This page is designed for
people new
to Amateur
Radio or VHF
long distance (DX) communications.
When
I was first licensed as a Radio Amateur in 1985, with my
then VHF only callsign of G1MOG,
I had already spent 2 years as a Short Wave Listener (SWL) listening to the
Amateur Radio HF and VHF bands, with QSOs (conversations) heard from all round
the World. This time was well spent as it taught me a lot of procedure, etiquette,
and operating practices, before I ever transmitted when I became licensed
to. Since passing the 12wpm Morse Code test in 1987 I have held my FULL licence
callsign G0ISW.
The same is true for those of you who are
newly licensed, or new to VHF DX, as time spent listening before you ever
transmit will be time well spent and will avoid
you making unnecessary mistakes, rather like the characters from 'Wallace &
Gromit', who mean well, but sometimes do silly things whilst they experiment
with new inventions and ideas. Believe me, every Radio Amateur makes mistakes at
some time.
If you cannot see the full
index shown on the left edge of your screen, please go to my main page athttp://www.qsl.net/g0isw
If you have no
existing Amateur radio or short wave receiver and want to 'simulate' the HF
(worldwide) amateur radio experience, then you could try downloading and
using the new 'Hamsphere' software
(you do not require an amateur radio licence). I haven't tried this yet
myself, but it seems an easy and cheap way to see if you would ultimately
like to invest in a real radio and become a Radio Amateur or
Short Wave Listener (SWL).
Here in the UK there are currently 3
different classes of
Amateur Radio license
M6
2E0
M0
Each class of
license requiring different levels of technical and practical knowledge and
each having different permissions for frequencies and power levels. The old
requirement of having to pass a 12 wpm morse code examination, before access
to the HF bands was permitted no longer exists, so now it is easier than ever
to become licensed. The Foundation license, for example, requires you to
attend about 10 hours on a
training course,
spread over several weeks (or a weekend) and after passing you will be
allocated a M6 plus 3 letter callsign and will be able to get on the air and talk to people
around the World.
Did you know that it is
now possible to listen to Amateur Radio and Shortwave signals without having
a radio? Thanks to the internet you can use your home computer to link to
other people's radios and listen, without costing you a penny! Simply click
on the Global Tuners image below and follow the instructions.
I
will describe below how you can move on from simple line of sight (short range)
144 MHz FM QSOs at VHF, to
working Long distances (DX) and using new more complex data modes. This is based upon my own
experiences of the last 25 years.
50 MHz is
probably the easiest VHF band to achieve regular long distance (DX)
communications (Summer only), but radio conditions can vary tremendously depending on the time
of year and the solar cycle.
The best time of year is from May to August during
the
Sporadic Es season, where with low power and simple aerials anyone
in the UK can work
most of Europe, up to 2,300km distance from your
station, and with very strong signal strengths in both directions. However,
outside of the summer months conditions can generally be poor and the band
appear totally deserted. There are exceptions as at the maximum of the solar
cycle 50 MHz signals are reflected by the F2 layer
just like on HF and it is possible to work all continents including Australia!
The pileups can be frustrating to break though.
Also it is possible at all times
of year to work stations in Europe up to 2,300km
away by bouncing your signals off the ionised trails left by meteors entering
the Earth's atmosphere. You will need WSJT
software and a computer linked by a
soundcard interface to your USB transmitter, but there is plenty of
Meteor Scatter activity, most
mornings and evenings, around 50.230MHz using
JT6M
mode. You will also need a directional aerial.
N.B. 50MHz
is considered poorer than 144MHz for
Tropo Scatter
communications, which are available day or night for ranges in the region of
100-500 Km.
New to
Amateur Radio? Start on this band for local contacts either simplex or through
repeaters.
144 MHz is the mainstay of VHF amateur bands around
the World. Most
Radio
Amateurs will have a handheld or small mobile radio capable of transmitting on the
144 MHz (2m) band, which is where most local VHF activity will be found. If your radio is only capable of FM
transmissions, then until recently you had fairly limited options for working
further than very local distances in the order of 0-50km. This
is because at VHF, signals are 'line of sight' and are blocked by obstructions
such as hills, buildings, trees etc. Also because of the curvature of the
Earth's surface your signal will eventually disappear into Space, unless
reflected back by something.
In the UK the 2m calling
frequency is 145.500 MHz FM, listen for CQ calls
and respond or call CQ yourself, but move away from the calling frequency to
continue your conversation as soon as you can. The 'S20' shown after
145.500 MHz on the listing below relates to the
'old' original UK system of numbering 2m simplex channels, which is still used
by many amateurs as the newer system of numbering channels following the move
away from 25kHz channel spacing to 12.5 KHz channel
spacing is too complicated for most to understand and use. Often you will hear
stations saying 'QSY to S23'which means move from the calling frequency to
145.575 MHz for example.
145.300
(S12)
145.325
(S13)
145.350
(s14)
145.375
(S15)
145.400
(S16)
145.425
(S17)
145.450
(S18)
145.475
(S19)
145.500
Calling channel (S20)
145.525
(S21)
145.550
(S22)
145.575
(S23)
In Cities there can be a lot
of activity on simplex channels between 145.300 - 145.575
MHz but often there is more activity on repeaters which retransmit
signals from high locations and cover greater areas. In the UK the repeater
channel outputs on which you listen are from 145.600 MHz -
145.775 MHz, with -600kHz offset, so you
transmit on a slightly lower frequency. For example for my local repeater GB3EV
the output is on 145.700 MHz and the input is on
145.100 MHz.
If the repeater is 'open'
after a station's transmission is over, the repeater will signal by a tone or
pip that it is ready to retransmit a new signal. Wait for this otherwise the
repeater timer isn't reset and after approximately 2-5 minutes the repeater will
switch off and go into standby mode.
To 'open' a repeater that is
in standby mode, you need to either transmit a single
1750Hz tone before you speak (old fashioned way of doing this) or you
need to transmit a sub audible CTCSS tone on the correct setting for your area,
click on link below to see map.
UK 2m repeater CTCSS tone map
You will also need to see what frequency your local repeaters are on so click on
this link
Full UK repeater list
To achieve reliable long distance (DX)
communications on this band you will need a multimode radio, at least 25 watts
and a directional yagi type aerial, that can be turned with a rotator. Contrary
to popular opinion you do not need the maximum permitted 400 watts and a massive 17 element yagi, but if you
have this available then obviously it will be superior to a smaller setup. I
only use 50 watts and a small Log Periodic antenna which is only 3m long, but
have still managed to work North Africa on 144MHz
USB via
Sporadic Es
as well as Estonia and Iceland via
Meteor Scatter
from England.
432 MHz can be a very frustrating band. Long distance communications are
possible via
Tropo Ducting,
which appears when there is very high air pressure and no wind, often with fog
present, but if there are mountains in the way they will block this.
When I lived in
London, which is fairly flat and has a good view to the horizon, I could work
Switzerland with 10watts and an ex-military phased array of 16 dipoles. Since
moving to the Lake District in 1990 the furthest distance that I have achieved
has only been around 200km via
Tropo Scatter. The mountains simply block all
Tropo Ducting for me as I live in the valley floor.
In 2006 there was a
fantastic
Tropo Ducting opening
from the UK to Scandinavia, which we could hear from the top of the Pennine
hills 20km to the East of my QTH, but as soon as you drove slightly down the
hill they all disappeared.
There are other methods of achieving long distance
communications on this band such as Satellites or
Moon bounce (EME), but this can get
very complicated and often may require an elevation rotator and extensive
antennas. Signals on 432 MHz are much weaker than on
144 MHz. It is however a good
band for mobile repeaters using FM and the UK has an extensive network in most
areas.
Which VHF/UHF radio is
the the one to have as a base station for DX work? Well, I have tried several and would currently recommend
either the Yaesu FT-847,
Icom 746/7400 or my current radio the
Kenwood TS-2000.
The sensitivity of the Yaesu FT-847
is particularly good and they can also transmit on 70 MHz, but are rather deaf on
that band. The HF side of the radio is basic with no internal ATU though. The
VHF/UHF power output is a maximum of 50 watts, but on 70MHz varies from 10w to
25w depending on batch number.
The
Icom 746/7400 is an excellent HF radio and has
respectable performance on both 50 MHz and
144 MHz, but lacks the ability of cross band
144/432 MHz required by some satellites. It has an
internal ATU for HF and 50 MHz and has 100 W on all
bands including 2m.
The
Kenwood TS-2000 is good on both HF,
50 MHz, 144 MHz, 432 MHz and can be fitted with
1296 MHz too! It has an internal ATU for HF and
50 MHz. Its one fault is that all models apparently
have an internally generated
carrier signal on 435.300MHz, which is a downlink
FM frequency used by a number of amateur radio satellites. The Kenwood was unique in that it
was one of the first to be able to be upgraded through software downloads.
Your antenna height above sea level will affect how far
your signal can travel, try the
VHF/UHF
Line of sight calculator by G4VWL
to see for yourself how far your signals can travel from home via conventional
line of sight propagation. Don't be
concerned that you do not live at a great height above sea level! This
will only affect your ability to work greater line of sight distances up
to a maximum of 100km, even more important is your ability to have an
unobstructed view of the horizon. Believe me it is better to be located
in Norfolk than amongst the mountains of the Lake District, from a VHF
DXer's perspective.
Height
km
VHF
Propagation modes
Different propagation modes enable VHF/UHF signals to travel further than
normal 'line
of sight'
because they are reflecting your signals from different heights, above sea
level, in the Earth's atmosphere.
Tropo Scatter
takes place below
10,000m (10km)
height (Mt. Everest is by comparison
8,850m
high), whereas the majority of
Meteor Scatter takes place at
90km altitude and
Sporadic Escan be up to
110km height, allowing much greater distances to be achieved.
The
exception is
Tropo Ducting,
between 450-3000m
height asl, where the signals are trapped between layers of hot and cold air (temperature
inversion) and if over a good calm sea path may extend for huge
distances. Contacts between Scotland and the Canary Islands on
144MHz
have been achieved this way.
Why
are
Auroral signals shown to typically achieve a lesser distance than
Meteor Scatter even though the reflection takes place at a greater height
in the Atmosphere? They do actually travel further reflected off the Auroral
curtain near the Arctic and back again, but the receiving station may be a lot
closer to you in Europe.
The International space Station and the
Space Shuttle are both over
200km
in height.
This is
the mode by which most of your local 144/432 MHz
FM
simplex conversations will be made, either direct to stations or via
repeaters.
Dependant upon
antenna height above sea/ground level and visible radio horizon distance. Line
of sight (LOS) distance can be increased with height or decreased by
obstructions such as mountains, buildings etc.
Line
of sight is the direct free-space path that exists between two points. Using
binoculars on a clear day, it is easy to determine if visual line of sight
exists between two points that are miles apart. To have a clear line of
sight there must be no obstructions between the two locations. Often this
means that the observation points must be high enough to allow the viewer to
see over any ground-based obstructions.
The following
obstructions might obscure a visual link:
Topographic
features, such as mountains
The curvature of
the Earth
Buildings and
other man-made objects
Trees
If
any of these obstructions rise high enough to block the view from end to
end, there is no visual line of sight.
Obstructions
that can interfere with visual line of sight can also interfere with radio
line of sight.
But one must also consider the Fresnel effect. If a hard object, such
as a mountain ridge or building, is too close to the signal path, it can
damage the radio signal or reduce its strength. This happens even though the
obstacle does not obscure the direct, visual line of sight. The Fresnel zone
for a radio beam is an elliptical area immediately surrounding the visual
path. It varies in thickness depending on the length of the signal path and
the frequency of the signal.
As
shown in the picture above, when a hard object protrudes into the signal
path within the Fresnel zone, knife-edge diffraction can deflect part of the
signal and cause it to reach the receiving antenna slightly later than the
direct signal. Since these deflected signals are out of phase with the
direct signal, they can reduce its power or cancel it out altogether. If
trees or other 'soft' objects protrude into the Fresnel zone, they can
attenuate (reduced the strength of) a passing signal. In short, the fact
that you can see a location does not mean that you can establish a quality
radio link to that location.
There are several
options to establish or improve the line of sight:
·Raise the
antenna mounting point on the existing structure
·Build a
new structure, i.e. radio tower.
·Increase
the height of an existing tower
·Locate a
different mounting point, i.e. building or tower, for the antenna
Your LOS signal, which can be blocked by
high terrain can sometimes be diffracted or bent over the top of the
obstruction, particularly in mountainous areas if the top of the obstruction
is 'sharp', hence the term 'Knife-edge diffraction'.
I live in a mountainous area and have
experienced a few instances where contacts have been made with stations that
should have been totally obstructed by high mountains in between.
This propagation mode is available all the time and is the main one for longer
contacts, particularly at 144 MHz on SSB within
the UK or to mainland Europe. Slow fading of signals often apparent and
reasonable signal strengths.
This
propagation mode was used by NATO, from around 1956 to the late 1980's, as
part of the
ACE HIGH
Troposcatter system on frequencies between 832 MHz
and 959 MHz, in a chain of
49 stations running
from Norway to Turkey. Transmitting power was around 10 KW and huge dish
antennas were used!
I
remember seeing the huge dishes at
Cape Greco (JCGZ) in
SE Cyprus in the late 1980's, but am struggling to find any photos of them
apart from this one.
Looking at Google Earth imagery below, from 2003, it appears the dishes have now
been removed.
Aircraft scatter propagation is subject to rapid fading of signals and not particularly easy to catch or use.
You can liken it to bouncing your radio signals off the metal aircraft body,
which will be travelling extremely fast, in the same way you would bounce
light off a mirror.
RADAR (Radio Detection And Ranging) has used radio signals since before WW2
to determine the flight path of aircraft. Early German WW2 radar used
frequencies near to the amateur 144 MHz band.
Modern stealth aircraft such as the US Air Force F-117 were designed so that
their shape would not easily reflect Radar signals back to the receiving
station, by avoiding having any vertical angles.
Some experimentation has been done by
SM6FHZ and his
website detailing how to work regularly via this mode, using flight
timetables
is here.
Frequencies of 144 MHz,
432 MHz and 1296 MHz have all been used
successfully. Some imagery and an explanation of how you can experiment to
listen yourself can be found on the website of
G3CWI here.
Aurora favours Northern
Europe. March is often a good month. You need to point your antenna between
North and East and reflect your signal off the moving Auroral curtain.
Speak much slower than normal and
compensate for the Doppler shift, which makes everyone sound like Daleks!
50 MHz is particularly good for this mode,
144 MHz is useable and
432 MHz is extremely difficult due to the high Doppler shift.
Field
Alignment Irregularities (FAI), can occur in the late afternoon from
May to August, and favour Southern Europe. The signal is usually
very weak and the scatter area is located at a height of approximately
110km.
During
exceptional VHF openings some amateurs worked DX stations located
8000 km away crossing the Equator. Imagine:
From Southern Europe to South Africa on 50MHz
or even 144MHz ! This phenomenon seems to occur
when both stations are located at equal distances North and South of the
Equator and experiencing a high level of electron density in Autumn and
Spring, during periods of solar maximum activity and the equinoxes.
The
stations located over 45° of latitude north (or south) are usually too far
off the geomagnetic equator to make use of F-layer FAI. Sometimes however,
these latitudes can be worked via an additional sporadic-E hop, even if
signals are usually weak and typically exhibit the fluttery and hollow like
sound of pure FAI.
It was
observed that there were two distinctly different types of TEP that could
occur:
The
first type occurred during the late afternoon and early evening hours and
was generally limited to distances under 6000 km.
Signals propagated by this mode were limited to the low VHF band (<60
MHz), were of high signal strength and suffered moderate distortion
(due to multipath). Single sideband voice communications were possible with
this mode.
The
second type of TEP occurred from around 1900 to 2300 hours local time.
Contacts were made at 144 MHz, and even very
rarely on 432 MHz.
The
signal strength was moderately high, but subject to intense rapid fading,
making morse code (narrow band CW) the only possible communication mode. One
amateur described the signal quality in the following words: "we tried SSB
but there was so much distortion that not a single word could be identified.
[this mode] has a lot of flutter and fading and ... even the morse comes
through like a breathing noise, not a clear tone" (from the Dawn of Amateur
Radio in the UK and Greece by Norman F Joly).
Signals can be quite strong. Look for periods of high air
pressure over the UK and Europe. Often extensive fog can indicate the right
conditions for this propagation mode. Once established paths can be open for
many hours or days. Often you may hear far away 144
MHz/432 MHz repeaters that normally cannot be heard.
Sea path possible
exceptionally up to 3000km on
144MHz SSB, paths between Scotland and the Canary
Islands have been worked.
October often
the best month.
These Ducts form at heights between 450m to 3000m, but are blocked by higher mountains along the
path.
Select Europe map and then click on
site to view
readings. Gif image to 700mB best. Look for
temperature inversions, where the inversion thickness layer is
wide enough to support ducting at 144 &
432MHz, using the table below.
Not commonly useable by
radio amateurs. Ionoscatter is the scattering
of radio waves in the ionosphere due to irregularities in the electron
distribution, which causes changes in the refractive index. Scattering is most
pronounced in the D-region between 70 and 90 km and is best from
30-60 MHz.
Ionoscatter is a
propagation mechanism available 24H a day like meteor scatter, but it is
different from meteor scatter. Ionoscatter deliverer's a continuous weak
signal and does not have the characteristic bursts in signal strength of
meteor scatter.
Ionoscatter starts about
900 km and extends to almost
2,000 km. Troposcatter works on all frequencies
50 MHz to 10 GHz,
whereas Ionoscatter is only useable on 30-60 MHz.
NATOMilitary radio systems from around the years 1950-1960 used huge aerials and around 40kW of power to
maintain reliable signals via this mode! The Distant Early Warning Line
DEWLine
being a good example. Therefore it is rare for Amateur
Radio transmissions to be powerful enough to utilise this mode. The Military Ionoscatter system was replaced by Troposcatter systems
in the 1960's.
Summer months best for major showers, but winter months
active too. Random meteors occur all the time day or night. Can be a mode that
can revolutionise 50/144 MHz SSB contacts using WSJT
software for long distance contacts. My favourite mode!
Reflections of radio signals can last from around 250 milli seconds (1/4 of
a second) to 30 seconds plus, but the vast majority are extremely brief. It
usually takes a long time to complete a QSO in the region of 30 minutes or
an hour, unless there is a major Meteor shower such as the Leonids in 2001.
To easily hear Meteor
pings tune your transceiver to a strong Band 1 TV station video carrier such
as 48.242.2 MHz CW or
49.739.7 MHz CW and you will hear nothing, until the signal is
reflected briefly by a passing meteor! Please note that during the Summer
months
Sporadic E (Es)
may allow you to hear the TV carrier continuously.
Unfortunately Band
1 analogue TV is being phased out in Europe and so the availability of these
TV carriers is being much reduced for monitoring Meteor Scatter. There are
some alternatives, such as the
French GRAVES
space surveillance radar system on 143.050 MHz CW.
Sporadic E (Es)
at mid-latitudes occurs mostly during summer season, from
May to August in the
Northern hemisphere and from November to
February in the Southern hemisphere. Very strong signal strengths are
common.
There is no single cause for this
mysterious propagation mode. The reflection takes place in a thin sheet of
ionisation around 90 km height. The ionisation patches drift westwards at
speeds of few hundred km per hour. There is a weak periodicity noted during
the season and typically Es is observed on 1 to 3 successive days and remains
absent for a few days to reoccur again. Es do not occur during small hours,
the events usually begin at dawn, there is a peak in the afternoon and a
second peak in the evening. Es propagation is usually gone by local midnight.
Sporadic E (Es)
clouds have been observed to initially occur within approximately
150
km (90 mi) to the East of a severe thunderstorm cell complex in the
Northern hemisphere, with the opposite being observed in the Southern
hemisphere. To complicate matters is the fact that
Sporadic E (Es)
clouds that initially form to the East of a severe thunderstorm
complex in the Northern hemisphere, then move from ESE-WNW and end up
to the West of the severe thunderstorm complex in the Northern
hemisphere.
So one has to look for
Sporadic E (Es)
clouds on either side of a severe thunderstorm cell complex. Things
get even more complicated when two severe thunderstorm cell complexes
exist approximately 1000–2000 miles apart.
Not all
thunderstorm cell complexes reach severe levels and not all severe
thunderstorm cell complexes produce
Sporadic E (Es).
This is where knowledge in Tropospheric physics and weather
analyses/forecasting is necessary.
50MHz 2,350km is max single hop distance.
50MHz
Sporadic E (Es)
season is from
May to August in the Northern Hemisphere. Double hop often seen
vastly increasing the distances worked.
Some distances worked
when at solar minimum in 2007 have been in the order of
6000km, is this triple hop Sporadic-E or something else such as
Short-path Summer Solstice Propagation (SSSP)?
Only open on 50MHz towards the peak of a solar cycle, in the Winter months from
October to April, but possible to work all Continents including Australia.
Next peak due in 2012/2013. Get ready for the
pileups!
VHF DX Year Planner
In
the UK the 2m calling
frequency is 145.500 MHz
FM.
This is where you would listen to hear someone calling 'CQ'
which means they want to have a conversation with anyone, or you might hear them
call 'CQ DX', which
means they want a conversation only with someone who is a long distance away
from them. If they call 'G9ABC from M9ABC' then they only want to speak to
'G9ABC' and not you. Once you are confident enough you can call 'CQ' and someone
will hopefully reply to you. Then you have to QSY (change frequency) away from
the calling frequency to a clear frequency. Always listen and ask if that new
frequency is in use, the UK Bandplans
should always be adhered to.
You
may now have spent some time speaking to other local Radio Amateurs and you now
want to work stations further afield. One option is to work through a repeater,
which will retransmit your signals. Another option is to improve your 'line of
sight' to other stations, which can simply be achieved by getting your aerial as
high as possible. At home this might involve something simple like attaching an
aerial to your chimney or installing a mast onto which you can place an aerial.
I used a
Tennamast
telescopic tilt over mast, which allows me to attach new aerials or cables at
ground level before I wind the mast up to its 10 Metre height, which clears the
top of my house. Another form of repeater are the Amateur
Radio satellites, some of which are
FM and allow communications using a
handheld radio with other stations around the World. Satellite
FAQ. The International Space Station (ISS) also regularly has crew members
who are licensed radio amateurs.
When
not at home, another option of improving your aerial height is either by driving
your car to a hilltop or walking to the top of a hilltop. With a
2m
handheld radio and 1
watt of FM
for example, from a
3000'
hilltop, it is fairly easy to work distances in the region
of 0-125 km
without
using a repeater! Activating hilltop summits has become very popular recently
and more information on this subject can be found on my
SOTA
page.
Sometimes
you can experience VHF DX communications due to unusual Propagation.
Probably the best example of this is
Tropo
Ducting,
where following a period of sustained high air pressure over the UK, around
1030mb, signals
from the Continent, or far flung parts of the UK, can be heard at strong signal
strengths. This used to occur quite frequently in October of each year, but can
occur at any time. FOG and High Pressure on
Weather
maps can help to identify likely occasions.
Distances
achievable are in the region of
200-1000
km,
but with a good sea path distances of up to
3000km
have been achieved between Scotland and the Canary Islands. The best times of
year are the Spring and Autumn. In the weather chart shown below there is not an
area of equal pressure between Scotland and the Canary Islands, so that
tropo ducting between the two would not be possible.
In addition to speech on
144 MHz
FM it is easily possible to use some data modes for
communications too. I used to use RTTY in the 1980's on the
145.300 MHz
FM frequency and had great fun seeing messages from other Radio Amateurs
appearing on my computer screen as they typed each key. Advances in computers
and software have made it possible to connect your
144MHz
FM radio to your computer
and experiment with all sorts of data modes including Slow Scan Television
(SSTV). It is also possible to connect to other Amateur stations around the
World using your radio and/or computer and
Internet Linking
which
is the latest development in the hobby with free software such as EchoLink.
For
really serious VHF DX though, you will need a multimode transceiver capable of
Single Sideband (SSB) transmissions and you will also need a horizontally
polarised beam antenna, which has significant gain compared to a dipole.
Probably the best and most commonly used is a Tonna 9 element beam. Ideally you
will also need a rotator so that you can point your aerial at the station or
Country you are trying to work/hear.
An essential question you need to be able
to answer is your Maidenhead Locator square, as this is the information, which
allows amateurs to determine your location anywhere in the World and is used for
Award purposes. Use either Maidenhead
Locator Finder or QTH
Locator converter to find
yours and look at Euro
Grid Square Map to see the
locations of other Amateurs.
Lots
of us use DXclusters and a link to the Internet to find DX stations more easily.
A nice piece of software that I have used is
DX
Monitor
Using
your multimode radio in Upper Side Band (USB) and calling initially on
144.300
MHz it is possible
daily to have speech contacts in the region of
50-500km
using Tropo
scatter
propagation, depending on where you are in the UK you may be able to have
regular QSO's with amateurs in Europe.
During
the months of
May
to
August you may be very
lucky to experience a rare form of propagation called 'Sporadic
E', which can appear from nowhere and allow you to work vast distances.
Distances achievable are in the region of
1100-2350km
on 144MHz.
I
have managed to work North Africa,
EA9IB
on 144MHz
USB with only
25
watts
and a small Log Periodic aerial (equivalent to a 4 element yagi) via this mode. A distance of
2154 km.
Once
you have worked DX using speech and SSB and are familiar with chasing DX, it
becomes a challenge to collect and work new Maidenhead locator squares and
Countries. A very good piece of software for keeping track of your VHF
achievements is
VQlog
3.0B.
When
you are really struggling to find any new locator squares because you have
worked all the ones close to you then you can try
Meteor
Scatter,
which is where I am
concentrating now, but it requires considerable skill to be successful.
Distances achievable are in the region of
500-2200km.
You will need to download the fantastic
WSJT software and use
this in conjunction with a computer to transmit high speed data over your
radio, which can be decoded at the receiving end, for meteor reflections
lasting typically less than 1/4 of a second!
If you have an older
computer download version 4.9.8 and not the latest version 5.9.5. You must do this if
you have a RigExpert interface too.
Use
JT6M mode for
50MHz meteor scatter, tropo scatter and sporadic
E qso's.
Use
FSK441A mode for
144MHz meteor scatter qso's.
Adjust your soundcard
received audio level to show 0db on the WSJT screen, for every mode.
Be patient, meteors can
be very elusive outside of showers. Some qso's may take up to an hour!
Disable your internet
browser from playing sounds in web pages, otherwise you are likely to play
them over your radio by accident
The
excitement of communicating with an Astronaut onboard the
International Space
Station or speaking through an Amateur Radio satellite to someone thousands of
km away is good fun, but it can be daunting for the beginner. You do not need to
have an antenna system that is steer able and has elevation control, but it does
help, also you do not need to have automatic satellite tracking or Doppler
frequency control for your radio however you will be at a disadvantage if you do
not.
I will
describe below how it is possible with modest equipment to have some success.
You should start by visiting the AMSAT satellite status to
establish the current operational status of the Amateur Radio satellites. The
easiest to work will be the Low Earth Orbiting (LEO) satellites which have 2m
and 70cm FM uplinks and downlinks, currently these include
AO-27,
SO-50,
AO-51 and the
International Space Station.
You will need to identify the uplink
and downlink frequencies and programme your radio accordingly, also some of the
uplinks require a PL or CTCSS tone too. Next
you need some satellite tracking software to determine when these satellites
will be within range of your station, I can recommend either
SatScape 2.02 or SATPC32
software. Both programmes download the latest Keplarian elements automatically,
from the Internet.
Now you will know when these satellites
will next be in range. Listen to them first and observe the operating procedure
of other Radio Amateurs, you can use any sort of aerial including a collinear
for this purpose. Once you are comfortable with what to do, you can try working
your first satellite, but it requires patience, for example when the
International Space Station is in range of you, its footprint may cover most of
Europe and numerous other amateurs will all be calling at the same time as you!
That is all part of the challenge, and remember that some Hams have just used
their handheld radios and have been successful.
If you
really want to work satellites properly, you might want to use either a
Yaesu
FT-847 or
Kenwood TS-2000
transceiver, which are both designed for this purpose
and have all the bells and whistles required.
The ultimate VHF/UHF DX has to be bouncing
your signals back from the Moon (EME). With this mode it is possible to work
stations in other Continents, but it requires large antenna arrays, high power
and suffers from very weak reflected signals.
In early 2006 I became interested in working
the
International Space Station,
Low Earth Orbiting Amateur Radio Satellites and trying EME (using the
JT65B
digital mode). This has come about because band conditions are so
poor on HF at present and realistically I have worked as much as I can via the normal
VHF/UHF propagation modes. I am however finding it a very steep learning curve.
I use
Nova for Windows software to give me audible alerts in the shack, when the
Satellites are coming into range. I use
SATPC32 software to CAT control my Kenwood TS-2000 radio and correct my
144MHz and 432MHz
speech signals for doppler shift.
I use
AGW packet engine software to give me the ability to transmit and receive
packet without a TNC and only using my computer soundcard. The
UISS software works in tandem with AGW and is a very useful tool for working
the ISS or digipeating through it. Within a day of downloading the software (on
Saturday 17th March 2006 at 1145UTC), and on my first attempt, I managed to have
my 145.990MHz FM packet signal digipeated by the
ISS (RS0ISS-3) as it flew overhead at 345km, this was achieved using my
normal VHF horizontal beam and using 25w.
See the image below, showing my QTH and
those of other successful Hams,
displayed in real-time, as heard by the ISS. The ISS position is shown and
where it will be in 5 minutes later (ISS-5).
If you have no
existing Amateur radio or short wave receiver and want to 'simulate' the HF
(worldwide) amateur radio experience, then you could try downloading and
using the new 
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