schrieb:

My own understanding of a digital radio - only the keypad and the
frequency display is digital and all the rest is analog . Pl. correct
me if I am wrong .

Add the digitally controlled frequency synthesis via PLL to that. (Only
simple receivers use analog synthesis plus a frequency counter these
days.) But apart from that, the signal path from the front end over the
mixing, filtering, demodulation and output is indeed completely analog.
This is why a 40..50 year old tube equipped Collins boatanchor like the
R-390A can still keep up with good receivers today - it was built to the
highest standards of the time, and that is still pretty good even today.
(Though of course a tube rig will usually require - but also handle -
more antenna.) Solid-state equipment only caught up with tube gear in
the late 70s. It has been possible to build excellent short wave
receivers for a pretty long time, with the cost for a given level of
performance usually declining. Not extremely so, however - a Drake R7
would still be a far better choice for DXing than, say, the little Degen
DE1102.
It is in the "value" segment where you notice advances the most -
looking at Sony's "7600s", for example, you can see how at a rather
constant price point the SW reception and features got better and better
in the course of more than 20 years (due to higher integration and
general advances): The first set was a single conversion analog, the
second one was a dual conversion set and featured more bands, the third
one (more expensive at first) featured PLL synthesized tuning and
continuous shortwave coverage with 5 kHz steps and SSB along with
memories and other digital niceties (while neglecting speaker sound),
the sixth one added selectable sideband SSB and a better SW IF filter
along with much reduced PLL noise (though it lost a bit in terms of FM
reception), the seventh one featured 1 kHz steps and selectable sideband
synch detection along with some more memories, the 8th one added
significantly more memories and other minor improvements. Something that
the radio designers of years gone by were apparently better in was
building a well sounding radio...
At the moment, no real revolutions are to be expected. Some impulses on
the low-end market are coming from China, but that's more a matter of
labor costs. On the higher end, things have been slowing down for a
while, with no further "consumer level" IF DSP rigs in sight. (The
market for ham radio gear is a lot more active in this respect.)

Stephan
--
Meine Andere Seite: http://stephan.win31.de/
PC#6: i440BX, 2xCel300A, 512 MiB, 18+80 GB, GF2MX AGP 32 MiB, 110W
This is a SCSI-inside, Legacy-plus, TCPA-free computer
Reply to newsgroup only. | See home page for working e-mail address.