by ham radio
The regulations limit in France the allowed subjects of conversation to technical subjects, the amateur service is a service having for sole purpose: the individual instruction, the intercommunication and technical studies, carried out by amateurs who are authorized people being interested in the technique of radioelectricity on a purely personal basis and without pecuniary interest; the transmissions must be done in an open language, or a code recognized by the ITU, and be limited to messages of a technical nature.
There is the difference with the CB (citizen's band) where the content of the conversations is not regulated, but with the drifts which one can imagine.
We could fear ham radio is not very interesting, but, and fortunately, thanks to the many allocated bands, and the multiple available modes of transmission , it is exactly the opposite.
The possible activities are so wide that one ham radio cannot practise everything, and must self limits to some fields of predilection.
The discussion inside common lobbys
In general in telephony, but sometimes for some in telegraphy, the various available frequencies make it possible to found each other regularly on the ideal frequency to allow a comfortable connection: metric bands for local groups (same city, same area), the low decametric bands (80 m 40 m) for discussions on a country scale, the high decametric bands (20, 15 or 10 m) for international or intercontinental contacts.
The subjects are multiple, pleasure to meet friends, the weather, study of the propagation, special tests, new station, modification of the hardware, antennas, data processing, electronics, etc etc.
Seek for new correspondents (I seek you-CQ)
After sending a general call on a frequency, a correspondent answers, from anywhere, that can be antipodes on certain bandes, and the conversation begins: exchanging codes, controls of reception, first names, geographical situation, description of the station and weather, and more if common points of interest are found.
The search of the performance
From France,it is easy on 14 MHz to contact an European station, but it is more difficult to contact Australia or New Caledonia, the call then specifies the wish to contact such aera on the earth; it is possible on every band; for example on 144 MHz, contact its own city or department is easy, but to contact Belgium from south of France is another business, the search of the correspondent is then done by taking account of the possibilities of propagation at this time of the day.
After the first radio contact, the amateur often exchange a confirmation card known as QSL card, these cards can be personalized, often esthetics, sometimes exotic and allow the realization of beautiful memory album.
Certain countries, either by their distance, or by the few number of hams living there, are rarer or more difficult to contact than others, they are purchased, and to get QSL card is sometimes an exploit; it is as with post stamps, there are rare cards, except that QSL cards are personal, are not sold (I hope), and do not have a financial value.
The islands or territories far away from the motherland are considered by amateurs as separated countries, the Guadeloupe for example account differently of the Metropolitan France, there is less of inhabitants in Guadeloupe than in metropolis, a QSL card from this area is thus rarer.
But certain territories are completely uninhabited and even difficult to access, so expeditions are set up to activate them during a few days. Such a country can be wished by thousands of ham radios all over the world; let us say that the day it is activated, the listening of the frequency can be a the great moment of anthology.
Some week-ends are organized international contests, whose simplifyed rule is the following one: you must contact the most correspondents during this week-end; the teams interested by this activity polish their station months in advance, and even will organize expeditions to be more performant (tops of mountains) or more called (displacement in a rare country).
All this does not apply only with telephone or telegraphic traffic, all the other modes are concerned:
The radio operator teleprinter
The transmissions are made with a keyboard, with reception on screen (in the past on a typewriter which awoke all the family), it is the traditional TELEX
Transmissions from computer to computer, digital packet transmission, with automatic error correction, servers, repeaters allows safe and error free exchanges: files, text, images or others (but slower than with Internet).
Slow scan television
With SSTV, the fixed image is analyzed by a special camera, it can also be provided by a computer, from a file or a camescope, the transmission in analog form takes a few seconds, but requires little bandwidth, which makes it possible to use the decametric bands and to reach remote correspondents.
Or FSTV (Fast Scan TV), in this case, the image is produced directly by a commercial caméscope or a video tape recorder, the standards of transmission used are those of the networks in public television: NTSC in North America, PAL or SECAM 625 lines, 25 images a second in Europe.
Amplitude modulation is used on the 70 cm band, as on the hertzian european public chains. On higher frequencies, frequency modulation is used, as on the satellite channels. The audio is also transmitted.
The Fax Simile
Like the traditional Fax.
In metric or shorter waves, the connections tend to be limited to the optical range, the installation of amateur repeaters on high points or mountains, allows the contacts between stations over the horizon, therefore which cannot contact directly.
There are two principal types of repeaters: phone repeaters, in narrow band frequency modulation, and television repeaters , or ATV repeaters, in amplitude modulation on the 70 cm band, and in frequency modulation on the shorter wavelengths (in Europ).
Ham radios, grouped in associations, build satellites, and benefit from the flights of certification of the various launchers to obtain either low prices, or the complete exemption from payment; the satellites being small, they obtain sometimes the agreement for a launching in joined load.
More than twenty satellites amateurs were launched to date, the orbits are low or elliptic, there are no geostationary satellite at the moment
In low orbit, the passage is fast, the satellite is used as repeater, the two radio hams in connection, permanently turn their antennas towards the satellite and remain in contact as long as it is visible from the two correspondents.
In distant elliptic orbit, the satellite can move away to more than 40000 km of the ground (beyond the geostationary orbit) in this case its displacement is slow, which makes an easier poursuit but the signals are weak, on the other hand, the satellite " sees " a third of the earth and allows intercontinental contacts.
Higher still than the most remote satellite, the moon makes it possible by reflexion to practically contact correspondents on the antipodes; one needs high powers and antennas to obtain an exploitable signal in return.
Mobiles and maritime mobile
The French ham radios may use their stations on terrestrial or maritime vehicles; the use whithin an aircraft is not allowed.
Sailing ship " the deïxon " on the mediterrenean sea;
the preventer shroud is isolated and used as antenna
For those which do not know the emission of amateur:
Frequency bands propagation types of modulations organizations
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