nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Kenneth — Wed, 25 Apr 2018 14:10:41 GMT

This is normal I would say.

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Nitin Solanki — Thu, 12 Apr 2018 09:48:03 GMT

And all of the above measurements are in line-of-sight with various orientations.

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Nitin Solanki — Wed, 11 Apr 2018 15:03:08 GMT

I tried it, and do see some effect on the output.

With tx_power = -40, I got rssi of -100 at 1m.

With tx_power = 4. I got rssi of -61 at 1m.

Is it normal that there is such a huge difference between tx power and rssi@1m?

When it is transmitting at +4dbm, shouldn't I receive a much stronger signal than -61dbm at 1 meter?

Thanks,

Nitin

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Nitin Solanki — Tue, 10 Apr 2018 17:53:07 GMT

I have tried various values from -20 to +4, but there is no difference in measured rssi@1m. I have also tried the same code on our custom PCB with nRF51822. I am not getting higher transmit power there as well.

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Kenneth — Tue, 10 Apr 2018 14:51:14 GMT

Is there any difference if you use:

int8_t tx_power = 0; // -40, -20, -16, -12, -8, -4, 0, 3, and 4

err_code = sd_ble_gap_tx_power_set(tx_power);

APP_ERROR_CHECK(err_code);

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Nitin Solanki — Mon, 09 Apr 2018 17:10:52 GMT

Hi Kenneth, I have tried measuring the as several locations, I just mentioned the closest measurement of atround-35dbm. At around 1 meter, I am consistently getting measured rssi in the range of -60dbm or less.

int main(void)
{
    uint32_t err_code;
    // Initialize.
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);
    err_code = bsp_init(BSP_INIT_LED, APP_TIMER_TICKS(100, APP_TIMER_PRESCALER), NULL);
    APP_ERROR_CHECK(err_code);
    ble_stack_init();
    advertising_init();
		
		err_code = sd_ble_gap_tx_power_set(0); //Radio transmit power in dBm (accepted values are -40, -30, -20, -16, -12, -8, -4, 0, and 4 dBm).
    APP_ERROR_CHECK(err_code);
		
    // Start execution.
    advertising_start();

    // Enter main loop.
    for (;; )
    {
				err_code = sd_ble_gap_tx_power_set(0); //Radio transmit power in dBm (accepted values are -40, -30, -20, -16, -12, -8, -4, 0, and 4 dBm).
				APP_ERROR_CHECK(err_code);
        power_manage();
    }
}

I have even tried calling sd_ble_gap_tx_power_set(0) inside the for loop, which has no effect either.

-Nitin

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Kenneth — Mon, 09 Apr 2018 16:16:46 GMT

Hi, that explains your problems. You should measure conducted or according to the ibeacon guidelines (1 meter away > 10 seconds). If you want to measure any difference it is essential that neither phone or ibeacon change orientation, distance, or location when changing the output power. In your case you are measuring in the near fields of the antenna, which will give strange results.

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Nitin Solanki — Mon, 09 Apr 2018 15:17:07 GMT

I am measuring it using a smartphone apps such as Beacon Analyzer, Beacon Scanner, etc. The measured RSSI when I keep the smartphone right on top of the dev kit is always around -35dbm.

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Kenneth — Mon, 09 Apr 2018 15:12:57 GMT

Hi, how are you measuring this? Are you observering RSSI on a peer device or are you measuring conducted using a spectrum analyzer?

RE: nRF51 DK SDKv10 with S110 iBeacon beacon example: How to increase TX power?

Nitin Solanki — Mon, 09 Apr 2018 10:48:31 GMT

I tried the same with S130 softdevice as well, but I am getting the same issue. The actual transmit power is not increasing