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Chaney
New member
Username: Chaney
Post Number: 1
Registered: 6-2004
| | Posted on Sunday, June 27, 2004 - 8:42 pm: | 
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I am new to this so please excuse my lack of knowledge. Can you help me to understand what uppers and lowers and the SSB's are and how they are used. I just bought the Galaxy 48T. I want to eventually be able to talk to these people I hear on the skips. Thanks for the help. Hope to talk to some of you from North Texas soon. |
Alsworld
Advanced Member
Username: Alsworld
Post Number: 829
Registered: 1-2002
| | Posted on Monday, June 28, 2004 - 2:42 am: |
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Chaney,
welcome to the forum! Here is some information that may help. I did not write this but copied from the web some time ago. Great explaination. I wish I could give due credit but cannot remember where I got it.
Alsworld
What is Single Sideband.
Before you can understand what SSB is, you must understand how audio is transmitted via radio waves. The method by which audio is impressed on a radio signal is called modulation. The two types of modulation that most people are familiar with are AM (amplitude modulation) and FM (frequency modulation), for which the AM and FM broadcast bands were named.
The Carrier.
In an AM-modulated radio signal, a base signal, called the carrier, is continuously broadcast. The two modulating signals are called the sidebands. Any audio that you hear on an AM broadcast station is from the two sidebands. When the radio station is not transmitting any sound, you can still hear that a signal is present; that is the carrier.
These two modulating (audio) sidebands are located on either side of the carrier signal--one just above the other just below. As a result, the sideband located just above the carrier frequency is called the upper sideband and that which is located just below the carrier frequency is called the lower sideband.
The Sidebands.
The pieces that fit together to form an AM broadcast signal are quite important. Although AM signals were transmitted almost exclusively for decades, it was discovered that the AM signal could be dissected. The first amateur radio operators to experiment with these processes often used both sidebands without the carrier. This is known as double sideband (DSB). DSB was typically used in the earlier operations because it was much easier to strip out just the carrier than to strip out the carrier and one of the sidebands.
Several years later (and still true today), it was much more common in the amateur bands to transmit merely using one of the sidebands, which is known as single sideband (SSB). Single sideband transmissions can consist of either the lower sideband (LSB) or the upper sideband (USB).
If you listen to an SSB signal on an AM modulation receiver, the voices are altered and sound a lot like cartoon ducks. As a result, you must have a special SSB receiver to listen to these transmissions. Although this was often difficult for the amateur radio operators of the 1950s to obtain, it is no longer a problem with today's modern SSB transceivers.
Broadcasters Need Fidelity.
You might wonder why SSB modulation is used for some applications and AM is used for broadcasting. Broadcasters must have excellent audio fidelity when transmitting music; otherwise, the typical radio listener will tune to another station. In order to achieve excellent fidelity when transmitting music, both sidebands and the carrier are necessary.
To produce this AM signal, the transmitter is, in effect, working as three transmitters: one to produce a strong carrier for each of the sidebands, an upper sideband, and a lower sideband. The result is that approximately half of the transmitter power is "wasted" on a blank carrier and the rest of the power is divided between the two sidebands. As a result, the actual audio output from a 600-watt AM transmitter (300 watts of carrier + 150 watts on each sideband) would be the same as a 150-watt SSB transmitter.
SSB's High Efficiency.
Let's run some numbers: Suppose you have a typical 5-kW broadcast transmitter. You will only be able to impress 2.5 kW of audio power on that signal. This means that each of the two sidebands will have only 1.25 kW of power. But in highly effective communications using single sideband, a single sideband signal removes the carrier and one sideband and concentrates all of its energy in one sideband. Thus, a 1-kW SSB signal will "talk" as far as a 4-kW conventional AM or FM transmitter. It is one reason why long distances can be covered effectively with SSB.
Single sideband's benefit is not only evident on transmission. The reverse happens on receive. When you work out the math, the efficiency with an SSB signal is 16 times greater than with a conventional AM signal.
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Wendy
New member
Username: Wendy
Post Number: 7
Registered: 6-2004
| | Posted on Monday, June 28, 2004 - 7:14 am: |
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SSB is single side band. Am is 4 wats power ssb is 12 wats (legally that is). 27.650 to 27.405 is the regular cb bands. Sideband is better for talking skip than AM. All you do is call out your station number. Calling CQ and then your station number means you are calling a local person. Calling CQ-DX and then your number means you are calling a distant station. CQ-DX station 54 central florida calling and standing by for contact. Something like that. I live in florida and seem to hear a lot of people on 38 Lowersideband. Hopes this helps.
Wendy
CEF# 350 |
Bruce
Senior Member
Username: Bruce
Post Number: 1310
Registered: 9-2003
| | Posted on Monday, June 28, 2004 - 7:32 am: |
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2 things "UPPERS" or "LOWERS" for SSB mean just that your on the upper sideband or the lower sideband but its on the same channel. There is also a use of "UPPER" and "LOWER" channels refuring to ILLEAGAL frequencys added to a CB set remember the only leagal ones are between CH-1 (26.965 ) and ch 40 (27.405) Most EXPORT sets will go from 26-30 mhz in 4-6 bands of 40 channels and some of these frequencys are in use by other people. |
That ELCO Guy (Unregistered Guest)
Unregistered guest
| | Posted on Monday, June 28, 2004 - 5:46 pm: |
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The easiest way to describe sideband is to think of an oreo cookie. The cream center is the carrier and when you talk you impress/alter the carrier to reflect signal above and below the carrier frequency aka the cookie part of the oreo cookie. The upper part is upper sideband and the lower part is lower sideband. Each of the three parts, upper/carrier/lower, each has 4 watts of power. When you transmit in upper sideband the radio supresses the carrier and the lower sideband addint their 8 watts to the 4 upper watts to get 12 watts upper sideband. When you transmit on lower sideband you supress the upper and carrier giving thowe 8 watts to the lower half.
When the signal is received by another sideband radio the signal is reconstructed back into the whole 3 pieces of the oreo cookie allowing you to fine tune the reconstruction via clarifier.
Now the above may not be entirely scientific but I hope it lets you understand how in basic principle single sideband works.
BY THE WAY there used to be double sideband radios. In double sideband only the carrier was supressed at the transmitter and both the upper and lower parts were transmitted. |
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