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Old Jan 19, 2004, 4:12 AM   #21
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Just a quick departure from this interesting digital architecture discussion. Perhaps you may have picked up that a number of Fuji S7000 users in UK reported battery discharge problems with 'certain' cards.

Fuji issued a statement and identified the problem as due to certain cards having larger supply capacacitors on the card, with higher leakage current. So the amount of decoupling on a cards supply rails may vary from card to card.

................Hey - this sounds like a good topic for my master's thesis! We could simulate some bit errors - build a ECC algorithm (such as that employed by CF) - and feel through some images. If we get the right pattern of errors - who knows!................

and......... did you know that if you can read their CIS block on physical sector '0' you should be able to find out more about the masked errors. I'd like to do that on different vendors cards, use them for a while, do an smprep which re-calibrates the error table, and see how the numbers have changed. VOX
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Old Jan 21, 2004, 11:34 AM   #22
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Quote:
Originally Posted by voxmagna


and......... did you know that if you can read their CIS block on physical sector '0' you should be able to find out more about the masked errors. I'd like to do that on different vendors cards, use them for a while, do an smprep which re-calibrates the error table, and see how the numbers have changed. VOX
It makes sense that they would record the corrected error rate. Definitley sounds like a statistic they wouldn't want to share with users though. Do you know of a practical way to read this block with off-the-shelf commercially available equipment?
Also, interesting note about capacitance variation amoung card vendors. There is an allowable voltage tolerance specified for the interface so I guess it follows that manufacturers at the higher end of the tolerance will require more juice and in turn drain more battery on each read/write. Since I tend to use my LCD display I would assume this difference negligible in my case but interesting never the less.
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Old Jan 21, 2004, 1:03 PM   #23
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I guess I shouldn't have stopped reading this thread. It went in some interesting directions.

The original question was about different brands. Then it went into interference and other issues. I guess its possible that different brands could do a better job at shielding their parts, using good grounds and the like.... so in that respect different brands could make a difference. Since I don't believe that jpg has any ECC in the format (does any picture format? Wait, creatively thinkg... I guess they do if they are compressed, 'cause the uncompress would fail. But that is really a checksum, not an ECC.)

I would think the odds of interference making its way into the bit stream and not corrupting the picture would be small. But maybe I'm way off?

Eric
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Old Jan 21, 2004, 1:40 PM   #24
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I agree - I think it is very unlikely although not impossible.

Can't comment on JPG compression having an ECC and/or a checksum - never read up on the algorithm. Not sure what other image formats have either. Thinking about this I guess we should see if JPG has a checksum though - because I have seen cases where a web browser only loads half an image (so either there are a series of checksums that occur for each block of data or ???) - and then I have run a packet capture utility to verify that the TCP stream was broken before all the data was received by my PC. So if the browser could display a partial JPG, either the decompression can ignore the checksum, or the checksum isn't across an entire image. In any case, based upon this case, I believe a browser decodes JPG in blocks, not in full so a checksum across the entire image can't be necessary for decoding. Time to find a good place to read up on JPEG compression....
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Old Jan 21, 2004, 2:08 PM   #25
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..............I would think the odds of interference making its way into the bit stream and not corrupting the picture would be small. But maybe I'm way off?..................

Hey all, the problem with keeping your head in the digital world is you fool yourself into thinking 'cos the file checksum is ok everything's hunky: garbage in = garbage out!. That's the problem with pc thinking! Here's something I included in a post in the Fuji section earlier today. Nice of Polaroid to agree to a prog about their development of this camera, it was very enlightening and timely to see close ups of actual circuit boards and camera architecture explained by the development guys! James Kirk would be on home ground!


"Just by co-incidence, I watched a school prog yesterday, describing how Polaroid at their Scotland factory designed and debugged their new integrated (large!) digital printing camera. The main problem they had during prototype trials was the appearance of black lines on saved JPEGS, caused by pickup around the CCD processing. circuit. They solved the probs in the usual way with ferrite beads, inductors and caps added around the CCD processor chips. Regards VOX"
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Old Jan 21, 2004, 2:31 PM   #26
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I may be stating the obvious but in this case the interference was caused during CCD capture. I believe it is far less likely that interferance would get added after capture - as in the case of transfer to, or from, a compact flash card which was the original subject of this discussion.
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Old Jan 22, 2004, 8:35 AM   #27
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cczych........Do you know if a CF card is sitting dead in the camera slot with no power when the camera is on? I thought that since the camera controller was talking to the card, even in a ready state it must be digitally active all the time the camera is powered? VOX
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Old Jan 22, 2004, 1:48 PM   #28
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I don't know the asnwer to that off-hand. Good point though - perhaps it is powered in the ready state whenever the camera is on - this would save time to power-up the device and initialize the interface everytime you take a picture.
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Old Jan 22, 2004, 2:27 PM   #29
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That is a very interesting question. I don't know if its powere down. From my experience of flash memory programming, there is no reason to keep the flash powered (and probably a benefit of keeping them cooler) but the controler logic/chips are another matter. Maybe they need power.

I might know someone who knows something about this, I'll ask.

We are an inquisitive bunch, aren't we? Just the way I like it.

Eric
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Old Jan 23, 2004, 7:56 AM   #30
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..............We are an inquisitive bunch, aren't we? Just the way I like it

Yes I agree, It's rather like David and Goliath. The Manufacturers are often economical with the truth and prefer to keep consumers in ignorance, whilst expecting us to part with the cash.

They, must also get quite fed up when bad feedback occurs and Internet hysteria sets in on new product launches. But then if they came round to being more open and realised that their marcomms methods can look decidedly ineffective, compared to credence of user feedback, they might realise being more answerable to the end user, at a reasonable speed, could be beneficial.

I'd definitely like to see more cameras with a usb/web firmware upgrade route. My PC, modems, software and MP3 players all have this, and whilst we accept new products are not always perfect - at least minor issues can be fixed without a return. Another idea I had was that a camera could be connected to a manufacturers site, then given a remote controlled diagnostic function test. This would be great for those buying second user cams or contemplating a warranty or store return. Would save money on wasted returns I'd have thought, and those posts from Newbies "My camera does this is something wrong?". VOX
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