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TECHNICAL STUFF SSB - Single Side Band The information presented below is an explanation adapted from the Ranger Superstar SS158EDX manual. It is a detailed explanation and, I feel, it is reasonably easy to understand, so I thought that there was little point trying to re-write it! "There are four types of signals presently used for communications in the Citizens Band : FM, AM, USB and LSB. When
the MODE switch on is placed in the AM position only a standard double-side band signal is transmitted. When in the FM position, only frequency deviation, full carrier signals will be transmitted. When receiving an SSB signal, it may be recognized while in the AM or FM mode by its characteristic "Donald Duck" sound and the inability of the detector to produce an intelligible output. The USB and LSB modes will detect upper side band and lower side band respectively, and standard AM signals. SSB reception differs from standard AM reception in that an SSB receiver does not require a carrier or opposite side band to produce an intelligible signal. A single-side band transmitted signal consists only of the upper or the lower side band and no carrier is transmitted. The elimination of the carrier from the AM signal helps to eliminate the biggest cause of whistles and tones heard on channels which make even moderately strong AM signals unreadable. Also, SSB takes only half the space of an AM channel, therefore two SSB conversations will fit into each channel, expanding the 40 AM channels to 80 SSB channels. The reduction in channel space required also helps in the receiver because only half of the noise and interference can be eceived with 100% of the SSB signal. An SSB signal may be received only when the listening receiver is functioning in the same mode. In other words, an upper side band signal (USB) may be made intelligible only if the receiver is functioning in the USB position. If a lower side band (LSB) signal is heard when the receiver is in the USB mode, no amount of tuning will make the signal intelligible. The reason for this may be understood if you consider that when the modulation is applied to the transmitter's microphone in the USB mode, the transmitter output frequency is increased whereas in the LSB mode the transmitter's output frequency is decreased. The result in listening to the receiver is that when the MODE switch is in the proper position (either USB or LSB), a true reproduction of a single tone of modulation will result, and if the tone is increased in frequency (such as a low-pitched whistle or a high-pitched whistle) you will hear the increase in the output tone of the receiver. If the incorrect mode is selected, an increase in tone of a whistle applied to the transmitter will cause a decrease in the resultant tone from the receiver. Thus when a voice is used in place of a whistle or tone, in the proper listening mode the voice will be received correctly whereas in the incorrect mode, the voice will be translated backwards and cannot be made intelligible by the FINE/COARSE (clarifier) control. When listening to an AM transmission, a correct side band is heard in either mode since both upper and lower side bands are received. Once the desired SSB mode has been selected, frequency adjustment may be necessary in order to make the incoming signal intelligible. The FINE/COARSE control allows the operator to vary frequency above or below the exact frequency of the channel. If the sound of the incoming signal is high or low pitched, adjust the operation of the FINE/COARSE. Consider it as performing the same function as a phonograph speed control. When the speed is set too high, voices will be high-pitched and if set too low, voice will be low-pitched. Also, there is only one correct speed that will make a particular record produce the same sound that was recorded. If the record is played on a turntable that is rotated in the wrong direction (opposite side band) no amount of speed control (FINE/COARSE) will produce an intelligible sound. An AM signal received while listening in one of the SSB modes will produce a steady tone (carrier) in addition to the intelligence, unless the SSB receiver is tuned to exactly the same frequency by the FINE/COARSE control. For simplicity, it is recommended that the AM modes be used to listen to AM signals."  Ranger Superstar SS-158EDX multi-mode transceiver Join the Foxtrot Bravo group here:  If you have any questions relating to CB Radio then there is no better place to go than these specialist forums :-   Be sure to say that BigCat sent you!  . |
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Mike Smith - MDS975.co.uk © 2003 - 2008