蓝牙-TX Power and rssi [英] bluetooth - tx power and rssi

问题描述

我正在试验两个低功耗蓝牙4.我在下载的android应用中获得了uuid，tx功率电平和rss值.

I am experimenting two low energy bluetooth 4. I am getting uuid, tx power level and rss values on the android app that I downloaded.

我注意到这两个中的一个正在发送0的tx功率电平，但另一个正在发送4的tx功率电平，即使我将它们放在同一位置，在android应用程序上也会看到不同的RSSI值.这意味着我的android手机和这两个蓝牙设备之间的距离是相同的.我理解，如果差异为+/- 5，但差异为+/-15.是因为发射功率电平吗?

I noticed that one of these two is sending 0 for tx power level, but the other one is sending 4 for tx power level and see different RSSI values on the android app even though I put them in the same spot. It means that the distance is same between my android phone and these two bluetooth devices. If the difference is +/- 5, I understand, but the difference is +/- 15. Is is because of the tx power level?

而且，我需要考虑tx功率水平，以计算BLE 4和我的android应用之间的接近度吗?

And oo I need to take tx power level into consideration to calculate the proximity between the BLE 4 and my android app?

推荐答案

您不能直接将RSSI与BLE中心与外围设备之间的绝对距离联系起来.当然，RSSI受(但不仅限于)距离的影响.但是，还有其他重要因素，例如干扰，传输介质等.如果您的两个BLE外设是两个不同的型号，则值甚至可能相差更大.

You cannot directly relate RSSI and absolute distance between BLE central and peripheral. Of course RSSI is affected by, but not only, distance. However there are other significant factors such as interference, transmittion medium, etc. If your two BLE peripherals are two different models, the values may even vary more.

对于BLE连接，RSSI波动大约+ -15是非常正常的，在实际情况下几乎不可能消除.因此，如果您希望误差小于几米，那么基本上就不能仅依靠RSSI来计算距离.

RSSI fluctuating for around +-15 is very normal for BLE connections, and nearly impossible to eliminate in practical cases. So basically you cannot only rely on RSSI for calculating distance if you want the error to be less than several meters.

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