I have a Casio GW-M5610 watch, but since i bought it, i never receive time signal successfully. I used to use an application called "JJY simulator" to sync time. But it is not so convenient because I need to change home city code to JPY to sync time, and after finished, I need to change time location to my own in GA. Few days ago, I found a convenient application called "Radio Wave Sync" in apple appStore, no need to change timeZone or home city code, just put the watch into manual receive mode and turned the volume all the way up on my phone, put the phone speaker very close to the watch and hit “Start” in the app. 2-3 minutes later it was properly synced. Highly recommend if you’re having reception issues with your radio-controlled watch.