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RF output out of spec #58

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tadibatt opened this issue Jul 15, 2019 · 0 comments
Open

RF output out of spec #58

tadibatt opened this issue Jul 15, 2019 · 0 comments

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@tadibatt
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tadibatt commented Jul 15, 2019

I have noticed that the TX gain table in the global_conf.json file is exceeding the max RF output power that the internal power amplifier on the iC880a can handle. See the Datasheet https://shop.imst.de/media/pdf/22/67/a8/iC880A_Datasheet_V0_50.pdf at page 18.
The datasheet contains also an example how the tx_lut should look: https://shop.imst.de/media/pdf/22/67/a8/iC880A_Datasheet_V0_50.pdf at page 26 to 27.

And the datasheet also mentions on page 21 that the rssi_offset of both radios should be set on -169 instead -166.

Should the global_conf.json be modified to avoid damage to the amplifier or I'm missing something?

Edit 1: I have found the right settings to do in the global_conf.json: see https://www.wireless-solutions.de/downloads/Evaluation-Tools/LoRa_Lite_Gateway/WiMOD_LiteGateway_QuickStartGuide_V1_5.pdf at page 15.
They use this settings in their own LiteGateway which use the same iC880A concentrator board.
This is also confirmed in the datasheet of the LiteGateway. See the "Transmitter power level configuration in TX gain table" in https://www.wireless-solutions.de/downloads/Evaluation-Tools/LoRa_Lite_Gateway/WiMOD_LiteGateway_Datasheet_V1_5.pdf at page 9.

So the tx_lut in the global_conf.json should look like:

        "tx_lut_0": {
            /* TX gain table, index 0 */
            "pa_gain": 0,
            "mix_gain": 8,
            "rf_power": -6,
            "dig_gain": 2
        },
        "tx_lut_1": {
            /* TX gain table, index 1 */
            "pa_gain": 0,
            "mix_gain": 11,
            "rf_power": -3,
            "dig_gain": 3
        },
        "tx_lut_2": {
            /* TX gain table, index 2 */
            "pa_gain": 0,
            "mix_gain": 10,
            "rf_power": 0,
            "dig_gain": 0
        },
        "tx_lut_3": {
            /* TX gain table, index 3 */
            "pa_gain": 0,
            "mix_gain": 14,
            "rf_power": 3,
            "dig_gain": 1
        },
        "tx_lut_4": {
            /* TX gain table, index 4 */
            "pa_gain": 2,
            "mix_gain": 8,
            "rf_power": 6,
            "dig_gain": 3
        },
        "tx_lut_5": {
            /* TX gain table, index 5 */
            "pa_gain": 2,
            "mix_gain": 8,
            "rf_power": 10,
            "dig_gain": 2
        },
        "tx_lut_6": {
            /* TX gain table, index 6 */
            "pa_gain": 2,
            "mix_gain": 8,
            "rf_power": 11,
            "dig_gain": 1
        },
        "tx_lut_7": {
            /* TX gain table, index 7 */
            "pa_gain": 2,
            "mix_gain": 9,
            "rf_power": 12,
            "dig_gain": 2
        },
        "tx_lut_8": {
            /* TX gain table, index 8 */
            "pa_gain": 2,
            "mix_gain": 11,
            "rf_power": 13,
            "dig_gain": 3
        },
        "tx_lut_9": {
            /* TX gain table, index 9 */
            "pa_gain": 2,
            "mix_gain": 10,
            "rf_power": 14,
            "dig_gain": 2
        },
        "tx_lut_10": {
            /* TX gain table, index 10 */
            "pa_gain": 2,
            "mix_gain": 11,
            "rf_power": 16,
            "dig_gain": 2
        },
        "tx_lut_11": {
            /* TX gain table, index 11 */
            "pa_gain": 2,
            "mix_gain": 12,
            "rf_power": 20,
            "dig_gain": 0
        },
        "tx_lut_12": {
            /* TX gain table, index 12; this is a duplicate of index 11 due to hardware limitations, see datasheet */
            "pa_gain": 2,
            "mix_gain": 12,
            "rf_power": 23,
            "dig_gain": 0
        },
        "tx_lut_13": {
            /* TX gain table, index 13; this is a duplicate of index 11 due to hardware limitations, see datasheet */
            "pa_gain": 2,
            "mix_gain": 12,
            "rf_power": 25,
            "dig_gain": 0
        },
        "tx_lut_14": {
            /* TX gain table, index 14; this is a duplicate of index 11 due to hardware limitations, see datasheet */
            "pa_gain": 2,
            "mix_gain": 12,
            "rf_power": 26,
            "dig_gain": 0
        },
        "tx_lut_15": {
            /* TX gain table, index 15; this is a duplicate of index 11 due to hardware limitations, see datasheet */
            "pa_gain": 2,
            "mix_gain": 12,
            "rf_power": 27,
            "dig_gain": 0
        }
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