| In SW (short wave) communications, SSB (single side band) modulation is widely used in commercial, military communications and navigations because of its reduced bandwidth, the advantages of improved spectrum utilization, better signal-to-noise ratios at low signal levels, and improved transmitter efficiency. But there’s also some disadvantages because SSB needs very high frequency stability and selectivity in all stages. And the high cost ofmulti-pole crystal filters limits the use of the SSB mode to the most demanding applications. In this article, a phasing method SSB generator was introduced, and the receiver is designed of classic superheterodyne. The using of DDS (direct digital synthesizer) greatly improved the local oscillator stability and provides a frequency tuning resolution of0.0291Hz! Both the transmitter and the receiver are controlled by a MCU, the user can control the machine by using the keypad and read out all useful information from the LCD on it. |
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