[R-390] Filters

[mlmccauley at att.net]

Charles has a good point RE not going back into the radio.

Even given it's deficiencies, I think using an outboard SDR makes more 
sense.

You wouldn't have to go with the expense of a Flex. As a couple of guys 
have already pointed out, there are simpler, less expensive options 
available in that sort of thing. It's at least worth checking out.



On 2/16/2013 8:51 AM, Charles P. Steinmetz wrote:
> John wrote:
>
>> Anyhow, you folks have my curiosity up about the software 
>> requirements to do a DSP filter suitable for Collins mechanical 
>> filter replacement.  Can some of you gurus point me to where the math 
>> algorithms are defined?  Gotta be on the web someplace
>
> For the software, start with Hayward, et al., Experimental Methods in 
> RF Design and then move to dedicated DSP texts.
>
> The software isn't the problem -- processing horsepower is. Digitizing 
> and manipulating 455 kHz with sufficient bit depth is still close to 
> cutting edge.  Most DSP radios use a final IF in the 12-20 kHz range, 
> and even that is taxing to process in real time.  This is not a job 
> you can do with microcontrollers.
>
> But my previous question still stands -- once you have developed the 
> DSP capacity to do the filtering, why in the world would you convert 
> back to analog and put it through the 390A IF?  It would be plain 
> silly not to have the DSP also handle AGC, passband shift, notch 
> filtering, noise blanking, all-mode detectors, and synchronous AM, at 
> the least.
>
> Best regards,
>
> Charles
>
>
>
>
>
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>