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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.
makes me think of riding around in the AM radio days and going silent when going under an overpass.
What kind of antenna did they use? "High gain" isn't all that descriptive.
-Randy
The speeds indicated look too slow to be useful except for remote low overhead / slow data acquisition stuff.
9600 baud is pretty darn slow, even with compresion.
Agent K: A *person* is smart. People are dumb, stupid, panicky animals, and you know it.
Anyone notice the 9600 baud bit rate? Marc
I'd never heard of this, but after some reading: Wireless over modems it's out there, and well supported. I can see it being a less touchy solution in that it's old school analog, but 40 miles? THat's hard to believe.
CBSD
free ipod and free gmail!
For what it's worth, I once used a 5 watt HF radio to contact the Canary Islands from Atlanta, GA. The signal was not strong, but we had no trouble carrying on a brief conversation. RF is pretty amazing stuff when the conditions are right.
Our radiolinks (which are like wi-fi) were sending line-of-sight transmissions, 9600 baud, with about 3 milliwatts. I cannot remember the frequencies we used but they were in the microwave range so I'm not sure it's comparable with the radiomodems mentioned in the article using 900 MHz band. Cool stuff anyway!
No time penalty is incurred during AES encryption or decryption.
That's pretty interesting. Perhaps they meant to say that there is no additional processing overhead beyond that which is introduced by performing the full number of rounds for a 256 bit key in hardware.
It seems you still need a shared secret. I assume it isn't doing any authenticated Diffie-Hellman to establish a session key.
Sorry, it's just kind of irritating when you hear things like "security through encryption." Great. You get integrity protection and data confidentialy while the data is in trasit. There are many other opportunities for an attacker to get your data besides when it's flying around in mid-air.
I bootleg Fizzy Lifting Drinks.
is the world flat?
I am the Alpha and the Omega-3
In ham radio, there's a 1000 miles per watt award that's not particularly hard to get....I made 1842 miles per watt (Palo Alto, California to Sakhalin Island in Russia) using a data modulation called PSK-31 and a wire antenna on my roof, and just over 1000 miles per watt from San Luis Obispo, CA to Estonia using CW: 5700 miles with 4.5 watts to a 28 foot wire thrown from a second-story window into a small tree, running on a pack of AA batteries.
* Up to 3000 feet range (Indoor/Urban environments, @9600 RF data rate)
We're talking about this thing for what reason?
CmdrTaco, please, drink some Jolt and wake up. That's twice in one day you've made me want to smack you around for wasting my time. 9600 baud? Really, why would we want to use this?
To compare this to 802.11b, they have what looks like a version that operates in the 2.4GHz band, guess what? 1500ft range, at 9600 baud.
While I'll admit this thing might have some very specific uses, like remote data collection where you don't have a lot of data, but you want it delivered at regular intervals over a distance where it'd be hard to put in relays or run a real link... but the damn thing costs more than $400, so if you *can* use 802.11g instead, you'll probably want to!
On earth, the horizon is about 5 miles away if you are in a totally flat plain or ocean, and you're eyes are 6 feet up off the ground. Stand on top of a 100 foot tower and the horizon becomes 36 miles away. So, what planet is this 40-mile line of sight transmission designed for?
Don't label something "offtopic" unless you know the topic well enough to tell what's on topic.
Sounds like it would be easier to go pick up a couple used Richochet modems on ebay. 128kbps and 1 mile line of sight out of the box. USB interface and all. Linux has the network drivers already.
Geekdom is becoming more and more mainstream every day. Ask a 16 year old about *Insert what used to be something only us computer geeks knew about*. Look about the number of registered /.'ers. It keep growing and fast. You know how many people I've turned on to /., many of them arent' even tech savy. They still check it everyday, and each month a higher percentage of the articles peak their interest, slowly but surely they start learning and the articles mean more to them. Before you know it they ask me "Hey did you see that article on arstechinca last week?"!
I boycott signatures
The Canopy Group has a set of office buildings in Lindon that has great connectivity. SCO occupies one of them, and some Canopy companies occupy others, but the rest are rented out to other companies, one of which I work for, which have nothing to do with SCO, and are happy about that.
Tweet, tweet.
GPRS here in the States starts at around $20 a month for unmetered service. And people say we're behind the times here.....
I do wish they would standardise on frequency allocations worldwide, as I live in the UK and might have a use for one of these, as it might be cheaper than what we have, the 458MHz band where things like this have been around for a long time, similar power, same baud rate, similar range with a directional antenna. I note that this one seems to be specified with a 4dB external antenna gain. Now that would be about a 4 element yagi, or a helix or dish, but maybe more as you would have a lot of attenuation in the coax unless it was very short, so the whole package is actually not so small as it seems.
But we have seen better than this on Slashdot, not so many weeks ago someone had fitted up dish antennae to a standard WiFi card IIRC, and were getting better range on less power (100mW?), and very much greater bandwidth, but of course very directional. That too ought to be allowed worldwide but probably is not.
This thing is not by any means a technical breakthrough, except possibly in terms of power efficiency, and even there I think the improvement is marginal.