The XBee Concept?

Wireless & IoT
1

Hi Everyone

I’ve been having a look at these Xbee products. They seem great. But I’m still confused by the basic concept

Are these modules Transmitters or Transcievers?

And how do you set them up for communication between each other. ie do you just buy two modules and have them on the indentical frequency?

or do you require a specific reciever unit?

And how does the range work, for example, if i had a 1mW unit and a 100 mW unit communicating between each other, how would range work?

Any help on explaining the all encompassing concept of these nifty modules would be great.

Cheers

YF

2

Xbees are transceivers.

Two product lines: Series 1 and Series two. Most hobbyists/students will use Series 1. Series 2 is focused on mesh routing/ZigBee.

Xbees have extensive application firmware built in. Most other RF transceivers are just that.

XBees use the IEEE 802.15.4 standard for the wireless interface. Without ZIgBee or Digi’s better proprietary scheme, DigiMesh. Think of it as 802.11 without TCP/IP. Or think of it as Ethernet without IP, where source and destination are the MAC addresses of the NICs.

All the bother of modulation, coding, error detection/correction, is done by 802.15.4. You just use it.

You can use these out of the box as wireless serial port extensions, where the UART serial port on the XBee connects to something. that may be a USB adapter going to a PC’s USB, an RS232 adapter going to a PC’s serial port or the serial port on some gizmo.

Or you can use them out of the box to do data acquisition, analog or digital bits, and pass that wirelessly to a another XBee. That’s what Digi’s firmware calls Virtual Wire.

Or you can use the optional Digi API mode - to pass packets of data to the XBee via its serial port and vice-versa. With this, you can address data to a destination XBee of your choice, etc.

That’s a terse summary.

As to range: it’s all about your choice of antennas. One XBee product has a U.fl connection and you may attach a high gain antenna.

The XBee PRO product has about 60mW at the antenna jack. I’ve used them with 12dBi gain antennas (legal in the US). Range all depends on obstructions in the path. Range line of sight is easily calculated/predicted.