The November issue of High Frequency Electronics includes a short article on WWV with some little-known facts (at least to me!) on the time- and frequency standard station. For exampe:
- WWV began transmitting in 1923 on frequencies from 75 to 2000 kHz.
- Telegraphic announcements were added in 1945, with phone announcements beginning in 1950.
- When it first began broadcasting, the frequency accuracy of the signal was 0.3% or better. Today, the accuracy of the signals is in the range of 5 parts in 10**13.
For the complete article, download this PDF file.
For more information than you’d ever want to know download NIST Special Publication 432, NIST Time and Frequency Services.