Editing QRP operation

{{short description|Low-power amateur radio}}
{{use dmy dates|date=May 2021}}
[[File:Trevqrp.png|thumb|right|A [[Amateur radio homebrew|homebrew]] QRP low-power transmitter and receiver that fits inside an [[Altoids]] tin.]]
In [[amateur radio]], '''QRP operation''' refers to transmitting at reduced power while attempting to maximize a station's effective range. QRP operation is a specialized pursuit within the hobby that was first popularized in the early 1920s. QRP operators tend to limit their transmitted [[radio frequency|RF]] power to 5&nbsp;W or less, although some also consider [[single-sideband modulation|single-sideband]] (SSB) operations of up to 10&nbsp;W to be QRP.<ref name="QRP">
{{cite web
 |title=Why QRP?
 |website=arrl.org
 |publisher=[[American Radio Relay League]]
 |url=http://www.arrl.org/why-qrp
 |access-date=10 December 2019
}}
</ref>

Reliable two-way communication at such low power levels can be challenging due to changing [[radio propagation]] and the difficulty of receiving the relatively weak transmitted signals. QRP enthusiasts may employ optimized [[antenna (radio)|antenna]] systems, enhanced operating skills, and a variety of special modes, in order to maximize their ability to make and maintain radio contact. Since the late 1960s, commercial [[two-way radio|transceivers]] specially designed for QRP operation have evolved from [[vacuum tube]] to [[Solid state electronics|solid state]] technology.

A number of organizations dedicated to QRP operation exist, and aficionados participate in various [[Ham Radio Contesting|contests]] designed to test their skill in making long-distance contacts at low power levels.

== Etymology ==
The term "QRP" derives from the standard [[Q code]] used in radio communication, where '''QRP''' is used to request "''Reduce power''" and '''QRP?''' is used to ask "''Should I reduce power?''".<ref name=Marchant/>{{efn|The opposite of '''QRP''' is '''[[QRO]]''', or increased power operation.<ref name=Marchant/>}}

== Philosophy ==
Most amateur transceivers are capable of transmitting approximately 100&nbsp;watts,<ref>
{{cite book
 |title=The ARRL General Class License Manual
 |date=1998
 |publisher=[[American Radio Relay League]]
 |isbn=978-0-87259-676-4
 |quote=The maximum power output from most amateur transceivers is about 100&nbsp;W.
 |pages=[https://archive.org/details/isbn_9780872596764/page/3 3]
 |url=https://archive.org/details/isbn_9780872596764
 |url-access=registration
 |via=Archive.org
}}
</ref> but in some parts of the world, such as the U.S., amateurs can transmit up to 1,500&nbsp;watts. QRP enthusiasts contend that this practice is rarely necessary, and doing so wastes power, increases the likelihood of causing [[electromagnetic interference|interference]] to nearby [[television]]s, [[receiver (radio)|radios]], and [[telephone]]s and, for [[United States]]' amateurs, is contrary to [[Federal Communications Commission|FCC]] Part&nbsp;97 rule, which states that one must use "the minimum power necessary to carry out the desired communications".<ref name=Wells>
{{cite magazine
 |last=Wells |first=Bradley
 |date=April 1984
 |title=QRP: More than a state of mind
 |magazine=QST Magazine
 |page=52
 |location=Newington, CT
 |publisher=[[American Radio Relay League]]
 |url=http://www.arrl.org/qrp-more-than-a-state-of-mind
 |access-date=24 November 2019
}}
</ref> QRP can also be used for [[Amateur radio emergency communications|emergency communications]] during [[Emergency management#Recovery|disaster recovery]], when frugal use of available battery power and generator fuel is crucial.<ref name=Arland2007>
{{cite book
 |last=Arland |first=Richard H.
 |year=2007
 |title=ARRL's Low Power Communication: The art and science of QRP
 |publisher=American Radio Relay League
 |isbn=978-0-87259-104-2
 |url=https://books.google.com/books?id=kVpoihOUjNgC
 |via=Google Books
}}
</ref><ref name="Dobbs2012">
{{cite book
 |first=George |last=Dobbs
 |date=1 September 2012
 |title=QRP Basics
 |publisher=[[Radio Society of Great Britain]] (RSGB)
 |isbn=978-1-905086-84-9
 |url=https://books.google.com/books?id=npwFrgEACAAJ
 |via=Google Books
}}
</ref><ref name="Silver2018">
{{cite book
 |author=H. Ward Silver
 |date=25 February 2011
 |title=Ham Radio For Dummies
 |publisher=John Wiley & Sons
 |isbn=978-1-118-05419-2
 |pages=218
 |url=https://books.google.com/books?id=N7usav6Ddf8C&pg=PT218
 |via=Google Books
}}
</ref>

== Practice ==
[[File:QRP HF Coverage 1W vs 99W.png|thumb|[[VOACAP]] simulation of propagation against distance, comparing effective radiations of 1 watt (top) and 99&nbsp;watts (bottom).]]
The practice of operating with low power was popularized as early as 1924, with a variety of reports, editorials and articles published in U.S. amateur radio magazines and journals that encouraged amateurs to lower power output, both for purposes of experimentation, and for improving operating conditions by reducing interference.<ref name="HistoryOfQRP">
{{cite book
 |last=Weiss |first=Adrian
 |year=1987
 |title=History of QRP in the U.S., 1924-1960
 |location=Vermillion, SD
 |publisher=Milliwatt Books
 |isbn=978-0-9614139-1-0 |ol=2411449M
}}
</ref>

Although not universally agreed upon, the ARRL makes a recommendation for QRP power limits. Most amateur organizations agree that for [[Morse code|CW]], [[Amplitude modulation|AM]], [[Frequency modulation|FM]], and [[data]] [[Modulation|modes]], the [[transmitter]] [[transmitter power output|output power]] should be 5 [[watt]]s (or less).<ref>
{{cite book
 |last=Rutledge |first=David |author-link=David Rutledge (engineer)
 |year=1999
 |title=The Electronics of Radio
 |publisher=Cambridge University Press
 |page=312
 |isbn=978-1-107-39366-0
 |url=https://books.google.com/books?id=ccQLAQAAQBAJ&q=QRP&pg=PA312
 |via=Google Books
}}
</ref> The maximum output power for [[single-sideband modulation|SSB]] (single sideband) is sometimes agreed to be no more than 10&nbsp;Watts [[peak envelope power]] (PEP), while some organisations opine that the power limit should be 5&nbsp;Watts. QRPers are known to regularly use less than 5&nbsp;Watts, sometimes operating with as little as 100&nbsp;milliwatts or even less. Extremely low power — 1&nbsp;Watt and below — is often referred to by hobbyists as "QRPP".<ref name=Wells/><ref name=Arland2007/><ref name=Dobbs2012/><ref name=DeMaw1991/>

Communicating using QRP can be difficult since the QRPer must face the same challenges of [[radio propagation]] faced by amateurs using higher power levels, but with the inherent disadvantages associated with having a weaker signal on the receiving end, all other things being equal. QRP aficionados try to make up for this through more efficient [[antenna (radio)|antenna]] systems and enhanced operating skills.<ref name=DeMaw1991>
{{cite book
 |first=Doug |last=DeMaw
 |year=1991
 |title=W1FB's QRP Notebook
 |publisher=[[American Radio Relay League]]
 |isbn=978-0-87259-365-7
 |url=https://books.google.com/books?id=hPBINAAACAAJ
 |via=Google Books
}}
</ref><ref name="Silver2018" />

=== Weak signal modes ===
QRP enthusiasts may use special modes that employ technology and software designed to enhance reception of the relatively weak transmitted signals resulting from low power levels.<ref name=WSM/>

'''QRSS''': Very slow speed Morse code 
:QRSS uses very slow speed [[continuous wave|CW]] (Morse code) to compensate for the decreased [[signal-to-noise ratio]] involved in QRP operation.<ref name=WSM/>{{efn|''QRSS'' is an exaggerated version of '''QRS''', the standard [[Q code]] used in radio communications. "'''QRS?'''" asks "''Shall I send more slowly?''".<ref name=Marchant>
{{cite book
 |last=Marchant |first=William Henry
 |year=1914
 |title=Wireless Telegraphy: A handbook for the use of operators and students
 |publisher=Whittaker
 |page=[https://archive.org/details/wirelesstelegra00marcgoog/page/n236 220]
 |url=https://archive.org/details/wirelesstelegra00marcgoog
 |via=Archive.org
}}
</ref>}} QRSS enthusiasts may record a transmission for later analysis, sometimes decoding "by ear" while playing it back at much faster speeds, or decoding "by eye" on the waterfall display of a spectrum analyzer.<ref name=DennisonFielding2007>
{{cite book
 |first1=Mike |last1=Dennison
 |first2=John |last2=Fielding
 |year=2007
 |title=Radio Communication Handbook
 |publisher=[[Radio Society of Great Britain]] (RSGB)
 |isbn=978-1-905086-33-7
 |url=https://books.google.com/books?id=f6AeAQAAIAAJ
 |via=Google Books
}}
</ref><ref>
{{cite web
 |title=Grabber compendium
 |department=QRSS Knights
 |website=digilander.libero.it
 |publisher=I2NDT
 |place=Bergamo, IT
 |url=http://digilander.libero.it/i2ndt/grabber/grabber-compendium.htm
}}
</ref>

'''Coherent CW''': Critically-timed Morse code transmission
:Coherent CW uses transmitters that clock-out signals calibrated to a precise rate, allowing receivers to employ extremely narrowband filtering to increase readability.<ref name=WSM/>

'''[[WSJT (amateur radio software)|WSJT]]''': Weak Signal – Joe Taylor
:WSJT is a software system that utilizes several separate modes, each optimized for a different signal path; these include [[Meteor burst communications|meteor scatter]], [[troposcatter]], and [[Earth–Moon–Earth communication|EME communications]]. WSJT was named after [[Joseph Hooton Taylor Jr.|Dr. J.H. Taylor]] to acknowledge his work in developing weak signal communication modes for radio.<ref name=WSM/>{{efn|Dr. [[Joseph Hooton Taylor Jr.]] is an astrophysicist who won the [[Nobel Prize in Physics]] in 1993 for discovery of a new type of [[pulsar]] which is useful for the study of [[General Relativity]] by [[radio astronomy]]. He is an [[amateur radio]] operator (currently K1JT), and has generously contributed his technical expertise to the development of successful transmission of weak signals over otherwise rarely usable propagation paths.}}

'''[[WSPR (amateur radio software)|WSPR]]''':  Weak Signal  –  Propagation Reporter
:WSPR is a software suite and computer network used to monitor propagation paths for optimal communication conditions.<ref name=WSM>
{{cite web
 |title=Weak signal modes
 |website=ARRL.org
 |publisher=[[American Radio Relay League]]
 |url=http://www.arrl.org/weak-signal-modes
 |access-date=24 November 2019
}}
</ref>

== Equipment ==
[[File:Elecraft K2.jpg|thumb|right|Example of transceiver optimized for QRP CW operation: [[Elecraft]] K2]]
Many of the larger, more powerful commercial transceivers permit the operator to lower their output level to QRP levels. Commercial [[two-way radio|transceivers]] specially designed to operate at or near QRP power levels have been commercially available since the late 1960s.

In 1969 the American manufacturer Ten-Tec produced the Powermite-1, one of Ten-Tec's first assembled transceivers, and featured modular construction. All stages of the transceiver were on individual [[printed circuit board|circuit boards]]: the transmitter was capable of about one or two watts of RF, and the receiver was a [[direct-conversion receiver|direct-conversion]] unit, similar to that found in the [[Heathkit]] HW-7 and HW-8 lines, which introduced many amateurs to QRP'ing and led to the popularity of the mode.<ref>
{{cite magazine
 |last=Chaffin |first=Kenny A.
 |date=February 1990
 |title=Why QRP?
 |magazine=QST magazine
 |location=Newington, CT
 |publisher=[[ARRL]]
 |page=43
 |url=http://www.arrl.org/why-qrp
 |access-date=24 November 2019
}}
</ref>

Enthusiasts operate QRP radios on the [[high frequency|HF]] [[band (radio)|bands]] in [[amateur radio station#Portable stations|portable modes]], usually carrying the radios in [[backpack]]s, with [[whip antenna]]s. Some QRPers prefer to construct their equipment from kits, published plans,<ref>
{{cite book
 |last=Brown |first=George
 |date=2001
 |title=Radio and Electronics Cookbook
 |chapter=CW QRP transmitter for 80&nbsp;meters
 |publisher=Newnes
 |isbn=978-0-7506-5214-8
 |chapter-url=https://books.google.com/books?id=IbqPQz68lfkC&pg=PA297
 |via=Google Books
}}
</ref> or [[Amateur radio homebrew|homebrew]] it from scratch. Many popular designs are based on the [[NE612]] mixer IC, i.e. the K1, K2, ATS series and the Softrock SDR.<ref name=Weiss>
{{cite report
 |last=Weiss |first=Adrian
 |title=The Five-Watt QRP Movement in the US, 1968-1981
 |publisher=Miliwatt QRP Books
 |url=http://www.n5dux.com/ham/files/pdf/QRP%20History%20-%20The%20Five-Watt%20QRP%20Movement%201968-1981.pdf
 |access-date=24 November 2019
 |via=n5dux.com/ham/files
}}
</ref>

== Organizations ==
Amateur radio organizations dedicated to QRP include QRP Amateur Radio Club International (QRPARCI), American QRP Club, G-QRP Club based in the [[United Kingdom]], and The Adventure Radio Society emphasizing portable QRP operation. Major QRP gatherings are held yearly at [[hamfest]]s such as [[Dayton Hamvention]], Pacificon, and [[Friedrichshafen]].<ref name=Silver2018/>

== Contests and awards ==
There are specific operating [[award]]s, [[contesting|contests]], [[Club (organization)|clubs]], and [[convention (meeting)|conventions]] devoted to QRP enthusiasts. In the United States, the November Sweepstakes, June and September VHF QSO Parties, January VHF Sweepstakes, and the [[American Radio Relay League|ARRL]] International DX Contest, as well as many major international contests have designated special QRP categories. For example, during the annual ARRL's [[Field Day (amateur radio)|Field Day]] event, making a QSO (ham-to-ham contact) using "QRP battery power" is worth five times as many points as a contact made by conventional means. The QRP ARCI club sponsors 12 contests during the year specifically for QRP operators.<ref name=Wells/><ref name=Silver2018/>

Typical awards include the QRP ARCI club's "thousand-miles-per-watt" award, available to anyone presenting evidence of a qualifying contact. QRP ARCI also offers special awards for achieving the ARRL's [[Worked All States]], [[Worked All Continents]], and [[DX Century Club]] awards under QRP conditions. Other QRP clubs also offer similar versions of these awards, as well as general QRP operating achievement awards.<ref>
{{cite web
 |title=QRP – what, why, and how
 |website=ARRL.org
 |place=Newington, CT
 |publisher=[[American Radio Relay League]]
 |url=http://www.arrl.org/tis/info/qrpwhtwy.html
 |access-date=April 4, 2007 |url-status=dead
 |archive-url=https://web.archive.org/web/20070927223047/http://www.arrl.org/tis/info/qrpwhtwy.html
 |archive-date=September 27, 2007
}}
</ref>

== See also ==
* [[Amateur radio homebrew]]
* [[List of amateur radio transceivers#QRPTransceivers|List of amateur radio QRP transceivers]]

==Notes==
{{notelist}}

==References==
{{reflist|25em}}

{{Amateur radio topics}}

[[Category:Amateur radio]]