Shortwave (HF,High Frequency) Spectrum from 2.3Mhz to 30Mhz covers Speech (phone) CW (Morse Code) and data mode some are S.S.T.V, P.S.K, R.T.T.Y, Packet Radio and Weather Fax,
Some shortwave band users are Amateur radio, Weather Stations, Military, Civil Aircraft, Shipping and News Agency's.
Shortwave radio waves are reflected from the ionosphere a region of the upper atmosphere, where neutral air is ionised by solar photons and cosmic rays. When radio waves reach the ionosphere at a shallow angle, they are partly reflected by the surface. The ionosphere can also be similar to a prism refracting light; different frequencies are "bent" by different amounts. Some time the radio waves bounce between the ionosphere and earth this is known as skip and can travel thousands of miles on very low power.
Top Russian Vega Broadcast Band Radio with Homemade VFU on Top.
Below Realistic DX-394 General Coverage Communications Receiver.
Basic portable for shortwave broadcast bands or with a VFO for side band operation.
For better reception a communications receiver with LSB and USB possible AM/FM and narrow/wide filters.
Or build a Direct Conversion. single or multi band Receiver for amateur bands.
Long wire Antenna as long and as high as possible, this is fine for broadcast bands and to get started with.
Antenna Tuner will help match the antenna input.
Active antenna's can be used where there is limited space for long wire or dipole antenna's,
home-made or from radio shops
A good antenna system will help bring in distance stations and reduce noise
Tuning normal AM FM broadcast bands speech is fairly easy depending on how selective or sensitive the receiver is.Single Side Band (S.S.B) and Morse (CW) C.W (Morse) does not work in the same way, or sound like A.M and FM broadcast transmission. As you adjust the main tuning control slowly the pitch of signal changes, Adjust for a comfortable pitch for C.W note
The pitch of S.S.B speech varies in the same way. As you tune through the signal the pitch varies, but with speech you need to be more accurate in tuning to get a human voice to sound right. Remember the voice being resolved may be in a foreign language or a poor quality signal. It takes time to tune in to SSB signals but will come with practice.
Below 10Mhz lower Side Band (L.S.B) is used above 10Mhz Upper Side Band (U.S.B) is normally used for Speech and C.W
To receive data transmissions a way to decode the signals is required. The best way I have found is a computer with software like MULTIPSK, Digipan, CPIX, DXPSK to name a few, some are freeware.
An interface cable is needed between the receiver and computer, A length of 1 or 2 core miniature screened cable with two 3mm jack plugs from the ext spkr socket to the line in socket on the computer sound card.
|Morse||RTTY||SSTV & Fax||BPSK31/QPSK31||HF Packet|
|3.50Mhz-3.58Mhz||3.58Mhz-3.62Mhz USB||3.73Mhz-3.74Mhz LSB||3.580Mhz USB||3.590Mhz-3.60Mhz USB|
|7.00Mhz-7045Mhz||7.035Mhz-7.45 USB||7.035Mhz LSB||7.035Mhz USB|
|10.10Mhz-10.14Mhz||10.14Mhz-10.15Mhz||10.14Mhz USB||10.15Mhz LSB|
|14.00Mhz-1407Mhz||14.07Mhz-14.099Mhz USB||14.230Mhz USB||14.070Mhz USB||14.090-14.099Mhz USB|
|18.10Mhz-1838Mhz||18.100Mhz-18.109Mhz USB||18.100Mhz USB||18.102Mhz USB|
|21.00Mhz-21080Mhz||21.080Mhz-21.120Mhz USB||21.340Mhz USB||21.080Mhz||21.100Mhz-21.120Mhz|
|24.890Mhz-24.920Mhz||24.920Mhz-24929Mhz USB||24.920Mhz USB|
|28.150Mhz-28.190Mhz||28.050Mhz-28.150Mhz USB||28.680Mhz USB||28.070Mhz & 28.120Mhz USB||28.120Mhz-28.150Mhz USB|
There are far to many frequency's and times of transmission's to list but a up to date directory will help, also look for frequency list on line
Morse (CW) is used mainly on amateur bands and for maritime stations. Speed of sending is in words per minute eg = 12 wpm. Morse can also be sent in non English characters as well Arabic, Greek, Hebrew and Japanese.
MULTIPSK Computer software can decode Morse and most other data modes
RTTY stands for Radio TeleTYpe this a fairly old mode the original equipment was mechanical and the speed was set by gearing, the use of electronics makes it easy today.
Radio amateurs use a speed of 45 baud on shortwave at 170Hz shift USB, Commercial stations use 50 and 75 baud normally at 400Hz or 425Hz shift LSB. ZCZC means start of message NNNN is end of message.
BPSK31 in this mode the data transmission rate is 31.25 baud and the bandwidth is about 31Hz. The advantage or BPSK is it's very good signal to noise ratio (SNR or S/N ) allowing communication when severe noise, interference and fading are present and other forms of communication would fail.
PSK is a digital modulation that sends data buy changing or modulating the phase of a reference signal.
These modes are QRP (low power 5 Watts) They are used very little.
Try Frequency's and times below
14.076 Mhz at 17h00 UTC 10.149 Mhz at 22h00 UTC
SSTV is used on amateur bands the modes used are Martin 1, Martin 2, Scottie 1, Scottie 2, Scottie DX, Robot 36, Robot 72, and B/W 24. Martin is the most common in Europe. Robot and B/W 24 are the early modes. Depending on software the slant needs to be adjusted to correct the sound card sample frequency.
Is used on amateur bands and commercial stations. Commercial uses USB 120 lpm
Examples are Hamburg Meteo 3.855 Mhz, 7.880 Mhz, Bracknell Meteo 2.615 Mhz, 4.610 Mhz, 8.040 Mhz.
There are few BBS, communications are rather done from a Ham to another Ham.
Not to interesting to monitor some times packet found around 14.099 Mhz
Means of Identifying aircraft automatically on HF bands with selcals decoder software
This system as been in use since the 1960's
CB can be found on 27Mhz it is mainly used for short distance and mobile contacts. When skip conditions
are right long distance (DX) can be heard even on 4 watts FM.
27/UK 40 UK channels from 27.60125 Mhz to 27.99125 Mhz FM UK use only.
PR27GB mid block 40 EU channels from 26.965 Mhz to 27.405 Mhz FM UK and Europe.
Some countries in Europe permit the use of other modes (Packet) (SSTV) also other frequencies and some AM and SSB Channels. In UK FM only the power legal limit is 4 watts.
The USA and Canada the same 27.965 Mhz to 27.405 Mhz but AM, SSB used instead of FM also more power allowed than UK. USA can be heard in UK when skip conditions are good.
A receiver that covers FM or a CB transceiver with 40 or 80 channels mobile or homebase type will be needed and a vertical antenna mobile or 1/2 wave base type is better than horizontal dipole or long wire.
If you transmit a licence may be required.
DRM is a high near FM quality transmissions on long Medium and Short wave broadcast bands. At present there are not many stations to listen to. And you will need a receiver that receives DRM stations. You will not hear the crackles and whistles but reception will still be subjected propagation conditions.
Morphy Richards produce a radio that receives AM, FM, DAB and DRM.
There is a winradio computer controlled receiver that receive DRM also.
They generally broadcast numbers or letters or some times words. The origins of these numbers stations is uncertain and are in many different languages. Evident supports that the broadcasts are sending messages to spies. But as not been acknowledged by any government so far. The stations decreased since the cold war finished. Recently activity as increased again.
More information can be found on line about these number stations (Time, Frequencies, power etc).
There are many pirate stations from all over the world South America, North America, Europe and Asia. Most transmissions are illegal and often closed down when found.
Sample below of broadcast music station
Radio Free London on 5.805 Mhz every Sunday
Laser Hot Hits 6.220 Mhz, 6.275 Mhz, 7.415 Mhz and 9.390 Mhz
Some use illegal 6.600 Mhz for person to person and other modes including SSTV.
Beacons are transmitted from a fixed location from all over the world. Amateur beacons are sent in Morse at regular intervals a call sign in Morse at 22 wpm followed by four dashes 1st dash at 100w 2nd dash at 10w 3rd dash at 1w 4th at 0.1w.
0n the 10 meter band (28Mhz) beacons are between 28.1247 Mhz and 28.300 Mhz
Beacons are used to test propagation (Skip conditions)
Ships and aircraft pin point their position by reference to continuous signals given out by two or more beacons. These days GPS as taken over more from fixed beacons.
A number of software programs to help listeners work out which beacon is transmitting on what frequency at a given time. Faros 1.1 is freeware by Alex VE3NEA may be worth a try if you want to find beacons.
All the above information is given to the best of my knowledge if you find any parts are wrong or misleading please let me know and I will try to correct it