În limbajul radioamatorilor, SWL înseamnă "radioamator receptor" (cei care nu dețin autorizație de emisie-recepție, dar care au dreptul să asculte traficul din benzile alocate serviciului de amator din România - unde scurte sau ultrascurte).
http://www.qsl.net/yo9kxc/pag3/SWLinYO.htm

Propun o traducere pentru contextul dat:
Desigur, sunt invitați și radioamatorii receptori.

Aşa aş spune.

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Note added at 2 jours3 heures (2015-05-13 15:14:26 GMT)
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Cred cà se face o confuzie între SWLing si DX-ing.

Cf. http://en.wikipedia.org/wiki/Shortwave_listening,
Shortwave listening, or SWLing, is the hobby of listening to shortwave radio broadcasts located on frequencies between 1700 kHz and 30 MHz.[1] Listeners range from casual users seeking international news and entertainment programming, to hobbyists immersed in the technical aspects of radio reception and collecting official confirmations (QSL cards) that document their reception of distant broadcasts (DXing). In some developing countries, shortwave listening enables remote communities to obtain regional programming traditionally provided by local medium wave AM broadcasters. One 2002 estimate placed the number of shortwave listeners worldwide in the hundreds of millions.

The practice of long-distance radio listening began in the 1920s when shortwave broadcasters were first established in the US and Europe. Audiences discovered that international programming was available on the shortwave bands of many consumer radio receivers, and a number of magazines and listener clubs catering to the practice arose as a result. Shortwave listening was especially popular during times of international conflict such as World War II, the Korean War and the Persian Gulf War.

Listeners use inexpensive portable "world band" radio receivers to access the shortwave bands, and some advanced hobbyists employ specialized communications receivers featuring digital technology designed for optimum reception of shortwave signals, along with outdoor antennas to enhance performance.

With the advent of the internet, many international broadcasters have scaled back or terminated their shortwave transmissions in favor of web-based program distribution, while others are moving from traditional analog to digital broadcasting modes in order to allow more efficient delivery of shortwave programming. The number of organized shortwave listening clubs has diminished along with printed magazines devoted to the hobby; however, many enthusiasts continue to exchange information and news on the web.

Aceasta este ascultarea radiourilor care emit pe unde scurte.

Cf. dexonline,

RADIOAMATÓR, radioamatori, s. m. Persoană care, ca amator, stabilește legături între o stație de radio2 proprie și o stație de radio2 străină, cu scopul de a comunica în bune condiții cu aceasta, de la o distanță cât mai mare. [Pr.: -di-o-] – Din fr. radio-amateur, germ. Radioamateur.

DX-ing

Cf. http://en.wikipedia.org/wiki/DXing#Shortwave_DX,

DXing is the hobby of receiving and identifying distant radio or television signals, or making two way radio contact with distant stations in amateur radio, citizens' band radio or other two way radio communications. Many DXers also attempt to obtain written verifications of reception or contact, sometimes referred to as "QSLs" or "veries". The name of the hobby comes from DX, telegraphic shorthand for "distance" or "distant".[1]

The practice of DXing arose during the early days of radio broadcasting. Listeners would mail "reception reports" to radio broadcasting stations in hopes of getting a written acknowledgement or a QSL card that served to officially verify they had heard a distant station. Collecting these cards became popular with radio listeners in the 1920s and 1930s, and reception reports were often used by early broadcasters to gauge the effectiveness of their transmissions. Although international shortwave broadcasts are on the decline, DXing remains popular among dedicated shortwave listeners. The pursuit of two-way contact between distant amateur radio operators is also a significant activity within the amateur radio hobby. [2][3]