#ham radio

Standard Time and the Importance of Accurate Time

Standard time is the synchronization of clocks within a geographical region to a common reference rather than local solar time.

During the nineteenth century, expanding railroad and steamship networks made accurate scheduling increasingly important. Great Britain's railways adopted Greenwich Mean Time in 1847, while railroads in the United States and Canada introduced a five-zone system in 1883. On November 18th of that year, it was agreed all United States and Canadian railroads would readjust their clocks and watches to a telegraph signal from the Allegheny Observatory in Pittsburgh at exactly noon on the 90th meridian.

Standard time became U.S. law with the Standard Time Act of 1918, which also established daylight saving time.

Time touches nearly every part of modern life. Whether you're checking your phone, navigating with GPS, making an online purchase, or watching a live sporting event, you're relying on clocks that are synchronized with remarkable precision.

Behind those clocks is Coordinated Universal Time, or UTC, the international time standard maintained by a network of atomic clocks around the world. Time is distributed by satellites, the Internet, telephone networks, and radio transmissions, allowing devices everywhere to stay in step.

Accurate time is far more than a convenience. Telecommunications networks depend on precise synchronization to move enormous amounts of data. Electric power systems require accurate timing to monitor and balance the grid. Financial markets record transactions to the millisecond, while scientific experiments often measure events in millionths or even billionths of a second.

For radio enthusiasts, accurate time has always been close at hand. Since the early twentieth century, stations around the world have transmitted standard time and frequency signals that anyone with a suitable receiver could hear. These broadcasts not only set clocks but also provide precise frequency references and a convenient way to judge radio propagation.

Many countries have operated time and frequency stations over the years. Some have fallen silent as Internet time services became widespread, while others continue to broadcast around the clock. Their familiar ticks, tones, voice announcements, and digital time codes remain valuable to laboratories, industry, radio amateurs, and shortwave listeners alike.

We'll take a closer look at two of the best-known CHU, WWV (WWVH, WWVB, and WWVL).

Other known Frequency and Time Signal services:

ATA New Delhi, India (now silent) BPM Pucheng, China 2.5, 5, 10, & 15 MHz BSF Chung-Li, Taiwan, RoC 5, 15 MHz DCF77 Mainflingen, Germany 77.5 kHz EBC Cádiz, Spain 4.998 MHz HLA Taejon, Republic of Korea 5 MHz HBG Switzerland (now silent) IAM Rome, Italy 5 MHz JJY Tamura City & Saga City, Japan 40, 60 kHz LOL Buenos Aires, Argentina 5, 10, & 15 MHz MIKES Espoo, Finland 25 MHz MSF Anthorn, UK 60 kHz OMA Prague, Czech Republic 2.5 MHz (now silent) PPE Rio de Janeiro, Brazil 10 MHz RWM Moscow, Russia 4.996, 9.996, 14.996 MHz YVTO Caracas, Venezuela 5 MHz

Shortwave Radiogram now switches to MFSK64 …

Before RSID: <<2026-08-01T23:08Z MFSK-32 @ 9455000+1500>>

This is Shortwave Radiogram in MFSK64

Please send your reception report to [email protected]

The history of CHU

The broadcast of time signals in Canada began in the early 20th Century. In 1907, station VCS in Halifax, Nova Scotia began The first time signal broadcasts. In 1914 a survey crew at the Quinze Dam on the Ottawa River tried to use signals transmitted from Canadian Forces Base Kingston Ontario to calibrate equipment. Unfortunately the signal from did not work out so they used a signal from U. S. Navy station NAA operated in Arlington, Virginia.

In 1923 the experimental station 9CC began time signal broadcasts on 275 metes/ 1090 khz of time signals from the Dominion Observatory in Ottawa. In 1938, this station would become CHU after several call sign and frequency changes.

CHU initially broadcast at a power of 10 watts on three frequencies, 3300, 7355, and 14670 khz sending a coded time signal and Morse Code to send its ID once per hour. As coverage was spotty across all off Canada CHU, upgraded to 300 watt transmitters.

The 1950s saw even further changes as the transmitter on 14670 khz was upgraded to 3 kilowatts and English only voice announcements recorded on motion picture film played back under clock control. were added.

In 1967 CHU began using cesium atomic clocks greatly improving the accuracy of the time standard. The voice announcements were moved to a more reliable speaking clock system in 1960. Harry Mannis of the CBC was the English language announcer. French announcements were added in 1964 and were recorded by Miville Couture of CBC Montreal.

Operation of CHU was transferred to the National Research Council from the Dominion Observatory in1970. Eventually all the transmitters and the antenna farm were upgraded to provide better service, with 3330 and 14670 both running at 3 kilowatts and 7355 running at 5 kilowatts.

Until 1990, the time on CHU was announced as Eastern Standard Time. That year saw not only a change to using UTC, but to digital for the spoken time and ID speech. While it was still the voice of Harry Mannis for English ones, Simon Durivage of Radio-Canada now provided the French versions.

In 2009, CHU moved from 7355 to 7835 under spectrum re-allocations by the ITU. Nonetheless, reception across all of Canada proved to be difficult. For consumers in western Canada and the Arctic, CHU’s signal was unusable. In 2026, tuational Research Council ended all shortwave broadcasts from CHU, ending over a century of keeping Canada on time. For many in North America, CHU was among the first shortwave broadcasts they received and QSLed.

Coming up … historic QSLs from WWV and WWVH

First, The sound of WWV in the late 1960s…….

⏰ ⏰ ⏰ WWV QSL Cards ⏰ ⏰ ⏰ QSL from WWV before the move from Greenbelt Maryland to Ft Collins Colorado February1966

Image: WWV_Maryland_February_1966 ⏰ ⏰ ⏰ QSL from WWV issued on the first day of operation from Ft Collins in 1966

Image: WWV_Ft_Collins_1966 ⏰ ⏰ ⏰ WWV's current QSL

⏰ ⏰ ⏰ Next up, QSLs from WWVH. But first the sound of WWV today….

⏰ ⏰ ⏰ WWVH QSL Cards ⏰ ⏰ ⏰ QSL from WWVH for the first day of operation from Kauai July 1971 February1966 WWVH_Kauai_July_1971 ⏰ ⏰ ⏰ WWVH's current QSL

Some rare QSL cards from WWVB and WWVL ⏰ ⏰ ⏰ WWVL: 20 kHz. Discontinued in July 1972

⏰ ⏰ ⏰ WWVB: 60 kHz

⏰ ⏰ ⏰ Next up, QSLs from CHU But first the sound of WWVH today….

CHU QSL Cards ⏰ ⏰ ⏰ QSL from CHU when operated by Dominion Observatory in Ottawa

⏰ ⏰ ⏰ The last QSL issued by CHU

Shortwave Radiogram now returns to MFSK32….. But first….the last several seconds of CHU……

Before RSID: <<2026-08-01T23:28Z MFSK-64 @ 9455000+1500>>

This is Shortwave Radiogram in MFSK32 …

Transmission of Shortwave Radiogram is provided by: WRMI, Radio Miami International, http://wrmi.net & WINB Shortwave, http://winb.com

Please send reception reports to [email protected] And visit http://swradiogram.net http://swradiogram.bsky.social X/Twitter (for now): @SWRadiogram

This is Tony Pavick in Hope, British Columbia, Canada and Al Holt in Alachua, Florida, USA Please join us for the next Shortwave Radiogram.