DSP and SDR terminology seems to be used interchangeably a lot. I think
the lines dividing this classification tend to be rather blurry. I'm not
sure we can define a truly "SDR" radio.
There are two aspects to consider:
One is the user interface, whether the radio has front panel controls or
not. At the extremes we have the Flex, Pegasus, and Kachina on one end
of this line, and radios like the Kenwood TS-830, and all pre-computer
controlled radios on the other end of the line.
In between are radios that have some front panel controls and also
computer control. Radios like the recent Flex radios can also be said to
be the other way around with computer control and optional front panel
type controls.
In this aspect, radios with a computer connected, software is defining
some or all of the user interface.
The other aspect is the signal processing. In pre-computer days, all
signal processing was done with analogue hardware. Little by little more
digital techniques were added. The early years saw digital filtering
such as switch capacitance audio filtering (SCAF) and the beginning of
software controlled audio digital signal processing (DSP). This
progressed into DSP at the IF level, and in the latest incarnation,
direct sampling and processing of the signals right from the antenna.
Where do we draw the line? Is a radio an SDR because it has no front
panel controls and software creates a virtual front panel on a computer
screen? If DSP techniques are used at the audio or IF level, software is
used to create the filters, and modulation/demodulation (in the case if
IF DSP), is this software defined radio? If we directly sample an
antenna, and do all processing in DSP, does this make it an SDR? What
happens if we install a bandpass filter between the antenna and the the
analogue to digital converters? This bandpass filter is now analogue
signal processing. Does this negate the classification as an SDR? Do we
limit SDR to only radios that do not have analogue mixers?
I do not think there is an easy answer to the classification of SDR. See
the Wikipedia article on Software-defined radio for more information at
https://en.wikipedia.org/wiki/Software-defined_radio.
73, Darrell VE7IU
On 16-09-26 06:54 AM, Duane Calvin wrote:
And they are both DSP radios, not truly "SDR" radios.
73, Duane
Duane Calvin, AC5AA
Austin, Texas
ac5aa@ac5aa.com
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Gary J
FollettDukes HiFi
Sent: Monday, September 26, 2016 8:54 AM
To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Post to the Amps Reflector from Dishtronix
The Kachina DSP 509 predated the Pegasus by quite a few years…
Gary
--
Darrell Bellerive
VE7IU
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