One wonderful thing about the holidays is that it gives one time to
think. In my case, I think I'll spend a little time thinking about the
future of radio design.
If we look at the past 20 years of design, we have seen the advent of all
solid state radios, improved miniaturization, improved sensitivity via
lower-noise components and monolothic circuits, and the advent of DSP. I
was wondering to myself, "what's next." Thought it might be fun to
crystal-ball a bit on near-term technology.
1) DSP will continue to take leaps in performance, much as the personal
computer market has. This will, however, meet a limit (say in 3 years or
so), as the algorithms to extract signal from noise run out of signal to
extract. Look for another S-unit of sensitivity.
2) New-mode digital communications, much akin to the digital cellular
waveforms, will make inroads into ham radio. I look for pulse-coded
waveforms to extract another 2 S-units from our radios. The sad part of
this will be the almost instantaneous obsolescence of way too much radio
gear. Imagine a 100W digital radio having the punch of a 1500W station
of today. All we need is to digitize the speech, add pulse compression,
send, receive, decompress, and D-to-A the info. Come to think of it,
maybe I'll try this out as a project sometime. ; )
3) New-process semiconductor chips (GaAs, SiGe, InP, etc.) will offer
ultra-low-noise receive amplification at higher frequencies. This will
allow for more up-converting radios, more bands in the same radio, and
possibly another S-unit. We may also see more integration of RF and
digital circuitry into the same chip. Maybe a second S-unit from this.
4) Direct over-sampling of RF will allow for elimination of mixing and
filtering stages. Fast 1-bit D/A converters already run in the multi-MHz
range. Bump that into the 500MHz range and run the data into a digital
FIR filter and voila, no filters and no down conversion. May have to
work the dynamic range issues, though. Sensitivity bump - 2-3 S-units.
Tally for radio of the near future:
5-7 S-units over current best (1500 W today = 0.1 to 1.5W tomorrow)
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