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Most amateur digital modes are transmitted by inserting audio into the microphone input of a radio and using an analog scheme, such as amplitude modulation (AM), frequency modulation (FM), or single-sideband modulation (SSB). Amateur teleprinting over radio (AMTOR) D-STAR (Digital Data) a high speed (128 kbit/s), data-only mode.
Illustration of the spectrum of AM and SSB signals. The lower side band (LSB) spectrum is inverted compared to the baseband. As an example, a 2 kHz audio baseband signal modulated onto a 5 MHz carrier will produce a frequency of 5.002 MHz if upper side band (USB) is used or 4.998 MHz if LSB is used.
Information in this chart supersedes that in File:United States Frequency Allocations Chart 2011 - The Radio Spectrum.pdf. ... Version of PDF format: 1.4
In the US and Canada the portion of the band from 3.600–4.000 MHz, regulation permits use of single-sideband voice as well as AM voice; this sub-band is often referred to as "the 75 metre band", in part to distinguish it from the internationally available frequencies below it. 60 metres – 5 MHz region – around 56 m
Note: Information in the chart has been superseded by the information in File:United States Frequency Allocations Chart 2016 - The Radio Spectrum.pdf, which was downloaded from the US Department of Commerce web site and archived at archive.org.
Frequency modulation, Single channel containing analogue information, Facsimile (still images) H3E Single-sideband with full carrier, Single channel containing analogue information, Telephony (audio) J3E Single-sideband with suppressed carrier (e.g. Shortwave utility and amateur stations), Single channel containing analogue information ...
Single-sideband modulation with full carrier (e.g. as used by CHU) J: Single-sideband with suppressed carrier (e.g. Shortwave utility and amateur stations) K: Pulse-amplitude modulation: L: Pulse-width modulation (e.g. as used by WWVB) M: Pulse-position modulation: N: Unmodulated carrier (steady, single-frequency signal) P: Sequence of pulses ...
This original form of AM is sometimes called double-sideband amplitude modulation (DSBAM), because the standard method produces sidebands on either side of the carrier frequency. Single-sideband modulation uses bandpass filters to eliminate one of the sidebands and possibly the carrier signal, which improves the ratio of message power to total ...