One-Watt Wireless Radio Modem Reaches 40 Miles

maxstreampr wrote in to plug their radio modem. It's the size of a credit card, one watt, and can transmit 40 miles line of sight or 3000 feet indoors. Something about using the AT command set to fire off a command 40 miles through the air amuses me.

Comments

Testimonial

[TheVampire]

Our company uses the MaxStream RS485 modems, and I can attest that they do work very well.

Not very impressive

[jandrese]

Wow, that's some marketing. The "40 miles" claim is when you're in deep space and using high gain antennas. Actual performance will be less than a mile. Also, in case people want to compare this with 802.11 (which is difficult because they are in different bands), a typical 802.11b card radiates 30mW, instead of the 1W these guys are apparently claiming. The data rate is nothing exceptional either, 115.2kbps (and these are 1000 bits/kb sized), which pales in comparison to 802.11g at ~55000kbps. This technology would have a much higher "wow" factor 5 years ago, but nowadays that kind of range for that kind of throughput just isn't all that new or special.

9k6

[Anonymous Coward]

And the awesome radical speed of... 9600 bauds.
You might want to share some movies with your friend... 40miles away... you'll have your 700MB downloaded in just about... 580000 secs. (not bad.. 7 days)

Nothing amazing here

[Anonymous Coward]

Amateur radio operators have been doing this for years. The higher the antenna, the better. Put up a tower, say 50-60ft, put the antenna on top using good feedline and fittings, and you will get out to good distances. Better yet, take your laptop up to a mountain location, and you will be able to tx and rx for easily many times that distance. Hams do this routinely.

Re:Nothing amazing here

[dougmc]

But only with a license.

Yes, but it's not hard to get one.

I'm assuming they're unlicensed.

Well, they're likely FCC certified, but the spectrum they use is unlicensed, so ...

Obviously there are, but what are those limits?

For most of the unlicensed bands, under 1 watt. The WiFi `shootouts' and the like typically do not use amplifiers at all (microwave amplifiers are expensive), just high gain antennas, though I don't think the Part 15 rules (which is what things like this and WiFi are allowed under) allow the use of high gain antennas for transmitting. (If correct, this is very often violated, though obviously the FCC doesn't care that much.)

As for encryption, it's only the ham rules (part 97) that prohibit encryption. They also require that you ID yourself at the end of each message (and at least every 10 minutes) and that the usage be non-commercial. The FCC itself doesn't frown upon encryption, at least not publically.

I guess I need to read up on my FCC rules

Yup. This link might be an interesting place to start.

it's 900MHz

[Koyaanisqatsi]

40 miles alone is not impressive, HAMs talk all over the world on less than a watt (QRP) routinely, on HF bands off-course

But than I read this modem works on 900MHz, so that's quite a feat, worthy of a "Pringles can award"

Re:What kind of antenna??

[YankeeInExile]

Do the math ...

Po = +30 dBm
path loss over 64km at 915 MHz: -130
Pr = -100 dBm ... let's see ... at 9600 bps it requires -103 so that gives you 3 dB of fade margin even with isotropic radiators.

Put a +6dBi yagi (I think that is the maximum allowed on ISM under Part 47 anyway) at each end and you've got 15dB of fade margin, which should give you a couple of orders of magnitude of BER performance (the datasheet was notably lacking a BER / EbNo chart ).

Re:wow, I learn something new everyday

[BrookHarty]

I can see it being a less touchy solution in that it's old school analog, but 40 miles? THat's hard to believe.

Thats where the external directional antennas come in. Works for bluetooth and wifi.

Remember "baud" != "bps"

[Anonymous Coward]

The actual bps rate could be significantly higher the the listed baud rate which is only the physical switching speed of the unit.

Cool Stuff

[soapee01]

I'm faimiliar with MaxStream, good company, good products. They even gave us a little student discount. Used their 9xStream in my senior design project. Great for low bandwidth/low power embedded applications and extremely easy to integrate (simple UART IIRC). Just pick your own protocol and let the radio do its magic (ie nothing but basic RF knowledge required). This makes me think about picking up that project again and seeing what the extra distance might do.

It's not an 11b replacement!

[don.g]

I'm not really sure why this was worthy of a slashdot article -- judging by most of the posts, people are just complaining that it's slower than 802.11*.

But that's not what it's aimed at. Look at the interface it has on the non-RF side: multidrop serial. It's designed for telemetry applications. And when you're doing telemetry, lower power usage is good (as you may be running off solar-charged batteries) and bandwidth needs are minimal - you're not going to need more than a few bytes for a current water level or similar :-)

Re:And I'm getting 14,400 bps on my HSCSD mobile

[bhtooefr]

Last I checked, Sprint was the only cheap unmetered. BTW, it's 2.5G - it's under 300k rated.

Also, I think you're wrong on what plans there are. Here's what they've got:

Sprint PCS Vision Pictures Pack
Perfect for people who have a PCS VisionSM Picture Phone.Take, upload and send an unlimited number of pictures with Sprint PCS Picture MailSM. Includes 100 SMS Text Messages and Web access.
Obviously, you need a camera phone. It's $15, and comes with $5 free downloads/month.

Sprint PCS Vision Premium Pack
Perfect for people who want to download Ringers, Games, Screen Savers and other Sprint PCS Vision Services. Includes 100 SMS Messages and Web access.
$15, $10 free dl/mo.

Sprint PCS Vision Professional Pack
Read and send personal or company email with Sprint PCS Business ConnectionSM Personal Edition. Includes Messaging, Web access and Sprint PCS Picture Mail. ( Additional $15/month for Sprint PCS Vision Smart Devices that use the Microsoft® Pocket PC Operating System.)
It's really a waste if you've got ReqWireless WebViewer ($10, but Sprint doesn't offer it, so it's not free) and webmail, but there's a reason NOT to get a Pocket PC from them - $30/mo internet (because it's got Pocket IE), and no free downloads... It's $15/mo if you've got a regular phone.

They've also got picture and video mail packages ($5/ea, video needs picture) that can be standalone (1 cent/kb w/o Vision).

It appears that if you've got $100 or more per month in regular charges, you get free Vision (I thought it was the 2000 minute plan or greater, but...) I don't know what service level, but I BELIEVE it's Pro.

Get Free & Clear America, for the love of $DEITY, if you want to roam without getting raped ($5).

Now, I just need a way to get something like the Vi660, even with an early contract renewal (I've heard enough bad reviews about the Vi600, and I know the 660 works fairly well (except signal is weaker than my 3588i)) - I HATE THIS PIECE OF NOKIA CRAP THAT ISN'T VISION COMPATIBLE (and is a piece of Nokia crap). The Sprint salesdroid (OK, so there actually was GOOD customer service IN THE STORE - senior salesdroid) said the Nokia had FCC maximum power, and didn't say the same about the Vi660.

One thing I noticed - the thing has a wireless modem and CDMA2000 1x support. The thing is a fscking 2.5G phone, and doesn't even have internet access. At least the Vi660 is free online...

Re:Ribbit!

[ScuzzMonkey]

I shudder to think of the size of the handset needed to hold the processing power required for the insanely complex smart routing this concept would take to realize. Not to mention the batteries!

I agree that it's a neat concept, but early experiments with WiFi meshes seem to indicate that it will have problems scaling without a lot of horsepower behind it. And that's with fixed "pads" as it were.