SparkFun Forums

[ikrase]

Is there any way I can set up a wireless link that goes for some miles THROUGH SUBURBS?

It seems like everything sold here uses the high frequency ISM bands. I am looking at something to transmit from zero to maybe 5 miles through suburbs, trees, and ground. The remote is mobile and cannot be taller than 5 feet, so no high gain. The base station can be much taller but more than 20 feet is impractical. Data rate does not need to be super fast but non-slouchy would be nice. Cellular and wifi are both out. Power budget can take a few watts, but not too much more.

[skimask]

Uni-directional?
Bi-directional?
Battery power capability?
Mobile?
Total mobile involved?
Antenna capability?
Data rate? (non-slouchy doesn't say a lot...my 4mbps DSL line isn't slouchy to me, but for somebody on cable internet it is)
Accuracy of data sent/received?

[Roko]

SATCOM FTW:
http://www.digi.com/products/wireless-w ... p#overview

[Roko]

SATCOM FTW:
http://www.digi.com/products/wireless-w ... p#overview

Overkill, yes, but so cool.

Otherwise, maybe you can investigate lower frequency bands where you can use ground wave propagation. HAM license would probably be required, however.

The tricky part is you want relatively short range but through very solid obstacles...

[ikrase]

Bidirectional.

One remote, one base station talking at a time. Does not really need to be full duplex.
Data rates as low as 2400 baud would be acceptable if this works, is reliable, and satifies the other requirements well. Hopefully it would be more like 100k baud. Much more than that becomes overkill.

It's looking at solar, battery power, so a high power drain is not good. 5 watts requirement is fine, unless the low speed necessitates overly long transmissions.

The antenna can potentially be aimed, but the mobile section is not going to weigh more than 40 pounds or be more than four feet high not including thin booms and rods.

[stevech]

Is there any way I can set up a wireless link that goes for some miles THROUGH SUBURBS?

It seems like everything sold here uses the high frequency ISM bands. I am looking at something to transmit from zero to maybe 5 miles through suburbs, trees, and ground. The remote is mobile and cannot be taller than 5 feet, so no high gain. The base station can be much taller but more than 20 feet is impractical. Data rate does not need to be super fast but non-slouchy would be nice. Cellular and wifi are both out. Power budget can take a few watts, but not too much more.

Suggestions:

1. MURS band (150MHz) data radios. Several for sale. Can, with the right antennas, provide miles of coverage.

2. Get an amateur radio license (HAM). Pretty easy these days. Then you can use any of their bands, and their existing repeaters for data. The modems are low cost. The coverage is citywide in most cities, and perhaps 75 miles around each repeater. You can use 2meter band (146MHz), 450MHz band, etc. Check out ARRL.org and the leading ham radio packet data radio club http://www.tapr.org/. Lots of low cost used gear on the hams' on line flea markets if you don't want to buy new. Ham radio usage must be not-for-profit.

[nickersonm]

If you know it will always be in a suburban area, perhaps you could use a cellular module and TCP/IP? I have not tried anything similar, but it seems to me that it should work if you're in an area that will always have cellular coverage, and are willing to buy a prepaid data plan.

[stevech]

If you know it will always be in a suburban area, perhaps you could use a cellular module and TCP/IP? I have not tried anything similar, but it seems to me that it should work if you're in an area that will always have cellular coverage, and are willing to buy a prepaid data plan.

OP said above that cost of cellular was prohibitive. Hence the alternatives suggested above which have no airtime costs.

[Trigger]

There are specific frequency ranges assigned to digital packet in the HAM bands. The downside of using it is that you can't encrypt data traffic on HAM bands. The only exception being AMSAT control channels.

The lowest frequency you can use for data unlicensed is 900mhz. Though unless you get a good directional antennas you won't reach that far with your power budget. The 900mhz band is noisy as well which can limit range for low power radios without the advanced modulation, filters, and power to punch through it.

You can use this to help figure out your locations and the capabilities of the radios needed.
http://www.ligowave.com/linkcalc/

The alternate is to use something that supports a mesh topology and use small solar powered repeaters. (tell people they're for gathering environmental data or something for school)


.

[Trigger]

There are specific frequency ranges assigned to digital packet in the HAM bands. The downside of using it is that you can't encrypt data traffic on HAM bands. The only exception being AMSAT control channels.

The lowest frequency you can use for data unlicensed is 900mhz. Though unless you get a good directional antennas you won't reach that far with your power budget. The 900mhz band is noisy as well which can limit range for low power radios without the advanced modulation, filters, and power to punch through it.

You can use this to help figure out your locations and the capabilities of the radios needed.
http://www.ligowave.com/linkcalc/

The alternate is to use something that supports a mesh topology and use small solar powered repeaters. (tell people they're for gathering environmental data or something for school)


.

Rather 900mhz is the lowest useful band you get enough transmission power in to get any kind of range for data without a license. 443mhz is for low power remote control. 43-49mhz might be possible since it's in the range of consumer devices but I'd do some research before using it as likely devices have to be FCC approved to use it.