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Medium wave (MW) is a part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. During the daytime, reception is usually limited to more local stations, though this is dependent on the signal conditions and quality of radio receiver used. Improved signal propagation at night allows the reception of much longer distance signals. This can cause increased interference because on most channels multiple transmitters operate simultaneously worldwide. In addition, amplitude modulation (AM) is often more prone to interference by various electronic devices, especially power supplies and computers. Strong transmitters cover larger areas than on the FM broadcast band but require more energy and longer antennas. Digital modes are possible but have not reached momentum yet.
AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave transmissions, but also on the longwave and shortwave radio bands.
A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broadcast. There is no physical difference between a carrier and a subcarrier; the "sub" implies that it has been derived from a carrier, which has been amplitude modulated by a steady signal and has a constant frequency relation to it.
C-QUAM is the method of AM stereo broadcasting used in Canada, the United States and most other countries. It was invented in 1977 by Norman Parker, Francis Hilbert, and Yoshio Sakaie, and published in an IEEE journal.
AM stereo is a term given to a series of mutually incompatible techniques for radio broadcasting stereo audio in the AM band in a manner that is compatible with standard AM receivers. There are two main classes of systems: independent sideband (ISB) systems, promoted principally by American broadcast engineer Leonard R. Kahn; and quadrature amplitude modulation (QAM) multiplexing systems.
WTVN – branded as "News Radio 610 WTVN" – is a commercial news/talk radio station licensed to Columbus, Ohio. Owned by iHeartMedia, the station serves the Columbus metro area. The WTVN studios area located in the McKinley Avenue Corridor northwest of Downtown Columbus, and its transmitter site is near Obetz. In addition to a standard analog transmission, the station simulcasts over the HD digital subchannel of co-owned 93.3 WODC, and streams online via iHeartRadio. WTVN began broadcasting in HD Radio in June 2005, but the in-band on-channel subcarrier was discontinued by 2015.
FM broadcasting is a method of radio broadcasting that uses frequency modulation (FM) of the radio broadcast carrier wave. Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to transmit high-fidelity sound over broadcast radio. FM broadcasting offers higher fidelity—more accurate reproduction of the original program sound—than other broadcasting techniques, such as AM broadcasting. It is also less susceptible to common forms of interference, having less static and popping sounds than are often heard on AM. Therefore, FM is used for most broadcasts of music and general audio. FM radio stations use the very high frequency range of radio frequencies.
CHED is a radio station licensed to Edmonton, Alberta. Owned by Corus Entertainment, it broadcasts a news/talk format, and first signed on in 1954. Its studios are located on 84th Street and Roper Road in Edmonton, while its transmitters are located southeast of Edmonton.
CBOF-FM is a non-commercial radio station located in Ottawa, Ontario, Canada. It airs a French language news/talk format, much of which comes from the Ici Radio-Canada Première network. The studios and offices are located at the CBC Ottawa Broadcast Centre on Queen Street in Downtown Ottawa.
CHQR is a radio station owned by Corus Entertainment operating in Calgary, Alberta, Canada. Broadcasting at AM 770, it airs talk programming. With the exception of one show, all of CHQR's weekday programming is produced in-house. CHQR is also the exclusive radio voice of the Calgary Stampeders. CHQR is also the last AM station in the Calgary market to broadcast in C-QUAM AM Stereo. CHQR is a Class B station on the clear-channel frequency of 770 kHz.
WYLD is a commercial AM radio station in New Orleans, Louisiana. The station is owned by iHeartMedia, Inc., and it broadcasts an urban gospel radio format, known as "Hallelujah 940" Some Christian talk and teaching programs are also heard.
CJMS was a French language radio station located in Montreal, Quebec, Canada.
WPLO is an Atlanta area AM broadcasting station, licensed to Grayson, Georgia, that broadcasts Spanish language music programming. It transmits at a frequency of 610 kHz with 1,500 Watts of power during the daytime and 225 Watts during nighttime using a non-directional antenna. WPLO is a Class-D AM broadcasting station according to the Federal Communications Commission. The station has applied to the Federal Communications Commission to change its licensed city to Lawrenceville, Georgia, the location of its current transmitting facility and tower.
WRAW is a commercial AM radio station licensed to Reading, Pennsylvania. The station is owned by iHeartMedia and calls itself "Newsradio 1340 WRAW." It broadcasts a conservative talk radio format.
WBLQ is a radio station licensed to serve Westerly, Rhode Island. The station is owned by DiPonti Communications. Its programming is also carried on FM translator W276DF (103.1).
KWAL was a radio station broadcasting a country format to the Wallace, Idaho, United States, area. The station was owned by Metals Broadcasting Co. and featured programming from Westwood One. KWAL was unique because it was the only AM antenna array that had an interstate highway running through it. The station broadcast in C-QUAM AM stereo.
Leonard R. Kahn was an electrical engineer, who invented technology for AM broadcasting. He held over 100 patents. He was primarily known for advocating several technologies designed to improve the sound quality of AM radio. His Kahn-Hazeltine system was the chief competitor to Motorola's C-Quam AM Stereo system. More than 100 stations used his stereo system before Motorola's system ultimately won out as the AM Stereo standard. Later, a part of that system was used to develop the CAM-D AM digital broadcasting technology. His other notable inventions include maximum ratio combining used in multiple output systems. Leonard also developed the Symmetra Peak for AM radio which was used to equalize the negative and positive modulation peaks prior to the F.C.C. permitting asymmetrical modulation. Another one of Leonard's developments was a system called the Voice Line. It was a combination 4 input remote mixer and studio decoder. The system modulated a carrier at approximately 3 kHz. with the low frequency components 50 Hz-250 Hz at the remote site then demodulated the 3 kHz carrier at the studio end. This was then combined with the telephone quality audio and produced a much more natural sounding broadcast ranging from 50 Hz to as high as the telephone line would permit with the exception of the sharp notch at 3 kHz to filter out the carrier.
The following radio stations broadcast on AM frequency 1053 kHz:
4WK is an Australian commercial radio station located in Toowoomba, Queensland.