[chbot] Long distance data link, advice from the guru's please

Sat May 10 21:32:21 BST 2014

Interesting. So for the Dyers Pass Road location that would be a very 
short distance from the diffracting edge to the other station, but for 
the Wairakei Rd one it would be more equal and at a much "straighter" 
angle. And between you and the edge, and also the edge and the 
respectively other station, there would be quite a good open LOS 
connection.

Unfortunately, the Alska case at hand sounds more like "110 km of open 
sea" and nothing else. I haven't calculated anything, but seeing that 
Jasper was mentioning 90 m masts, which wouldn't provide LOS (unless 
there are hills to mount them on at either end?), this mast height may 
already take into account diffraction. But would diffraction over 110 km 
of sea not be really poor? Wouldn't it be even worse than the same over 
smooth land, due to the good conductivity of seawater?

We are somewhat OT here - this might be more productive on a radio ham list?

Kind regards,

Helmut.

On 10/05/14 23:00, Richard Jones wrote:
> The line of sight rule can be interesting. From my lounge window in
> Diamond Harbour I can communicate using a hand held 5W radio with our
> Tait DMR base stations at 156MHz on Dyers Pass Road by the green and
> 540 Wairakei Road near the airport. I put this down to diffraction on
> the sharp edges of the port hills.
>
> Richard
>
> On Sat, May 10, 2014 at 10:34 PM, Mark Beckett <m.beckett at amuri.net> wrote:
>> Yep that right, but he has another thats lower at Halswell (about 300m)
>> My Gridpack is on a pole on the roof to clear the 4m hedge, and we can get
>> 3.5 - 4Mb/sec.
>>
>>
>> I think you'll find that the satellite uplink is probably 128Kb, and the
>> down is 256/512kb.
>> The problem is that its limited to a total of 4GB/week.
>>
>> Adding a second modem is not going to help with the total limit.
>>
>>
>> Unlike us in NZ who have poor broadband, my Australia friend complains when
>> he has to plug his computer in the get faster than his 54MB WiFi ...
>> I imagine our American friends are probably similar, and used to fast almost
>> unlimited internet.
>>
>> Mark
>>
>>
>>
>>
>> Helmut Walle wrote:
>>> If "Gondola" is the restaurant on Mt Cavendish, then that's equivalent to
>>> a 400 m mast...
>>>
>>> On 10/05/14 21:25, Mark Beckett wrote:
>>>> My wifi is 32km link to the Gondala, and uses a gridpack antenna and
>>>> licenced 600mW AP unit.
>>>>
>>>> Even with good antennas at both ends, I doubt you could extend it to
>>>> 110km.
>>>>
>>>>
>>>> Problem with most of these is that its "line of sight", so unless you can
>>>> put something in-between you're stuck.
>>>> Might be easier to move the Mainland, or use carrier pidgeons to
>>>> transport the SD cards.
>>>>
>>>> Mark
>>>>
>>>>
>>>>
>>>> Richard Jones wrote:
>>>>> Tait Radio Communications spun off a company called MimoMax that
>>>>> specialises in data links: http://mimomax.com/ This kit is completely
>>>>> licensable and uses diversity to achieve almost unbelievable bandwidth
>>>>> over a narrow band. This kit probably does not achieve 110km, but you
>>>>> could ask them.
>>>>>
>>>>> The best I've managed with Wifi type technology requiring no license
>>>>> is about 4km.
>>>>>
>>>>> I suspect when you discover cheap broadband link that does 110km you
>>>>> will be able to give up your day job :-)
>>>>>
>>>>> Best of luck with the visit.
>>>>>
>>>>> Richard
>>>>>
>>>>> On Sat, May 10, 2014 at 9:03 PM, Jasper Mackenzie
>>>>> <jasper.mackenzie at gmail.com> wrote:
>>>>>> Good day fellow ROboticisers,
>>>>>>   I have the privilage of flying off to visit my gf's family in Alaska
>>>>>> (you
>>>>>> know, the cringing Meet The Family awkward silences...), and her Dad
>>>>>> runs a
>>>>>> lodge for people to show off their enormous lenses and fancy new
>>>>>> gigapixel
>>>>>> cameras and glut out on Bears and stuff etc.
>>>>>>
>>>>>> Anyway, he has bandwidth issues, all these fancy photographers want to
>>>>>> upload photos etc etc and he has one sattelite link limited to 4gb per
>>>>>> week.
>>>>>> So I was thinking that maybe they could do a VHF (or similar) link to
>>>>>> the
>>>>>> mainland which is 110km away across the sea. I have found a russian
>>>>>> company
>>>>>> that had an interesting solution, but all seemed to need towers ~90m
>>>>>> tall
>>>>>> which would be a massive hazard as small planes are what these
>>>>>> outlanders
>>>>>> use to get around.
>>>>>>
>>>>>> Is there a solution? A data link with usable bandwidth for image
>>>>>> uploading,
>>>>>> VoIP etc. that could work over 110km without a huge tower, that I could
>>>>>> get
>>>>>> before june 1st? (Lets deal with licensing later 8)
>>>>>>
>>>>>> Cheers
>>>>>>
>>>>>> Jasper
>>>>>>
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