NRF52840 Coded Phy Sensitivity with soft device 6.0.0-6.alpha

[Christian]

Hi,

although the NRF52840 has a nominal receiver sensitivity of -103 dbm I am only able to get a sensitivity of around -97 dbm. I know there was a bug in older soft device versions resulting in a decreased sensitivity, but I am using soft device 6.0.0-6.alpha in which this bug should be fixed. I used a modifiedatt_mtu_throughput example to print the RSSI when changed, but connection between two nrf52840 boards is still lost at around -97 dbm.

Is there anything else that needs to be considered apart from the soft device version?

Thanks in Advance

Christian

[Christian]

Hi Martin,

I used the att_mtu_throughput example and modified it to start RSSI measurement after connection establishment (by using sd_ble_gap_rssi_start(m_conn_handle, 0,0);). The RSSI is then printed by adding the following lines to the event handler:

case BLE_GAP_EVT_RSSI_CHANGED: { NRF_LOG_INFO("RSSI: %i",p_ble_evt->evt.gap_evt.params.rssi_changed.rssi); } break;

For the measurement I used two nRF52840 boards, each one of them in a Rohde & Schwarz shielding box to avoid external interferences. The boards are connected to the output of the boxes via SMA Cable and an SWF to SMA Adapter on the J1 Port of the Boards. The boxes itself are connected via a digital attenuator to guarantee a controllable channel.