I’ve been working on a project where I’ve needed to download wirelessly to an Arduino Pro. The XBee Series 2 units I have I could not get to work, by the end of the project I wanted to use XBee pros so that I can get a long distance out of them and I was wondering if the wireless boot loading would work the same on series 1 Pro and the series 1 regular before I buy.
Thanks!
Yep. Same chip…but pro has more powa
macman20:
I’ve been working on a project where I’ve needed to download wirelessly to an Arduino Pro. The XBee Series 2 units I have I could not get to work, by the end of the project I wanted to use XBee pros so that I can get a long distance out of them and I was wondering if the wireless boot loading would work the same on series 1 Pro and the series 1 regular before I buy.Thanks!
A little antenna 101…
XBee Series 1 (non-ZigBee) - there’s an XBee, capable of about 2mW transmit power, and the XBee Pro capable of about 60mW. the difference between the two powers, expressed as dBm rather than milliwatts, is:
0dbM = 1mW
3dBm = 2mW
…
10dBm = 10mW
20dBm = 100mW
An XBee Pro then is about 18dBm.
Note the difference between the XBee and the XBee Pro: about 16dB.
So if you use gain antennas, though larger, you can get much the same benefit as higher transmitter power.
Remember too, that a gain antenna benefits receiving too, whereas higher transmitter power does not.
So in dBm, one can simply add the antenna gain you might use…
3dBm + 8dB antenna = 11dBm radiated power. Compare that to the XBee non-Pro.
The short wire antenna on the XBees has about 0 or -2dB of gain (negative gain, yes.)
The PC board chip antenna has less yet, and is is more directional than the wire antenna.
Antenna gain comes only from an antenna being directional. Focused power this way, less that way.
Confusion corrector:
An omnidirectional antenna with some gain, isn’t. It can be omni in the horizontal (compass headings). But the power “focus” is because on the vertical, it’s not omnidirectional. It’s at least a dimpled sphere (low gain), or a doughnut, higher gain, or a bagel, higher yet gain.
A yagi TV antenna is directional on the horizontal, and to an extent, also on the vertical. A satellite dish (parabolic) is directional on both H and V.
And so it goes.
A perfect antenna with a real spherical pattern is a common reference for stating antenna gain. The gain is relative to this sphere, called an isotropic radiator. So often, in wireless data, we see antenna gain in units of dBi - that’s just dB of gain relative to the isotropic radiator.
So a 3dBi antenna doubles the power in some directions. In other directions, the dBi is negative. An antenna with gain on the H might have 3dBi gain at zero degrees bearing. But at + or - 30 degrees the gain may fall to 0dBi. This 3dBi for 60 degrees total is called the 3dB gain beamwidth. Again, the gain can be on the H (a flashlight), or on the V (a doughnut).
You’ll see polar plots for H and another for V, for antenna gain. For a quality antenna. Lots of crap antennas have no polar plots because they were not really designed - just tossed together. Like a lot of WiFi junk.
In 2.4GHz. it’s easy to buy a 12dBi omni. It’s 3dB beamwidth on teh V is about 7 degrees. So don’t tilt it! Also, one can buy for 2.4GHz lots of yagi type antennas, directional on the H.
OK. more than you wanted to know. But antenna basics are very useful. That the gain applies bi-directionally, unlike the benefit of higher transmitter power - is good to know. Esp. since antennas consume no power.