Enhanced Single Sideband

The best sounding voice signals on the amateur bands!

Single sideband is a voice mode that HF operators have both loved and hated since its first over the air use in the 1930s. Though it is very efficient, it is a tempermental mode, requiring accurate and steady tuning, cleaner oscillators, and sharper filters than conventional amplitude modulation. Technology now is at the level enabling everyone using this mode to enjoy superior signal quality with the same ease of use as broadcast AM.

In the so-called good old days...

Many years ago, in a galaxy far, far away, there were amateur radio operators using a mode called "ancient modulation," or AM. Now we call it "H3E," but that's another story...In the old days, these hams were mostly using tube equipment that was not hard to modify, if one had a reasonable level of knowlege and skill. Stock equipment was manufactured for "communications quality" and didn't sound much better than a standard telephone. The signals sometimes had 60 Hz hum, moderate frequency drift, and restricted audio bandwidth. Hams who aspired to a higher standard of signal quality set out to improve the way their equipment sounded.

I recall these fellows working with negative feedback loops, changing component values, and doing other thingsto make their signals clean, stable, and of higher fidelity. Now, these same operators are advancing the art of H3E by going to solid state class E transmitters, using advanced signal processing, and advanced receiving techniques to sound better than at any time in amateur radio history. In fact, many of these operators are technically more advanced than their AM broadcast counterparts!

Similar trends exist among the users of single sideband, also known as J3E operation. I remember those early tinny, and drifty sideband radios. Some were of great quality for communications service. A few, such as the Central Electronics 100V, used the phasing method of single sideband generation and sounded splendid. Most had narrow bandpasses due to sharp crystal filters in the signal path, and the speech processing left much to be desired. AM operators used the term "slop bucket" to describe the worst of the signals heard on the ham bands. Things are different now...

We are now in the age of digital signal processing! One can process audio, generate a radio signal, and have that signal received, demodulated, and post-processed all in the digital domain. It lifts many limitaions from what is possible. It multiplies performance without a corresponding multiple in cost. DSP enables a radio operator to manimulate his signal with a finesse that was a dream a few years ago. Transceivers now have internal circuits that drift only a few Hertz over many hours and tune in single Hertz steps. Audio equipment similarly can enable one to selectively alter any aspects of ones voice signal. Operators may create a sound very true-to-life, or perhaps opt for interference-cutting as conditions dictate. Considering the potential of modern radio technology, it only makes sense for amateur radio operators to go to its cutting edge. We are at the point where efficiency and quality of SSB operation is pulling ahead of AM. One no longer needs a carrier wave for high fidelity sound - or to cut through noise and cover more miles-per-watt.

Spectrograms and audio clips of ESSB stations are powerful evaluation tools.

What separates ESSB from common single sideband operation? What would be the ultimate ESSB definition? Here is a set of technical goals all ESSB operators should adopt:

• Audio bandwidth capable of going beyond the standard 300 - 3000 Hz and approaching the range of 10 Hz - 8000 Hz, and used judiciously.
• Digital audio processing, immediately prior to modulator stage (excellent control of gating /EQ/compression / limiting)
• Hum, digital hash, and other noise reduced below discernable levels
• Digital signal modulation and detection (freedom from limits due to component tolerances)
• DSP filtering control and interference rejection (freedom from phase shift and shape factor limits)
• Minimal use of transmitter ALC
• All oscillator frequencies derived from one stable and accurate master circuit (disciplined by an NIST referenced signal)
• VFO tuning possible in one Hertz increments
• Transmit signal enters digital domain at the microphone; back to analogue prior to final RF amplification stages.
• Direct sampling software defined reception.
• All circuits designed for minimum harmonic and intermodulation distortion (consider H mode mixing).
• All circuits designed for minimum necessary power consumption.

At this point, I must mention two hams who have distinguished themselves by putting together stations that sound truly flawless over the air: John Anning, NU9N and Tyler Stampfli, KA0KA. Both of them have set up very good web sites on the topic of extended single sideband.

Tomorrow...

There is my humble opinion! Many hams today are realizing many of the goals listed above. It may be a while before they're all totally realized, but the thrill of amateur radio's technical side is the pursuit of these kinds of goals. Sometimes operator ability and attitude doesn't keep up with the technological changes happening in amateur radio...I've seen one very wideband noise jammer on 75 meters, and noticed one or two hams running more bandwidth than apropriate for the band conditions. All I can say is good operating takes constant practice and a willingness to evolve. Generally, if you find someone running an extended / enhanced sideband signal,you have found someone working at improving themselves and the state of the radio service. These skills are absolutely in accordance with Part 97 of the Commission's rules. Trained operators must always extend the state of the radio art, apply lessons learned to providing emergency communications, and promote good will among the occupants of our planet.