DX Code of Conduit at dx-code.org

Wednesday, August 25, 2010

From TS590 yahoo group - Re: Extra Filter Slots?

Hello to all.

I would associate my opinion with the same from Peter - HB9PJT.
Clear points Peter. Also the last one it's clever: " We will see".

One more point that I would give for discussion is that, citing the FLEX software and hardware architecture, a big enhancement in the filter shape occurs with bigger buffers. I mean those buffers in the DSP processor, as far as I know. This seems quite independent from the DSP algorithms used. I just leave the standard one offered by default.
What I mean is that when I choose inside POWERSDR(tm) smallest buffers. As to decrease latency inside those buffers, let's say a 512 bytes buffer size. The filter shape degrades by any mean. RTTY signal nearby 100/300 Hz from a 230Hz filter leaks visibly on MMTTY waterfall. There is also the associated audible signal in the speaker. With bigger buffers, let's say 2048 byte, there is a perfect shaped effect with the same IF filter. No nearby signals at all.
In RTTY or any other digital modes that is not CW I don't think that those IF buffers need to be so tight.
And there are several other aspects to benefit the filter shape and the whole IF circuitry response, as peter wrote. I could associate also MMTTY BF processing after all.
I have no doubt that as it's done by me manually, with the simplest cause and effects process, it could be done flawless and better by the firmware. This last would be made, i hope, around a drill down processing of all the choices involved in. But there is also marketing.

Nonetheless, as this will be firmware controlled inside a 590 there is the possibility that something could go wrong. We have a lot of transceivers that looks really interesting but that are at least poor in real world performance. Not to say that some of those are good as door stop from perspective to perspective. By any means a single button action, a mode change to an AGC set, have several things to set and reset, code & data flow. I hope that there was no the wrong approach during the development of this so hoped and nice looking RTX. "We will see".

The famous and over speak K3 have had and could have several changes on it's firmware. But the habit about is that everything is well done at any time and for any season. More a mental habit and perception than a real issue as for everyone other builder on the market.

Lastly, SDR are the answer for today needs. But there are strengths ans weakness as usual. Different words than in the analog world but same final problems. Not speaking about the void of software and human interfaces. What we see is that all the commercial builders are, for the greater parts of the work done, approaching the soft way to SDR. But this is another story.

73 de iw1ayd Salvo