RSSI and range efficiency in nrf51822

[trk]

Hello everyone, i just stuck with bluetooth Range in nrf51822. I am transmitting data using bluetooth at +4dBm(which is maximum). In my experiment my nrf51 dongle is moving. when i am going little far distance connection is not established. So i calculated RSSI and i found when i was transmitting at 4 dBm., even at very near distance from transmitter RSSI was observed as -50dBm in MastercontrolPannel App. So are there any other factors which effect the range and scan efficiency. I want atleast 10 m Range. Any suggestions?

[Dave_couling]

You have to account for Transmitter Loss, Receiver Loss and Path Loss. Seeing -50dB at close distances sounds about right for a decent Transmitter and Receiver. Example Calculation below:

+4dB - 10dB (Tx loss) - 30dB (~close range path loss) - 10dB(Rx loss) = -46dB

[trk]

Thanks dave.how do you come up with those values for tx loss, close path loss and Rc loss?So by any chance is there a threshold rssi,untill where connection remains stable? And any other techniques to increase range?

[Dave_couling]

Those are just estimated values based on experience. I find my connection is stable until MCP reads ~90dB.

Techniques for increasing range are all hardware based. Tuning your Transmission line to 50Ohms, selecting a proper antenna. Tuning for that Antenna. It takes experience and RF knowledge to optimize these parameters. There are alot of whitepapers available online to get you started.

[trk]

Thanks Dave. That was helpful