Manual

SECTION VIII
TIME & FREQUENCY STANDARD
BROADCAST STATIONS
DESCRIPTION OF SERVICES
A worldwide network of high frequency radio stations has been
established to broadcast time and frequency signals and other infor-
mation on HF frequencies. Although this information is broadcast for
a wide variety of users, it can be very useful to pilots.
WWV AND WWVH
In the United States, two of these stations are operated by the
National Institute of Standard Technology (NIST). These are WWV
located at Fort Collins, Colorado, and WWVH located at Kekaha,
Kauai, Hawaii. The NIST broadcasts continuous signals from these
high frequency radio stations on 2.5, 5.0, 10.0 and 15.0 Mhz. WWV
also broadcasts on an additional frequency of 20.0 Mhz. Use the AM
receiver mode when listening to these stations.
Frequency Mhz Radiated Power, KW
WWV WWVH
2.5 2.5 5.0
5.0 10.0 10.0
10.0 10.0 10.0
15.0 10.0 10.0
20.0 2.5
All frequencies carry the same program, but because of changes in
ionospheric conditions which adversely affect the signals transmis-
sion, the KHF 950 will normally not be able to receive the signal on all
frequencies at all times in all locations. Except during times of severe
magnetic disturbances, however, it should be able to receive the sig-
nal on at least one of the broadcast frequencies.
As a general rule, frequencies above 10 MHz provide the best day-
time reception while the lower frequencies are best for nighttime
reception.
The time and frequency broadcasts are controlled by the primary
NIST Frequency Standard in Boulder, Colorado. The frequencies as
transmitted are accurate to within one part of 100 billion (1 x 10-11) at
all times
Services
8-1
KHF 950/990 Pilots Guide
Rev. 0
Dec/96