USB Extender for remote observatory control

[Philip Benson]

I'm wondering if there are any other SGL members using a Startech 4 port USB network extender system.  It comprises of a local box which plugs into the host computer and a remote box into which all your USB devices plug into. The two boxes are then connected via a standard Cat 5/6 network cable.

The system works fine if you use a network cable to connect the local and remote boxes directly but this would involve running a long lead from the house all the way down the garden. That kind of defeats the point of having it!  Instead I want to use Powerline plugs so I can use a mains socket in the house and another in my observatory and then use two shorter Cat 5 network leads.

The two power sockets are on the same ring but when I connect everything up I don't get a link between the boxes.  The powerline plugs are fine as I have used them before in the house. Anyone else got any similar experience?

[LightBucket]

I use that same Startech system, and too have thought about using with powerline pugs, but not yet tried...so will watch with interest, and if i do get round to trying i will let you know how i get on..

[RayD]

50 minutes ago, Philip Benson said:

I'm wondering if there are any other SGL members using a Startech 4 port USB network extender system.  It comprises of a local box which plugs into the host computer and a remote box into which all your USB devices plug into. The two boxes are then connected via a standard Cat 5/6 network cable.

The system works fine if you use a network cable to connect the local and remote boxes directly but this would involve running a long lead from the house all the way down the garden. That kind of defeats the point of having it!  Instead I want to use Powerline plugs so I can use a mains socket in the house and another in my observatory and then use two shorter Cat 5 network leads.

The two power sockets are on the same ring but when I connect everything up I don't get a link between the boxes.  The powerline plugs are fine as I have used them before in the house. Anyone else got any similar experience?

Post deleted due to the usual talking rubbish

[Macavity]

I have tried both budget (£10?) and mid-priced (£50-60?) USB 1.n (Note!) extenders
and found them to be equally (non) reliable! I have now achieved reliable (low speed)
Mount & Focuser control to my observatory via 30m Cat.5 via an ICRON USB extender.
I chose the single channel version, but it works with an "exterior" Startech USB Hub! 

http://www.icron.com/products/icron-brand/usb-extenders/

As with many Astro things, PRICE is the issue? I sense cheap ones are little more
than "level shifters" or provide a few more "amps" to overcome cable resistance? The
ICRON ones know about the problem of buffering data to simulate a "short" cable?

As a "Mk.1"(!) type Video Astronomer, my Watec *camera* signals come back via
50 Ohm coax so I can sit in the comfort of my lounge! But If I want to do Solar or
Planetary imaging, I have to brave the great outdoors with Laptop + USB 2.0 cam!

Sometimes I fantasise, but extending USB 2.0... 3.0,  adds even more to the cost? 

[LightBucket]

26 minutes ago, RayD said:

@Skipper Billy used these with seemingly great success.  They were up for sale so if he hasn't sold them yet it may be worth looking up in the for sale forum.

I've used the Devolo 1200 power line adaptors (still do in Spain) and they work great.  I have no issues at all, but I am off grid so have no interference from other sources. 

I have stopped using them here now for the obsy as I ran and external CAT6 cable, but I had zero issues in the 4 months or so that I used them.

I think the OP has already got the adapters and not looking to buy any, and wants to know if they will work with powerline adapters...

[RayD]

4 minutes ago, LightBucket said:

I think the OP has already got the adapters and not looking to buy any, and wants to know if they will work with powerline adapters...

You are indeed correct Sir.  Will teach me to open eyes before reading!

[RayD]

I'm not sure this would work but will be interesting to see.  

I thought USB data sent via these units was just that, and not tcp/ip which the extenders would use over the LAN.  In this case sending the USB data around the power line rather than a dedicated cable (up to a limited length) would probably degrade the data to point of being unusable.

Ps.  Apologies for misunderstanding the OP

[Dr_Ju_ju]

Powerline Adapters work on the basis of superimposing the network signal on top of the existing 50\60 hertz AC signal....  I have usually found this to be very unreliable, especially when attempting connection over longer distances over 'iffy' cables etc...  There is also a possibility for the network signal to be attenuted if there are mains suppresion devices plugged in ....

[Macavity]

I agree with above? I never did quite work out what caused long USB links
to fail, but I have a suspicion it was "spikes" on the Obsy. *mains* supply?

These days (for Video astronomy) I run the Obsy. from  a 12V deep cycle
battery and "cast off" completely from the Domestic Supply! It works - But
that is not irrefutable evidence - Indeed some/much of this is speculation!  

Whatever. Good general topic, that hasn't been raised for a while... 

[LightBucket]

I personally dont see why it wouldnt work, as the Startech device, takes in a USB signal and then sends down a CAT6 cable, then converted back the other end to USB for the PC to read, so by having powerline connectors in the middle of the CAT6 cable, so sending the now network signal down the mains cable, and then converted at the other end, then it should in theory work fine, BUT the OP cant get this to work....so i will have to try for myself and report back..

[LightBucket]

One other thing for the OP to check is that his powerline plugs are compatible with CAT6 and not just CAT5 cable..or at least try with both types of cable..and see if either works

[Dr_Ju_ju]

The other thing to remember is that the Startech device IS NOT a network device, it just uses CAT5\6 cable connection using its own proprietry protocol \ signalling system, you would probably see the same issues plugging into a local wired network....

[RayD]

24 minutes ago, LightBucket said:

I personally dont see why it wouldnt work, as the Startech device, takes in a USB signal and then sends down a CAT6 cable, then converted back the other end to USB for the PC to read, so by having powerline connectors in the middle of the CAT6 cable, so sending the now network signal down the mains cable, and then converted at the other end, then it should in theory work fine, BUT the OP cant get this to work....so i will have to try for myself and report back..

The LAN extenders work by utilising tcp/ip protocol on the power line, the OP would be looking to send clean USB data which is a very different thing, and why even if on a dedicated cable is limited to quite short lengths in comparison to IP. 

[LightBucket]

46 minutes ago, RayD said:

The LAN extenders work by utilising tcp/ip protocol on the power line, the OP would be looking to send clean USB data which is a very different thing, and why even if on a dedicated cable is limited to quite short lengths in comparison to IP. 

So if this is the case, why with astro gear is USB limited to around 30m max on USB repeater cables, where as with the Startech system which you say still sends USB signals can that work up to and over 60m on CAT6 cable, what make sit work over a longer distance..??

[RayD]

10 minutes ago, LightBucket said:

So if this is the case, why with astro gear is USB limited to around 30m max on USB repeater cables, where as with the Startech system which you say still sends USB signals can that work up to and over 60m on CAT6 cable, what make sit work over a longer distance..??

Because the boxes boost the signal, that's what makes them clever.  USB as a stand-alone is very low power, in the region of ma, so its distance is limited.

[RayD]

Don't forget of course LAN cable is also larger than data (USB) cable, so will work better, and being twisted pairs this helps with interference.  When connecting this is why it is important to use the right colours as the layout affects the way the cable works.

[Dr_Ju_ju]

As I said, they use their own proprietry sysytems of signal level\send~receive, and are able to use all 8 cores in the CAT cable for better CRC checking etc. 

[mallorcasaint]

I use the Startech system but my Cat 6 cable is run into the observatory in a trench. Startech does not use ethernet, it uses an ethernet cable. I can't see how Powerline adaptors would work as the use network protocols over the mains electrical circuit so the have yo be plugged into a 13amp socket.

[saac]

I've tried using the star tech over poweline adaptor and couldn't get it to work - I think the reason is as Mallorcasaint states above. I couldn't even identify them on the network. I run the star tech instead over a buried cat 6 cable and it works perfectly.

Jim

[symmetal]

As Julian says the CAT5e or CAT6 cable is just used as a tie-line (wired connection) between the two StarTech units to send the USB data.

USB 2.0 has a max transfer speed on 480Mb/s (MegaBits per second). Ethernet has a maximum speed of 100Mb/s and Gigabit Ethernet has a maximum speed of 1000Mb/s. Most homes will have standard ethernet networks.

Sending one USB 2.0 port data over ethernet its usable speed would be down to 20% of maximum.

Cat5e and CAT6 cable is an 8 core cable arranged as 4 twisted pairs. Ethernet uses 2 pairs and Gigabit ethernet uses all 4 pairs.

The StarTech unit will use 1 twisted pair for each of its 4 USB ports. As there are no network protocols to observe it can send the data at 480Mb/s on each pair. As the cable connecting the units gets longer the signal will degrade until above a certain length it is too degraded to be recoverable at the other end. This will be the maximum useful length specified by the StarTech unit which is 40m for CAT5e and 50m for CAT6.

Cat5e or CAT6 tie-lines with an RJ45 panel mounted socket at each end can be used for a multitude of things and not just ethernet. At the BBC we used them to send four balanced analogue audio signals per tie line. Perfectly usable for broadcast quality audio up to 50m or so even though it was un-screened. 

Alan