SSB vs. AM CB radio range advantages

Picked up a dusty Realistic TRC-453 AM/SSB CB Radio to complement the TRC-465. This means we can have base-mobile communications–it’s so much clearer than AM, particularly when skip conditions are up. On AM, you get a squealing noise with multiple transmitters on the same channel. The squeal frequency is the difference between the transmitter carrier frequencies.

SSB vs. AM

On SSB, there is no carrier. If two people are talking, you just hear one quieter and one louder, within the dynamic range of the respective communications channel.

Another perhaps greater advantage of SSB is the 9dB (nearly 10x) advantage vs. AM. First, you have 6dB more power (well, legally it’s 3x for CB–12W vs. 4W–but the final transistors are typically capable of 4x (16W) ahem). Then, the receiver has 3dB less noise. So overall each one way path has 8x-10x improved SNR–that’s like say 30% or so more range in these wide open spaces.

The audio quality is never quite as good–the circuitry has to hold the phase constant over a wide frequency range, and that always falls through a little bit, and the most noticeable factor is the slight difference in frequency causing Donald Duck sounding audio. After a while you get used to it, but at first voices you knew are AM are indistinguishable from each other for a few days.

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Written by Michael Hirsch, Ph.D. //

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