Author Topic: Issues transmitting data, ideas for data transfer other then cell modem  (Read 2028 times)

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Offline geofb13

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So I've been brought in to help with a system of stations that are already in place south of Montreal. It's a system of let's say roughly 15 stations that are currently set up to transmit via a cell modem to the servers. However, cell signal at some of these locations is shoddy at best and I'm not sure the modems and antenna are really the best. From my experience with two other systems cell modems seem to be the norm but I was wondering if anyone who deals with these if there's something better out there that won't break the bank.

Any ideas would be great as the guys who have hired me want to try RF transmitting via 900Mhz so that we can create a mesh network between the stations in case one station is more of a liability then others transmitting at certain times or during certain weather events.

Offline SLOweather

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More data would be great. What kind of antennas? Indoor? Outdoor? Omni? Beam?  Feedline? How old is that infrastructure? Got a map or lat and lons? Site photos? Got modem make and model number?

Offline geofb13

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Sorry SLOweather for the lack of info, most of it is because I was just literally dropped on this project and I've had one day of maybe 4 hours to look over some simple tests so far. I'll try to answer some of the questions as best as I can. The stations that are in use are the Spectrum Watchdog 2000 series with a mix of Full and Mini stations in the network.

Antennas? etc. -- Didn't really have a good look at them other then whomever set up the stations has them attached to the inside of the box that holds the modem, battery, COM board, and regulator for the battery and solar hook-up. From what I've looked over on the Spectrum website and documentation that seems to be a normal practice with this model/version.

It's at least 5 years old as the documentation that seems to be on the Spectrum website now does not include a a modem like the one's that are in this system. I'm not one hundred percent sure but I believe it's GPRS but obviously not the one they are selling to folks now, and not the ones that I've seen that are were sent to replace old ones in the current units. The new ones are bi-directional but that would have me assume that the old ones are not if they're also promoting that.

Here are the lat/lon for the area covered, mainly farm land except for clusters of homes or buildings in the small towns or farm centers that sprinkle the area. Lats run from 4519'48.48"N down to 456'32.34"N and Lon runs from 7341'50.00"W to 7321'06.04"W roughly. I don't have any photos of the sites but I do have their locations roughly approximated with their lat and lons.

Sorry that I wasn't able to answer more of the questions, I should be working on it more this week hopefully so I'll try to grab photos and other information when I can.

As for now, it looks like they want to as I mentioned before use RF but this has only been tested by one of the Agro-scientists north of where we are using a Raspberry Pi Model B, two Xbee Pro 900 RPSMA modules linked by two 900MHz 2dBi Duck antennas. That however, is not connecting more then one station and at the Raspberry Pi's end it goes straight through that farms network to the server. That might end up being the best option for some of these locations but others are farther away from the growers produce buildings.

I hope this helps a bit more. And thanks for the help so far!

Offline Beaudog

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I do not know anything about the equipment you are using. But it sounds like there is power at each site and maybe some type of modem.

Something like this could be put at each location and transmit to a central location and then upload using a regular internet access.

http://www.ubnt.com/airmax/nanostationm/

Offline geofb13

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Thanks for replying Beaudog. I don't know if I saw those on another thread that you've posted on or not, but at the moment those are out of the price range if I remember the prices correctly.

Offline geofb13

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Re: Issues transmitting data, ideas for data transfer other then cell modem
« Reply #5 on: August 30, 2014, 08:35:31 PM »
Just as an update, as of next season we will be using a mixture of two new communication setups. One of which will be for the farmers who have their stations close to one of their warehouse/farm buildings while the other will be for all other cases.

Case one where the stations are located relatively close by to a building (<1km) which will be a Digi Xbee Pro 900 on a Sparkfun Xbee Explorer Serial board that will attach to the station and to an omni-directional antenna. That will send to the receiving station which is another Xbee Pro 900/antenna on a Sparkfun Xbee USB board connected to a Raspberry Pi Model B+  that sends the data using the farms network and the internet to our servers.

Case two will involve a Texas Instruments board that was designed for us with some help from the Engineering Dept at Trois Rivieres CEGEP. That will use some higher powered antennas to connect multiple stations in a mesh network where we will be sending multiple stations data to which ever output/master station they can connect to. That master station will be connected to the old cellular modems (I've attached the link to what is currently in the systems) unless something changes and send its data as well as any satellite stations data out to the server.

This should removes most of the issues with the cellular network problems we've had at some locations.

Here are the modems that were standard with the older Spectrum Watch Dog stations we have. (http://www.multitech.com/en_US/PRODUCTS/Families/MultiModemGPRS/) The newer stations come with the modem as part of the communications board similar to what we have with the Texas Instruments boards. We shall see how it goes.