World of Ham Radio 1997/WOHR97_AmSoft_(1997-02-01).iso/swl/docs/wwv.doc

Text File | 1997-02-01 | 20KB | 535 lines

          NBS TIME AND FREQUENCY DISSEMINATION SERVICES






Time and Frequency Division
National Measurement Laboratory
National Bureau of Standards
Boulder, Colorado 80303




issued September 1979






















FORWARD:  This publication presents a description of the time and
frequency dissemination services of the National Bureau of
Standards.  Those interested in information on the NBS atomic clock
system, transmitting antennas, or discussion of technological
applications of the dissemination services should refer to Section
9, OTHER PUBLICATIONS.

          This SPECIAL PUBLICATION 432 will be revised and reissued
only as necessary to update information.







                          INTRODUCTION

     The time and frequency community is a small community,
generally unknown to the world at large, yet vitally important to
many of the basic activities of everyday living.  Electric power
companies, radio and television stations, telephone companies, and
navigators of ships and planes all depend heavily on precise
frequency and time information.  They must have a constantly
available source - a reliable, nationally and internationally
recognized STANDARD - with which to compare and regulate their own
timing equipment.  For over 55 years, the National Bureau of
Standards (NBS) has been providing this standard for most users in
the United States.
     Since the inception of the broadcast services from radio
station WWV in 1923, NBS has continually improved and expanded its
time and frequency dissemination services to meet the ever-growing
needs of an ever-widening community of users.  Today, still
striving for better ways to serve its public, NBS is making major
contributions to the nation's space and defense programs, to
worldwide transportation and communications, and to a multitude of
industrial operations, as well as providing convenient, highly
accurate time service to many thousands of users throughout the
world.  Services are presently available from stations WWV and WWVB
in Fort Collins, Colorado, and from WWVH in Kauai, Hawaii.  In
addition, services using network television and satellite signals
are also available.  This booklet is offered as a guide to these
services.

                        1.  WWV and WWVH

     NBS broadcasts continuous signals from its high-frequency
radio stations WWV and WWVH.  The radio frequencies used are 2.5,
5, 10 and 15 MHz.  WWV also broadcasts on an additional frequency
of 20 MHz.  All frequencies carry the same program, but because of
changes in ionospheric conditions, which sometimes adversely affect
the signal transmissions, most receivers are not able to pick the
signal on all frequencies at all times in all locations.  Except
during times of severe magnetic disturbances, however - which make
all radio transmissions almost impossible - listeners should be
able to receive the signal on at least one of the broadcast
frequencies.  As a general rule, frequencies above 10 MHz provide
the best daytime reception while the lower frequencies are best for
nighttime reception.
     Services provided by these stations include:

     Time announcements, Standard time intervals, Standard
frequencies, Geophysical alerts, Marine storm warnings, Omega
Navigation System status reports, UT1 time corrections, BCD time
code

     Figure 1 gives the hourly broadcast schedules of these
services along with station location, radiated power, and details
of modulation.

                            Figure 1
*** This section has been SLIGHTLY modified by KB9FRJ to adopt it
more sufficiently to a text file presentation.



         The Hourly Broadcast Schedules of WWV and WWVH


              W W V  B R O A D C A S T  F O R M A T


via telephone [phone]

Latitude:   40 degrees, 40 minutes, 49 seconds North
Longitude: 105 degrees, 02 minutes, 27 seconds West

NBS Radio Station WWV
2000 East County Rd 58
Fort Collins, CO 80524

Standard Broadcast Frequencies and Radiated Power:

 2.5  MHz:  2500 Watts
 5.0  MHz: 10000 Watts
10.0  MHz: 10000 Watts
15.0  MHz: 10000 Watts
20.0  MHz:  2500 Watts


* BCD TIME CODE on 100 Hz Subcarrier
* Beginning of each hour is identified by 0.8 sec long 1500Hz TONE
* Beginning of each min. is identified by 0.8 sec long 1000Hz TONE
* The 29th and 59th SECOND pulse of each minute is omitted


Hourly Schedule

Minutes after the top of the hour/Broadcast information

00 min    Station Identification
02 min    440 Hz 1-HOUR mark
04 min    reserved
08 min    Storm information
09 min    Storm information
10 min    Storm information
16 min    Omega reports
18 min    Geo Alerts, Solar-terrestrial indices
30 min    Station Identification

In addition, minutes 45-50 have no audio tones so that storm
forecasts from WWVH can be heard


             W W V H  B R O A D C A S T  F O R M A T

via telephone [phone]

Latitude:   21 degrees, 59 minutes, 26 seconds North
Longitude: 159 degrees, 46 minutes, 00 seconds West

NBS Radio Station WWVH
PO Box 417
Kekaha, Kauai, HI 96752

Standard Broadcast Frequencies and Radiated Power:

 2.5  MHz:   5000 Watts
 5.0  MHz:  10000 Watts
10.0  MHz:  10000 Watts
15.0  Mhz:  10000 Watts


* BCD TIME CODE on 100 Hz Subcarrier
* Beginning of each hour is identified by 0.8 sec long 1500Hz TONE
* Beginning of each min. is identified by 0.8 sec long 1200Hz TONE
* The 29th and 59th SECOND pulse of each minute is omitted

Hourly Schedule

Minutes after the top of the hour/Broadcast information

01 min    400 Hz 1-HOUR mark
03 min    reserved
29 min    Station Identification
47 min    Omega reports
48 min    Storm information
49 min    Storm information
50 min    Storm information
59 min    Station Identification

In addition, minutes 08-10 and minutes 15-19 have no audio tones so
that informational broadcasts out of WWV can be heard.












*** END figure 1 as edited by KB9FRJ for text file presentation ***


                   1a.  Accuracy and Stability

     The time and frequency broadcasts are controlled by the
primary NBS Frequency Standard in Boulder, Colorado.  The
frequencies as transmitted are accurate to within one part in 100
billion at all times.  Deviations are normally less than one part
in 1,000 billion from day to day.  However, changes in the
propagation medium (causing Doppler effect, diurnal shifts, etc.)
result in fluctuations in the carrier frequencies as received by
the user that may be very much greater than the uncertainty
described above.

                  1b.  Antennas and Modulation

     The broadcasts on 5, 10, and 15 MHz from WWVH are from phased
vertical half-wave dipole arrays.  They are designed and oriented
to radiate a cardioid pattern directing maximum gain in a westerly
direction.  The 2.5 MHz antenna at WWVH and all antennas at WWV are
half-wave dipoles that radiate omnidirectional patterns.

     At both WWV and WWVH, double sideband amplitude modulation is
employed with 50 percent modulation on the steady tones, 25 percent
for the BCD time code, 100 percent for the seconds pulses, and 75
percent for voice.

                     1c.  Time Announcements

     Voice announcement are made from WWV and WWVH once every
minute.  To avoid confusion, a man's voice is used on WWV and a
woman's voice on WWVH.  The WWVH announcement occurs first - at 15
seconds before the minute - while the WWV announcement occurs at
7.5 seconds before the minute.  Though the announcements occur at
different times, the tone markers referred to are transmitted
simultaneously from both stations.  However, they may not be
received at the same time due to propagation effects.
     The time referred to in the announcements is "Coordinated
Universal Time" (UTC).  It is coordinated through international
agreements by the International Time Bureau (BIH) so that time
signals broadcast from the many stations such as WWV throughout the
world will be in close agreement.
     The specific hour and minute mentioned is actually the time at
the time zone centered around Greenwich, England, and may be
considered generally equivalent to the more well-known "Greenwich
Mean Time" (GMT).  UTC differs from your local time only by an
integral number of hours.  By knowing your local time zone and
using the chart of world time zones in figure 3, the appropriate
number of hours to add or subtract from UTC to obtain local time
can be determined.  The UTC time announcements are expressed in the
24-hour clock system -i.e., the hours are numbered beginning with
00 hours at midnight through 12 hours at noon to 23 hours, 59
minutes just before the next midnight.




                  1d.  Standard Time Intervals

     The most frequent sounds hears on WWV and WWVH are the pulses
that mark the seconds of each minutes, except for the 29th and 59th
seconds pulses which are omitted completely.  The first pulse of
every HOUR is an 800-millisecond pulse of 1500 Hz.  The first pulse
of every minute is an 800-millisecond pulse of 1000 Hz at WWV and
1200 Hz at WWVH.  The remaining seconds pulses are brief audio
bursts (5 millisecond pulses) that resemble the ticking of a clock.
All pulses commence at the beginning of each second.  They are
given by means of a double-sideband amplitude modulation.
     Each seconds pulse is preceded by 10 milliseconds of silence
and followed by 25 milliseconds of silence to avoid interference
which might make it difficult or impossible to pick out the seconds
pulses.

                 1e.  Standard Audio Frequencies

     In alternate minutes during most of each hour, 500 or 600 Hz
audio tones are broadcast.  A 440 Hz tone, the musical note A above
middle C, is broadcast once each hour.  In addition to being a
musical standard, the 440 Hz tone can be used to provide an hourly
marker for chart recorders or other automated devices.

                   1f.  Official Announcements

     Forty-five-second announcement segments are available on a
subscription basis to other Federal agencies to disseminate
official and public service information.  The accuracy and content
of these announcement are the responsibility of the originating
agency, not necessarily NBS.
     Most segments except those reserved for NBS use and the semi-
silent periods are available.  Arrangements for use of segments may
be made through the Time and Frequencies Services Group, 524.06,
National Bureau of Standards, Boulder, CO 80303.

+ Omega Navigation System Status Reports

     Omega Navigation System status reports are broadcast in voice
from WWV at 16 minutes after the hour and from WWVH at 47 minutes
after the hour.  The international Omega Navigation System is a
very low frequency (VLF) radio navigation aid operating in the 10
to 14 kHz frequency band.  Eight stations are in operation around
the world.  Omega, like other radio navigation systems, is subject
to signal degradation caused by ionospheric disturbances at high
latitudes.  The Omega announcements on WWV and WWVH are given to
provide users with immediate notification of such events and other
information on the status of the Omega system.
     For more information about the Omega Navigation System,
contact Mr. David Scull, United States Coast Guard HQ, (G-ONSOD
43), Washington, DC 20590.


+ Geophysical Alerts

     Current geophysical alerts are broadcast in voice from WWV at
18 minutes after each hour.  The messages are changed approximate
every six hours at 1800, 0000, 0600, and 1300 UTC.  Part A of the
message gives the solar-terrestrial indices for the day; namely,
the 1700Z solar flux from Ottawa, Canada at 2800 MHz, the estimated
A value for Fredericksburg, Virginia, and the current, Boulder,
Colorado, K-index.  Part B gives the solar-terrestrial conditions
for the previous 24 hours, and Part C gives the forecast for the
next 24 hours.  If stratwarm conditions exist, a brief advice is
given at the end of the message.

1. Solar activity is classified as:

VERY LOW       Usually only quiet regions on the solar disk and no
               more than five of these; fewer than ten class-C
               subflares without centimetric radio burst of SID
               observed or expected.

LOW            Usually more than five but less than ten quiet
               regions on the solar disk; only class-C subflares
               without centimetric radio bursts or SID (sudden
               ionospheric disturbances) observed or expected.

MODERATE       Eruptive regions on the solar disk; fewer than five
               class-M X-ray events with centimetric radio bursts
               and SID observed or expected.

HIGH           Active regions on the solar disk; several class-M
               X-ray events with centimetric radio bursts and
               strong SID; and/or one to two importance=2
               chromospheric flares or class-X X-ray events
               observed or expected.

VERY HIGH      Region capable of producing protons on the sun; one
               or more chromospheric flares of importance-2 or
               greater; with outstanding centimetric radio bursts
               (500 flux units or greater), Class-X X-ray bursts,
               and major SID observed or expected.

2.  The geomagnetic field is classified as:

QUIET          A <= 7, usually no K-indices > 2
UNSETTLED      7 < A < 15 usually no K-indices > 3
ACTIVE         15 <= A < 30 a few K-indices of 4

3.  The geomagnetic storms are classified as:

MINOR          30 <= A < 50, K-indices mostly 4 and 5
MAJOR          A > 50, some K-indices 6 or greater.  Sudden
               commencements indicated by beginning time to
               nearest minute.  Gradual commencement indicated by
               beginning time to nearest hour.
4.  The rest of the report as follows:

SOLAR FLARES

CLASS C        any solar X-ray burst with a peak flux at 1-8
               angstroms of less than 1 microwatt per square meter

CLASS M        a solar X-ray burst with a peak flux at 1-8
               angstroms, greater than or equal to 10 but less
               than 100 microwatts per square meter.

CLASS X        a solar X-ray burst with a peak flux at 1-8
               angstroms, greater than or equal to 100 microwatts
               per square meter.

MAJOR SOLAR
FLARE          a flare of optical importance (at least 2B -
               BRIGHT) with a centimetric outburst of 500 flux
               units or more; or an X-ray event of Class-X
               intensity of duration 3 hours or more regardless of
               optical flare importance.

PROTON FLARE   protons by satellite detectors (or polar cap
               absorption by riometer) have been observed in time
               associated with Ha flare.

SATELLITE LEVEL
PROTON EVENT   a proton enhancement detected by Earth orbiting
               satellites with measured particle flux of at least
               10 protons per square centimeter per second per
               steradian of at least 10 Million electronvolts.

POLAR CAP
ABSORPTION     proton-induced absorption at least 2 dB as measured
               by a 30 MHz riometer located within the polar cap.

STRATWARM      reports of stratospheric warmings in the high
               latitude regions of winter hemisphere of the earth
               associated with gross distortions of the normal
               circulation associated with the winter season

Inquiries regarding these messages should be address to NOAA, Space
Environment Services Center R43, Boulder, CO 80303.  These messages
are also available by dialing [phone]

PROPAGATION FORECASTS

     The radio propagation forecasts broadcast on WWV were
discontinued on September 30, 1976.  Some of the information
previously contained in these forecasts is now included in the
Geophysical Alert announcements at 18 minutes after each hour.
However, neither NBS nor the Space Environment Services Center
which sponsors the Geophysical Alerts make radio propagation
predictions, nor do they maintain a literature file on the subject.
Users interested in further reading material on the effect of solar
and geophysical activity on radio propagation should consult the
latest edition of the AMATEUR RADIO HANDBOOK, published by the
American Radio Relay League.

MARINE STORM WARNINGS

     Weather information about major storms in the Atlantic and
eastern North Pacific are broadcast in voice from WWV at 8, 9, and
10 minutes after each hour.  Similar storm warning covering the
eastern and central North Pacific are given from WWVH at 48, 49,
and 50 minutes after each hour.  An additional segment (at 11
minutes after the hour on WWV and at 51 minutes on WWVH) may be
used when there are unusually widespread storm conditions.  The
brief messages are designed to tell mariners of storm threats in
their areas.  If there are no warnings in the designated areas, the
broadcasts will so indicate.  The ocean areas involved are those
for which the U.S. has warning responsibility under international
agreement.  The regular times of issue by the National Weather
Service are 0500, 1100, 1700, and 2300 UTC for WWV and 0000, 0600,
1200, and 1800 UTC for WWVH.  These broadcasts are updated
effective with the next scheduled announcement following the time
of issue.
     Mariners might expect to receive a broadcast similar to the
following:
  "North Atlantic weather West of 35 West at 1700 UTC.  Hurricane
Donna, intensifying, 24 North, 60 West, moving Northwest, 20 knots,
winds 75 knots; storm 65 North, 35 West, moving east, 10 knots;
winds 50 knots, seas 15 feet."
     Information regarding these announcements may be obtained from
the Director, National Weather Service, Silver Spring, MD 20910.


                      1g.  "Silent" Periods

     These are periods with no tone modulation.  However, the
carrier frequency, seconds pulses, time announcements, and 100-Hz
BCD time code continue.





END TRANSCRIPTION

I have ended the transcription from the original literature here.
The remaining material is on WWVB, the 60 kHz sister station to WWV
and WWVH, and other totally unrelated topics.






Here's a few more things you might like to know (TRIVIA):

The telephone numbers listed in Figure 1 dial-in directly to the
broadcasts of WWV and WWVH.  If you don't have a radio, this is the
only way to get these broadcasts

The station identification and time-of-day announcement are pre-
recorded -- not "live".  The announcer for WWV is Don Elliott of
Atlanta, Georgia.  Mrs. Jane Barbe is the announcer for WWVH, and
she is also from Atlanta.

TOURS:

Guided tours are available at all NBS radio station.  However,
arrangements for visiting the sites should be made in advance with
the EIC.  There aren't any 'regular' visiting hours.

Tours of the NBS Boulder Labs, including visits to the atomic clock
and the other dissemination services, are available.  Information
can be obtained from the Program Information Office, NBS, Boulder,
CO 80303.

Correspondence pertaining directly to station operations may be
address to:

Engineer-in-Charge
NBS Radio Stations WWV and WWVB
2000 East County Road 58
Fort Collins, CO 80524
[phone]

Engineer-in-Charge
NBS Radio Station WWVH
PO Box 417
Kekaha, Kauai, HI 96752
[phone]




If you wish to receive the document I have copied this material
from, so that you can read about the other frequency standard and
about radio station WWVB at 60kHz, write to the station locations
given in Figure 1 and ask for the document entitled "NBS TIME AND
FREQUENCY DISSEMINATION SERVICES".



vy 73 de KB9FRJ   "Kyle"