[6] How do bands, wavelengths & frequencies, kHz & MHz, differ?
A band can refer to any choice from a set of tuning ranges on a given
radio, as well as any sub-range of frequencies 'on the dial'. Some
antique radios have dials calibrated according to wavelength (as a
whole number of metres) instead of frequency (kHz or kcps) to convey
tuning location: e.g. the "16m" position on such dials is within a
sub-range of frequencies whose wavelengths border on 16 metres.
* To convert MHz to kHz, multiply the former by 1000 kHz/MHz:
9.625 MHz x 1000 kHz/MHz = 9625 kHz
* To convert kHz to MHz, divide the former by 1,000 kHz/MHz:
21,725 kHz divided by 1,000 kHz/MHz = 21.725 MHz
* To convert kHz to metres, divide 299,792 km/s by the former:
299,792 km/s divided by 7,135 kHz = 42.02 m
* To convert metres to kHz, divide 299,792 km/s by the former:
299,792 km/s divided by 14 m = 21,414 kHz
299,792 km/s divided by 15 m = 19,986 kHz
299,792 km/s divided by 16 m = 18,737 kHz
299,792 km/s divided by 17 m = 17,635 kHz
299,792 km/s divided by 19 m = 15,779 kHz
299,792 km/s divided by 21 m = 14,276 kHz
( Note that as frequencies get lower, wavelengths get longer.)
Low Frequencies
The 30 - 300 kHz range is known as the low frequencies' band, for
which 'longwave' is a synonym. Reception for this range is best
between 6 p.m. & midnight (your time).
Many longwave stations serve as beacons for aircraft and marine
navigation by continuously transmitting their call letters. Many
broadcasts use Morse code (CW), but some transmit in binary coded
decimal (BCD), such as the time station WWVB on 60 kHz.
On longwave, there is an AM broadcast band from 153 to 279 kHz in
Europe, N. Africa and N. Asia, but in America the only AM voice
broadcasts are typically weather reports.
Medium Frequencies
The medium frequencies' band is between 300 & 3000 kHz. On mediumwave,
there is an AM broadcast band from 525 to 1600 kHz, extended to 1700
kHz in Argentina, Australia and the U.S. A few more stations are
between 2300 & 2500 kHz, particularly in Australia & Brazil.
Coastal shipping uses 415 - 535 kHz: three CW calling & distress
stations monitor 500 kHz in Arctic Canada; internationally, most
NavTex automated warning stations use 518 kHz. Similarly, other
coastal stations & boats, especially coast guards and pleasure
boaters, have use of 2000 - 2300 kHz, with 2182 kHz set aside
internationally as a voice calling & distress channel.
Spanning the 160 metre dial position, there is an amateur radio band
from 1800 to 2000 kHz. Most of the transmissions are in SSB mode.
High Frequencies
The 3,000 - 30,000 kHz range is known as the high frequencies' band,
for which 'shortwave' is a synonym. Certain sub-ranges are set aside
as 'band allocations' for specific purposes, such as for: Aircraft,
Amateur Radio, Citizens' Band Radio, International Broadcasts, Ships
& Coastal Stations.
Aircraft Frequencies
Aircraft on trans-oceanic routes often use shortwave, mostly in SSB
although AM mode might still be used, to communicate with air traffic
controllers. Here are some bands where you might hear them:
2,850- 3,155 kHz
3,400- 3,500 kHz
4,650- 4,750 kHz
5,450- 5,730 kHz
6,525- 6,765 kHz
8,815- 9,040 kHz
10,005-10,100 kHz
11,175-11,400 kHz
13,200-13,360 kHz
15,010-15,100 kHz
17,900-18,030 kHz
21,870-22,000 kHz
23,200-23,350 kHz
Amateur Radio ('ham') Frequencies
Scanning the amateur radio frequencies can be interesting and also
helpful at times, because amateur radio operators often broadcast
emergency information when other means of communication break down:
e.g. the Salvation Army Team's Emergency Radio Net on 14,265 kHz in
USB mode. One may obtain a basic licence to transmit only above the
HF band, after passing just a written exam. Those who qualify for the
more senior amateur licences may also transmit on shortwave, but must
also pass a proficiency test for sending messages via Morse code in
CW mode. However, in many countries such tests are no longer required
(e.g. Australia, Chile, New Zealand & Papua New Guinea), or will be
phased out. As shown below, voice operators usually transmit in a
band just above that for code.
...wavelength.....code.band.............voice.band.........
....(metres)........(kHz)..................(kHz)...........
80 3,500 - 3,750 3,750 - 4,000
56 (5,167.5- 5,403.5)
42 7,000 - 7,150 7,150 - 7,300
30 10,100 - 10,150
21 14,000 - 14,150 14,150 - 14,350
16 18,068 - 18,110 18,110 - 18,168
14 21,000 - 21,200 21,200 - 21,450
12 24,890 - 24,930 24,930 - 24,990
10 28,000 - 28,300 28,300 - 29,700
Note: These designations are not observed everywhere (including
the United States - the first country to open up five USB
channels bordering on 56 metres to hams).
American CB Frequencies (applies partly to Oceania: Guam, etc.)
65 frequencies around 11 metres are allocated as channels 10 kHz wide
with a separation of 10 kHz from 26,895 to 27,535 kHz. The 40 channels
designated for voice communications from 26,965 to 27,405 kHz comprise
the Citizens' Band, and the rest are set aside for other uses such as
controlling objects. The 11 metre wavelength is within CB Channel 23
(centred on 27,255 kHz). In North America, Channel 19 (27,185 kHz) is
often used as a highway information channel; Channel 9 (27,065 kHz) is
reserved for emergency use. Unlike for ham radio, a licence is not
required for CB transmissions. Most of these are in AM mode, but a few
CB radios can use SSB, such as the Realistic TRC-459:
http://support.radioshack.com/support_electronics/doc46/46897.htm
International Broadcast Frequencies
Frequencies in shortwave bands near the following 13 wavelengths are
allocated as channels 10 kHz wide with a separation of 5 kHz for use
by foreign and domestic stations. Their broadcasts are mainly AM
transmissions containing news, commentary, music and special features
reflecting their own country's cultural canvas. You can often find
more such stations transmitting just above or below these bands:
90 m * 3,200 to 3,400 kHz
75 m ** 3,900 to 4,000 kHz
60 m * 4,750 to 5,060 kHz
49 m 5,900 to 6,200 kHz
41 m ** 7,300 to 7,550 kHz
31 m 9,400 to 9,900 kHz
25 m 11,600 to 12,100 kHz
22 m 13,570 to 13,870 kHz
19 m 15,100 to 15,700 kHz
17 m 17,480 to 17,900 kHz
15 m 18,900 to 19,020 kHz
13 m 21,450 to 21,850 kHz
11 m 25,670 to 26,100 kHz
* These bands are reserved for transmissions with tropical coverage.
** Interference can be heavy around 41 & 75 metres, because hams in
many countries may operate here.
Ship & Coastal Station Frequencies
Most HF voice transmissions from ships & coastal stations are in SSB.
You can hear these transmissions in the following bands:
4,000- 4,143 kHz
4,351- 4,435 kHz
6,200- 6,525 kHz
8,100- 8,815 kHz
12,230-12,420 kHz
13,107-13,200 kHz
16,360-16,565 kHz
17,100-17,410 kHz
18,780-18,900 kHz
19,680-19,800 kHz
22,000-22,855 kHz
25,070-25,210 kHz
26,100-26,175 kHz
WWV broadcasts marine weather conditions for the NW Atlantic 8 minutes
past the hour; WWVH for the Pacific 48 minutes past; and each for the
NE Pacific 10 & 51 min. past with a status report for GPS satellites
14 & 52 min. past, respectively, on frequencies as given below.
Time & Standard Carrier Frequencies
The following stations broadcast their carriers exactly on-frequency,
which is useful to also calibrate SSB fine-tuning dials or BFOs (even
on some digitally-tuned radios). They also signal the exact time of
day at regular intervals (24 hours a day in standard AM mode except
where noted) which can be used to calibrate GPS devices. The time is
stated in terms of UTC. Most international broadcasts are scheduled
according to UTC, rather than the originating station's time zone.
CHU at Ottawa, Ontario:
3,330 & 7,850 & 14,670 kHz
(all in a fully 'AM-compatible' SSB mode: USB + full carrier)
LOL at Buenos Aires, Argentina: 11-12h, 14-15h, 17-18h,
5,000 & 10,000 kHz 20-21h, 23-24h UTC
WWVH at Kekaha, Hawaii and (or) WWV at Fort Collins, Colorado:
5,000 & 10,000 & 15,000 (& 20,000) kHz
YVTO at Caracas, Venezuela:
5,000 kHz (USB)
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