The International Time Bureau ( BIH ) began a time scale, T < sub > m </ sub > or AM, in July 1955, using both local caesium clocks and comparisons to distant clocks using the phase of VLF radio signals.

* AM broadcasting, radio broadcasting using amplitude modulation

* AM ( ABC Radio ), an Australian radio programme

Amplitude modulation ( AM ) is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave.

Beginning with Reginald Fessenden's audio demonstrations in 1906, it was also the original method used for audio radio transmissions, and remains in use today by many forms of communication —" AM " is often used to refer to the mediumwave broadcast band ( see AM radio ).

Professional touring amplifiers often have input and / or output filtering to sharply limit frequency response beyond ; too much of the amplifier's potential output power would otherwise be wasted on infrasonic and ultrasonic frequencies, and the danger of AM radio interference would increase.

Field modulation of a very high speed AC generator was also used for some early AM radio transmissions .< ref >

In 1998, Belgium had 79 FM radio stations, 7 AM stations and 1 SW station, serving 8. 075 million radios owned in the country.

As of 2001, there were zero AM radio broadcast stations, four FM stations, and one shortwave one.

On July 14, 2005, Tom Biscardi, a long-time Bigfoot enthusiast and CEO of Searching for Bigfoot Inc., appeared on the Coast to Coast AM paranormal radio show and announced that he was " 98 % sure that his group will be able to capture a Bigfoot which they have been tracking in the Happy Camp, California area.

In Baltimore, Orioles games on radio can be heard over WBAL ( 1090 AM ).

Of the approximately 515 radio stations, 454 are AM ; 34, FM ; and 27, shortwave.

The Indians ' flagship radio station is WTAM AM 1100.

The first use for the diode was the demodulation of amplitude modulated ( AM ) radio broadcasts.

In summary, an AM signal consists of alternating positive and negative peaks of a radio carrier wave, whose amplitude or envelope is proportional to the original audio signal.

The diode ( originally a crystal diode ) rectifies the AM radio frequency signal, leaving only the positive peaks of the carrier wave.

Radio DJs or radio personalities introduce and play music that is broadcast on AM, FM, shortwave, digital, or internet radio stations.

While at WERE ( 1300 AM ) in Cleveland, Ohio, DJ Bill Randle was one of the first to introduce Elvis Presley to radio audiences in the northeastern US.

FM enabled the transmission and reception of a wider range of audio frequencies, as well as audio free of " static ", a common problem in AM radio.

He played a jazz record over conventional AM radio, then switched to an FM broadcast.

The signal ( at 42. 8 MHz ) could be heard clearly 100 miles ( 160 km ) away, despite the use of less power than an AM radio station.

While talk radio has historically been associated with AM / FM, starting around 2005 the technology for Internet-based talk-radio shows became cost effective in the form of podcasts.

The move of the FM band, an organized campaign of misinformation by RCA ( a company that competed with FM radio by focusing on AM radio and the emerging technology of television ), and adverse rulings by the FCC severely set back the development of FM radio.

LeMay became aware that the new single sideband ( SSB ) technology offered a big advantage over amplitude modulation ( AM ) for SAC aircraft operating long distances from their bases.

Many stations broadcast on shortwave bands using AM technology that can be received over thousands of miles ( especially at night ).

He also has his own technology talk radio show on Premiere Radio Networks ( previously exclusive to KFI AM 640 ), as well as being the host of numerous podcasts, most notably This Week in Tech.

The first, and currently only, digital technology approved for use on AM and FM broadcast frequencies by the Federal Communications Commission in the United States, is the proprietary HD Radio system developed by iBiquity Digital Corporation, which transmits energy beyond the alloted ± 100 kHz FM channel.

While the United Kingdom has chosen the Eureka 147 standard of digital audio broadcasting ( DAB ) for creating a digital radio service, the United States has selected IBOC technology for its digital AM and FM stations.

Caracol Radio began testing of the HD Radio technology in both the AM and FM bands in early 2008.

All Mexican radio stations within 320 km of the U. S. border are allowed to transmit their programs on the AM and FM bands utilizing HD Radio technology.

Approximately six Mexican AM and FM stations are already operating with HD Radio technology along Mexico ’ s border area with the US.

Voice of Vietnam ( VOV ) commenced AM and FM HD Radio transmissions in Hanoi in June, 2008 including multicasting, in anticipation of making HD Radio technology a standard.

HD Radio technology is the only digital technology approved by the FCC for digital AM and FM broadcasting in the US.

In all cases where negative video is used, FM is used for the standard monaural audio ; systems with positive video use AM sound and intercarrier receiver technology cannot be incorporated.

It is the only technology approved by the Federal Communications Commission for digital AM and FM broadcasting in the United States.

HD Radio is the trademark for iBiquity's in-band on-channel ( IBOC ) digital radio technology used by AM and FM radio stations to transmit audio and data via a digital signal in conjunction with their analog signals.

The AM version of HD Radio technology uses the 20 kHz channel (+/- 10 kHz ), and overlaps 5 kHz into the opposite sideband of the adjacent channel on both sides.

Unfortunately DRM shares many of the same flaws as DAB and HD Radio technology: shorter broadcast distance as compared to analog AM signal when in hybrid mode ; poor reception inside vehicles and buildings ; and interference with adjacent channels ( though in all-digital mode the signal fits inside the designated channel mask ).

* AM stereo ( related technology )

WOWO was the first Fort Wayne station to transmit in AM stereo ; it later became the first Fort Wayne AM station to transmit with HD Radio technology.

The system is an in-band on-channel technology that uses the sidebands of any AM radio station.