I just marvel at the work being done here.
Frank, you are to be congratulated on developing what appears to be a superb device nulli secundus.
Absolutely. I'd be more than happy to buy one once all the work is complete.
Hi Cardigan
Thanks for your kind comments.
It has been a long and enjoyable road getting this far and there is a quite bit to go yet. When I started I would have been very happy to have ended up with any sort of a working converter, even a straight forward line dropper.
It is only with the very generous help that I have received on this forum that it has turned into what it is. Jeffrey's encouragement to use a FPGA was truly a turning point.
Hi Trevor
I don't intend selling any, but I will make the programing and PCB files available free if anyone would like to build one.
If/when I get finished I will have some PCB's left over and I also have some extra FPGA boards so I could possibly offer a PCB and pre-programed FPGA board if anyone was interested but it is really too early to talk about that yet. I will provisionally put your name on a PCB and FPGA board.
The FPGA boards come from China and take quite a while to arrive from there so I keep a couple spare in case I let the magic smoke out of one. Generally I find the chances of the magic smoke escaping in inversely proportional to the amount of spare ones to hand.
Currently I am working on a test card generator for it. This is a part that I have been itching to do, as I think It interesting to compare implementing one on a FPGA compared to PIC. It will be similar to the PM5544 style one I did in a earlier project. So far predictably the FPGA is winning hands down.
Frank
Hi Frank
I would certainly be interested in a PCB and a FPGA if they become available.
Dave
In due course it would be interesting to see how your device compares under strict test conditions to the Aurora.
Hi.
There are many ways to do standards conversion, from simple off screen camera, through David Boynes converter that may have been the first amateur built one. through the Dinosaur, and others to the original Multistandard Aurora, SCRF & the WC01. The original Aurora must be now nearly 14 years old or thereabouts and the SCRF not a lot newer.
A fresh approach like Frank is doing will have teething troubles just like any other but it could perform just as well as the Aurora, I'm sure on test any bugs will be ironed out.
It would be almost impossible to outperform the SCRF Aurora. I can't think of any aspect of it's performance that could be significantly improved. Possibly VSB modulation but that's a lot of complexity for no real gain.
I can remember a few occasions, possibly on VRAT, where there have been requests for VSB modulators - for distribution on both B4 and B5, I think - presumably to accommodate a fixed frequency TRF tuned to B5.
I did play around with an idea which might work and relies on finding an 8MHz channel SAW filter from an old DTT set-top box.
This is as far as I got:
[
attachment=16639][
attachment=16640]
The adjacent channel sound is guaranteed to be =>40dB down anyway, but these were attempts to drop it into one of the sharper notches if possible.
A modulator working at IF would be needed and a mixer to produce the required output channel but it would be a feasible solution.
Any takers to finish the job?
For 1 or 2 channels the simplest approach is probably to get some filter design software and do it at RF. It won't be perfect unless you can use a spectrum or network analyser to trim the filters.
I know without any test that this converter don't come near the Aurora. It must be remembered that I am an amateur and one that is very wet behind the ears when it comes to standards conversion or FPGA's. I have spent much of my time falling flat on my face but that is part of the fun. So don't expect too much.
The interpolater in it is just a 2 line with 8 bit coefficients and the output lines position are defined to 5 bits.
Although after saying all that the output is pretty good. I had considered trying a 3 line interpolater but haven't don so. One reason is that on the TV's that I am using I doubt I would notice a difference, however with well tuned up TV's I would expect to notice an improvement.
Dave I will keep you in mind
Frank