Long Distance Transcievers

Hello all!

I've been working on a new project lately that involves sending data from the rear of a train all the way to the front. Obviously there's a lot of metal and other materials between the two points, and some trains have been said to be up to 3.5 miles long. This poses a problem as there's a lot of interference for standard wireless transmission and it's just too far to transmit data by wire. Satellite/SIM communication isn't a great idea since there is virtually no carrier that covers all of the USA and I don't want to constantly pay for data. I'm not sending very much data, just a live readout of a few variables (can't say) to the front from the back.

So far I've been thinking this (click) is my best bet with a 6 mile range LOS. I have no experience with radio communication and I don't know what LOS means or if it will be enough to get to the front of the train, but it seems to be one of the highest ranges for the price. Problem is, I have no idea how to transmit or recieve with this using an Arduino. Plus it draws more amps than the Arduino can output.

I've got virtually no price limit here, but it needs to be small, the XBee linked above is probably the biggest I want, something a little bigger is O.K. I also need this to be able to be interfaced by a standalone Atmega328P-PU. Lower power consumption is better but I can work with anything that's not too absurd. Again, the biggest thing here is being able to travel through a lot of material up to 3 miles long. It also needs to be a transceiver that can talk to and recieve data from the same model.

I know that may be a lot to ask but it seems like something of the nature probably exists. Any pointers, tips, suggestions, refferals, etc. are much appreciated.

Thanks and best regards,

Chris

I don't know what LOS means

LOS = Line of sight.

I have no idea how to transmit or recieve with this using an Arduino.

Connect the RX and TX pins, and ground, to the Arduino. Depending on where you connect the RX and TX pins, you can use an instance of the HardwareSerial class (Serial, Serial1, etc.) or the SoftwareSerial class.

Plus it draws more amps than the Arduino can output.

But not more than a decent power supply can output.

Again, the biggest thing here is being able to travel through a lot of material up to 3 miles long.

That radio won't. Why can't you put the transmitter on top of the train, though, so you don't have to transmit THROUGH the train? I doubt there is a radio on the market that can transmit THROUGH 3.5 miles of train, even if all the cars are empty.

LOS - line of sight. Six miles is the range you might achieve if the Tx and Rx antennas can “see” each other with no obstructions in between. However, that’s not all the spec says:

Up to 6 miles (10 km) RF LOS with high gain antennas

I’ve emphasized the significant bit. Using high gain antennas at the front and back of the train you should be able to get a range of 6 miles. The problem will then be the LOS thing. It won’t be possible to keep the two antennas pointing at each other on a train that’s up to 3.5 miles long when it is going round curves and/or on a gradient.

Back when trains still had a caboose, the engineer and brakeman could communicate via radio. Perhaps you could figure out how to use those radios to send the data.

Pete

It won’t be possible to keep the two antennas pointing at each other on a train that’s up to 3.5 miles long when it is going round curves and/or on a gradient.

A high-gain antenna is not necessarily that directional.

is there no way you can use a carrier to transmit the signal on the rails ?

Similar to domestic mains being used for ethernet distribution.

A high-gain antenna is not necessarily that directional.

Depends on what is meant by high gain but higher gain implies directionality.

Pete

I am considering this radio for ranges within your requirement range.

The XBee is 50mw (17dbm) transmit power. This Linx unit is 250mw (24dbm).

One of the requirements of my project is Frequency Hopping Spread Spectrum (FHSS). AFAIK, the XBee does not support that. The Linx does.

The downside: no library for the Arduino yet. I expect to hear from the Linx people tomorrow to discuss the technical aspects of my project.

edit: Here is the Linx evaluation board sold by Mouser.
http://www.mouser.com/ProductDetail/Linx-Technologies/EVM-915-250-FCS/?qs=%2Fha2pyFaduh6UzntcLIuBMERufHoPBTHp4xTDsvgMsMH%2FaYpZKgsnw%3D%3D

BTW, you will want to use an omni antenna, not directional. I don't know how much everyone knows about trains, but from my experience, on a long mountain climb or descent with switchbacks, the lead locomotives can be behind the caboose.

SurferTim: did you try putting that url in [url]...[/url] tags? Worked for me.

Pete

I tried earlier and the link didn't work. It does now. I must have screwed it up the first try. Thanks! :slight_smile:

These guys can make the link Microhard and if you need LOS with highly directional antennas you could use electronic compasses to determine direction of each radio and point the antennas correctly. Don't know if in your budget but they know what they talk about, they have made the links for a lot of UAVs at far greater distances at higher data rates.

Yes the higher the gain the greater the directionality, a bunch of ways to calculate it but the easiest way to understand is conservation of energy/power.

Build_and_Break:
Hello all!

I've been working on a new project lately that involves sending data from the rear of a train all the way to the front. Obviously there's a lot of metal and other materials between the two points, and some trains have been said to be up to 3.5 miles long. This poses a problem as there's a lot of interference for standard wireless transmission and it's just too far to transmit data by wire. Satellite/SIM communication isn't a great idea since there is virtually no carrier that covers all of the USA and I don't want to constantly pay for data. I'm not sending very much data, just a live readout of a few variables (can't say) to the front from the back.

Do you now, or have you ever worked for a railroad? Or been around railroads at all? Telemetery and radio control is transmitted from front engines to back engines and sometimes mid engines. Trains also go through tunnels and the front of the train may be on the other side of a mountain from the back.

Railroads have whole divisions charged with communications on board trains and from train to control centers. When communications may be questionable, they use repeaters. Railroads have many, many frequencies available to them for communications.

Also, you don't want to interfere with normal railroad communications. What will you do with multiple trains on parallel tracks, or one behind the other, or one on a siding while the other passes it?

I am concerned that you have not communicated with the railroad communications people.

Paul

I've been pondering ways to provide real time telemetry and video from the N&W 611 engine (recently refurbished after 20 years in a museum) to the passenger cars on excursions. I think one way might be bridged wireless routers atop the engine and passenger cars such that there would always be a LOS connection between adjacent routers along the length of the train.

35 tons of coal
22,000 gallons of water
872,600 pounds of engine and tender weight

zoomkat:
I've been pondering ways to provide real time telemetry and video from the N&W 611 engine (recently refurbished after 20 years in a museum) to the passenger cars on excursions. I think one way might be bridged wireless routers atop the engine and passenger cars such that there would always be a LOS connection between adjacent routers along the length of the train.

35 tons of coal
22,000 gallons of water
872,600 pounds of engine and tender weight

THE QUEEN [NORFOLK & WESTERN] 611 With SPIRIT!! & Insane Whistle & Chase & Pacing N&W 957 - YouTube

This should have been you first post! Now we know what you are working with and towards. Sounds like a neat idea. Since all the cars and the engine have electrical power, have you considered coax cable between each? Sure, one more thing to connect/disconnect, but they already have a bunch of stuff to deal with.

Each car would have it's own video monitor. The project then becomes how to use an Ardiono at the engine end to generate the picture and send it on a coax cable.

If you use any RF generation on the train, check with the people contracting for time on the commercial RR tracks for any statements about radio use.

Paul

@PaulS and @el_supremo Thanks for the clarification. Obviously there isn't much of a direct line of sight available in my case.

@Boardburner2 unfortunately there is seemingly no carrier that covers all railroads, at least none that are reasonably priced or are available for use still.

@SurferTim thanks for the link and tips. I'll definitely look into Linx.

@wwbrown Thanks! As mentioned earlier though, I will likely actually need an omni-directional antenna as the recieving end could move around (significantly).

@Paul_KD7HB The readings being transmitter must be read from the back anyway, so I cannot transmit from the front. The only time anything is being transmitted is while the train is at a station and is stopped completely. Repeaters don't make a lot of sense because then every time the train stops, someone has to place repeaters along the train. To answer your question, no, I haven't personally done any work with a railroad or train systems. I've already got a solution for multiple nearby trains, esp. because that'd be a problem when it's at a station.

Sorry for the delay in my reply, my desktop was offline for a while with Windows 10 problems :frowning:

I've considered using transceivers with wired antennas that can by mounted by magnet to the exterior of the train, which doesn't have to be too strong because it won't be mounted when the train is moving.

I'll also talk with a few friends who are in the railroad industry to see how plausible it is to wire it in to the existing communication system on the train instead.

Thanks for all the replies, I'm still open to suggestions and feedback.

Thanks again and regards,
Chris

I have access to the user manual for the Linx stuff now. No library is really needed. It is a direct replacement for wired TTL serial communication. Only a couple of settings need to be changed, and that can be done from a PC prior to use.

Build_and_Break:
@wwbrown Thanks! As mentioned earlier though, I will likely actually need an omni-directional antenna as the recieving end could move around (significantly).

That is why I had the following in my original reply
"and if you need LOS with highly directional antennas you could use electronic compasses to determine direction of each radio and point the antennas correctly."

Higher gain on the antennae is almost always a better choice than higher power on the transmitter, the antenna pointer could be setup very easily and each unit could send what direction they are pointing say every 15 seconds and then a quick calculation on each end would tell you what angle your antenna should point. A small servo could do the hard work, no problem these things are done in the UAV world all the time and we have to do it in 3D here you are in 2D pretty much.

Still don't want directional antennae just crank the power up to its max, the guys at microhard will be able to tell what is needed.

Might be application of A wireless mesh network?

A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology.

Put a group of nodes between front and end, let them self form and self heal.

@sonnyyu I've considered that, but these radio systems have to be removed and placed quickly, which makes having a lot of them to pickup and place and turn on and off inconvenient. Thanks for the suggestion though!

Key issue:self form and self heal. any given time few node turn off cause no problem, neighbours will be cover up.

One more thing It take place much higher layer than physics layer and could use lower frequency for longer distance.

wwbrown:
...

Still don't want directional antennae just crank the power up to its max, the guys at microhard will be able to tell what is needed.

If I recall it right, Max power will be 1W/1000mW, 30dBm at North American ( FCC rule)