QRP

from Wikipedia, the free encyclopedia
This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.
There is no actual reference to any kind of definition, documentation of the alleged event, or to the alleged advantages or the simplicity of the construction.
Kit transceiver for shortwave Elecraft KX3
Yaesu FT-817ND
Do-it-yourself transceiver for Morse code

In amateur radio, QRP is the term used to describe low-power transmission. The term comes from the abbreviation for "reduce the transmission power" from the Q key and is the counterpart to QRO .

Radio sports

The radio sport challenge with QRP operation is to bridge maximum distances with the lowest possible transmission power . By definition, the transmitter output power must not exceed 5 watts for CW and 10 watts for SSB . The choice of antenna and location are particularly important here.

Records are often achieved by taking advantage of specific ionospheric conditions. In 2001, a QRP connection was established in CW and SSB (5 watts each - that's roughly the power of a car rear light) in the 20 m band over 22,593 km between Greece (SV1UY) and New Zealand (ZL1BK). The radio waves were reflected several times within the F-layer in the ionosphere, which is stable on the night side of the earth (so-called chordal hop ). Accordingly, the connection did not come about on the direct, but on the indirect, "long" route.

QRP operation can be carried out with all radio devices if their controllable transmission output power is reduced to the above-mentioned level. The industry also produces devices that can be used for QRP if the maximum QRP output power is not reached or exceeded due to the design. Some of these devices, such as the Yaesu FT-817 , are equipped with accumulators or batteries to enable radio operation when on the move.

Advantages and disadvantages

Weak signals, such as those produced by a low-power QRP transmitter, are often overlaid by all kinds of interference , which makes reception considerably more difficult. In addition, a weak signal easily "disappears" due to fluctuations in the stability of the transmission path; it is subject to fading . This reduces the probability of a secure radio connection. In the case of weak signals, the information transmitted is often difficult to read, making it difficult to converse. Sometimes all that is possible is not to transmit much more than the callsign. It must be mentioned here that with QRP operation the fact of the radio connection itself often replaces the connection content that would have provided a secure connection.

Not every radio partner enjoys having to "crawl into the loudspeaker" in order to be able to pick up a remote station that could have transmitted with a higher output. It is one of the privileges of the amateur radio to be able to transmit with high power. The attraction of QRP is also not to work with high performance when QRP is still usable.

The fact that a QRP transmitter with a low output power consumes much less energy should be the most obvious advantage. Small, light, easy to assemble (do-it-yourself), battery-operated, these are all things that only QRP can offer.

DIY

One advantage of radio operation with low transmission power is the simplicity of self-assembly of radio devices. This is reflected in a large range of kits as well as a wealth of literature (magazines and books) on the subject with suggestions for self-construction. Due to the low voltages and currents used, the kits can be built without major health risks and at moderate costs, require a much more profound understanding of electronics and high-frequency technology as well as manual skills in the construction of electronic circuits than the relatively simple knowledge that is required for the Preparation for an amateur radio exam are required.

Operating modes

Telegraphy signal over 700 km distance Sweden-Netherlands, 30 meter tape , 500 milliwatts

Morse code telegraphy is extremely suitable for simple devices with low transmission power , since it is technically easy to implement and because a weak transmission signal can be recorded on the receiver side without any further decoding technology. Other digital operating modes are also ideally suited for QRP, but require comparatively complex encoders / decoders, which are usually implemented in software on a connected computer. These include WSPR and PSK variants , among the latter, PSK31 in particular is widespread. In general, however, all operating modes (modulation types) are used in QRP.

Web links