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Old 05-06-2016, 08:52 PM
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Can you get a wireless router with a range of 75 metres?

My home observatory is about 50 metres away from my home office.
The observatory has colorbond walls with aircell insulation on the walls and roof (foil backed foam).

With advances in wireless routers is it possible to use a wireless router to connect the observatory computer to my indoor computer do you think?

I also have a large Ethernet cable I was planning to install. It would mean digging about 12 metres of a small trough to bury it in but apart from that its also a viable possibility.

Greg.
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Old 05-06-2016, 09:06 PM
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Hi Greg,

You could get a wireless extender, most of which have an ethernet port on them, which acts as an ethernet connection back to the home router. I have 2 and both of them do this, allowing me to connect the ethernet of my Foxtel IQ1 to the wireless and back to the router and the internet.

If you mount this securely on the outside of the obs and it locks on to the wireless, you should get a secure ethernet link back inside. One of the ones I have, is a DLINK which looks a little larger than an old iphone 4 charger, so it has its 3 pin plug built in.

I connect this to my ip ethernet camera on the garage, simply with an extension cord and an ethernet cable from the extender to the camera. You could try something like this for about $40 and should work if your indoor wireless router is strong enough to be seen with say a laptop when standing outside the obs wall.

I'm using Enterprise class Aruba Access Points in my house, with a wired ethernet Access Point inside, and an access point in the obs, dropping ethernet to the computer I am typing this on, while connecting to inside via meshed wireless LAN.

You can also get some cheap Ubiquity solutions with gain antenna built in, that can make a point to point wireless bridge, with good speed, for a couple of hundred dollars all up.

You should be able to snag a cheap wireless extender in Harvey Norman, JB hifi, Good Guys etc.

Cheers

Chris
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Old 05-06-2016, 09:06 PM
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What sort of computer is in the observatory?

If it's a desktop, does the network card have ONE external antenna that you can unscrew?

If so, I'd recommend trying this LINK

You can get extensions to go between the antenna and the computer - ideally you'd mount the antenna on the outside of the observatory.

I've got a couple of these, one for home and one at Leyburn. I can pickup a signal over 50metres across the paddock. The routers use their standard antennae.

If the network card has multiple antennas, you might need to look for something a bit fancier.

DT

Last edited by DavidTrap; 05-06-2016 at 09:09 PM. Reason: added a bit
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Old 05-06-2016, 09:15 PM
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Originally Posted by DavidTrap View Post
What sort of computer is in the observatory?

If it's a desktop, does the network card have ONE external antenna that you can unscrew?


Its a Sony Laptop. I also have a desktop in there as well.


If so, I'd recommend trying this LINK

Looks good.


You can get extensions to go between the antenna and the computer - ideally you'd mount the antenna on the outside of the observatory.

I've got a couple of these, one for home and one at Leyburn. I can pickup a signal over 50metres across the paddock. The routers use their standard antennae.

If the network card has multiple antennas, you might need to look for something a bit fancier.

DT
Quote:
Originally Posted by Screwdriverone View Post
Hi Greg,

You could get a wireless extender, most of which have an ethernet port on them, which acts as an ethernet connection back to the home router. I have 2 and both of them do this, allowing me to connect the ethernet of my Foxtel IQ1 to the wireless and back to the router and the internet.

If you mount this securely on the outside of the obs and it locks on to the wireless, you should get a secure ethernet link back inside. One of the ones I have, is a DLINK which looks a little larger than an old iphone 4 charger, so it has its 3 pin plug built in.

I connect this to my ip ethernet camera on the garage, simply with an extension cord and an ethernet cable from the extender to the camera. You could try something like this for about $40 and should work if your indoor wireless router is strong enough to be seen with say a laptop when standing outside the obs wall.

I'm using Enterprise class Aruba Access Points in my house, with a wired ethernet Access Point inside, and an access point in the obs, dropping ethernet to the computer I am typing this on, while connecting to inside via meshed wireless LAN.

You can also get some cheap Ubiquity solutions with gain antenna built in, that can make a point to point wireless bridge, with good speed, for a couple of hundred dollars all up.

You should be able to snag a cheap wireless extender in Harvey Norman, JB hifi, Good Guys etc.

Cheers

Chris
Thanks Chris. It looks like it can be done fine.

Do you think there is any health risk from exposure to wifi or is that unlikely?

Greg.
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Old 05-06-2016, 09:27 PM
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Quote:
Originally Posted by gregbradley View Post
Thanks Chris. It looks like it can be done fine.

Do you think there is any health risk from exposure to wifi or is that unlikely?

Greg.
Wifi poses no health threat at all, the energy in the waves are simply much much to low.

However I would recommend Ethernet over a local network, somthing like this http://www.ebay.com.au/itm/100m-Blue...AAAOSwe-FU2Vf0 and running it underground.

Then (If needed) setup a shared folder on your PC inside that you can access over the Ethernet cable and you should see speeds of 50mb/s. This is especially useful for me when imaging planets, having over 150gb of data just going straight over Ethernet from my imaging laptop to my desktop inside for processing!
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Old 05-06-2016, 09:56 PM
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You can get an external directional antenna which will give you a range of few km. Look up yagi antenna. You can get them on ebay for under $20.
Just make sure it is one that matches your WiFi frequency (usually 2.4GHz but there are other frequencies as well).
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Old 05-06-2016, 10:03 PM
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If you can, hard wire it.

I had the luxury of building my own house and integrating the observatory into the home network and I have to say that a gigabit lan is an absolute pleasure. The dome is similarly 50m or so from the house and I had used WiFi prior to the final installation - the final trenching happened a little while after the house build.

Whilst the WiFi worked, the Lan really blew it out of the water when using remote desktop and when transferring large amounts of data. Suddenly I could use the max settings on RDP and now I sit in the office connected to the observatory as if I was in the dome myself without ever a glitch or stutter.

I do have to fess up though; being a video astronomer, I use enormous bandwidth.
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Old 06-06-2016, 03:34 PM
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Thanks for the replies. I guess I was being lazy and should dig the trench and use a hard cable which I already bought!

Greg.
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Old 06-06-2016, 03:41 PM
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Assuming the observatory has mains power from the house? On the weekend I installed some ethernet-over-power devices for my home networking. Works a treat. No need for running new cables. My range is nowhere near 75m, but pretty sure I read that it's fine for that sort of distance.

Apparently they don't necessarily need to be on the same circuit, but they do need to be behind the same meter.
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Old 06-06-2016, 05:16 PM
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Note that the speed of ethernet-over-power devices is overstated by a lot. See this to see what speeds you may expect.

I actually had two 500Mbs devices plugged into powerpoints next to each other (on one wall plate) and could not get more than 11MB/s transfer speed. That is only 1/5 of what is expected.
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Old 06-06-2016, 05:20 PM
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Mine is connecting cable modem, which is much less than LAN speeds anyway.
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Old 06-06-2016, 05:39 PM
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Quote:
Originally Posted by gregbradley View Post
Thanks for the replies. I guess I was being lazy and should dig the trench and use a hard cable which I already bought!

Greg.

Hi Greg,
I would put in a cable.
Radio is always subject to interference from other devices
which can emit harmonic frequencies on the same frequency you are using.
You'd be so annoyed if a wonderful frame of data was ruined by interference.
Optic fiber is the most noise immune of all - but expensive.

cheers
Allan
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Old 06-06-2016, 05:58 PM
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Quote:
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I would put in a cable.
Radio is always subject to interference from other devices
which can emit harmonic frequencies on the same frequency you are using.
You'd be so annoyed if a wonderful frame of data was ruined by interference.
WiFi data is digital and is subject to data integrity checks and retransmission on error. Interference is irrelevant unless it is so bad that it impacts on overall throughput (don't site your network next to a Tesla coil.)

Greg: WiFi will be perfectly adequate with halfway decent directional antennas if you want to avoid the cost of a trench. A few years ago they used to make them with Pringles cans (not joking... a colleague of mine used to beam an internet connection a few km to another family member with homebrew antennas like this.)

Have a look at the Ubiquiti gear.

Cheers,
Rick.
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Old 06-06-2016, 08:57 PM
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Originally Posted by RickS View Post
WiFi data is digital and is subject to data integrity checks and retransmission on error. Interference is irrelevant unless it is so bad that it impacts on overall throughput (don't site your network next to a Tesla coil.)

Cheers,
Rick.


TV digital signals have data correction but still I find if
I flick a light switch or an air con switches off I get a glitch on the picture.
Yes - there are error checks & re-transmission but if the interference is bad then it can't
give perfect files - no matter how many times it tries to re-transmit - there are still errors.
If I'm wrong then explain why I've seen NC milling machines in factories
controlled by optic fiber cables from an office 100 meters away?
Why don't they run them on WIFI?
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Old 07-06-2016, 06:15 AM
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Quote:
Originally Posted by alpal View Post
TV digital signals have data correction but still I find if I flick a light switch or an air con switches off I get a glitch on the picture.
TV digital systems are broadcast. It's not a peer-to-peer file transfer and it's not designed to avoid the occasional drop out.

Quote:
Originally Posted by alpal View Post
Yes - there are error checks & re-transmission but if the interference is bad then it can't give perfect files - no matter how many times it tries to re-transmit - there are still errors.
The data is in small packets and these are retransmitted when an error occurs, not the whole file. It *is* possible to have reliable file transfer in the presence of even high error rates.

Quote:
Originally Posted by alpal View Post
If I'm wrong then explain why I've seen NC milling machines in factories controlled by optic fiber cables from an office 100 meters away?
Why don't they run them on WIFI?
I don't know for sure but here are some possible reasons:
  • they are designed to operate in very hostile environments (welding, etc.)
  • they are concerned about interfering with other analog devices (WiFi uses shared spectrum)
  • timing is critical and retransmit delay is a potential problem
  • they were designed that way back when WiFi technology was less mature and there's no cost pressure to change
  • they are over engineering and butt covering in case of lawsuits
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Old 07-06-2016, 08:40 AM
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Quote:
Originally Posted by RickS View Post
TV digital systems are broadcast. It's not a peer-to-peer file transfer and it's not designed to avoid the occasional drop out.



The data is in small packets and these are retransmitted when an error occurs, not the whole file. It *is* possible to have reliable file transfer in the presence of even high error rates.



I don't know for sure but here are some possible reasons:
  • they are designed to operate in very hostile environments (welding, etc.)
  • they are concerned about interfering with other analog devices (WiFi uses shared spectrum)
  • timing is critical and retransmit delay is a potential problem
  • they were designed that way back when WiFi technology was less mature and there's no cost pressure to change
  • they are over engineering and butt covering in case of lawsuits
Hi Rick,
Good points.
The NC milling optic fiber cables were passing by huge 3 phase motors.
Maybe the strong magnetic fields would have interferred with a cable?

I think a standard Ethernet cable would be fine for the short distance of less
than 100 meters in the case we're talking about -
a telescope, observatory control system.

cheers
Allan
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Old 07-06-2016, 09:57 AM
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Originally Posted by alpal View Post
Hi Rick,
Good points.
The NC milling optic fiber cables were passing by huge 3 phase motors.
Maybe the strong magnetic fields would have interferred with a cable?

I think a standard Ethernet cable would be fine for the short distance of less
than 100 meters in the case we're talking about -
a telescope, observatory control system.

cheers
Allan
Allan,

I agree that a wired or fiber connection will always be faster and less fuss than WiFi. It just comes down to convenience and cost.

Cheers,
Rick.
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Old 07-06-2016, 01:44 PM
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I have been through this with my shed at home, roughly 50M from the house. I set up a wifi link to get an intercom going between the house and shed. IMO, Wifi is good for short range browsing on tablets and phones, and fixed assets only if you have no other choice.

Wifi, rubbish! I even used outdoor AP's with directional antenna, the link was patchy and unreliable, I had trouble getting a link of good enough quality to play music from a NAS in the house properly! The IP phone interom setup would loose connection and fail to reconnect.

I tried Ethernet over power extenders, again, rubbish! They would only connect if I used the GPO closest to the meter box in the house and closest to the house in the shed and throughput was poor!

Over the Christmas break we did a trench and had a 50mm comms pipe installed between the house and shed. A fibre link is the final plan but there has been a temporary cat5 link for about four months, th result is a reliable GigE connection and no dropouts! I still plan to get a fibre over there as I prefer the electrical isolation it affords but there is no great urgency now seeing that it works properly. Bluray resolution video, no problem, music, no problem and the IP phone has not fallen off the network since.

Whenever I finally manage to build an observatory out there I will extend the trench and cable that up too.
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Old 12-06-2016, 08:10 PM
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Hi Greg,
I use one of the powerline POE adapters mentioned above and I use RealVNC to control my observatory either from my office PC, Tablet or Samsung phone. I get 100Mbs transfer rate which is more than adequate. I use SGpro running on my Obs PC to control the gear. I also have an IR security camera in the obs so I can physically see where my mount is pointing or moving if I happen to be awake and wish to do so. All this runs concurrently with no time lapse that I have noticed. Real VNC transmits the screen data when you first log on, and then only transmits the screen data for any pixels that change . This way the bandwidth required is kept to a minimum. Yep in the mornings when I transfer the images from Obs pc to Office PC it can take a bit longer than full network speeds, but normally less than 10 minutes, and the transfer size of an entire nights images is somewhat dependent but usually between 4 and 5 Gb at most.
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Old 13-06-2016, 11:05 AM
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Somehow missed this thread... was curious as to which direction Greg finally took.

Anyway, another alternative would be to setup Yagi's on both the house and observatory. I've made a few antenna's in the past (my first one was a Pringle can) and it is not difficult. Google is your friend here... make sure to include DIY. Search for Yagi or Cantenna.

Commercially made Yagi's are readily available. These can throw a signal many kilometers. My Pringle's can could just touch half a mile, albeit with a dubious signal. You'll need solid mounts if you have high winds in your area.

Note: the one's I've built were for the 2.4Ghz range (802.11b/g/n). I've never built one for 5Ghz (802.11ac).

Last note: Ethernet is still your best option as the throughput is 1Gbps if your router's LAN ports supports 10/100/1000 (see discussion here)

OIC!
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