BLE long range (coded phy) is same than 1MBit

[RichardHdrd]

Dear Community,

I implemented the beacon-example with S112 and 1MBit mode and with S140 and coded-phy 125k sending one beacon per second continuously at +0dBm (sd_ble_gap_tx_power_set).

I implemented a BLE scanner with S140 and choice of 1MBit and coded-phy 125k mode reception, the latter using the cfg:

static ble_gap_scan_params_t const m_scan_param_coded_phy =
{
    .extended       = 1,
    .active        = 0x00,
    .interval      = NRF_BLE_SCAN_SCAN_INTERVAL,
    .window        = NRF_BLE_SCAN_SCAN_WINDOW,
    .timeout       = NRF_BLE_SCAN_SCAN_DURATION, // No timeout.
    .scan_phys     = BLE_GAP_PHY_CODED,
    .filter_policy = BLE_GAP_SCAN_FP_ACCEPT_ALL,
};

Now performing tests, I get similar results for both, 1MBit and coded-phy 125k mode.

As I can well understand, that the RSSI values don't differ as there is no difference in expected transmission/reception signal strength, I do not understand, why devices in both modes stop detecting beacons at an RSSI value of about -92dBm.

The vendor (FANSTEL) states for the BM833(A) module which uses a nordic 52811 chip:

BLE Sensitivity is increased to -97 dBm at 1Mbps and -104 dBm at 125 kbps with CODED PHY.

So is there any reason, why reception stops at RSSI -92dBm, especially for coded-phy mode?

Best regards,

Richard

[Sigurd]

Hi,

What nRF5-SDK version and SoftDevice version did you use?

How are you perform the test? Outside, in a open area with line-of-sight between the devices?

Do you see any difference if you send the bacon packet more frequently ? Try to change .active to 0x01 as well.

Have you tested this in a BLE- connection, or scanning/advertising only?

We did some testing a while ago, I'm not sure about the RSSI values, but there was a big difference in range: 
https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/testing-long-range-coded-phy-with-nordic-solution-it-simply-works-922075585