Question about AT+QRFTEST parameters for BG* serie

IoT Modules LPWA Module
1

Hi,

I currently need to run some RF testing with my BG77.

To do so, I was reading the application note “RF_FTM” (Quectel_BG95&BG77&BG600L_Series_RF_FTM_Application_Note_V1.2) available here.

In the NB-IoT mode, there is a “ul_offset” parameter to set within the range “-10 to 9”.

AT+QRFTEST=<band>,<channel>,<tx_enable>,<rgi>,<waveform>,<ul_offset>,<mod_type>,<power>,<tone_bw>,<tone_idx>
<ul_offset> Integer type. Uplink carrier frequency offset. Range: -10 to 9

Few time latter in the same documentation, there is some examples using the AT+QRFTEST command: the ul_offset is always set to the value “100”.

//In NB-IoT RAT
AT+QRFTEST="LTE BAND1",18300,"ON",50,1,100,0,50,4,0 //Enable RF Tx on 18300 channel of LTE B1

My question is: “Can you help me to understand the ul_offset parameter of the AT+QRFTEST=xxx command ?”

Thanks for your help

2

5.7.3F Carrier frequency and EARFCN for category NB1 and NB2

The carrier frequency of category NB1/NB2 in the downlink is designated by the E-UTRA Absolute Radio Frequency Channel Number (EARFCN) in the range 0 – 262143 and the Offset of category NB1/NB2 Channel Number to EARFCN in the range {-10,-9,-8,-7,-6,-5,-4,-3,-2,-1,-0.5,0,1,2,3,4,5,6,7,8,9} for FDD and in the range {-10,-9,-8.5,-8,-7,-6,-5,-4.5,-4,-3,-2,-1,-0.5,0,1,2,3,3.5,4,5,6,7,7.5,8,9} for TDD. The relation between EARFCN, Offset of category NB1/NB2 Channel Number to EARFCN and the carrier frequency in MHz for the downlink is given by the following equation, where FDL is the downlink carrier frequency of category NB1/NB2, FDL_low and NOffs-DL are given in table 5.7.3-1, NDL is the downlink EARFCN, MDL is the Offset of category NB1/NB2 Channel Number to downlink EARFCN.

FDL = FDL_low + 0.1(NDL – NOffs-DL) + 0.0025*(2MDL+1)

The carrier frequency of category NB1/NB2 in the uplink is designated by the E-UTRA Absolute Radio Frequency Channel Number (EARFCN) in the range 0 –262143, and the Offset of category NB1/NB2 Channel Number to EARFCN in the range {-10,-9,-8,-7,-6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9} for FDD and in the range {-11,-10,-9.5,-9,-8.5, -8,-7.5,-7,-6.5,-6,-5.5,-5,-4.5,-4,-3.5,-3,-2.5,-2,-1.5,-1,-0.5,0,0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10, 11} for TDD. The relation between EARFCN, Offset of category NB1/NB2 Channel Number to EARFCN and the carrier frequency in MHz for the uplink is given by the following equation, where FUL is the uplink carrier frequency of category NB1/NB2, FUL_low and NOffs-UL are given in table 5.7.3-1, NUL is the uplink EARFCN, MUL is the Offset of category NB1/NB2 Channel Number to uplink EARFCN.

FUL = FUL_low + 0.1(NUL – NOffs-UL) + 0.0025*(2MUL)

NOTE 1: For category NB1/NB2, NDL or NUL is different than the value of EARFCN that corresponds to E-UTRA downlink or uplink carrier frequency for in-band and guard band operation.

NOTE 2: For FDD MDL = -0.5 is not applicable for in-band and guard band operation. For TDD MDL {-0.5,+3.5,-4.5,+7.5,-8.5} is not applicable for in-band and guard band operation.

NOTE 3: For the carrier including NPSS/NSSS for in-band and guard band operation, MDL is selected from {-2,-1,0,1}.

NOTE 4: For the carrier including NPSS/NSSS for stand-alone operation, MDL = -0.5.

3

Hi,

thanks a lot for your answer. I think you shared the 3GPP (do you have a link to this documentation in order to be able to read table 5.7.3-1 which describes NOffs-UL ?).

My trouble is that I do not see the match with ul_offset value of AT+QRFTEST command.

It could be easiest to fully describe one command example:
AT+QRFTEST=“LTE BAND1”,18300,“ON”,50,1,100,0,50,4,0 //Enable RF Tx on 18300 channel of LTE B1

This is running a Tx test using:

  • band = “LTE BAND1” : LTE band 1
  • channel = 18300 : using the channel 18300
  • tx_enable = 1 : activate the transmission
  • rgi = 50 : the LTE Tx power level is 50 (no unity ?)
  • waveform = 1 : the Tx use the LTE modulated TxMode
  • ul_offset = 100 : I do not know what it means (and it is outside of [-10;9])
  • mod_type = 0 : using BPSK
  • power = 50 : the Tx power is 50dBm
  • tone_bw = 4 : this Tx is using Multi-tone, 12 x 15 kHz
  • tone_idx = 0 : the Tone start index is 0

Could you help me to clarify these bold parts ?

Thanks for your help.

4

36101-h10_s00-07.rar (3.4 MB)