Best way to connect a USB powered DSI to a PC more then 5 metres away?

g__day (Matthew) · #1 30-06-2006, 01:10 PM

This appears to be an ugly problem, after reading the USB 2 specification today.

What I want to do is set my PC up in the backyard, and after aligning it on nights when I want to do astro-photography run everything from inside. It's easy to control the mount from 20 - 30 metres away, a simple phone line spliced into the right DB connectors and serial dongle does the trick. But the CCD is proving a nightmare.

I don't want a desktop or laptop outside near my scope running my CCD that I could in turn remotely control from another PC inside (although it looks like a slaved server may be where I end up). I simply wanted the equivalent of a 20 - 25 metre USB 2 cable. So I thought a few 5 metres USB 2 cables daisy changed would do the job.

Each 5m cable has a repeater / signal booster and re-sychroniser in-built. I can't even go through one daisy chain length before it says Imager not attached or device not working. The problem is likely not the device not getting enough clean power, it may well be the signal timings. USB can be very, very sensitive to timings. Even an extra 5cm would kill the signal on a 5 metres cable.

So I asked tthe comm's techies at work. They considered:

1. Bluetooth - but it requires USB for power too
2. Router with a USB connector - but they are built to send data to a USB printer - not sure if it would read from a USB camera
3. USB 2 / RJ45 (network cable) converter - that's my next hope.

LAN cable (Cat 5 or better) can run well beyond 100 metres before you need repeaters, although I'm not sure of how much power they can deliver to a USB powered camera.

Can anybody please offer me their suggestions.

Either how can I get a USB cable daisy chained far enough (must I edt Windows XP device settings) or can I convert my USB to a LAN cable somehow and run this back into a remote PC?

Mant thanks for any help you can give!

alandee · #2 30-06-2006, 02:32 PM

I've seen somewhere where you can get usb extenders with ac power injectors, it may be something to google for ?

mojo (Terry) · #3 30-06-2006, 02:56 PM

Something like this maybe?
It's USB 1.1
I'm sure there are USB2 extenders through cat5 on ebay.

g__day (Matthew) · #4 30-06-2006, 09:22 PM

That might work, but you probably need USB 2 compliance, not just USB 1.1. There are things like a USB 2 to fast ethernet extender

http://www.ramelectronics.net/html/u...t_adapter.html

But it's unclear if this would work, i.e. supply enough power through the Cat 5 and get the signalling right - it's more for a PC to cable modem conversion. It's unclear whether a CCD would work okay.

EzyStyles (Eric) · #5 30-06-2006, 11:21 PM

Hi g__day,

I have tried USB 2 cables with repeaters inbetween it doesn't work. I'm currently doing my astro work with my DSI II indoors (gets to 4-5 degrees at night here in melb) and the only way to go by is via remote desktop from wireless connections.

My setup is I have my laptop outside connected to the DSI and my desktop in my room controlling it via a wireless router. I run a 25 metres CAT5E for my hand controller so I can control my EQ6 mount indoors at the sametime while imaging.

Because the DSI is a sensitive device, even if you get say 15 metres of USB 2 cables running through it, you'll loose picture signals and the result will turn out grey (i have tried it).

I'm not quite sure with the CAT5e converters i guess that might be an option for you. If it works, please let me know .

Cheers.

g__day (Matthew) · #6 01-07-2006, 01:05 AM

Will do Eric,

There may be a way, else its build and ultra cheap PC and slave it to one of my big PCs - pretty over-engineered solution if that's what it takes!

Matt

Shawn · #7 01-07-2006, 04:02 AM

Hi g__day
Got it mate, Its a good way to justify the observatory the wife wont let you build,,

. but seriously Im goint to have a similar problem, where the observatories being built "on a hilltop" up the back of the block, yes we have quite a few acres here, theres no power, so its solar , bateries , inverters and the like. but data ,,? here lies the problem, anyone used wireless with success. Id like to here about the setup if so.

Cheers

g__day (Matthew) · #8 02-07-2006, 01:08 PM

No one have a mate or know of a store that has definite expertise in this field?

g__day (Matthew) · #9 02-07-2006, 04:36 PM

Some success!

I figured it may well be the power not the data that is screwing up my USB 2.0 extension cable + repeaters. So I bought a tiny 4 port USB 2.0 POWERED hub, and connect one then two extender cables between my HUB and the PC and then plugged the CCD into the hub. And it worked!

So now I just have to either get a few more 5 metre extender / repeater cables (i.e. a simple Jaycar purchase), or figure if I can go wireless.

The wireless solution intrigues me. If I plug a fast wireless USB router and wireless USB antenna into my powered hub would this work? I ponder that the CCD into the hub needs the Meade Windows XP device driver to operate. Directly wiring to a PC works, but I am not sure if the wireless equivalent would too.

Alternately you could wire USB 2.0 to fast ethernet converters to a 20 meter LAN cable and run these into a PC, but again unclear if this would work.

But I'm getting closer!

EzyStyles (Eric) · #10 03-07-2006, 12:34 AM

Hi G__day,

You wouldn't need a usb hub with wireless. Ive got an ADSL wireless router connected to the desktop PC. my laptop has wireless built in. I make sure the laptop is configured to use the same network as my desktop PC. I then use remote desktop from my desktop PC to my laptop and wolla! im controlling my laptop outside connected to the DSI with my desktop PC. This method works really well. what you see on your desktop screen is exactly identical to the laptop screen.

g__day (Matthew) · #11 03-07-2006, 05:58 PM

That would sure work, but its a PC direct to a CCD, you need that to supply the USB driver to the camera. That is the challenge with a remote USB device -> getting the Windows driver to the "unit" driving it. There is no way of getting this driver to anything but a PC.

I could try with USB over IP to provide a remote connection (e.g. Anywhere USB USBoverIP 5 port powered hubs), but these new devices tend to be limited to USB 1.1 throughput.

Maybe it's time to make my shed waterproof and secure!

EzyStyles (Eric) · #12 03-07-2006, 06:03 PM

i see where you at. The DSI will only reconise the driver via a PC. I don't think using a remote USB hub will work at all. Can always give it a go.

gluck with it and let us know how you go.

g__day (Matthew) · #13 03-07-2006, 10:51 PM

Buying the cables tomorrow and will give it a go in the evening.

One thing that puzzles me is when I start the imager with the lens cap on I get a picture with alot of faint red snow. I expected it to be pretty black, but its like the gain is going overboard. Is that normal for these units?

Dennis · #14 04-07-2006, 09:02 AM

Quote:

Originally Posted by g__day

Buying the cables tomorrow and will give it a go in the evening.

One thing that puzzles me is when I start the imager with the lens cap on I get a picture with alot of faint red snow. I expected it to be pretty black, but its like the gain is going overboard. Is that normal for these units?

If you are exposing for several seconds with a non-cooled camera, you will see thermal noise. Assuming the camera is working okay, I reckon that's what you may be seeing?

With my SBIG ST7E ccd camera I expose several "dark frames", to later subtract them from the image, thus removing the noise from the real data. So, a dark frame, exposed for the same duration and at the same temperature of the light frame, will reveal the on-chip thermal noise that is present in every ccd or cmos camera.

Cheers

Dennis

EzyStyles (Eric) · #15 04-07-2006, 03:14 PM

Quote:

Originally Posted by g__day

Buying the cables tomorrow and will give it a go in the evening.

One thing that puzzles me is when I start the imager with the lens cap on I get a picture with alot of faint red snow. I expected it to be pretty black, but its like the gain is going overboard. Is that normal for these units?

Dennis is absolutely correct. You will notice hot and cold pixels. The DSI unit has to be well cooled. Remember to take dark frames when imaging as well that will help with colour pixels.

g__day (Matthew) · #16 04-07-2006, 08:26 PM

Well more success. I just ran the CCD inside into a powered USB hub and connected this via 4 daisy chained 5 metre USB extender cables with repeaters.

So now I can image up to about 22 metres, big improvement.

Next I will see if I can use USB over IP by running a cat 5 cable into fast ethernet / USB 2 converters into my HUB and PC respectively. May work but probably needs some configuration if it will!