Sony ICF-SW7600GR Operating Instructions - Page 41

Specifications Tips on radio waves Tips on radio waves What is SSB (Single Side Band)? SSB is very popular among ham and business radio transmissions, and is commonly used in many amateur bands because of its superiority in signal intelligibility. Its impressive signal intelligibility is achieved with minimum interferences when compared to DSB (Double Side Band) owing to its half bandwidth structure. In general, SSB transmissions employ the USB (Upper Side Band) modulation, while amateur band transmissions below 10 MHz employ the LSB (Lower Side Band) modulation. Conventional radios without a BFO (Beat Frequency Oscillator) circuit cannot receive SSB transmissions successfully. This unit can receive SSB transmissions successfully with the built-in BFO (Beat Frequency Oscillator) circuit. Amplitude Carrier LSB USB Frequency What is CW (Continuous Wave)? CW is also popular among ham and business radio transmissions. Unlike other signals, the amplitude of a carrier is not modulated for CW transmissions. CW transmissions convey information by interrupting the carrier and use Morse code as a means of communication. This unit can receive CW transmissions successfully with the built-in BFO (Beat Frequency Oscillator) circuit as beat sound only. To fully comprehend the information transmitted by CW transmissions, an understanding of the Morse code is prerequisite. What is synchronous detection? There are two underlying obstacles in optimum AM reception: distortions due to fading and interferences from adjacent broadcast stations. Synchronous detection is effective in solving these obstacles. Distortions due to fading are generally caused by over-modulation which occurs when a carrier component of the received signal is attenuated along the way. The synchronous detection circuit of this unit generates a pure carrier frequency with no level variation which is ideally synchronized with the original carrier to compensate for the attenuated carrier component, thus dramatically reducing distortion. Likewise, AM (LW, MW, and SW) broadcast generally employs DSB (Double Side Band) signals for transmissions in which the modulated signals are transmitted using both the upper and lower side bands (USB and LSB). In most cases, one of the side bands is affected by interferences from adjacent broadcast stations (i.e., beats). The synchronous detection circuit of this unit extracts one of the two sides (USB or LSB) of the DSB (Double Side Band) signal which is free from interferences. This allows clear reception without the Carrier Interference LSB USB interferences from adjacent broadcast stations. Only this side is received. Additional information 41GB