41. Attached time signal systems generally use audible tones or phase modulation of the carrier wave. 42. The BBC does not allow the pips to be broadcast except as a time signal . 43. WWVH time signals can also be accessed by telephone. 44. It can be heard in the transmission of certain radio time signal stations . digital. 45. Systems using dedicated time signal stations can achieve accuracy of a few tens of milliseconds. 46. Early in the 20th century, the Arlington Time Signal broadcast this service to wireless receivers. 47. This approach is applied for filtering space-time signals . 48. The gunshots have served as time signals for many generations of old inhabitants of Hong Kong. 49. Times and frequencies of radio time signals are listed in publications such as Radio Navigational Aids. 50. Other radio controlled clocks use the time signals transmitted by dedicated transmitters in the shortwave bands.
