Search results
Results from the WOW.Com Content Network
The power of an AM radio signal plotted against frequency. fc is the carrier frequency, fm is the maximum modulation frequency. In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, that are the result of the modulation process. The sidebands carry the information transmitted by the radio ...
The engineering compromise is vestigial-sideband transmission. In vestigial sideband, the full upper sideband of bandwidth W2 = 4.0 MHz is transmitted, but only W1 = 0.75 MHz of the lower sideband is transmitted, along with a carrier. The carrier frequency is 1.25 MHz above the lower edge of the 6 MHz wide channel.
Five 2.8 kHz-wide channels are available in the U.S., centered on 5.332, 5.348, 5.368, 5.373, and 5.405 MHz. Since most radios in SSB mode display the (suppressed) carrier frequency, in USB mode the dial frequencies would all need to be set 1.5 kHz lower. Voice operation is generally in upper sideband mode, which is mandatory in the U.S. . The ...
The collection of the former frequencies above the carrier frequency is known as the upper sideband, and those below constitute the lower sideband. The modulation m(t) may be considered to consist of an equal mix of positive and negative frequency components, as shown in the top of figure 2.
This is apparent when the spectrum of the output signal is viewed. In the picture shown below we see four peaks, the two peaks below 5000 Hz are the lower sideband (LSB) and the two peaks above 5000 Hz are the upper sideband (USB), but there is no peak at the 5000 Hz mark, which is the frequency of the suppressed carrier.
For Canadian and U.S. Amateurs with infeasibly perfect transmitters, the highest usable frequency in the 80 m band for lower side band voice ("phone") would be 3.999 MHz. But depending on quality and condition of radio, audio characteristics, and proper adjustments the bulk of emissions on lower sideband will typically occupy 3.9970–3.9997 MHz.
PSK31 operators generally use upper sideband (USB), even on frequencies below 10 MHz where the convention normally calls for lower sideband. This is because (a) signals then spread upwards into the digimode section from the "base" frequency, and (b) using QPSK requires both stations to use the same sideband.
The frequency spectrum of a typical radio signal from an AM or FM radio transmitter. The horizontal axis is frequency; the vertical axis is signal amplitude or power. It consists of a signal (C) at the carrier wave frequency f C, with the modulation contained in narrow frequency bands called sidebands (SB) just above and below the carrier.