TV and FM DX

Lore & Background

The history of TV and FM DX began soon after the introduction of television. In November 1938, engineers at the RCA Research Station in Riverhead, Long Island, accidentally received a 3,000-mile transatlantic F2 broadcast of the BBC's 405-line television service from London. This reception, recorded on 16 mm film, is considered the only surviving example of pre-war live British television. After the BBC Television Service recommenced in 1946, distant reception reports came from Italy, South Africa, India, the Middle East, North America, and the Caribbean.

In the early days of FM broadcasting, the FCC allocated the 42–50 MHz band for FM in May 1940. Distant FM signals from up to 1,400 miles often interfered with local stations during summer months, which was seen as a nuisance by station management. In February 1942, the first known published long-distance FM reception report detailed the reception of W51C Chicago in Monterrey, Mexico. In June 1945, the FCC moved FM to the 88–108 MHz band, citing sporadic E co-channel interference, F2 layer interference, and extent of coverage as factors.

During the 1950s and early 1960s, long-distance television reports circulated through hobbyist periodicals. In 1957, the world record for TV DX was extended to 10,800 miles with reception of BBC TV in Australia. The UK magazine Practical Television began a regular TV DX column in the early 1960s, edited by Charles Rafarel, which continued after his death in 1971 under Roger Bunney until 2008.

Reader's Guide

TV and FM DX has grown as a hobby over time, with enthusiasts installing and upgrading HF/UHF antennas to gain higher range. The hobby is similar to amateur radio, Medium Wave DX, and short-wave radio. Organizations such as the Worldwide TV-FM DX Association have developed to coordinate and foster the study and enjoyment of VHF/UHF television and FM broadcast DX. The propagation mechanisms that enable DX include tropospheric ducting, which can carry signals for 800 km or more when temperature inversions occur; F2 propagation, which reflects signals off the ionosphere at altitudes around 200 miles during high sunspot activity, enabling reception over 2,000 miles; and sporadic E (E-skip), which involves irregular patches of ionization in the E region that reflect frequencies up to about 150 MHz, typically over distances of 600 to 1,400 miles. Sporadic E signals can be extremely strong and range from just detectable to overloading. The legacy of TV and FM DX includes the preservation of early television history, such as the 1938 transatlantic reception, and the continued documentation of propagation phenomena through enthusiast networks and publications.

Did You Know?

• In November 1938, engineers accidentally received a 3,000-mile transatlantic F2 broadcast of BBC television from London.
• The first known published long-distance FM reception report was of W51C Chicago received in Monterrey, Mexico in February 1942.
• Sporadic E can produce extremely strong signals that range from just detectable to overloading.