WL127x TX Testing

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Introduction

This section will review the calibrator commands that may be useful when performing transmission (TX) testing on the WL127x.

Tune Command

Purpose

The purpose of the tune_channel command is to configure the WL127x chip to operate in a specific Wifi band and channel.

Method

The tune_channel command can be called using the following format:

 calibrator wlan0 plt tune_channel <band> <channel>
Where:
  • <band> is the wifi band. Ex: 0 means we are in g band equal to 1 means we are in a band
  • <channel> is the channel within the wifi band. See the picture below for details:
WL6 bandchannel.PNG

Example

The following tune_channel example configures the chip to opera in the 2.4 GHz band at channel 1.

 calibrator wlan0 plt tune_channel 0 1


Tx Continuous Test

Purpose

The purpose of the Tx Continuous test to perform continuous transmission to evaluate the WLAN transmission quality.

Method

Tx Continuous test sends packets of data to the air, where the data packets parameters are controlled by the PLT command and include parameters such as transmitted rate, transmitted power, destination MAC address, etc...

calibrator wlan0 plt tx_cont <delay> <rate> <size> <amount> <power> <seed> <pkt mode> <DC on/off> <gi> <preamble> <type> <scramble> <clpc> <seq nbr mode> <dest mac>
Where
  • <delay> - Delay between packets measured in microseconds
  • <rate> - Parameter assumes the input is hexidecimal, e.g., 20 for 11Mbps (you do not need to use 0x prefix). The preamble (another parameter) has to match the modulation type for the command to be successful.


Rate (Mbps) Value (hex)
0x1 
2 0x2
5.5 0x4
6 0x8
9 0x10
11 0x20
12 0x40
18 0x80
24 0x200
36 0x400
48 0x800
54 0x1000
MCS0 0x2000
MSC1 0x4000
MSC2 0x8000
MSC3 0x10000
MSC4 0x20000
MSC5 0x40000
MCS6 0x80000
MSC7 0x100000


  • size - Size of data field in MPDU (in bytes, 0 - 2284)
  • amount - number of packets in case of using series mode
  • power - output power in dBm*1000
  • seed - value for the scrambler
  • pkt mode - 0-single, 1-multiple, 3-continuous, 4-FCC
  • DC on/off - activate DCF
  • gi - guard interval on/off for 11n rates
  • preamble - Packet preamble
Preamble Value Available Rates (Mbps)
LONG_PREAMBLE_MODE 0 1, 2, 5.5, 11
SHORT_PREAMBLE_MODE 1 2, 5.5, 11
OFDM_PREAMBLE_MODE 4 6, 9, 12, 18, 24, 36, 48, 54
N_MIXED_MODE_PREAMBLE_MODE 6 MCS0, MCS1, MCS2, MCS3, MCS4, MCS5, MCS6, MCS7
GREENFIELD_PREAMBLE_MODE 7 MCS0, MCS1, MCS2, MCS3, MCS4, MCS5, MCS6, MCS7
  • type - 0-data packet, 1-ack, 2-probe req, 3-random data, 4-user data
  • scrambler - on/off
  • CLPC - range 0-100, 0 is disable calibration
  • Sequence - number mode (incremented or fixed)
  • Destination Mac address

Example

Following is a typical example of common used parameters:
First step is to get in to PLT (Production Line Testing) mode, and configure the transmitted packets parameters.

ifconfig wlan0 down
calibrator wlan0 plt power_mode on
calibrator wlan0 plt tune_channel 0 7
calibrator wlan0 plt tx_cont 2000 1 100 0 5000 0 3 0 0 0 0 0 1 0 11:22:11:22:11:22

at this point the transmission had started, and should be seen with WLAN sniffer or any other testing tool.
In order to complete the PLT test, we should stop the transmission and exit from PLT mode, that is done by the following commands:

calibrator wlan0 plt tx_stop
calibrator wlan0 plt power_mode off


Sniffer

Tx Cont.png

If you take a look at the second column you can see that the destination MAC address (11:22:11:22:11:22) matches the one we entered in calibrator command line. The same applies for the channel number (4th column) which is 7, and data rate (7th column) which is 1 bps.

Let's have another example, where we change the data rate and the packet size as follows:

ifconfig wlan0 down
calibrator wlan0 plt power_mode on
calibrator wlan0 plt tune_channel 0 7
calibrator wlan0 plt tx_cont 2000 4096 400 0 5000 0 3 0 0 4 0 0 1 0 11:22:11:22:11:22

The data rate is set to 4096 (0x1000) corresponding to 54 Mbps and the packet size is set to 400 bytes. The sniffer log of such command is:

Tx cont 54Mbps.jpg

Here we can see that the data rate (7th column) changed to 54Mbps.
The packet size (8th column) has also changed to 428 bytes (there is a constant addition of 28 bytes).

TX Tone Test

Purpose

The purpose of the tx_tone command is to create and transmit a carrier wave that can be modulated with a fixed audio tone.

Method

The tx_tone command can be called using the following format:

 calibrator wlan0 plt tx_tone <tone type> <power>
Where:
  • <tone type> [1 or 2] 1 will give a carrier feed through. 2 will give a single tone.
  • <power> [0-10000] is the output power range scaled to 0-10 dBm.

Example

The following example set shows how to send a CW modulated at a single tone at an output power of 10 dBm.

calibrator wlan0 plt power_mode on
calibrator wlan0 plt tx_tone 2 10000    // Transmit single tome at 10dBm power
calibrator wlan0 plt tx_stop
calibrator wlan0 plt power_mode off

External Links

For detailed information you can visit the following link: <Wl12xx Calibration>