wrist walkie talkie has 300 megawatt output from Li-Ion!!!

[Greebe]

http://start.msn.com/connecting.aspx?item=4

"It's 300-megawatt output is powered by replaceable, rechargeable lithium-ion batteries."

Of course they ment 300 milliwatt output... hehe

[Technoid]

ROFL

[Brian Ellis]

Must have a big wrist AND big muscles! For the technologically-challenged, 300 MW is the output of a medium-sized thermal power station! The user would also be fried with 300 MW on his wrist. Diathermy isn't in it. About three former lives ago, I used to have a ham transmitter, about the size of a bookcase. It had the then max legal power of 150 W in the UK, so this marvel of modern engineering has shrunk 2,000,000 bookcase-sized transmitters into something on your wrist. I guess the Li-ion batteries may last about 1 ps (picosecond = 1-trillionth of a second).

Duh! what a mistake, they mean microwatts, not even milliwatts, which is next to bugger-all!

[GuchiGuh]

See above for an engineer talking

You see what engineering does to you? NEERRRRDDDD...ahemz...

[Greebe]

Naw they mean milliwatts. The FCC limits broadcast power for personal non licensed power to 750milliwatts in the typical handhelds using the new "Family band" sold for ~$50 (more or less) a pair these days.

Shoot the "wire" that undercover cops use are 1 watt and they're smaller than a pack of cigarettes. reason for being so large is that they are powered by two 9v batteries which take up 80% of their volume.

As fas as Lithium-Ion batteries they're old news. They latest Lithium Polymer batteries are far far better and can output a significant amout of current in an extremely small size/weight. Example an iRate 2600 (mah) LiPo can sustain a 8C continous discharge rate (ie 20.8 amps) per cell with a short term discharge(~5 minutes) of 10C (26amps) or a 15C burst (<8 sec) of 39amps. This is all done in a package size of 3.5"(88mm) x 2.2"(55mm) x 0.18"(4.6mm) and weigh 1.83oz. (51.88g)

[Brian Ellis]

You surprise me.

A cellular phone usually operates with the GaAs power amplifier drawing a collector current of about 55 mA at 2.8 V, consuming ~150 mW (Nokia dixit). The RF conversion efficiency cannot be higher than about 30%, or ~50 mW RF power output, assuming perfect coupling to the antenna. Are you telling me that a toy such as this should be 6 times more powerful?

[Greebe]

Yes I am. You are very out of date on todays tech (btw that "wire" is based on 20 year old tech, nothing even close to what's available today

[Greebe]

Think about what you've said for a sec...

if this were µW power levels think of what the recievers sensitivity/selectivity must be to RX at a 1.5 mile LoS range (as spec'd for this wrist device)

The "Family band" radios have upto a 5 mile LoS range, with 2 miles being typical for the non licensed versions...

Let me find a link to one...

[Greebe]

http://commerce.motorola.com/cgi-bin/ncommerce3/CategoryDisplay?cgrfnbr=8&cgmenbr=126

[agallag]

Cell phones are designed to transmit relatively short distances. That's why there are big ugly cell towers everywhere. These radios don't have the help of a huge powerful tower, and have to transmit the 2-5 mile distance to the recipient all by their lonesome.

The old analogue phones were much higher power than todays little digital units.

[Jon P. Inghram]

if this were µW power levels think of what the recievers sensitivity/selectivity must be to RX at a 1.5 mile LoS range (as spec'd for this wrist device)

GPS receivers work just fine with signals weaker than the ambient noise levels.

[the main lobe]

Nah, maybe it is effective 300MW. It is just ultra efficient (so you don't get burnt) and incredibly directive (super high gain).

Just kidding, but it is interesting to note that when a television station says they are operating at say 150kW that doesn't mean they have a 150kw transmitter. Their transmitter is actually much smaller and is elevated enough that they don't have to waste energy radiating in a full sphere.