Mods KENWOOD TS-590S

KENWOOD TS-990S

Kenwood TS-590S (TS 590 S) Better broadcast AM (0.5 - 1.7 MHz) reception Mods


Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength (amplitude) of the transmitted signal in relation to the information being sent. For example, changes in signal strength may be used to specify the sounds to be reproduced by a loudspeaker, or the light intensity of television pixels. This contrasts with frequency modulation, in which the frequency of the carrier signal is varied, and phase modulation, in which the phase is varied, by the modulating signal.
AM was the earliest modulation method. In the mid-1870s, a form of amplitude modulation—initially called "undulatory currents"—was the first method to successfully produce quality audio over telephone lines. Developed during the first two decades of the 20th century beginning with Reginald Fessenden's radiotelephone experiments in 1900, AM was the original method used for transmitting sound by radio. It remains in use today in many forms of communication; for example it is used in portable two way radios, and in computer modems. "AM" is often used to refer to its largest remaining use, mediumwave AM radio broadcasting.
In electronics and telecommunications, modulation means varying some aspect of a higher frequency continuous wave carrier signal with an information-bearing modulation waveform, such as an audio signal which represents sound, or a video signal which represents images, so the carrier will "carry" the information. When it reaches its destination, the information signal is extracted from the modulated carrier by demodulation.
In amplitude modulation, the amplitude or "strength" of the carrier oscillations is what is varied. For example, in AM radio communication, a continuous wave radio-frequency signal (a sinusoidal carrier wave) has its amplitude modulated by an audio waveform before transmission. The audio waveform modifies the amplitude of the carrier wave and determines the envelope of the waveform. In the frequency domain, amplitude modulation produces a signal with power concentrated at the carrier frequency and two adjacent sidebands. Each sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other. Amplitude modulation resulting in two sidebands and a carrier is called "double-sideband amplitude modulation" (DSB-AM).
One disadvantage of AM transmission is that it is vulnerable to electromagnetic interference from natural and manmade electronic noise, caused by atmospheric static electricity and certain kinds of electromechanical devices such as motor and generator. For this reason the broadcasting of music is mostly done by frequency modulation (FM), and AM radio broadcasting specializes in talk (sports, news, talk radio).
Another disadvantage of AM is that it is inefficient in power usage; at least two-thirds of the power is concentrated in the carrier signal. The carrier signal contains none of the original information being transmitted (voice, video, data, etc.). However, it does contain information about the frequency, phase and amplitude needed to demodulate the received signal most simply and effectively. In some communications systems, lower total cost can be achieved by eliminating some of the carrier, thereby lowering electrical power usage even though this requires greater receiver complexity and cost. If some carrier is retained (reduced-carrier transmission, or DSB-RC) receivers can be designed to recover the frequency, phase, and amplitude information from this "pilot" carrier and use it in the demodulation process. If the carrier is eliminated (Double-sideband suppressed-carrier transmission or DSB-SC) the receiver must provide a substitute carrier, with inevitable loss of fidelity. Completely suppressing both the carrier and one of the sidebands produces single-sideband modulation, widely used in amateur radio and other communications applications. SSB occupies less than half the spectrum of AM so it also has greatly improved bandwidth efficiency. In AM broadcasting, where there are many receivers for each transmitter, the full carrier is provided to allow reception with inexpensive receivers. The broadcaster absorbs the extra power cost to greatly increase potential audience.
A simple form of AM, often used for digital communications, is on-off keying: a type of amplitude-shift keying in which binary data is represented by the presence or absence of a carrier. This is used by radio amateurs to transmit Morse code and is known as continuous wave (CW) operation.
For better AM broadcasting radio in AM (0.5 - 1.7 MHz) on Kenwood TS 590S, set the local/norm CN102 switch, located near DRV connector.
Kenwood TS-590S (TS 590 S) Better broadcast AM (0.5 - 1.7 MHz) reception Mods
Антеннадля Kenwood TS-990S