For a start, I should make it clear that Bluetooth class 1, class 2 and class 3 all refer to Bluetooth power classes, not to be confused with Bluetooth device classes.
The following table compares the available Bluetooth power classes:
| Class | Maximum Power | Operating Range |
| Class 1 | 100mW (20dBm) | 100 meters |
| Class 2 | 2.5mW (4dBm) | 10 meters |
| Class 3 | 1mW (0dBm) | 1 meter |
The actual range for each power class may vary depending upon environmental factors where the Bluetooth device is used. Class 3 devices have a very limited range and not very common, hence, they will be ignored for the rest of this discussion
So which power class should you choose for your new Bluetooth product? The two most important question that should be asked here are: "over what distance do I need my Bluetooth devices to operate?" and "what is the power class of the other Bluetooth device I want to communicate with?" Here are the two important pieces of information that you need to understand:
- If you wish to communicate over the 100m range, you will need a class 1 Bluetooth device at both ends.
- If you wish to communicate over the 10m range, you can have a class 1 or class 2 device at both ends.
Hopefully this post has cleared up any confusion regarding Bluetooth power classes.
5 comments:
Thanks for the info... But wondering, how do you tell if the bluetooth device is class 1 or not, even if it says it's class 1?
I think you will just have to trust the manufacturers info. You can double check by looking at the power rating - 100mW or 20dBm for class 1. Hope that helps.
contrary to what was said here i read somewhere else that all you need is a class 1 in one end in order to communicate 100m apart. i am not suer if that is true or not, but in my mind that was analogous to "if person A yells loud enough for their voice to travel over 100m, person B will be able to hear what person A is saying" and "when person B replies they only yell loud enough for their voice to travel over 10m" however person A also possesses the ability to also hear from 100m away (class 1) and will obviously hear the response.
so the question is, does a class 1 device able to transmit from 100m but not able to receive from 100m away? this requires further research but it makes sense to me that a class 1 device with a better antenna would be able to pick up transmissions from 100m away as well
Roni, you are not making sense. Of course a class 1 device can receive transmissions sent 100m away, but ONLY if they're from a device that is capable of transmitting that far, i.e. another class 1 device. The class isn't about how sensitive your receiver is (though it does come into account) but about how much power you transmit at. Skip the concern about whether you understood the analogy right and just trust that no device is going to receive a transmission from any class 2 or 3 device that is 100m away.
Anyway who cares - who is really ever more than 30 feet (10m) away from their BT device? Almost all BT devices are class 2 because 30 feet is a pretty good range. Sure there are use cases for needing to be much further away, but it's not a common use case. (If you need that, get yourself class 1 devices. :) )
Would be nice if I could find a class 1 bluetooth gps. Anybody know where I can get one?
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