CHU Canada, Leap Second: June 30, 2015

(Image: NASA)

SRAA contributor, Richard Langley, writes:

Live recording of time signal station CHU, Canada, on 30 June 2015 beginning at exactly 23:55:00 UTC on a frequency of 7850 kHz. The recording last exactly 10 minutes and 1 second, ending at 0:10:00 UTC. A leap second occurs at 23:59:60 UTC. This can be noted by the 1 second of silence between the 5m:00s mark in the recording (23:59:60 UTC) and the 5m:01s mark (0:00:00 UTC) denoted by the start of the one-second-long tone. This is followed by 9 seconds of silence. Before the leap second, the forecast difference between UT1 and UTC (DUT1 = UT1 minus UTC) to a precision of one tenth of a second was -0.7 seconds. This is indicated by CHU by using a sequence of double tones at 9 seconds through 15 seconds after the start of each minute except for the minute beginning an hour. Following the leap second, DUT1 is +0.3 seconds, marked by double tones at 2 seconds through 4 seconds after the start of the minute, again, except for the minute beginning an hour. 

The strong CHU signal was received on a Tecsun PL-880 receiver with a Tecsun AN-03L 7-metre wire antenna in Hanwell, New Brunswick, Canada, in AM mode with 5 kHz RF filtering. There is some atmospheric noise (static).

Recording the 2015 Leap Second via WWV and CHU: June 30, 2015

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

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 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...

Recordings

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's adjustment included a long second tone and period of silence.

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.