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PRESIDENT LINCOLN Ham RADIO

What is AM broadcasting

AM and FM modulated signals for radio. AM (Amplitude Modulation) and FM (Frequency Modulation) are types of modulation (coding). The electrical signal from program material, usually coming from a studio, is mixed with a carrier wave of a specific frequency, then broadcast. In the case of AM, this mixing (modulation) is done by altering the amplitude (strength) of the carrier wave, proportional to the original signal. In contrast, in the case of FM, it is the carrier wave's frequency that is varied. A radio receiver contains  that extracts the original program material from the broadcast wave.

What is amplitude modulation (AM) transmitter

The person generally credited as the primary early developer of AM technology is Canadian-born inventor Reginald Fessenden. The original spark-gap radio transmitters were impractical for transmitting audio, since they produced discontinuous pulses known as "damped waves". Fessenden realized that what was needed was a new type of radio transmitter that produced steady "undamped" (better known as "continuous wave") signals, which could then be "modulated" to reflect the sounds being transmitted.

Fessenden's basic approach was disclosed in U.S. Patent 706,737, which he applied for on May 29, 1901, and was issued the next year. It called for the use of a high-speed alternator (referred to as "an alternating-current dynamo") that generated "pure sine waves" and produced "a continuous train of radiant waves of substantially uniform strength", or, in modern terminology, a continuous-wave (CW) transmitter.Fessenden began his research on audio transmissions while doing developmental work for the United States Weather Service on Cobb Island, Maryland. Because he did not yet have a continuous-wave transmitter, initially he worked with an experimental "high-frequency spark" transmitter, taking advantage of the fact that the higher the spark rate, the closer a spark-gap transmission comes to producing continuous waves. He later reported that, in the fall of 1900, he successfully transmitted speech over a distance of about 1.6 kilometers (one mile),[9] which appears to have been the first successful audio transmission using radio signals. However, at this time the sound was far too distorted to be commercially practical For a time he continued working with more sophisticated high-frequency spark transmitters, including versions that used compressed air, which began to take on some of the characteristics of arc-transmitters.attempted to sell this form of radiotelephone for point-to-point communication,PRESIDENT LINCOLN Ham RADIO

  • PRESIDENT ANDY Ham Radio

    PRESIDENT ANDY Ham Radio

    Andy 40 Channel President CB Radio 40 Channels AM 12/24V Manual Squelch And ASC Muliti-Functinon LCD Display S-Meter F Function Key ANL Filter NB EMG Programmable Talkback Public Address Weather Channel With Alert Front Microphone...

    $89.78
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  • President Electronics WALKER II

    President Electronics WALKER II

    40 channels AM, Channel rotary switch, Volume adjustment and ON/OFFManual squelch and ASC, Multi-functions LCD display, Frequencies displayS/RF vu-meter, Public Address, Scan, Talkback, Beep Function, Roger BeepTone, ANL filter, NB, HI-CUT, RF Gain/Mike...

    $159.98
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  • We've been anxiously awaiting the release of the President Lincoln II over the last year but little did we know that President was planning to release two SSB radios in 2014. Yes, the long dry spell is over and to kick things off we're going to be doing a review of the new President Grant II AM/FM/SSB 10/11 meter radio from President.

For North American consumers the release of these radios is going to be a little bittersweet; yes the radios are awesome, yes they are now available, but if you want one you're going to have to purchase from a dealer in Europe President Lincoln II Amateur Radio

    President Lincoln II Amateur Radio

    in stock today- Rotary switch and Up/down channel selector- VFO Mode (continuous scanning of 28.000 Mhz to 29.700 Mhz)- Volume adjustment and ON/OFF- RF Power- Manual squelch and ASC- Multi-functions LCD display- Frequencies display- S-meter- Public...

    $399.00
    Add to Cart