RE: The issue is that the radiated power at 2480 MHz during the Radio Test is 10 dB lower compared to other channels.

ketiljo — Wed, 27 Nov 2024 08:38:32 GMT

Ok, I need to see a picture of how you have connected the cable.

Can you test it with the unmodified radio test to rule out any FW issues?

Cheers,

Ketil

RE: The issue is that the radiated power at 2480 MHz during the Radio Test is 10 dB lower compared to other channels.

keigo.imaizumi — Tue, 26 Nov 2024 23:15:27 GMT

Hi.

Cut the antenna pattern and connect a coaxial cable to observe the frequency characteristics using a spectrum analyzer.

I read the RADIO.TXPOWER register, and it showed 8dBm.
This is the maximum value, so it is as expected.

Let me share an excerpt from the code again. The tx_power is set as NRF_RADIO_TXPOWER_POS8DBM, and it is never modified, so it shouldn't drop to 0dBm.

What’s strange is that the output power decreases each time—first from 2402 MHz to 2442 MHz, and then from 2442 MHz to 2480 MHz.

// =====================================================
// radio_cmd_handler.c

/**@brief Radio parameter configuration.
 */
typedef struct radio_param_config {
    transmit_pattern_t tx_pattern; /**< Radio transmission pattern. */
    nrf_radio_mode_t mode;         /**< Radio mode. Data rate and modulation. */
    nrf_radio_txpower_t txpower;   /**< Radio output power. */
    uint8_t channel_start;         /**< Radio start channel (frequency). */
    uint8_t channel_end;           /**< Radio end channel (frequency). */
    uint32_t delay_ms;             /**< Delay time in milliseconds. */
    uint32_t duty_cycle;           /**< Duty cycle. */
} radio_param_config_t;

static radio_test_config_t m_test_config; /**< Radio test configuration. */
static bool m_test_in_progress;           /**< If true, RX sweep, TX sweep or duty cycle test is performed. */
static radio_param_config_t m_config = {
    .tx_pattern = TRANSMIT_PATTERN_RANDOM,
    .mode = NRF_RADIO_MODE_BLE_1MBIT,
    .txpower = NRF_RADIO_TXPOWER_POS8DBM,
    .channel_start = 0,
    .channel_end = 80,
    .delay_ms = 10,
    .duty_cycle = 50,
};

radio_cmd_handler__ret_code_t radio_cmd_handler__tx_unmodulation_low_channel_start(void) {
    NRF_LOG_INFO("%s", __func__);
    if (m_test_in_progress) {
        radio_test__cancel();
        m_test_in_progress = false;
    }

    m_config.channel_start = 2;

#if USE_MORE_RADIO_MODES
    ieee_channel_check(m_config.channel_start);
#endif /* USE_MORE_RADIO_MODES */

    memset(&m_test_config, 0, sizeof(m_test_config));
    m_test_config.type = UNMODULATED_TX;
    m_test_config.mode = m_config.mode;
    m_test_config.params.unmodulated_tx.txpower = m_config.txpower;
    m_test_config.params.unmodulated_tx.channel = m_config.channel_start;

    radio_test__start(&m_test_config);

    NRF_LOG_INFO("%s. Start the TX carrier.", __func__);

    return RADIO_CMD_HANDLER__SUCCESS;
}

radio_cmd_handler__ret_code_t radio_cmd_handler__tx_unmodulation_middle_channel_start(void) {
    NRF_LOG_INFO("%s", __func__);
    if (m_test_in_progress) {
        radio_test__cancel();
        m_test_in_progress = false;
    }

    m_config.channel_start = 42;

#if USE_MORE_RADIO_MODES
    ieee_channel_check(m_config.channel_start);
#endif /* USE_MORE_RADIO_MODES */

    memset(&m_test_config, 0, sizeof(m_test_config));
    m_test_config.type = UNMODULATED_TX;
    m_test_config.mode = m_config.mode;
    m_test_config.params.unmodulated_tx.txpower = m_config.txpower;
    m_test_config.params.unmodulated_tx.channel = m_config.channel_start;

    radio_test__start(&m_test_config);

    NRF_LOG_INFO("%s. Start the TX carrier.", __func__);

    return RADIO_CMD_HANDLER__SUCCESS;
}

radio_cmd_handler__ret_code_t radio_cmd_handler__tx_unmodulation_high_channel_start(void) {
    NRF_LOG_INFO("%s", __func__);
    if (m_test_in_progress) {
        radio_test__cancel();
        m_test_in_progress = false;
    }

    m_config.channel_start = 80;

#if USE_MORE_RADIO_MODES
    ieee_channel_check(m_config.channel_start);
#endif /* USE_MORE_RADIO_MODES */

    memset(&m_test_config, 0, sizeof(m_test_config));
    m_test_config.type = UNMODULATED_TX;
    m_test_config.mode = m_config.mode;
    m_test_config.params.unmodulated_tx.txpower = m_config.txpower;
    m_test_config.params.unmodulated_tx.channel = m_config.channel_start;

    radio_test__start(&m_test_config);

    NRF_LOG_INFO("%s. Start the TX carrier.", __func__);

    return RADIO_CMD_HANDLER__SUCCESS;
}



// =====================================================
// radio_test.c

void radio_test__start(radio_test_config_t* p_config) {
    // NRF_LOG_INFO("%s", __func__);
    switch (p_config->type) {
    case UNMODULATED_TX:
        radio_unmodulated_tx_carrier(p_config->mode, p_config->params.unmodulated_tx.txpower, p_config->params.unmodulated_tx.channel);
        break;
    case MODULATED_TX:
        radio_modulated_tx_carrier(p_config->mode, p_config->params.modulated_tx.txpower, p_config->params.modulated_tx.channel, p_config->params.modulated_tx.pattern);
        break;
    case RX:
        radio_rx(p_config->mode, p_config->params.rx.channel, p_config->params.rx.pattern);
        break;
    case TX_SWEEP:
        // radio_sweep_start(p_config->params.tx_sweep.channel_start, p_config->params.tx_sweep.delay_ms);
        break;
    case RX_SWEEP:
        // radio_sweep_start(p_config->params.rx_sweep.channel_start, p_config->params.rx_sweep.delay_ms);
        break;
    case MODULATED_TX_DUTY_CYCLE:
        // radio_modulated_tx_carrier_duty_cycle(p_config->mode, p_config->params.modulated_tx_duty_cycle.txpower, p_config->params.modulated_tx_duty_cycle.channel, p_config->params.modulated_tx_duty_cycle.pattern, p_config->params.modulated_tx_duty_cycle.duty_cycle);
        break;
    }
}

static void radio_unmodulated_tx_carrier(nrf_radio_mode_t mode, nrf_radio_txpower_t txpower, uint8_t channel) {
    NRF_LOG_INFO("%s", __func__);
    radio_disable();

    nrf_radio_mode_set(mode);
#if !defined(NRF21540_DRIVER_ENABLE) || (NRF21540_DRIVER_ENABLE == 0)
    nrf_radio_shorts_enable(NRF_RADIO_SHORT_READY_START_MASK);
#endif
    nrf_radio_txpower_set(txpower);

    radio_channel_set(mode, channel);

#if defined(NRF21540_DRIVER_ENABLE) && (NRF21540_DRIVER_ENABLE == 1)
    (void) nrf21540_tx_set(NRF21540_EXECUTE_NOW, NRF21540_EXEC_MODE_NON_BLOCKING);
#else
    nrf_radio_task_trigger(NRF_RADIO_TASK_TXEN);
#endif
}

/**
 * @brief Function for starting the modulated TX carrier by repeatedly sending a packet with a random address and
 * a random payload.
 */
static void radio_modulated_tx_carrier(nrf_radio_mode_t mode, nrf_radio_txpower_t txpower, uint8_t channel, transmit_pattern_t pattern) {
    NRF_LOG_INFO("%s", __func__);
    radio_disable();
    generate_modulated_rf_packet(mode, pattern);

    switch (mode) {
#if USE_MORE_RADIO_MODES
    case NRF_RADIO_MODE_IEEE802154_250KBIT:
    case NRF_RADIO_MODE_BLE_LR125KBIT:
    case NRF_RADIO_MODE_BLE_LR500KBIT:
#if defined(NRF21540_DRIVER_ENABLE) && (NRF21540_DRIVER_ENABLE == 1)
        nrf_radio_shorts_enable(NRF_RADIO_SHORT_PHYEND_START_MASK);
#else
        nrf_radio_shorts_enable(NRF_RADIO_SHORT_READY_START_MASK | NRF_RADIO_SHORT_PHYEND_START_MASK);
#endif
        break;
#endif /* USE_MORE_RADIO_MODES */

    case NRF_RADIO_MODE_BLE_1MBIT:
    case NRF_RADIO_MODE_BLE_2MBIT:
    case NRF_RADIO_MODE_NRF_1MBIT:
    case NRF_RADIO_MODE_NRF_2MBIT:
    default:
#ifdef NRF52832_XXAA
    case NRF_RADIO_MODE_NRF_250KBIT:
#endif /* NRF52832_XXAA */
#if defined(NRF21540_DRIVER_ENABLE) && (NRF21540_DRIVER_ENABLE == 1)
        nrf_radio_shorts_enable(NRF_RADIO_SHORT_END_START_MASK);
#else
        nrf_radio_shorts_enable(NRF_RADIO_SHORT_READY_START_MASK | NRF_RADIO_SHORT_END_START_MASK);
#endif
        break;
    }

    nrf_radio_mode_set(mode);
    nrf_radio_txpower_set(txpower);

    radio_channel_set(mode, channel);

    m_tx_packet_cnt = 0;

    nrf_radio_event_clear(NRF_RADIO_EVENT_END);
    nrf_radio_int_enable(NRF_RADIO_INT_END_MASK);
#if defined(NRF21540_DRIVER_ENABLE) && (NRF21540_DRIVER_ENABLE == 1)
    (void) nrf21540_tx_set(NRF21540_EXECUTE_NOW, NRF21540_EXEC_MODE_NON_BLOCKING);
#else
    nrf_radio_task_trigger(NRF_RADIO_TASK_TXEN);
#endif
    while (!nrf_radio_event_check(NRF_RADIO_EVENT_END)) {
        /* Do nothing */
    }
}

RE: The issue is that the radiated power at 2480 MHz during the Radio Test is 10 dB lower compared to other channels.

ketiljo — Tue, 26 Nov 2024 14:48:01 GMT

You can decribe your measurement setup? Since it's a module, do you meassure this radiated?

It looks like the output power is set to 0 dBm on the last channel? If you have a debugger connected, you can read the RADIO.TXPOWER register to check what setting you're using. RADIO.TXPOWER registeret

Best regard,

Ketil Aas-Johansen

RE: The issue is that the radiated power at 2480 MHz during the Radio Test is 10 dB lower compared to other channels.

keigo.imaizumi — Tue, 26 Nov 2024 03:51:33 GMT

Additional information:

The sample firmware is designed to use a CLI for changing modes. However, since we do not have a PC to run the CLI, we use nrf_fstorage to store the state. On startup, the firmware determines the mode from the stored state and transitions to the corresponding radio mode.

The nRF52840 is connected to a GUI system running on a Raspberry Pi. Based on UI operations, commands are sent to rewrite the state in nrf_fstorage.
(Since the GUI system and the nRF52840 are part of a single solution, adapting it to work with the CLI was not feasible.)