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Broadcast Outages for WWVB

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    Notice of Change in WWVB Modulation Depth

The 60 kHz WWVB time code broadcast changed the modulation depth from 10 to 17 dB on July 12, 2005 at 0000 UTC. This was done to improve the performance of WWVB radio controlled clocks. Click here for a short technical paper that discusses the subject of increasing the modulation depth (PDF file).

During normal operation, the 60 kHz signal from WWVB is transmitted 24 hours per day, 7 days a week. The table includes periods since January 1, 2005 when the signal was off or intermittent for more than 5 minutes.

Date MJD Began (UTC) Ended (UTC)
11-19-2005 53693 0121 0216
07-28-2005 53579 0500 0550
06-23-2005 53544 0700 0800
05-22-2005 53512 1626 1707
05-10-2005 53500 1527 1539
04-20-2005 53480 0025 0055
01-26-2005 53396 1803 1829