SWL of shortwave radios in AM, Medium wave and Long wave, with WEB SDR in Europe by SWL F14368 Frank near Paris France. Informations about radio receivers for SWL, antennas, etc. Organiser of SWL contest 2023 and 2024.. This is my blog number ONE. Please visit my 2 other blogs about my listening. Thank you. 73
vendredi 21 juillet 2023
Why so much Pirates of The Airwaves in 2023
Invented by Al Gross in 1945, the CB radio originally served as a method of communication for troops during World War II. After the war, Gross worked to make it possible for two-way radios to be used for personal communication and the CB radio service was established by law in the U.S. in 1949.
I find a US (from 1963) magazine very interesting for CB radio opérators and SWL in PDF
Along with what is now the Family Radio Service (FRS) and General Mobile Radio Service (GMRS), the CB radio service was created as a method of short-distance communication using two-way radios and was popular with farmers, drivers, and radio hobbyists. It wasn’t until the 1970s that technology advanced and the CB market caught on as a method of communication between drivers.
When the U.S. government imposed a nationwide 55 mile per hour speed limit after the 1973 oil crisis that led to fuel shortages and rationing, drivers needed a method of communication to find service stations with available fuel. Commercial truckers used CB radios to locate fuel stations and notify others of speed traps. Since independent truckers were paid by the mile, a 55 mile per hour speed limit affected their productivity, and their paychecks. In 1974, drivers relied on CB radios to organize blockades and convoys in strikes that protested the new speed limit and other trucking regulations.
this band is very sensitive to variations in solar cycles and therefore very changeable. It has a large number of propagation modes. In periods of strong solar activity, the band opens at sunrise and closes a few hours after sunset. During these periods, a power of a few Watts makes it possible to establish contacts of several thousand kilometers. In periods of moderate activity, the band only remains open for low latitude transequatorial communications. During periods of minimum activity, DX communications are totally impossible.
The ES propagation begins to be important on 10 meters. It allows contacts over a distance of about 5000 kilometers. It reaches its maximum between the months of May and August.
Remeber 11 meter work with solar circle and SSN sun spoy numbers. When solar activity is good DX is easy but when you are at the end of 11 years slar circle its very have or you must have a good directive antenna. But every year we have sporadic E propagation
The E region of the ionosphere is located about 90 to 150 kilometers above sea level. Its altitude can vary, and the density of electrons (ionization) depends on the solar angle relative to the zenith and on solar activity. During daylight hours, the electron density (a measure of the level of ionization) can reach 105 electrons/cm3. At night, when the flow of X-rays from the sun is cut off, the level of ionization drops to 103 e/cm3. These ionization densities are evaluated under normal conditions, in the absence of E. sporadic.
Particularly ionized "clouds", organized in a single layer or in multi-layers, usually spaced about 6 kilometers apart, constitute the sporadic layer Es. Their formation can last from a few minutes to a few hours. The formation mechanisms of this layer are poorly understood. Its probability of occurrence is unknown and its parameters unpredictable.
Some possible theoretical mechanisms include upper level wind shears and geomagnetic activity.
The appearance of these phenomena in an intense way is mainly located in the period of one to two months preceding and following the summer solstice, that is from May to August in the northern hemisphere.
However, even during this period, the phenomena remain random: there may be no events for three consecutive weeks, or events almost every day for a whole week.
The radio propagation Es
Communication distances of 300 to 2,500 km are common from a single layer "cloud" of Es. They mainly concern very high frequencies. The variability in the propagation distance in Es and the frequencies involved is due to the size and density of the "clouds".
The frequencies from 20 to 70 MHz are the most affected by this type of propagation (the 27 MHz, 28 MHz and 50 MHz frequency bands of radio amateurs, the TV channels of band I, the FM band of 66 to 73 MHz of Eastern Europe).
During the most intense events, frequencies up to 250 MHz can be reflected (the FM band 88 to 108 MHz, the amateur radio band 144 MHz)1.
This type of propagation has the main characteristics of being directional (only certain geographical areas are concerned, variable according to ionospheric events) and very intense (very low power transmitters can be received hundreds of km away, distant transmitters can interfere with local transmitters).
Because of its random nature, this type of propagation is not used by regular telecommunications services, which on the contrary see it as a nuisance because of the risk of interference it entails, but mainly by radio amateurs, cibists, and amateurs of exotic radio and TV reception or short wave listeners
All frequencies in the HF spectrum (3–30 MHz) can be refracted by charged ions in the ionosphere. Refracting signals off the ionosphere is called skywave propagation, and the operator is said to be "shooting skip". CB operators have communicated across thousands of miles and sometimes around the world. Even low-power 27 MHz signals can sometimes propagate over long distances.
In times of high sunspot activity, the band can remain open to much of the world for long periods of time. During low sunspot activity it may be impossible to use skywave at all, except during periods of Sporadic-E propagation (from late spring through mid-summer). Skip contributes to noise on CB frequencies. In the United States, it is no longer illegal to engage in (or attempt to engage in) CB communications with any station more than 250 km (160 mi) from an operator's location.[43] This restriction used to exist to keep CB as a local (line-of-sight) radio service; however, in the United States the restriction has been dropped. The legality of shooting skip is not an issue in most other countries. A recent FCC decision now allows shooting skip in the United States.[44
In France the " buccaneers of 27 MHz " start with talkie walkies because no serious equipment was sale in the shops
But in 1980 radios and TV start to talk about this hobby even it was not legal.
The first cb radios arrive in the shops and we can find Midland, President, HAM international, etc.
Many operators just use the 40 channels in AM with low power.
But in you have a 120 channel with SSB you can listen to QSO ( contacts ) in english on for exemple 27555 kHz who was a calling frequencie for DXing. Of course you need a good antenna but propagation was great in 1980 and even you are in your car you can talk with other countries.
My i start with an antenna at my window but in was a level 6 so no problem for QSO with cb radio operator in Paris.
In 1981 i bought a nice base Jumbo HAM international who can work from 25 to 29 MHz !!!
My friend help me to add an amplifier 100 watts and i put a vertical antenna half wave groud plane on the roof at 18 meters above the ground.
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