CB World Informer Proposal To Improve 11 Meters As we discussed in the October issue, CB is getting crowded again. Proposals of adding channels are surfacing as they have so many times in the past. More channels are needed. But do we just want to add channels to the existing band as a continuation of what we already have? Remember when the FCC allotted more channels back in 1978. Before it happened many operators unsuccessfully appealed to the FCC for sideband only channels. We had to settle for a gentlemen's agreement. It was a nation wide effort and a remarkable one at that. Unfortunately, without one governing body to listen to all the input and compromise for the best interest of the majority, we wound up with a watered down agreement that changed from one area of the country to another. Some decided on lower sideband, others upper sideband. Then when it came to what channels were AM it was all over the place. This was OK in those areas, but when the skip was running we had every mode going on some frequencies. This drove more operators out of band. Back in the early days of sideband the radios were tighter. On sideband the transmitter and receiver intermediate frequency is run through a crystal filter. The early filters allowed a frequency of between 2.4 to 2.6 KHz wide to pass through. This is common for today's Ham radios. But to cut cost on CB equipment the manufacturers have opted to use 4 KHz filters. This widens the bandwidth of sideband transmission using more space than necessary. I don't know if any of you remember or new of Don Stoner. He designed and manufactured a sideband only radio. It was a remarkable piece of technology but it didn't sell for the lack of AM. This was the cleanest transceiver ever made for CB. Don had a proposal for CB back in the early 1980s. He proposed adding sideband only frequencies to the CB band and spacing them 5Khz apart. In this proposal, radios that were manufactured to cover this additional band would incorporate a compandor circuit. The compandor is a compressor and expander unit. The transmitted signal is compressed reducing splatter caused from peak over modulation. Then the signal is returned to its original form at the receiver when it's run through the expander. This was one of the best proposals I've seen. It made better use of the spectrum leaving room for further expansion in the future. Well expansion took place, not legally and not efficiently either. With the advancement in radio technology there are better solutions today that could be combined with Don Stoner's idea. DSP (digital signal processing) could and should be incorporated for noise reduction. Auto clarification or rock solid stability could also be incorporated, then everyone would want to use sideband. On the following page you'll find illustrations of how the space is or could be used by sideband signals.
Figure 1 illustrates the space taken by both sidebands transmitted from radios with 4 KHz SSB filtering and the standard 10 KHz channel spacing. Notice the USB & LSB overlap at center frequency. This is the cause of splash.
Figure 4 illustrates the space taken by 4 LSB signals from radios with 2.4KHz filtering and 5 KHz channel spacing. There is no overlap and the only way there would be splash is by overdriving the signal.
Figure 3 illustrates the space taken by 4 LSB signals from radios with 4 KHz SSB filtering and 5 KHz channel spacing. Notice we have 4 signals in the same amount of space with less overlap.
Figure 2 illustrates the space taken by both sidebands transmitted from radios with 2.4 KHz SSB filtering and the standard 10 KHz channel spacing. Notice that the USB &LSB is at a lower level of splash.