Gateway downlinking on the wrong frequency

Hi,

We have 3 active gateways and are using the AU915 band in Australia. We are seeing the one of our Cisco LoRaWAN gateways downlinking on the 869 MHz band. I am seeing this through TTN console

image

Does anyone have any suggestions as to where this one gateway is misconfigured? Is there anything I need to read or look into regarding downlinking and the frequency used?

Below is a copy of my config.json form my Cisco Gateway for reference:

“SX1301_array_conf”:[
{
“board_type”: “MASTER”,
“board_rx_freq”: 921500000, /* 908600000 radio RX central frequency in Hz /
“board_rx_bw”: 13000000, /
13000000 radio RX bandwidth in Hz /
“full_duplex”: false, /
radio mode /
“rf_chain_conf”:[
{
/
RX /
“rx_enable”: true,
“rssi_offset”: -202.5,
“rssi_offset_coeff_a”: 20,
“rssi_offset_coeff_b”: 2925,
/
TX /
“tx_enable”: true,
“tx_freq_min”: 923300000,
“tx_freq_max”: 927500000,
“tx_lut”:[
{ “rf_power”: 9, “fpga_dig_gain”: 5, “ad9361_atten”: 104, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -23, “ad9361_tcomp_coeff_b”: 3177 },
{ “rf_power”: 11, “fpga_dig_gain”: 5, “ad9361_atten”: 96, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -21, “ad9361_tcomp_coeff_b”: 2888 },
{ “rf_power”: 12, “fpga_dig_gain”: 5, “ad9361_atten”: 93, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -20, “ad9361_tcomp_coeff_b”: 2683 },
{ “rf_power”: 13, “fpga_dig_gain”: 5, “ad9361_atten”: 88, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -20, “ad9361_tcomp_coeff_b”: 2530 },
{ “rf_power”: 14, “fpga_dig_gain”: 5, “ad9361_atten”: 84, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -19, “ad9361_tcomp_coeff_b”: 2367 },
{ “rf_power”: 16, “fpga_dig_gain”: 5, “ad9361_atten”: 75, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -18, “ad9361_tcomp_coeff_b”: 1943 },
{ “rf_power”: 18, “fpga_dig_gain”: 5, “ad9361_atten”: 67, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -16, “ad9361_tcomp_coeff_b”: 1537 },
{ “rf_power”: 20, “fpga_dig_gain”: 5, “ad9361_atten”: 59, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -15, “ad9361_tcomp_coeff_b”: 1135 },
{ “rf_power”: 22, “fpga_dig_gain”: 5, “ad9361_atten”: 51, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -13, “ad9361_tcomp_coeff_b”: 714 },
{ “rf_power”: 24, “fpga_dig_gain”: 5, “ad9361_atten”: 42, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -11, “ad9361_tcomp_coeff_b”: 262 },
{ “rf_power”: 25, “fpga_dig_gain”: 5, “ad9361_atten”: 38, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -9, “ad9361_tcomp_coeff_b”: -6 },
{ “rf_power”: 26, “fpga_dig_gain”: 5, “ad9361_atten”: 33, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -8, “ad9361_tcomp_coeff_b”: -193 },
{ “rf_power”: 27, “fpga_dig_gain”: 5, “ad9361_atten”: 29, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -7, “ad9361_tcomp_coeff_b”: -356 },
{ “rf_power”: 28, “fpga_dig_gain”: 5, “ad9361_atten”: 24, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -6, “ad9361_tcomp_coeff_b”: -470 },
{ “rf_power”: 29, “fpga_dig_gain”: 5, “ad9361_atten”: 18, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -6, “ad9361_tcomp_coeff_b”: -534 },
{ “rf_power”: 30, “fpga_dig_gain”: 5, “ad9361_atten”: 11, “ad9361_auxdac_vref”: 3, “ad9361_auxdac_word”: 770, “ad9361_tcomp_coeff_a”: -4, “ad9361_tcomp_coeff_b”: -589 }]
}],
“SX1301_conf”:[
{
“chip_enable”: true,
“chip_center_freq”: 917500000, /
was 907800000 /
“chip_rf_chain”: 0,
“chan_multiSF_0”: { “chan_rx_freq”: 916800000 , “spread_factor”: “7-12” },
“chan_multiSF_1”: { “chan_rx_freq”: 917000000 , “spread_factor”: “7-12” },
“chan_multiSF_2”: { “chan_rx_freq”: 917200000 , “spread_factor”: “7-12” },
“chan_multiSF_3”: { “chan_rx_freq”: 917400000 , “spread_factor”: “7-12” },
“chan_multiSF_4”: { “chan_rx_freq”: 917600000 , “spread_factor”: “7-12” },
“chan_multiSF_5”: { “chan_rx_freq”: 917800000 , “spread_factor”: “7-12” },
“chan_multiSF_6”: { “chan_rx_freq”: 918000000 , “spread_factor”: “7-12” },
“chan_multiSF_7”: { “chan_rx_freq”: 918200000 , “spread_factor”: “7-12” },
“chan_LoRa_std” : { “chan_rx_freq”: 917500000 , “bandwidth”: 500000, “spread_factor”: 8 },
“chan_FSK” : { “chan_rx_freq”: 917500000 , “bandwidth”: 125000, “bit_rate”: 50000 } /
was 907800000 /
},{
“chip_enable”: false,
“chip_center_freq”: 909400000,
“chip_rf_chain”: 0,
“chan_multiSF_0”: { “chan_rx_freq”: 908700000 , “spread_factor”: “7-12” },
“chan_multiSF_1”: { “chan_rx_freq”: 908900000 , “spread_factor”: “7-12” },
“chan_multiSF_2”: { “chan_rx_freq”: 909100000 , “spread_factor”: “7-12” },
“chan_multiSF_3”: { “chan_rx_freq”: 909300000 , “spread_factor”: “7-12” },
“chan_multiSF_4”: { “chan_rx_freq”: 909500000 , “spread_factor”: “7-12” },
“chan_multiSF_5”: { “chan_rx_freq”: 909700000 , “spread_factor”: “7-12” },
“chan_multiSF_6”: { “chan_rx_freq”: 909900000 , “spread_factor”: “7-12” },
“chan_multiSF_7”: { “chan_rx_freq”: 910100000 , “spread_factor”: “7-12” },
“chan_LoRa_std” : { “chan_rx_freq”: 909400000 , “bandwidth”: 500000, “spread_factor”: 8 },
“chan_FSK” : { “chan_rx_freq”: 909400000 , “bandwidth”: 125000, “bit_rate”: 50000 }
}],
“FSK_sync”: “C194C1”,
“loramac_public”: true,
“nb_dsp”: 1,
“dsp_stat_interval”: 10,
“aes_key”: “YOUR KEY HERE”,
“calibration_temperature_celsius_room”: 22,
“calibration_temperature_code_ad9361”: 77,
“fts_version”: 1,
“fts_match_crc_error”: false
}],
“gateway_conf”: {
“gateway_ID”: “16 HEX DIGITS”,
/
change with default server address/ports /
“server_address”: “A web site”,
“serv_port_up”: 1700,
“serv_port_down”: 1700,
/
adjust the following parameters for your network /
“keepalive_interval”: 10,
“stat_interval”: 30,
“push_timeout_ms”: 100,
/
forward only valid packets /
“forward_crc_valid”: true,
“forward_crc_error”: false,
“forward_crc_disabled”: false,
/
link testing mote /
“link_mote”: “00CC01AF”,
/
Beaconing parameters */
“beacon_conf”:{
“period”: 128,
“freq_hz”: 923300000,
“freq_nb”: 8,
“freq_step”: 600000,
“datarate”: 12,
“bw_hz”: 500000,
“power”: 14,
“infodesc”: 0
}
},
“gps_conf”: {
“gw_latitude”: 0,
“gw_longitude”: 0,
“gw_altitude”: 0,
“fixed_altitude”: false
}
}

Downlink frequency is commanded by the network server, not the gateway.

The first thing to check would be that the gateway is actually registered in the correct region, and pointed at the correct server.

The next would be the details of the uplink which triggered this. Because it supports only class A, TTN never transmits except in response to an uplink, and seeing if that uplink is valid or invalid would be key.

The two downlinks shown use the settings for TTN-EU868 custom RX2; there’s been some past indication that this is a sort of “default” case and may happen when the uplink does not match any valid air setting.

1 Like

Great, thanks so much! Thanks for steering me in the direction to look.

The solution/problem was with the line:

“server_address”:

This did not point to the Australian server.

Thanks again,
Dave