Coded PHY distance testing

RE: Coded PHY distance testing

Simonr — Fri, 12 Jun 2020 06:03:06 GMT

A few things you might have missed:

First, make sure that adv_data.flags is set to BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE; This is required in order to advertise in Coded PHY. Also, please note that you can not have scan response data in your Coded_PHY advertisements, and you need to set the scan response data to 0 like this.

.scan_rsp_data =
{
.p_data = NULL,
.len = 0

}

If you're still having trouble, you can take a look at this thread, where a main file with a functioning Coded PHY advertisement can be found.

Best regards,

Simon

RE: Coded PHY distance testing

fackbell — Wed, 10 Jun 2020 16:58:41 GMT

Yes, I didn't show the line of code, but I have set to +8.

RE: Coded PHY distance testing

hmolesworth — Wed, 10 Jun 2020 15:08:17 GMT

Might not help, but we had this note:

    // If using BLE_GAP_PHY_CODED in Central change NRF_BLE_SCAN_BUFFER (31) to BLE_GAP_SCAN_BUFFER_EXTENDED_MIN (255)
    init.config.ble_adv_secondary_phy = BLE_GAP_PHY_CODED; // uint32_t PHY for the primary advertising. @ref BLE_GAP_PHYS (BLE_GAP_PHY_1MBPS, BLE_GAP_PHY_2MBPS or BLE_GAP_PHY_CODED)
    init.config.ble_adv_primary_phy   = BLE_GAP_PHY_CODED; // uint32_t PHY for the secondary (extended) advertising @ref BLE_GAP_PHYS (BLE_GAP_PHY_1MBPS, BLE_GAP_PHY_2MBPS or BLE_GAP_PHY_CODED)

Maybe try adjusting the tx power

  // Optional: Change transmitter output power
  // - If role is BLE_GAP_TX_POWER_ROLE_ADV, the advertising set identified with the advertising handle,
  //   will use the specified transmit power, and include it in the advertising packet headers
  //  - For all other roles the handle is ignored
  int8_t TxPower = +4;
  // Supported tx_power values: -40dBm, -20dBm, -16dBm, -12dBm, -8dBm, -4dBm, 0dBm, +3dBm and +4dBm.
  uint32_t err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV, m_advertising.adv_handle, TxPower);

RE: Coded PHY distance testing

fackbell — Wed, 10 Jun 2020 14:11:01 GMT

Here's how I change between 1M and coded:

if (use_coded)
{
m_adv_params.primary_phy = BLE_GAP_PHY_CODED;
m_adv_params.secondary_phy = BLE_GAP_PHY_CODED;
m_adv_params.properties.type = BLE_GAP_ADV_TYPE_EXTENDED_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED;
}
else
{
m_adv_params.primary_phy = BLE_GAP_PHY_1MBPS;
m_adv_params.secondary_phy = BLE_GAP_PHY_1MBPS;
m_adv_params.properties.type = BLE_GAP_ADV_TYPE_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED;
}

m_adv_params.scan_req_notification = 0;

m_adv_params.p_peer_addr = NULL; // Undirected advertisement.
m_adv_params.filter_policy = BLE_GAP_ADV_FP_ANY;
m_adv_params.interval = NON_CONNECTABLE_ADV_INTERVAL;
m_adv_params.duration = 0; // Never time out.

err_code = ble_advdata_encode(&advdata, m_adv_data.adv_data.p_data, &m_adv_data.adv_data.len);
APP_ERROR_CHECK(err_code);

err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_adv_data, &m_adv_params);
APP_ERROR_CHECK(err_code);

err_code = sd_ble_gap_adv_start(m_adv_handle, APP_BLE_CONN_CFG_TAG);
APP_ERROR_CHECK(err_code);

I'm I missing anything?

RE: Coded PHY distance testing

Gunnar P — Wed, 10 Jun 2020 13:10:27 GMT

Interesting problem and it seems odd that there is no difference in RX distances. Check to see if the application is correctly being configured between 1M and the 125ksps settings. It may not be utilizing the s=8 (125kbps) setting in your testing. Also, try the same test in a high RF environment since the coded PHY should definitely improve data TX/RX in noisy environments.

RE: Coded PHY distance testing

Jimmy Wong — Tue, 09 Jun 2020 23:48:28 GMT

You can refer to the example (https://jimmywongiot.com/2019/10/22/ble-range-estimator-on-the-nordic-nrf52840/) and my github for trying.

RE: Coded PHY distance testing

fackbell — Tue, 09 Jun 2020 23:04:02 GMT

We're doing an apples to apples comparison, comparing the 1M to the s=8 coded. We actually have not measured the distance as we're looking at how much further we can go over the 1M PHY. The assumption is that the coded can go close to double over the 1M. We can live with 50%. Right now, it's around 10 feet difference.

RE: Coded PHY distance testing

Gunnar P — Tue, 09 Jun 2020 20:38:45 GMT

What kinds of distances were you achieving? I've done some testing that verifies 250+ meters using the s=8 coded PHY setting.