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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 ...
When single-sideband is used in amateur radio voice communications, it is common practice that for frequencies below 10 MHz, lower sideband (LSB) is used and for frequencies of 10 MHz and above, upper sideband (USB) is used. [12] For example, on the 40 m band, voice communications often take place around 7.100 MHz using LSB mode.
In addition, the FCC continues to require that all digital transmissions be centred on the channel-centre frequencies, which the Report and Order defines as being 1.5 kHz above the suppressed carrier frequency of a transceiver operated in the upper side-band (USB) mode. As amateur radio equipment displays the carrier frequency, it is important ...
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.
Upper sideband (USB) must be used and the allocation is 5060–5450 kHz. All modes are allowed and the maximum power permitted is 3 kW on a non-interference basis. South Africa (ITU Region 1): On Friday 25 May 2018 South African regulator ICASA published the National Radio Frequency Plan 2018 in which amateur radio was allocated 100 kHz on a ...
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.
Independent sideband (two sidebands containing different signals) C: Vestigial sideband (e.g. NTSC) D: Combination of AM and FM or PM F: Frequency modulation (e.g. FM broadcast radio) G: Phase modulation: H: Single-sideband modulation with full carrier (e.g. as used by CHU) J: Single-sideband with suppressed carrier (e.g. Shortwave utility and ...
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.