HOW TO GET STARTED?
If you don't own a radio yet, you can try one of the many remote
receivers freely available online.
- If you are interested in the Buzzer we've got you covered, here's
a live feed
- WebSDRs are
radios that you can tune freely by using your browser
- Another site providing remotely tunable radios is GlobalTuners
- And finally, if you want to download client software you can try
SDR Radio
What can I hear?
If you are using your own radio at home it depends on your
location and setup what stations you can receive. With a basic
setup (no huge antenna towers or such) you can usually hear at
least some of what I have listed before; remember that shortwave
propagation means that what might be inaudible today might come in
very strong tomorrow and it is not unusual to hear common European
stations in North America and vice versa, just keep
listening!
And for those of you who are still using online remotes, this
guide might help you choose a radio location where you can hear
that next station.
North America: Cubans are running a huge
operation with hours and hours of numbers daily under 3 station
designators V02a, M08a and SK01. Taiwan broadcasts V13, South Korea
V24 and the Vietnamese send Morse with designation M97. Also, make
sure to check out VC01, the Chinese Robot, it's an air defense
network but it sounds so crazy that it just must be heard.
Europe: A lot of stations can be heard all over
Europe. Russians have a very active operation with many active
stations in different languages and also in Morse and digital
modes. Russian stations are for example E06, E07, E17z, G06, S06,
S06s, V07, M01, M12, XPA, X06 and the list goes on.
The polish run a few stations (E11/E11a, G11, S11a, M03) and if
you're in south Europe you must try the Egyptian (?) E25, one of
the weirdest number stations currently active.
Other parts of the world: We don't have many
listeners from other places so we don't know that much about the
stations active there. If you are from Africa or Asia you are in
luck, you might even discover whole new number stations! Make use
of the Priyom website and number station schedules, see what
stations you can pick up well and please send your reception
information to us.
Other number station resources
Priyom has station profiles, logs, research and a number station
schedule so it's a good place to start, but still a couple
newsletters deserve a shout, so make sure and check out:
ENIGMA2000 - http://www.brogers.dsl.pipex.com/enigma2000/
Numbers & Oddities - http://www.numbersoddities.nl/
CHOOSING YOUR OWN
SHORTWAVE RADIO
World band radio
A world band radio has always been a popular way to start
shortwave listening. These radios are inexpensive and yet they
offer quite good reception. With a basic world band radio you can
receive commercial radio stations all over your own continent and
the strongest ones from halfway around the world. Number stations
commonly broadcast with fairly high power, so the world band radio
is a fine way to start monitoring them.
Typical prices for new world band radios range from 30 euros to
few hundred euros. Tecsun PL-600 and Degen DE-1103 are popular
among people in Priyom IRC channel (I'm not affiliated with any
radio makers, this meant just as a helpful hint).
Communications receivers
Communications receivers are the heavyweights of radio monitoring.
They often feature better frequency coverage, replaceable bandwidth
filters, gain control, signal strength meters, multiple VFO's,
preamplifiers, attenuators, and a high price tag. These radios are
built for heavy-duty use, they can handle bigger antennas and are
designed to work for tens of thousands of hours without failure.
All these features and many more make them the preferred choice for
radio professionals and enthusiasts.
Typical prices for new communications receivers range from 500
euros to tens of thousands of euros. These radios don't come with
their own antennas so be prepared to invest in a proper antenna
setup too.
Software-defined radio (SDR)
Growing more and more popular, these little boxes plugged to
your computer can give you great control over the signal you
receive. The biggest benefit of SDRs is that the hardware only
takes care of the reception of the signal and then passes it on to
the computer. This allows for very cheap construction of these
devices as many expensive parts are not needed, the computer
software can take care of most functions. This design also makes
these radios very flexible as the software can support all possible
modulations and the user can add any kind of filters they like.
Traditional radios require the change of hardware to achieve these
results and such system would soon become forbiddingly expensive
and complicated. SDRs are available from commercial vendors and
private radio hobbyists who often design their own receivers and
sell a small batch of inexpensive kits.
The kits can go as cheap as under 20 euros and can go up to
several thousand euros. Be on the lookout for kits made by radio
hobbyists!
THINGS TO CONSIDER WHEN
CHOOSING A RECEIVER
Frequency coverage
Even the cheapest world band radios tend to have sufficient
overall frequency coverage, but some do have gaps. Try to find one
with an uninterrupted coverage, because there is nothing more
frustrating than hearing about an interesting station and finding
out that you cannot tune to it. The coverage that you should be
looking for is at least the shortwave band (3000 - 30 000 kHz), but
most radios go considerably lower than that. To hear the
medium-wave AM radio stations the coverage should go as low as 522
kHz.
Frequency display
Go for digital frequency display, it will make your life a lot
easier. Analog displays are often too small and inaccurate. Simple
as that.
Modulation
In simplified terms, modulation is the way the radio message is
mixed in with the carrier signal that is then broadcasted from the
radio station. Common modulations that you probably already are
familiar with are FM and AM.
In shortwave the common modulations used are AM and it's
derivative, SSB (single-sideband modulation). SSB has two common
implementations, USB (upper sideband) and LSB (lower sideband).
Make sure that your radio has at least AM and SSB modes (don't
worry about the particulars, if the manufacturer says the radio has
SSB, it has both LSB and USB). CW - commonly known as morse code -
is nice to have for those M-class number stations, but it is not
completely necessary. Basically it's SSB with narrow bandpass
filter.
Note that if you are buying an older radio SSB might be called
BFO, always check the product manual to verify this.
Antenna connector
Almost all world band radios come with a telescopic antenna which
works fine for the strong stations. Communications receivers and
SDRs usually do not come with a built-in antenna, but have instead
antenna connectors in the back for an external antenna. Whatever
radio you are purchasing, try to look for one with at least the
option to connect an external antenna. A common antenna for
shortwave listening is a "random wire", which literally means using
an arbitrary lenght of electrical wire as the antenna, so don't
worry about investing in huge antenna towers at this, this will do
just fine.
False advertising
There are no 30 euro communications receivers and there are no
antennas that can receive everything. There are, however, many
salesmen who will want to sell you both. Do your homework and don't
be afraid to ask for help. A bad receiver can kill the hobby before
it really even began.
ANTENNAS
Built-in antenna is a good way to start listening on the
shortwave, but soon you'll notice that you want to hear more
stations and fainter signals - this is when external antennas come
to play. Modern receivers are very sensitive and can be overloaded
easily, so choosing the right antenna for your purposes is
important. Luckily most antennas can be built at home for very low
cost, so experimentation is recommended. As a general rule, world
band receivers get overloaded quite easily, and all communications
receivers can handle a decent size antenna.
The antenna that people usually start with is a random/long wire
antenna which performs quite well as long as it is positioned away
from sources of interference and as high as possible. The lenght of
the wire will add more sensitivity, but once again you should
remember not to overload your receiver. Long wire antennas work
indoors too, but if an indoor antenna is your only choice you might
want to consider building a loop antenna or purchasing an active
antenna because they tend to pick up less interference and provide
better performance than random wire.
Always disconnect your antenna if there is a
thunderstorm nearby. Your antenna can pick up dangerous currents
from distant lightning strikes and kill you and your receiver.
Don't take the risk.
Overloading
Overloading means that the receiver's front-end can't handle the
very strong signals it's been fed.
This can cause you to hear many stations in a same frequency
making it hard to know what you are actually listening to.
Overloading can be caused by feeding a cheap world band radio with
a very big antenna and by nearby radio transmitters. If you hear
broadcast stations where they shouldn't be you are probably
experiencing overload. You can enable the attenuator circuit but a
much better solution is to try different antennas and if a local
broadcast station is the cause you could add a band-stop filter to
the antenna line to block broadcast frequencies out.
Few antenna tips
- Always make sure that your antenna cable doesn't touch any
electrical wiring, and that the cable is connected tight enough
that the wind cannot swing it to places where it can be a danger to
you or others.
- As a general rule, the higher the antenna is, the better. Trees
are good places to anchor your antenna. You can use a slingshot or
a weight at the end of your cable to get it up there. For temporary
"field" operations, telescopic fishing poles are easy and cheap way
to get your antenna very high up. Remember to keep an eye on your
fishing pole though, as it cannot stand very high wind loads.
- Always stay as far away from interference sources as you can.
Consider using a well-shielded coaxial cable for the indoor part of
your antenna.
- If you are using an indoor antenna, keep it as close to the
window as possible. Thick walls, metal objects and roofs, all
weaken the signal considerably and may introduce
interference.
- If your radio has a grounding connector make sure to take
advantage of it. Use as short a wire as possible and connect it to
a good ground, common ones are water pipes and radiators, just make
sure that they're metallic. This should help your radio deal with
interference a little bit better.
- If you have already tried the random/long wire antenna hit
Google with dipole, loop, T2FD, G5RV, Windom, Beverage, rhrombic
and Yagi to get to the next level.
- Do you remember what I said about disconnecting your antenna
during a thunder storm? I hope you do.
INTERFERENCE
Signals that interfere with your radio reception are unavoidable,
but there are ways to minimize the harm. For domestic RFI sources,
the easiest solution is to turn the interfering devices off.
However, this is not always possible and even if you manage to turn
everything off in your own house, you cannot escape the
interference from your neighbour, from the electric grid and from
wireless transmitters. Below is a list of devices that you should
especially avoid, and a few tips on what do to.
Common sources of interference
Everything that runs on electricity is a potential source of
interference, the following are often found to be very
prominent:
- TV (especially plasma television)
- Computer (laptops tend to cause more RFI than desktop
computers)
- Computer displays (TFT's tend to cause more trouble than
CRT's)
- Battery chargers, UPS'es
- Lamps (especially CFLs)
- Power lines, electrical outlets
- Everything wireless (keyboards, mice, CCTV's, security systems,
cell phones, etc)
- Extractor hoods
- Water pumps
Tips for preventing RFI
- If possible, turn off the devices that cause interference
- Keep your equipment further away from the RFI source
- Use well-shielded antenna cable
- Ground all your equipment well
- Try different antennas. Magnetic loop antennas are very popular
in high-interference areas
- If nothing else helps, consider building small faraday cages for
essential equipment
I hope that by now you know where to find number station
information, where you can listen to them online and you got so
into them that you know what radio you are going to buy tomorrow
and what things you need to look out for when you first turn it on.
Now the only thing left is for you to join Priyom IRC channel and
come tell us all about it. Direct your IRC client to
chat.freenode.net #priyom or use the webchat in the front page. See you
there!
---
Tucana
tucana@priyom.org
