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DisasterCom 15Mbps SatUp

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RolfGutmann
(@rolfgutmann)
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For a disaster training we have to fully design and engineer a 15Mbps sat uplink with electrical power generator failover and 2nd redundancy link prepared to move if a fully rain-cloud or evil jammer breaks the uplink.

Who can validate my engineering design? A long-experienced sat UPLINK crack is wanted.

Thank you for your support -)


   
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MDCR
 MDCR
(@mdcr)
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Iridium. Battery pack. Solar panels.

EDIT It's slow so only good as the backup solution.


   
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RolfGutmann
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Thank you, good approach. I only can design 30W electrical power and have to calculate the sat link budget for Eutelsat 7°E. The main link has to run 24h, then a breakdown and the failover has to work non-interruptable. The backup should run for 96h, which is quite difficult at night, also 15Mbps with a 1,5m dish.

To make the excercise more difficult the hemispheric reflection deducts 8,5dBm (difference, not absolute RF signal).

A question remains Is it helpful to move the sat unit to a higher elevation and install a directional link for broadcast up to 15km (no technical limitations, free in design, but add electrical power consumption). Solar is out, I would have to use a fuel cell instead. The sat unit gets during failover wind and is not fixed underpinned to avoid destruction of the dish. Not sure how to calculate the wind into angle adjustment for the dish pointing.

What impact has the sub-excercise of encrypting the link with a 512bit key?

Who has experience with disaster sat uplinks?


   
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MDCR
 MDCR
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Regular WiFi network with a directional antenna is a good alternative, 802.11 A and B have higher ranges vs the later broad spectrum variants (but they are also slower). Diesel electric generators is one option, battery banks is another.

One option if you do not need realtime data transfer, a terabyte hard drive in a rucksack and a mountain bike can beat the transfer rate of even a prioritised gigabit line… 15 km on a MTB take about 1 hour for an average person.

Always think practical.


   
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RolfGutmann
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MTB - very good approach. Previous trainings always had some struggle built-in, like unexpected equipment lost or delayed. Then we had to DIY-solder interfaces, cables and connectors.

For the sat uplink two major issues are power - e.g. diesel or battery banks and connectivity like SNR or adjusting the dish without precision tools like FSH3

https://upload.wikimedia.org/wikipedia/commons/8/85/Rohde_%26_Schwarz_FSH3_teardown.jpg

As delays and timing protocols are crucial over long distances, this time we have to use PTP IEEE1588v2 as maybe we have to cross-feed into a street small cell of Swisscom with the WiFi link to parasite use their wireless backhaul to avoid detection and interception by RF in a 'critical area'.

What do you think by daytime-to-night delayed or antedated transmission for better weather and space conditions?


   
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MDCR
 MDCR
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What do you think by daytime-to-night delayed or antedated transmission for better weather and space conditions?

Well, that is what backups solutions are for.

There are better solutions coming our way, i actually heard of this a few years ago and thought it already existed, but maybe I'm putting too much confidence in human ingenuity…

https://www.theregister.co.uk/2017/02/07/talking_to_satellites_with_frikkin_lasers/


   
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RolfGutmann
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-) I hope for future tech too but first I want to DIY to log thunderstorms in the sahara (in-link further down)

https://directory.eoportal.org/web/eoportal/satellite-missions/g/gpm


   
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RolfGutmann
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Got additional task to prepare. TWT calculation -((

Its almost impossible if the RF signal generator breaks and the TWTs got broken too. Is there a chance to handmade TWTs and solder them? I am not sure what tolerances in length are usable.

Have TWTs to be produced in mm accuracy or more secure?
How much of 'failure' of the TWTs can be compensated by the amplifier?
What materials are allowed/usable for TWTs?
Do they need to be specially galvanized inside?

If you are experienced in satcom, please help me!

To get a sense, see here (our dish only 1,5m)
http//www.ndsatcom.com/gfx/file/shop/mft_mtt/Datasheet_2.4m_mobile_station.pdf


   
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