Tag Archives: Time Stations

The Empire Strikes Back: Is that WWV I hear?

Fullscreen capture 12202015 40448 AMWith all of the Star Wars: The Force Awakens hype going on, I remembered that, as a kid, I thought I heard WWV in a scene from The Empire Strikes Back.

I looked through some video clips of the movie online and discovered it again this morning: I heard the WWV-like sound in the Battle Of Hoth scene. [Update: RadioGeek suggests this may actually be CHU’s date pips.]

This video clip will start around the :23 second mark; start listening for the metronomic tick in the background around :25 seconds and then again at :40 seconds:

I may be mistaken, but I believe that sounds like 1980s era WWV. Has anyone else noticed this?

Recording the 2015 Leap Second

Fullscreen capture 6302015 115321 PM

Yesterday, I posted a brief article about the leap second that occurred between 23:59:59 June 30, 2015 and 00:00:00 UTC July 01, 2015.

I decided to record the leap second on as many shortwave time station frequencies as possible. The only viable options for me–based on time of day and my reception location–were the WWV frequencies 10, 15, 20, and 25 MHz, and CHU frequencies 7,850 and 14,670 kHz.

I was able to record four different time station frequencies simultaneously on the TitanSDR Pro.

I was able to monitor four different time station frequencies simultaneously on the TitanSDR Pro. (click to enlarge)

Unfortunately, HF propagation was very poor yesterday, so the higher WWV frequencies–20 and 25 MHz–were completely inaudible, as was CHU on 14,670 kHz. There were numerous thunderstorms in our area, so static crashes were prevalent.

Still, since this was a first attempt to record a “leap second,” I didn’t want to take any chances.  I had the Titan SDR Pro monitoring and recording two CHU and two WWV frequencies [screenshot], the Elad FDM-S2 recording WWV on 15 MHz [screenshot], and the WinRadio Excalibur on WWV’s 10 MHz frequency, as well as recording the whole 31 meter band spectrum [screenshot].

In the end, the strongest frequencies I captured were CHU on 7,850 kHz and WWV on 15,000 kHz. WWV on 10,000 kHz was much weaker than normal and the band was quite noisy–still, it’s readable, so I included this recording, too. Recordings follow…


Photo I took in 2014 of the sign above WWV's primary 10 MHz transmitter.

The sign above WWV’s primary 10 MHz transmitter (2014).

All of the recordings start just before the announcement of 23:59 UTC.

WWV added the extra second and higher tone, then continued with their top of the hour announcements, including a note about leap second (which begins after the 00:04 announcement). CHU simply injects a one second silence before the long tone.

WWV on 15,000 kHz using the Elad FDM-S2:

CHU on 7,850 kHz using the TitanSDR Pro:

WWV on 10,000 kHz using the WinRadio Excalibur:

One interesting note about the 10 MHz WWV recording above: I believe I may be hearing BPM China in the background. I’m curious if anyone can confirm this because I don’t know BPM’s cadence/pattern well enough to ID it.

Other recordings…?

Did you record a shortwave time station as leap second happened? If so, please comment, and feel free to share a link to your recording!

Hang on a second…seriously


One of four WWV time code generators in late August, 2014

Tonight, for the first time in three years, we will experience a leap second. What is a leap second?  Wikipedia provides a concise explanation:

A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1. Without such a correction, time reckoned by Earth’s rotation drifts away from atomic time because of irregularities in the Earth’s rate of rotation. Since this system of correction was implemented in 1972, 25 such leap seconds have been inserted. The most recent one happened on June 30, 2012 at 23:59:60 UTC. A leap second, the 26th, will again be inserted at the end of June 30, 2015 at 23:59:60 UTC.

Like many of you, when I think of time–or UTC–I think about the NIST radio station WWV in Fort Collins, Colorado.

I had the honor of visiting the facility last year (yes, photo tour still forthcoming!).  During the tour, my guide and Chief Engineer at WWV and WWVB, Matthew Deutch, told me that he’s always going to be on site come Leap Second!


WWV’s Matthew Deutch with WWVB antennas in background

I wrote Matt this morning to ask what were his plans tonight?  His reply:

“The leap second happens at 0000 UTC tonight, which is 6:00 pm here in Fort Collins. All of the programming took place at the beginning of the month, so the equipment is armed…we just sit back and watch for the leap this evening.

Even though it is automated I hang around the station to make sure everything goes smoothly at the critical moment…”

WWV-First-Sign-SMMatthew closed his message by wishing me a “Happy Leap Second.”

Back at you, Matt! We hope that second leaps as smoothly as you’d like!

Not to put Matt on the spot, but you can listen to WWV (or the atomic clock of your choice) make the leap second tonight at 00:00 UTC. As for me, I’ll hop on 10 MHz and 15 MHz to hear (and hopefully record) the extra “tick.” At the end of this post, I’ve provided a list of time stations for your convenience.

Happy Leap Second!


WWV 20 MHz Collins transmitter

List of shortwave radio time stations

  • CHU Canada: 3330 kHz, 7850 kHz, 14670 kHz
  • BPM China: 2,500, 5,000, 10,000, and 15,000 kHz
  • HLA South Korea: 5,000 kHz
  • BSF Taiwan: 5,000 and 15,000 kHz
  • WWV (Ft. Collins)/WWVH (Hawaii) United States:  2,500, 5,000, 10,000, 15,000, 20,000 and 25,000 kHz


Click here to listen to Leap Second recordings from WWV and CHU.

Can you help George identify the mystery pip?

WWV format

WWV format

SWLing Post reader, George (NJ3H), writes:

I quite often see a spike in the evening on 4996 khz. From the listing, this is suppose to be RWM, in Moscow, a time signal station.

When I listen on remote receivers in Poland and Denmark, I do not hear time pips, but rather just hash.

On my Perseus, I can watch the spike go up and down each second. This makes me think it is caused by WWV. However, the 29th second seems to make the spike move up, even though WWV doesn’t have a pip at second 29. The remote receivers in Europe that I just mentioned do not have any time pips being broadcast. Does WWV cause a signal on 4996?

Can you shed any light on 4996? Should we be able to hear RWM in the Eastern US?

Good question, George, and I’m hoping a reader can shed some light on what you’re seeing on the spectrum display. I’m not sure what could be causing the 29th second spike unless it’s WWV transmitting a sub-audible tone.

WWV: experimental broadcasts on 25 MHz

WWV format

WWV format (Click to enlarge)

Want to catch WWV–the Fort Collins-based time station–on a frequency they haven’t used since 1977?

The National Institute for Standards and Technology (NIST) has sent out a press release stating that, as of April 4, 2014, WWV will resume broadcasting on 25 Mhz for a limited time.

Full details follow in their press release:

NOTICE: Experimental 25 MHz WWV Broadcast

As of Friday, April 4, 2014 WWV has resumed broadcasting on 25 MHz on a limited, experimental basis. The broadcast consists of the normal WWV signal heard on all other WWV frequencies, at the same level of accuracy.

Current 25 MHz Broadcast Specifications (subject to change):
Schedule: variable; as an experimental broadcast, the 25 MHz signal is not continuous. It will typically be on the air from approximately 1500 – 2100 UTC Mondays through Fridays, but may operate outside these hours as well. The broadcast may be interrupted or suspended without notice.

Radiated Power: varies; no more than 2500 W

Antenna: broadband monopole, coordinates: 40 deg. 40′ 50.8″N, 105 deg. 02′ 32.6″ W

Listener comments and reception reports may be emailed to: wwv@nist.gov, or sent via postal mail to:

National Institute of Standards and Technology
Radio Station WWV
2000 E. County Rd. 58
Fort Collins, CO 80524