Re: Curious minds want to know ... why no SSB?


dhsatyadhana <satya@...>
 

Hi Neil:

Thanks for your question! I'll put in my two cents.

In general, one of the attractions of Ultralights is that one can take a small consumer-grade, AM-only receiver (as opposed to one built with a DX hobbyist in mind) and still pull in an incredible amount of DX. With the limitation of AM-only, additional skill and luck is required, which is part of the fun and challenge. With SSB or synch, one has the ability to inject/augment the carrier (which enhances the ability to hear a weak or fading station), and more importantly to select an individual sideband, which is a tremendous advantage in tough DX situations. SSB also allows the detection of split-frequency heterodynes, another big advantage when listening for trans-oceanic signals. If one did not want this artificial handicap, then one would use a communications receiver, but for me part of the fun and challenge is to see what can be received using minimal equipment, analogous to crystal set builders who voluntarily place even bigger obstacles in front of themselves. The ULR definitions were crafted with this general principle in mind.

Some receivers now have DSP filtering, but are still exclusively AM receivers without the ability to isolate an individual sideband. As with all AM radios, they can favor one sideband to some degree, but it falls well short of what a synch or SSB-equipped receiver can do. For example, synch and SSB on my Sony 7600GR, even with its ho-hum filtering, make it a better DX rig IMHO than the Tecsun PL-380. Truth be told, the DSP filters on the newer radios don't have particularly good skirt selectivity, compared to even cheap filters found in analog sets, much less the DSP filters on a Perseus SDR: as such, the consumer-grade DSP filtering is something of a trade-off. Also, since DSP is the apparent wave of the future for even cheap consumer-grade receivers, disqualifying DSP sets would eventually rule out buying any new Ultralights(!).

If a small radio had an RF gain control or a pre-amp, being able to boost or cut the RF signal wouldn't, in my experience, provide the same sort of advantage as SSB or synch, and would not be a disqualifier. I am not aware of these controls being in a small, under-$100 set - my guess is that it would cost too much to implement - so it may not ever be an issue. As you say, large external antennas do indeed offer a big advantage, which is why we differentiate between "barefoot" class and "unlimited" class for reception records and contests. Putting new filters and ferrites into off-the-shelf receivers also propels one into the unlimited class. Even with these augmentations, as monstrous as they may be at times, one still has the limitation of processing the signal on a cheap little AM-only receiver.

For me, who like others had lost a degree of enthusiasm for DXing with a communications receiver, Ultralight DXing offered (and continues to offer) a much-appreciated shot in the DX arm for interest and enthusiasm.

Thanks - Kevin S
Bainbridge Island, WA

--- In ultralightdx@..., "neilkj6fba" <neil.bell@...> wrote:

The definition of "Ultralight" radios seemingly excludes radios with SSB
or sync capabilities since they would have an unfair advantage.
However, radios with DSP are readily accepted. Does not a DSP radio
have an advantage of over radios? How about small sized radios with RF
gain controls or pre-amps? What makes synchronous detection so
disqualifying?

Does not a LARGE external antenna give an advantage over a "barefoot"
radio? Is a radio using a 6 foot square directional loop still
"consumer grade?" Sure doesn't fit in my pocket!

I can certainly understand the goal of keep low cost as a factor in
ranking a radio as ultralight and also the importance of size. But
aren't both of these factors stretched substantially when large antennas
are used to create "records of achievement" or internal modifications
far beyond the ability of consumers?

I realize that there are criteria for the awards program that divide
into Barefoot and Unlimited.

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