WXG-DAQ-1G Data Acquisition Card API Interface Documentation

PCIe7820-API DLL Interface Function Description

simple introduction

PCIe-7820 has built-in IQ demodulation function for balanced detector DAS system, which supports both single-channel IQ demodulation and dual-channel IQ demodulation. The upload rate can be configured as 1G, 500M, 250M, 125M, 83.33M, 62.5M, 50M, etc. The PCIe-7820 supports single-channel, dual-channel and quad-channel;

Supports three data upload modes: single-channel, dual-channel and quad-channel. When using single-channel mode, the maximum number of points per frame (the number of points collected by a single trigger pulse) can support 262144 points, i.e., the length of a single optical fibre can reach a maximum of 262144*0.1m=26.2144km under the uploading rate of 1G (0.1m spatial resolution); longer optical fibre lengths can be supported if the uploading rate is lowered;

int pcie7820_open ()

/*****************************************************************/ 

Function Description：

Open the device

Function Parameters

    NO

Function Return Value：

Success, return 0

Failure, return -1

/*****************************************************************/

 void pcie7820_close ()

/*****************************************************************/

Function Description：

close the device

Function Parameters：

NO

Function Return Value：

NO

/*****************************************************************/

int pcie7820_set_trig_dir(unsigned int trig_dir)

/*****************************************************************/

Function Description：

Setting the trigger pulse direction

Function Parameters：

      trig_dir  ：0---Receive Trigger Pulse；1--- Send trigger pulse；                    

Function Return Value：

Success，0  

       Failure，-1

/*****************************************************************/

int pcie7820_set_scan_rate (double scan_rate)

/*****************************************************************/

Function Description：

Sets the scan rate, i.e. the frequency at which the board outputs trigger pulses. When set to trigger input (receive external trigger pulse), this function can not be called.

Function Parameters：

        scan_rate ：Scan rate in Hz；

 Function Return Value：

Success，0

Failure，-1

/*****************************************************************/

int pcie7820_set_pusle_width (unsigned int pulse_high_width_ns)

/*****************************************************************/

Function Description：

Sets the width of the high level of the trigger pulse. This function can not be called when it is set to trigger input (receiving an external trigger pulse).

Function Parameters：

       pulse_high_width_ns ：The unit is ns, an integer multiple of 4ns, with a minimum value of 4ns.

Function Return Value：

Success，0

Failure，-1

/*****************************************************************/

int pcie7820_set_upload_data_param(unsigned int upload_ch_num,unsigned int upload_data_src,unsigned int upload_data_rate)

/*****************************************************************/

Function Description：

Set up the board upload data parameters. Digital downconversion has been done on the board to perform digital I/Q demodulation of the captured data. The upload_ch_num parameter and upload_data_src are used together to select which position in the demodulation algorithm to read the data at.

Figure 3.2 Digital quadrature demodulation flow

Function Parameters：

upload_ch_num  ：Sets the number of upload channels;

1 - upload one channel of data; 2 - upload two channels of data; 4 - upload four channels of data;

upload_data_src ：Upload data source selection;

0 - upload raw acquisition data; 2 - upload IQ data; 3 - upload phase and magnitude data;

upload_data_rate ：Setting the upload data rate;

1---1GSps；2---500MSps；4---250MSps；8---125MSps；12---83.333MSps； 16---62.5MSps；20---50MSps；24---41.66MSps；28---35.714MSps；

32---31.25MSps；

Function Return Value：

Success，0

Failure，-1

pcie7820_read_data The data read by the function should be parsed according to the following table:

ch0_raw_data---ch1_raw_data---I0---Q0---I1----Q1--- arctan(Q0/I0)--- arctan(Q1/I1)，These 8 types of data need to be parsed as 16-bit signed data (short).； √(I02+Q02)--- √(I12+Q12)，Both types of data need to be parsed as 16-bit unsigned short.

The arctan phase value read up is a fixed point value, and its correspondence with π is: 25735 - positive π , -25735 - negative π

 /*****************************************************************/

int pcie7820_set_points_num_per_scan(unsigned int point_num_per_scan)

 /*****************************************************************/

Function Description：

Set the number of points per channel to be captured for each trigger pulse.

Function Parameters：

point_num_per_scan  ：The number of points to be captured per channel;

In single-channel mode, this parameter must be an integer multiple of 512, with a maximum number of points of 262144;

In dual-channel mode, the parameter must be an integer multiple of 256, with a maximum number of points of 131072;

In four-channel mode, the parameter must be an integer multiple of 128, with a maximum number of points of 65536;

Function Return Value：

Success，0

Failure，-1

/*****************************************************************/

int pcie7820_set_center_freq(unsigned int center_freq_hz)

/*****************************************************************/

Function Description：

If you use the IQ demodulation function, you need to set the centre frequency of the signal; for systems with 80M frequency shift of the acousto-optic modulator, the parameter can be set to 80000000; for systems with 200M frequency shift of the acousto-optic modulator, the parameter can be set to 200000000

Function Parameters：

center_freq_hz ：The centre frequency of the acquired signal in Hz;  

Function Return Value：

Success，0

Failure，-1

/*****************************************************************/

int pcie7820_point_num_per_ch_in_buf_query(unsigned int *p_point_num_in_buf_per_ch)

 /*****************************************************************/

Function Description：

Query the number of data points per channel in the cache

Function Parameters：

p_point_num_in_buf_per_ch ： Number of data points per channel in the cache

Function Return Value：

Success，0

Failure，-1

/*****************************************************************/

  int pcie7820_read_data(unsigned int point_num_per_ch,short *p_raw_data, unsigned int *p_points_per_ch_returned)

/*****************************************************************/

Function Description：

read data

Function Parameters：

point_num_per_ch ：The number of points read per channel, which must be an integer multiple of 512 in single-channel mode, an integer multiple of 256 in dual-channel mode, and an integer multiple of 128 in quad-channel mode.

This parameter must be 512 integer times in single-channel mode, 256 integer times in dual-channel mode, and 128 integer times in quad-channel mode; it is recommended to read at least 512*point_num_per_scan points at a time to increase the utilisation of the PCIe bus for data transfer.

p_raw_data ：Pointer to the read data buffer;

In single-channel mode, the buffer length represented by this pointer is point_num_per_ch;

In dual-channel mode, the buffer length represented by this pointer is point_num_per_ch*2;

in quad-channel mode, the buffer length represented by this pointer is point_num_per_ch*4;

Please refer to the table in the pcie7820_set_upload_data_param function location for the parsing method of the read data.

p_points_per_ch_returned ：Number of actual readings per channel

Function Return Value：

Success，0

Failure，-1

/*****************************************************************/

int pcie7820_start (void)

/*****************************************************************/

Function Description：

Start collecting

Function Parameters：

 NO

Function Return Value：

Success，0

Failed. Negative.

/*****************************************************************/

int pcie7820_stop (void)

/*****************************************************************/

Function Description：

Failed. Negative.

Function Parameters：

NO

Function Return Value：

Success，0

Failed. Negative.

/*****************************************************************/