John Beckman - W4BTX HAM RADIO "A PAST TIME FOR A LIFETIME"
I hope you had a nice Thanksgiving. We have much to be thankful for in Ameica. If it wasn't such an exceptional nation, why would so many people try to sneak into it?
A month or so ago WWV, pruported to be the oldest radio station in the world, celebrated its 100th year of operation. For many years the "voice" on WWV was Don Heald, the manager of WSB-TV when I worked there in the 1970s. Mr. Heald is now SK. When I got started in ham radio we all used WWV to calibrate our drifting receivers and VFOs.
Radio station WWV broadcasts time and frequency information 24 hours per day, 7 days per week to millions of listeners worldwide. WWV is located near Fort Collins, Colorado, about 90 miles north of Denver. The broadcast information includes time announcements, standard time intervals, standard frequencies, UT1 time corrections, a BCD time code, and geophysical alerts. WWV operates in the high frequency (HF) portion of the radio spectrum. The station radiates 10, 000 Watts on 5 MHz, 10 MHz, and 15 MHz; and 2500 Watts on 2.5 MHz and 20 MHz.
Each frequency is broadcast from a separate transmitter. Although each frequency carries the same information, multiple frequencies are used because the quality of HF reception depends on many factors such as location, time of year, time of day, the frequency being used, and atmospheric and ionospheric propagation conditions. The variety of frequencies makes it likely that at least one frequency will be usable at all times.
The WWV antennas are half-wave vertical antennas that radiate omni directional patterns. There are antennas at the station site for each frequency. Each antenna is connected to a single transmitter using a rigid coaxial line, and the site is designed so that no two coaxial lines cross. Each antenna is mounted on a tower that is approximately one half-wavelength tall. The tallest tower, for 2.5 MHz, is about 60 m tall.
The shortest tower, for 20 MHz, is about 7.5 m tall. The top half of each antenna is a quarter-wavelength radiating element. The bottom half of each antenna consists of nine quarter-wavelength wires that connect to the center of the tower and slope downwards to the ground at a 45 degree angle. This sloping skirt functions as the lower half of the radiating system and also guys the antenna..
The signals broadcast by WWV use double sideband amplitude modulation. The modulation level is 50 percent for the steady tones, 50 percent for the BCD time code, 100 percent for the second pulses and the minute and hour markers, and 75 percent for the voice announcements.
All of us now have clocks that set their time automatically. That is a service of WWVB winch is at the same location as WWV. It sets clocks by broadcasting a digital time code on a frequency of 60 kHz. The time code bits are sent by raising and lowering the power of the signal. A radio-controlled clock has an antenna and a radio receiver inside, which decodes the bits to get the time (UTC), day of year, daylight saving time, leap year and leap second indicators.
The user of a radio-controlled clock must select the time zone, so that the clock can convert UTC to local time. It typically takes several minutes for a radio controlled clock to synchronize when it is first turned on. After that, most radio controlled clocks will synchronize once per day, usually in the middle of the night when the signal is the strongest. You can check the WWVB web page for more information.
Thank you for dropping by...Send comments HERE. Until next week 73 and Straight Ahead ->