[Elphel-support] 10359: cables length and chaining

[Andrey Filippov]

>
> Do you mean having 48 lines (24 signal lines interleaved with ground ones)
> and "wiring" them at both ends to 30 pins output?
>
yes

> But as far as I understood this is not for mid-term future (say, 0.5 to 1
> year)? I've seen your post "Sensor interface in 373" about serial I/O in
> blog, but is it just an idea for now? Or is it already "in progress" in
> some way?
>

No, I'm not working on it yet and do not have particular timing on that -
there are many higher priority projects in the stack.

>
> The other reason is that I'm not that confident at all in my abilities to
> understand what went wrong exactly if problems surface: you've seen already
> how things behave when using long cables and besides that you know your
> hardware well, while I would have to start from scratch ...
>

We have very limited resources to work on such projects. Yes, we can plug
the cables and see if they will work, but not much more. On the other hand
such cables (the camera can stay the same) has low customs value and can fit
inside a regular letter envelope, so it should not be difficult to send it
later - even to Ukraine.

> Thanks! ;-) I will certainly contact you when we have those "particular
> questions", but for now - still one generic (probably dumb?) question: do
> you think that using shielding (something like here:
> http://jsbtech.com/Shield%20Flexible%20flat%20cable.html - i.e. having
> shield layer connected to ground lines) might help to increase cables
> length without going to lines interleaving & flex circuits? I know it is
> typically used to cancel noise/emission, but is it possible it might also
> help to decrease signal lines interference? Or do you think it's not worth
> to investigate that approach at all?
>

I'm not a gury in cables, but to my understanding such shielding makes it
even worse for cross-talk (reducing EMI is OK with that). We have a whole
box of such (several feet long) shielded cables that one of our customers
ordered - I did not even try them myself as they will not work.


> Also, what 12" flex jumpers exactly do you currently use? (I mean
> brand/part number)
>
>
Hmm. Digi-Key does not show now anything longer than 6". We were buying 12"
there.

Andrey
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