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Coordinated Universal Time (UTC)
Coordinated Universal Time (UTC), also referred to as
Greenwich Mean Time (GMT), Universal Time (UT), or "Zulu" is an
international time scale used in Amateur Radio, astronomical aviation
publications and applications, weather reporting, the military, NASA, and
other organizations and documents.
Most Amateur
radio operators refer to it as UTC.
UTC uses 24-hour (military)
time notation and is based on the local standard time on the 0? longitude
meridian which runs through Greenwich, England, hence, Greenwich Mean
Time. Midnight in Greenwich corresponds to 00:00 UTC, noon
corresponds to 12:00 UTC, and so on. It is a universal "reference" time so
anyone who uses it has a "point in time" reference to a specific
location.
Therefore, if you are in a different location than the
reference location, your local time would be either earlier or later
referenced to that UTC location point.
So in a manner of speaking,
everyone using UTC, uses the same clock!
The UTC time is the same
worldwide and does not vary regarding the time zone or daylight saving
time. UTC is a very accurate atomic time standard sustained by atomic
clocks located in national standards laboratories.
So in other words, it doesn't matter where you travel to,
whether you're in a hotel in San Francisco or in one of the many
Washington DC hotels, the UTC time is the same. Or for that matter,
anywhere on earth, the UTC time is still the same!
UTC Conversion
Table
Now although everyone uses the same clock so to
speak, most of us live in different locations of the earth and in
different time zones. If we need to know what time, (UTC), it is
somewhere else, we need to convert from our time zone to UTC.
The
following table provides for converting between UTC and U.S. and Canadian
time zones or in reverse.
UTC is in the far right hand section of
table below in red.
Notice that it starts at
00:00 (midnight). The blue numbers below it
indicate "AM", with a break at 12:00 (noon), then the colors change to red
"PM" all the way to 23:00
pm, then it changes back to the top of the column to 00:00,
(midnight) all over again indicating one complete 24 hour period. The
colors on the table have nothing to do with "telling time" except to
distinguish between AM and PM to help you use the table easier.
The
other sections labeled PST, PDT, MST, MDT, CST, CDT, EST, EDT, represent
YOUR LOCAL TIME ZONE. If you live in the Centeral Time zone, then you use
the section marked CST, if Daylight Savings Time is in effect, you use
CDT.
The same goes for the other time zones.
To use the conversion table, here is an
example:
Refer to the table
below,
Imagine your time zone was CST and your local time is
7:00PM....find the CST section, read down that section until you find
7:00PM then read to the right under the UTC section and read 01:00...so
the UTC time that corresponds with 7:00PM CST is 01:00...it's 1:00 AM
in Greenwich, England THE NEXT DAY! Now looking at this from the Greenwich
time zone at 00:00 to the left, then it would be 7:00 pm in the
Central Time Zone THE PREVIOUS DAY. Remember, at midnight, the day changes
either forward or backward depending on the direction of your conversion
and your location.
Another example:
It is 06:00
UTC...What time is it in the Eastern Standard Time zone?
Reading to the
left from 0:600 UTC until you find the EST zone = 1:00AM. If you were
looking at the PST section, it would be 10:00pm, the previous day.
Don't forget that the day advances at
midnight or retreats to previous day depending on where you are and the
dirction of the conversion! You can actually be talking to someone on the
radio who is in your future or in your past, depending on your point of
view and your reference in time! Time travel without a time
machine!........just rf and some distance!
Chart shows Standard and
Daylight Savings Time for each zone.
"S" = Standard and "D" = Daylight
Saving time (CST,CDT)
| PST |
PDT |
MST |
MDT |
CST |
CDT |
EST |
EDT |
UTC |
| 4 p.m. |
5 p.m. |
5 p.m. |
6 p.m. |
6 p.m. |
7 p.m. |
7 p.m. |
8 p.m. |
00:00 |
| 5 p.m. |
6 p.m. |
6 p.m. |
7 p.m. |
7 p.m. |
8 p.m. |
8 p.m. |
9 p.m. |
01:00 |
| 6 p.m. |
7 p.m. |
7 p.m. |
8 p.m. |
8 p.m. |
9 p.m. |
9 p.m. |
10 p.m. |
02:00 |
| 7 p.m. |
8 p.m. |
8 p.m. |
9 p.m. |
9 p.m. |
10 p.m. |
10 p.m. |
11 p.m. |
03:00 |
| 8 p.m. |
9 p.m. |
9 p.m. |
10 p.m. |
10 p.m. |
11 p.m. |
11 p.m. |
Midnight |
04:00 |
| 9 p.m. |
10 p.m. |
10 p.m. |
11 p.m. |
11 p.m. |
Midnight |
Midnight |
1 a.m. |
05:00 |
| 10 p.m. |
11 p.m. |
11 p.m. |
Midnight |
Midnight |
1 a.m. |
1 a.m. |
2 a.m. |
06:00 |
| 11 p.m. |
Midnight |
Midnight |
1 a.m. |
1 a.m. |
2 a.m. |
2 a.m. |
3 a.m. |
07:00 |
| Midnight |
1 a.m. |
1 a.m. |
2 a.m. |
2 a.m. |
3 a.m. |
3 a.m. |
4 a.m. |
08:00 |
| 1 a.m. |
2 a.m. |
2 a.m. |
3 a.m. |
3 a.m. |
4 a.m. |
4 a.m. |
5 a.m. |
09:00 |
| 2 a.m. |
3 a.m. |
3 a.m. |
4 a.m. |
4 a.m. |
5 a.m. |
5 a.m. |
6 a.m. |
10:00 |
| 3 a.m. |
4 a.m. |
4 a.m. |
5 a.m. |
5 a.m. |
6 a.m. |
6 a.m. |
7 a.m. |
11:00 |
| 4 a.m. |
5 a.m. |
5 a.m. |
6 a.m. |
6 a.m. |
7 a.m. |
7 a.m. |
8 a.m. |
12:00 |
| 5 a.m. |
6 a.m. |
6 a.m. |
7 a.m. |
7 a.m. |
8 a.m. |
8 a.m. |
9 a.m. |
13:00 |
| 6 a.m. |
7 a.m. |
7 a.m. |
8 a.m. |
8 a.m. |
9 a.m. |
9 a.m. |
10 a.m. |
14:00 |
| 7 a.m. |
8 a.m. |
8 a.m. |
9 a.m. |
9 a.m. |
10 a.m. |
10 a.m. |
11 a.m. |
15:00 |
| 8 a.m. |
9 a.m. |
9 a.m. |
10 a.m. |
10 a.m. |
11 a.m. |
11 a.m. |
Noon |
16:00 |
| 9 a.m. |
10 a.m. |
10 a.m. |
11 a.m. |
11 a.m. |
Noon |
Noon |
1 p.m. |
17:00 |
| 10 a.m. |
11 a.m. |
11 a.m. |
Noon |
Noon |
1 p.m. |
1 p.m. |
2 p.m. |
18:00 |
| 11 a.m. |
Noon |
Noon |
1 p.m. |
1 p.m. |
2 p.m. |
2 p.m. |
3 p.m. |
19:00 |
| Noon |
1 p.m. |
1 p.m. |
2 p.m. |
2 p.m. |
3 p.m. |
3 p.m. |
4 p.m. |
20:00 |
| 1 p.m. |
2 p.m. |
2 p.m. |
3 p.m. |
3 p.m. |
4 p.m. |
4 p.m. |
5 p.m. |
21:00 |
| 2 p.m. |
3 p.m. |
3 p.m. |
4 p.m. |
4 p.m. |
5 p.m. |
5 p.m. |
6 p.m. |
22:00 |
| 3 p.m. |
4 p.m. |
4 p.m. |
5 p.m. |
5 p.m. |
6 p.m. |
6 p.m. |
7 p.m. |
23:00 |
With
a little practice using the chart above, you can determine how far "ahead"
or "behind" you are by a + or - factor of hours. Comparing CST with UTC as
an example, UTC is 6 + hours ahead.
How do you
know what the correct UTC time is?
Listing
to Time Signals on HF
Several radio stations worldwide
transmit precise time signals on HF bands and other frequencies. NIST
(U.S.A.), continuously broadcasts time
signals with voice announcements
over hf radio frequencies from stations WWV in Fort Collins, Colorado
and WWVH in
Kauai, Hawaii. Both stations transmit on 2.500, 5.000, 10.000, and 15.000
MHz. WWV also operates on 20.000 MHz.
If your HF transceiver has
general coverage, you are in luck...Just tune in one of the frequencies
and get the exact time. They transmit on AM and you can use either the AM
mode on your receiver or zero beat the frequencies with either the USB or
LSB mode to hear the voice modulation.
Audio Sample of over the
air signal from WWV.
(Note that this is not the
actual time, it is an audio recording of about 1 minute and 25 seconds
taken from 10.000Mhz during the daytime (CST), using a Yaesu
FT-107 receiver in USB mode. You will hear the "time ticks" and the time
announced twice if you play it all the way to the
finish.
If propagation is
"right", you can use Canada's Institute for National Measurement station,
CHU. It transmits time signals and voice
announcements from Ottawa, Ontario. CHU
broadcasts continuously on 3.330, 7.335, and 14.670 MHz, also AM as with
WWV and WWVH.
So you see, you have several HF frequencies from
which to choose to get the "correct" UTC time using your general coverage
receiver.
There are also many other stations
around the world that transmits time signals and some are strong enough to
be heard in the U.S and Canada. There are many ore on the lower
frequencies below standard AM broadcast, but they are extremly difficult
to hear due to distances, static and power levels. They are not listed
here.
See chart below:
The frequencies are believe to be
accurate and remember...propagation plays a big part in receiving them.
You also have to remember that radio travel a near the speed of light
around the world so there is a split second error for listeners in the
U.S. tuned to WWV OR WWVH. Believe
me, it is accurate enough to set that old clock on your wall very
accurately!
The following is
a table of some major time stations reported to be in operation from
various sources including radio verification at the time of this article,
2007.
Most ham radio
operators will find that the stateside frequencies will be the best to
copy with the exception of CHU, Canada using a good general purpose
antenna. Those highlighted in green are usually very good copy with one or more
heard at different times of the day. Note that CHU changed frequency from
7.335Mhz to 7.850Mhz effective 01 January,
2009.
Frequency
(MHz) |
Callsign |
Location |
Comments |
|
1.5100 |
HD2IOA |
Guayaquil,
Ecuador |
Continuous |
| 2.5000 |
WWV |
Fort Collins, Colorado,
USA |
Continuous |
| 2.5000 |
WWVH |
Kekaha, Hawaii,
USA |
Continuous |
| 3.3300 |
CHU |
Ottawa,
Canada |
Continuous |
| 3.8100 |
HD2IOA |
Guayaquil,
Ecuador |
19:00-07:00
UTC |
| 5.0000 |
WWV |
Fort Collins, Colorado,
USA |
Continuous |
| 5.0000 |
WWVH |
Kekaha, Hawaii,
USA |
Continuous |
| 7.850
(New Freq) |
CHU |
Ottawa,
Canada |
Effective
1,1, 2009 |
| 10.0000 |
WWV |
Fort Collins, Colorado,
USA |
Continuous |
| 10.0000 |
WWVH |
Kekaha, Hawaii,
USA |
Continuous |
| 14.6700 |
CHU |
Ottawa,
Canada |
Continuous |
| 15.0000 |
WWV |
Fort Collins, Colorado,
USA |
Continuous |
| 15.0000 |
WWVH |
Kekaha, Hawaii,
USA |
Continuous |
|
20.0000 |
WWV |
Fort Collins, Colorado,
USA |
Continuous |
| CDT |
Central Daylight
Time |
| CST |
Central Standard
Time |
| EDT |
Eastern Daylight
Time |
| EST |
Eastern Standard
Time |
| MDT |
Mountain Daylight
Time |
| MST |
Mountain Standard
Time |
| PDT |
Pacific Daylight
Time |
| PST |
Pacific Standard
Time |
| UTC |
Coordinated Universal
Time |
Helpful links
with more info!
World
Time Zone Map (NIST)
The
Official U.S. Time (NIST) Java Application online
time
North America Time Zones (U.S.Time zones from
NIST)
Download....AlphaClock - v1.3.1
(Freeware!)
Freeware desktop
clock utility for Windows 95/98/Me/NT/2000/XP
Set it to display local
or UTC time on your Desktop!
More
Freeware Time syncronization software!
Download free computer time synchronization
software (Alpha Clock)
It automatically synchronizes
the computer system time clock with the National Institute of
Standards and Technology (NIST) time servers.
It uses Coordinated
Universal Time from the national time scale UTC(NIST) and sets the correct
time on your computer according to your local time zone.
(UTC clock at top of this page provided by
World
Time Server)
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