Apex (frequency band)
Apex was a frequency band used by radio stations in the United States in the 1930s and 1940s. The band was above the frequencies of the regular medium and shortwave bands. With the possibility of frequency-modulated broadcasts in the VHF band , the apex stations also quickly fell silent.
development
The first Apex station with a regular program is W8HX, which belonged to the WBEN station in Buffalo . From 1934 the transmitter broadcast the parent station's program on frequencies above 30 MHz. On January 14, 1936, the first twelve stations in the USA received approval to broadcast programs in AM on frequencies above 25 MHz. The operation should be done on an experimental basis. As part of this, W8HX received the license to broadcast on 31.6, 35.6 and 38.6 MHz.
The idea was to create transmission options for local stations in a frequency band that is less susceptible to interference than the medium wave band. Most of the transmitters were active in the shortwave range around 26 MHz and in a range around 43 MHz. Some stations also broadcast their first programs on much higher frequencies. The content was mostly the programs of regular medium wave stations. W9XAZ from Milwaukee , Wisconsin broadcast its own program on January 1, 1937 on 26.4 MHz. In January 1940 there were about 50 stations on the Apex frequency band. In 1941, all Apex stations in the US were closed or switched to FM.
The Apex stations almost exclusively used amplitude modulation with a larger bandwidth in order to achieve better sound transmission.
Surname
The name Apex ( Latin for "tip") is derived from the need to transmit from a high point in this frequency range, as the HF signal spreads optically. The FCC engineer Andrew D. Ring brought up the name.
Individual evidence
- ^ The Radio Historian. Retrieved January 24, 2018 .
- ^ History of FM broadcasting. Retrieved January 24, 2018 .
- ↑ RWO: A Detroit Apex Station in 1936 . In: Radio World . ( radioworld.com [accessed January 24, 2018]).