Hedghog 625-405 standards converter

[ppppenguin]

I also have a Hedghog thanks to Frank's generosity. I've put multiburst into both an Aurora and a Hedghog. The video outputs look very similar. This isn't surprising as both use the same TVP5150 video decoder chip. This chip has a good comb filter decoder. The analogue filtering at both input and output is simple on both designs and has little effect on HF response. The Aurora has an oversampling digital filter ahead of its DAC. I don't think the Hedghog does, so in theory its analogue output filter is more critical.

I'm surprised that Trevor is seeing significant differences.

I admit I haven't looked at the modulated output - I don't have any TVs that I can sufficiently trust to reliably resolve the highest frequencies in a 405 signal.

So my initial impression is that the basic video performance of both Aurora and Hedghog is as close to ideal as it needs to be. The higher frequency bursts look a bit odd due to filtering in the decoder chip so it's hard to say that the HF response is flat within a certain figure. Pretty sure it's within 2dB up to full BW. It may well be better. What I can't comment on yet is the vertical interpolation, simply because I haven't really looked. There's nothing blatantly wrong and it's not the easiest thing to quantify.

There will be no temproal aliasing as there is no temporal processing in either Hedghog or Aurora.

When I have time to do so, I hope to do more detailed measurements.