I have a few Atomic clocks that use WWVB on 60KHZ to sync the time. Living on the East Coast away from Fort Collins, CO the signal is not strong and worse inside. I got a suggest from Charlie WA4OSS of an iPhone App called Radio Wave Sync at a cost of $1.99 from the App Store. You start the App and put it next to the clock and within 10 minutes the clock is synced.

The App fulls the clock to thinking it is WWVB by emitting a sound from the iPhones speaker. The only downside is you must do the sync in a quit room and you can’t use the phone for about 10 minutes.