CHU Canada, Leap Second: June 30, 2015

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(Image: NASA)

(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

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

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)

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).

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.