[TenTec] Post to the Amps Reflector from Dishtronix

[Darrell Bellerive]

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 at ac5aa.com
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Gary J FollettDukes HiFi
> Sent: Monday, September 26, 2016 8:54 AM
> To: Discussion of Ten-Tec Equipment <tentec at 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