one for the telecomms gurus

My google-fu has failed me and as such i am turning to the learned denizens of arrse in the hope that they can turn something up regarding the following technical problem;

if i had a mobile phone and used this to communicate with a remote device (for example a 3/4G enabled raspberry pi) is there something on the market i could use in areas where there was no data network available to allow these to communicate with one another? some form of portable mobile repeater? i dont need to access the internet (and wont have it) i just want to link from the mobile to the remote device. is there a way to do this?

everything else i've looked at is obviously focused on taking a landline and then creating a 3/4G signal to allow smartphones to access the internet. as i want to connect the smartphone and the remote device in locations where a landline wont be available (and would be operating outdoors in areas with no infrastructure) then obviously this wont apply. i was wondering if there are any other devices i might try and research which would be better suited to this type of task
 

endure

GCM
Depends on how far apart they are. Bluetooth as previously suggested or ad hoc wifi if they're reasonably close together.
 
Blue tooth range is 10m(up to theoretical 60m with strong hardware), wifi range is ~90m, neither will give him enough range for his bomb drone.
 
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would be looking for longer range than that. at least 1km separation between smartphone and remote device which is why i'm picturing some form of mobile repeater, possibly on a mast
 
Blue tooth range is 10m(up to theoretical 60m with strong hardware), wifi range is ~90m, neither will give him enough range for his bomb drone.
if i was planning a terrorist attack i'd have taken the precaution of using an untraceable sock puppet account.

Daft Dodger or something
 
would be looking for longer range than that. at least 1km separation between smartphone and remote device which is why i'm picturing some form of mobile repeater, possibly on a mast
That is why I said you will want OpenBTS. Your range will depend on the amplifier and antenna that you plug into your SDR that is plugged into your computer that is running the system. And you and your team can call each other on your own private cell network in what ever area you are hiding out in.
 
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OpenBTS looks very interesting. It's voice-only at present though. SIP won't give you data. The interesting thing is that it's all software, so they could in theory add in the GTP layers and provide a data service over the top. The hard bit is the air interface, which they must have cracked in order to offer basic voice service. This does surprise me, because the encryption is non-trivial, and if it is open source, the crypto modules must be open source too. Massive security hole!

In the absence of data over openBTS, you could look at long-range wifi. My internet connection as I type this is over an 11KM wifi shot to a tower on top of a mountain.

Something like this ought to work, as long as you have line of sight between the RPi and wherever the network is.

 
That is why I said you will want OpenBTS. Your range will depend on the amplifier and antenna that you plug into your SDR that is plugged into your computer that is running the system.
cheers, i'll have a proper look in the evening but at first glance it looks like it might do the trick. i'd then need to understand the types of amplifier and antenna required.

squiggly line stuff make my head hurt
 
OpenBTS looks very interesting. It's voice-only at present though. SIP won't give you data. The interesting thing is that it's all software, so they could in theory add in the GTP layers and provide a data service over the top. The hard bit is the air interface, which they must have cracked in order to offer basic voice service. This does surprise me, because the encryption is non-trivial, and if it is open source, the crypto modules must be open source too. Massive security hole!

In the absence of data over openBTS, you could look at long-range wifi. My internet connection as I type this is over an 11KM wifi shot to a tower on top of a mountain.

Something like this ought to work, as long as you have line of sight between the RPi and wherever the network is.

ideally i'd be looking for something which would be portable, probably running on a genset. what i would say though is your (@Anonymous Yank 's) suggestions make me believe that it is possible even if i will need to find an adult to sort it out for me.
 
OK....I'm a little confused by the question.

Are you saying that you want the two to communicate locally with each other? Then either bluetooth or a cable connection.

If you want to be able to allow one, in a remote area, to dial up the other where there is service, or vice versa, then you are, in reality looking at Satellite phones.

Not as bad as you might think, but it all depends on the protocols that you want to use.

Again, it all depends on the part of the world that you want to work in. Thuraya has a number of sleeves and data terminals that would meed your needs, but if you are outside of their network (the Americas, for example) then you would be looking at the likes of Iridium or Inmarsat.

If it's just small amounts of data, on an irregular basis, it's probably not too much. If it's RS232, then you will need to find the equipment that will take the data ports and convert etc.

If you want to start shifting lots of data, then you would probably be looking at an INMARSAG BGAN (Broadband Global Area Network), but we are starting to talk big bucks now.

It's all horses for courses, nothing is impossible these days, you can even get data at the poles, you just have to pay for it!




Quite a bit of stuff on Ebay, second hand and ready to use for sensible money. You can also buy discounted SIM cards etc.

Enjoy
 
OpenBTS looks very interesting. It's voice-only at present though. SIP won't give you data. The interesting thing is that it's all software, so they could in theory add in the GTP layers and provide a data service over the top. The hard bit is the air interface, which they must have cracked in order to offer basic voice service. This does surprise me, because the encryption is non-trivial, and if it is open source, the crypto modules must be open source too. Massive security hole!

In the absence of data over openBTS, you could look at long-range wifi. My internet connection as I type this is over an 11KM wifi shot to a tower on top of a mountain.

Something like this ought to work, as long as you have line of sight between the RPi and wherever the network is.

Already handled... look up Range Networks RangeSDMN. (Software Defined Mobile Network)
As you can see the node configuration for call, text, data mix could be difficult...
rangesdmn-node-profile.png

OpenBTS works with the opensourced Range Networks SDR1 and you can dl the design files on the front page of the site.
 
OK....I'm a little confused by the question.

Are you saying that you want the two to communicate locally with each other? Then either bluetooth or a cable connection.

If you want to be able to allow one, in a remote area, to dial up the other where there is service, or vice versa, then you are, in reality looking at Satellite phones.

Not as bad as you might think, but it all depends on the protocols that you want to use.

Again, it all depends on the part of the world that you want to work in. Thuraya has a number of sleeves and data terminals that would meed your needs, but if you are outside of their network (the Americas, for example) then you would be looking at the likes of Iridium or Inmarsat.

If it's just small amounts of data, on an irregular basis, it's probably not too much. If it's RS232, then you will need to find the equipment that will take the data ports and convert etc.

If you want to start shifting lots of data, then you would probably be looking at an INMARSAG BGAN (Broadband Global Area Network), but we are starting to talk big bucks now.

It's all horses for courses, nothing is impossible these days, you can even get data at the poles, you just have to pay for it!




Quite a bit of stuff on Ebay, second hand and ready to use for sensible money. You can also buy discounted SIM cards etc.

Enjoy

to give some context i'd look for the remote device to tell the smartphone its location and for the smartphone to the be able to send commands to the device (small amounts of data, just telling the device to execute program X, Y, Z etc.)

this would be done via an app which would display the location of the device.

what i'm trying to figure out* is, if used in an area (temporarily) where there is no mobile data network available, how could this be done?



*if you havent guessed already, comms stuff isnt really my bag
 
C11 R210.jpg
This probably meets your needs, voice, and could be fitted with a decent modem for data, its battery powered, "portable" and can be supported via a small genset.
 
to give some context i'd look for the remote device to tell the smartphone its location and for the smartphone to the be able to send commands to the device (small amounts of data, just telling the device to execute program X, Y, Z etc.)

this would be done via an app which would display the location of the device.

what i'm trying to figure out* is, if used in an area (temporarily) where there is no mobile data network available, how could this be done?



*if you havent guessed already, comms stuff isnt really my bag
Well, in that case, if there is no GPRS/GSM/3G/4G data connection available in the area, and you are certain of that, then, really you are left with two choices. Some form of Radio connection (depending on how far away the two are) and frankly, that is likely to be difficult and expensive, or you revert to the existing satellite communications network.

The reality is that what you want to do, is not difficult, but it "could" be expensive.

DId you look at the THURAYA network coverage? Does it cover the area that you are interested?

THURAYA is the cheapest of all the sat networks, and some kit can be got for sensible money on Ebay. It gets cheaper if you are in the "Nova" areas...



Ideally, you would want one of the devices in a standard GSM area, so that will keep you costs down (or you will need two sat phones, but what you want to do is very "doable" it all comes down to cost.

For example....



clearly, you would want whatever device to be able to connect quickly to keep those minutes down...but deffo very doable.

If you wanted to go down the BGAN route....



So, the first thing to establish is that there is deffo no GSM/Mobile network where you want it....consider if a booster might help if it's fringe coverage.

If it's a deffo no, then can you keep one device, or the other, in a mobile coverage area, so you only need one sat terminal?

Then, you need to consider if you will have good views of the sky? Sat phones normally won't work inside, certainly not through a few layers of concrete anyway.....How are you going to set up the calls? Manually? Automatically? both are possible, but auto dialling etc would need to be set up and you'd need to make sure that any equipment purchased would allow it and that you could write the script to do so....

Lots and lots and lots of variable. All possible.

You need to do some thinking, consider a budget and then, maybe, get your hands on one and have a play. The good news is that, certainly THURAYA kit is not that expensive and you can always sell it on after if you decide it's not the way to go.
 
to give some context i'd look for the remote device to tell the smartphone its location and for the smartphone to the be able to send commands to the device (small amounts of data, just telling the device to execute program X, Y, Z etc.)

this would be done via an app which would display the location of the device.

what i'm trying to figure out* is, if used in an area (temporarily) where there is no mobile data network available, how could this be done?

*if you havent guessed already, comms stuff isnt really my bag
How much of an area do you need to cover? How much data are we talking about? Also, how much mobility do you need - full mobile (like a mobile), nomadic (it won't be in the same place all the time but it doesn't need to do seamless handoffs going 200mph), or can you rely on it standing still?
 
Well, in that case, if there is no GPRS/GSM/3G/4G data connection available in the area, and you are certain of that, then, really you are left with two choices. Some form of Radio connection (depending on how far away the two are) and frankly, that is likely to be difficult and expensive, or you revert to the existing satellite communications network.

The reality is that what you want to do, is not difficult, but it "could" be expensive.

DId you look at the THURAYA network coverage? Does it cover the area that you are interested?

THURAYA is the cheapest of all the sat networks, and some kit can be got for sensible money on Ebay. It gets cheaper if you are in the "Nova" areas...



Ideally, you would want one of the devices in a standard GSM area, so that will keep you costs down (or you will need two sat phones, but what you want to do is very "doable" it all comes down to cost.

For example....



clearly, you would want whatever device to be able to connect quickly to keep those minutes down...but deffo very doable.

If you wanted to go down the BGAN route....



So, the first thing to establish is that there is deffo no GSM/Mobile network where you want it....consider if a booster might help if it's fringe coverage.

If it's a deffo no, then can you keep one device, or the other, in a mobile coverage area, so you only need one sat terminal?

Then, you need to consider if you will have good views of the sky? Sat phones normally won't work inside, certainly not through a few layers of concrete anyway.....How are you going to set up the calls? Manually? Automatically? both are possible, but auto dialling etc would need to be set up and you'd need to make sure that any equipment purchased would allow it and that you could write the script to do so....

Lots and lots and lots of variable. All possible.

You need to do some thinking, consider a budget and then, maybe, get your hands on one and have a play. The good news is that, certainly THURAYA kit is not that expensive and you can always sell it on after if you decide it's not the way to go.
I’ll have a look at the THURAYA coverage but would have a concern that I might end up swapping one coverage issue for another.

Edited to add; I’m thinking remote rural locations within the UK. I’d say that for 90% of cases the solution would be provided by standard data networks.

How much of an area do you need to cover? How much data are we talking about? Also, how much mobility do you need - full mobile (like a mobile), nomadic (it won't be in the same place all the time but it doesn't need to do seamless handoffs going 200mph), or can you rely on it standing still?
I’d want to ensure I could separate the remote unit and the smartphone by at least 1km. I wouldn’t look to be transmitting much data, the remote device would be nomadic in the sense that once in place it wouldn’t need to move again* and I would would only look to send a command to initiate a program which was stored on the remote device**

*could program the app to send a response to say that it had acquired the device and this would tell the remote device to stop transmitting it’s position unless there was a change or a new request for its position

**it might send the smartphone a confirmation of the request but that’s about it
 
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In that case, building a private cellular network is huge overkill.

You might get away with WiFi using directional antennas if the remote station is going to stand still - this is a cheap and simple solution and one that could give you decent bandwidth if you want it.

Alternatively, if you are sure you don't need broadband, there is a free, open source, and unlicensed solution that will definitely cover the area and put up with some mobility - LoRA. The gateway costs about a hundred and the RPi shield about a tenner.

https://www.amazon.co.uk/s?k=lora+gateway&crid=EDBIYJIGPRLA&sprefix=LoRa+gate%2Caps%2C145&ref=nb_sb_ss_i_1_9

SK Telecom covered the whole of the ROK with this for $52 million. It won't do video, but short messages just fine, and it can even do positioning itself if you buy three gateways. The low band spectrum (864MHz) is great for coverage and the radio waveform designed for robustness.
 
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