battery and generator protection. The generator can also supply the transmitters. The announcements are made using digitally recorded voices. Individual vertical dipole antenna
Dipole antenna
A dipole antenna is a radio antenna that can be made of a simple wire, with a center-fed driven element. It consists of two metal conductors of rod or wire, oriented parallel and collinear with each other , with a small space between them. The radio frequency voltage is applied to the antenna at...
s are used for each frequency.
CHU has long been licensed as "fixed service" within the band allocations of the International Telecommunications Union.
CHU's 10 kW signal has been transmitted on 7850 kHz since January 1, 2009. Before then, the signal was transmitted on 7335 kHz, harmonically related to their 14670 KHz frequency. The frequency change was necessary due to an ITU HF global reallocation conference where the frequency region around 7300 kHz was turned over to different users.
Time signal format
The primary time signal is a series of 300 ms-long 1000 Hz tones, transmitted once per second, on the second. The following exceptions to the pattern provide additional information:- The top of the minute is marked by a half-second-long beep.
- The top of the hour is marked with a one second-long beep, followed by nine seconds of silence.
- The 29th second of a minute is always omitted (no beep).
- Between one and sixteen seconds past the minute (except at the top of the hour), CHU transmits the difference between UT1 and Coordinated Universal TimeCoordinated Universal TimeCoordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
(UTC) by using split tones. For positive DUT1 values from +0.1 to +0.8 s, seconds 1 through 8 are split. For negative DUT1 values from −0.1 to −0.8 s, seconds 9 through 16 are split. - Between 31 and 39 seconds past the minute inclusive, the once-per-second tones are reduced to 10-millisecond "ticks" while a digital time code is transmitted. The digital time code is formatted so that a Bell 103-compatible 300-baud modem can decode it, and CHU is the only time signal station that uses this format for its time code transmissions.
- For the last 10 seconds of each minute (seconds 50 to 59), the once-per-second tones are again cut to 10 milliseconds each, while CHU transmits a brief voice station identification, followed by voice announcements of the next minute in UTC, alternating between FrenchFrench languageFrench is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
and EnglishEnglish languageEnglish is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
. French announcements, using the voice of Radio-Canada news anchor Simon DurivageSimon DurivageSimon Durivage is a Canadian French-language television news anchor for RDI en direct. He was recruited by Radio-Canada in 1969 and has since hosted several newscasts and public affairs programs: Consommateurs avertis, Enjeux, Le Point, Montréal-Express, Montréal ce soir and Rédacteur en...
, are transmitted first on the odd minutes, while English announcements, voiced by former CBC RadioCBC RadioCBC Radio generally refers to the English-language radio operations of the Canadian Broadcasting Corporation. The CBC operates a number of radio networks serving different audiences and programming niches, all of which are outlined below.-English:CBC Radio operates three English language...
announcer Harry Mannis, come first on the even minutes.
The digital time code sends 10 characters at 300 bits per second using 8N2 asynchronous serial communication. This follows the Bell 103 standard, a 2225 Hz tone to represent a mark (1 bit) and 2025 Hz tone for a space (0 bit). Immediately after the 10 ms tick, a mark tone is sent until 133.3̅ ms, then 110 data bits, ending at precisely 500 ms. The final stop bit is extended by 10 ms of mark tone to ensure it is detected reliably, and the final 490 ms of the second are silent. The time of day (day of year through second) is transmitted twice during each second from 32 to 39. During second 31, additional information (year, DUT1, daylight saving time, and leap second warning bits) is transmitted.
Western Canada signal coverage
Western Canada
Western Canada, also referred to as the Western provinces and commonly as the West, is a region of Canada that includes the four provinces west of the province of Ontario.- Provinces :...
on any of its broadcast frequencies, as it universally uses lower transmitter powers than WWV.
Propagation conditions, lower transmitter power coupled with the typical two ionospheric hops distances from Ottawa result in relatively weak time signals for Western Canada. Electrical interference can further aggravate reception difficulty in suburban areas in the West. CHU can be practically unusable in most of Western Canada, as well as Nunavut
Nunavut
Nunavut is the largest and newest federal territory of Canada; it was separated officially from the Northwest Territories on April 1, 1999, via the Nunavut Act and the Nunavut Land Claims Agreement Act, though the actual boundaries had been established in 1993...
and the Northwest Territories
Northwest Territories
The Northwest Territories is a federal territory of Canada.Located in northern Canada, the territory borders Canada's two other territories, Yukon to the west and Nunavut to the east, and three provinces: British Columbia to the southwest, and Alberta and Saskatchewan to the south...
, for significant stretches of time.
Subject to limitations of their own, WWV and WWVH
WWVH
WWVH is the callsign of the U.S. National Institute of Standards and Technology's shortwave radio time signal station in Kekaha, on the island of Kauai in the state of Hawaii....
are the fallback in Western Canada as far as getting reliable time signals via shortwave is concerned. In the High Arctic, however, both the US shortwave time stations and CHU become essentially unreliable or unusable.
Unlike the US, Canada has no longwave time signals dissemination option. Technically WWVB
WWVB
WWVB is a NIST time signal radio station near Fort Collins, Colorado, co-located with WWV. WWVB is the station that radio-controlled clocks in most of North America use to synchronize themselves. The signal transmitted from WWVB is a continuous 60 kHz carrier wave, derived from a set of atomic...
is the only option for reliable time signals during solar storms in the Western Arctic, based on WWVB's published pattern maps. If WWVB is not available, those who need precision time transfer may be able to use GPS time transfer
Time transfer
Time transfer is a scheme where multiple sites share a precise reference time. Time transfer solves problems such as astronomical observatories correlating observed flashes or other phenomenon with each other, as well as cell phone towers coordinating handoffs as a phone moves from one cell to...
instead.
External links
- NRC Short Wave Station Broadcasts (CHU)
- CHU Western Canada coverage proposal http://cbc.am/CHU.ppt http://cbc.am/CHU.pdf