CC2541 RSSI Characteristics Table in Datasheet

Hi Marc,

The reported RSSI value in the HCI message is the actual measured RSSI for a received packet. The "RSSI Characteristics" is the HW capability of the receiver.

Best wishes

I'm not sure I understand how to correlate these spec points to what the expected range will be from the HCI RSSI read command reported by the BLE stack. For example, what is the min/max that a user would expect to see from the HCI RSSI read command? If the best case sensitivity is -94dBm and the "useful RSSI range" is 64dB does the HCI RSSI read command return values between -94dBm to -30dBm only? I'm not sure I'm thinking about this correctly as dBm is referenced to 1mW but dB is a ratio between 2 power levels.
Additionally how would someone characterize their PCBs RSSI offset? Please clarify for me.
Kind Regards,
Marc

1 additional thought is that 0dBm (power level received 1mW) compared with the power level received at -94dBm (3.98107 e-10 Watts) I will get an answer of 64dB. But the spec shows that the input RF amplifier doesn't saturate until 5dBm in standard gain mode, so if I'm in high gain mode does it saturate at 0dBm and is this where the 64dB comes from in the spec (0dBm compared to -94dBm)?
Kind Regards,
-Marc

Hi Marc. I can provide a small amount of more information here but mostly we'll need someone else to answer this.
The offset used by the stack depends on the rx gain and whether the range extender is used and is defined as:

// RSSI Correction Based on Rx Gain
#define PHY_RSSI_DB2DBM_STD_GAIN 0x61
#define PHY_RSSI_DB2DBM_HIGH_GAIN 0x6A
// RSSI Correction Based on Rx Gain for CC2590 RF Range Extender
#define PHY_RSSI_DB2DBM_STD_GAIN_CC2590 0x67
#define PHY_RSSI_DB2DBM_HIGH_GAIN_CC2590 0x71

Hi Tim,
Thanks. So if I'm in high gain mode does the input RF amplifier saturate at 0dBm and is this where the 64dB comes from in the spec (0dBm compared to -94dBm)?
Marc