PoBe - david-macmahon/wiki_convert_test GitHub Wiki

This project was carried out as a part of the summer project by Cambodge Bist, under the guidance of Kaushal Buch, Ajithkumar B. and Yashwant Gupta at the Giant Metrewave Radio Telescope, National Centre for Radio Astrophysics, TIFR, India.

Technical discussions and offline post-processing support: Sanjay Kudale

Testing support: Irappa Halagali

For further details or clarifications regarding this project please contact Kaushal Buch, Digital Backend Group, GMRT, NCRA-TIFR, India ([email protected], [email protected])

The Pocket Beamformer (PoBe) is FPGA (ROACH-1) based digital design that implements incoherent beamforming algorithm for 2 antennas required for pulsar studies at the Giant Metrewave Radio Telescope (GMRT).

The PoBe is an add-on to the Pocket Correlator (PoCo) which is a 2-antenna design that is used for correlation and has been developed a part of the GMRT upgrade activities. This project mentions the PoBe digital design in terms of modification on PoCo, incoherent beamforming algorithm and packetised design.

It uses 10Gbps network link for transporting data from the ROACH-1 board to the P.C. This is necessary for beamformer's short-time integration requirements. The project includes de-packetisation and offline data processing.

A detailed design is available as a CASPER memo: https://casper.berkeley.edu/wiki/Pocket_Beamformer%28PoBe%29_on_FPGA

The design has been tested for 600 MHz ADC clock (i.e. 300 MHz beamformer).

The design of two element incoherent beamformer was carried out on Xilinx System Generator 10.1 and Matlab R2008a on Windows platform for ROACH-1 board using the standard CASPER tool-flow. The design file, bof file, scripts for configuring and acquiring data from the correlator and beamformer and depacketization scripts are provided for the user. The following software are required for compilation and testing of this design

Matlab R2008a Xilinx ISE 10.1 (with System Generator) Python 2.6 Wireshark Gulp

Design file: Contains .mdl and .bof files

Python file: Contains python scripts for Pocket Correlator and Pocket Beamformer

Depacketization: Contains 'C' file and executable file for de-packetization of beam data

(i) Signal generator settings as CLOCK to iADC's clock input: Freq = 600MHz , Power = 0dbm (Note: Current version of design works for a maximum clock frequency of 600 MHz i.e. 300 MHz beamformer)

(ii) Connect broadband analog or noise source signals to iADC's inputs with a total channel power between -14dbm to -17dbm.

(iii) Power “ON” the ROACH board.

(iv) Configure ROACH board through control P.C.

Following changes may be required in the script according to your requirements  vim pobe_incoh_2k.py <br \>

my_corr.write_int("acc_cntrl_int_time",1024)  Note: This is the integration time for beamformer (1024 for 600MHz clock & 512 for 400MHz clock) <br \> Theoretically, the data rate can go much beyond this; however we found for our system, we could a get minimum integration time of 1.3 ms with this test setup and integration time settings as mentioned above. <br \>

my_corr.write_int("Input_mux",0)  Use '1' for digital noise and '0' for ADC input <br \>

Run the script to configure the design python_scripts$ ./pobe_incoh_2k.py <br \>

To ensure packets being received by the PC from ROACH-1 board <br \>

python_scripts$ sudo wireshark <br \>

"The Wireshark Network Analyzer" window opens  <br \>

Select Capture/Interfaces in the Menu. Another window "Wireshark: Capture  Interfaces" opens <br \>

Observe at Packets and Packets/sec. Counts here show that the packets are being  received (0 for no packets received) <br \>

Select File/Quit to exit  <br \>

For setting the number of packets to be captured, go to the directory where Gulp has been installed.  python_scripts$ cd /data/Gulp/ <br \>

gmrt@ctrlpoco:/data/Gulp$ vim gulp.c <br \>

int num_packets = ­-1;     Note: Change the value of num_packets to ­-1 to capture till ctrl+c or any number to capture  those many packets <br \>

gmrt@ctrlpoco:/data/Gulp$ sudo make <br \>

Capture packets using Gulp using the following command. Check the port on which 10GbE NIC is connected. In this case, it is 'eth2'. '>' operates dumps into the required destination (file).

python_scripts$ sudo /data/Gulp/gulp ­i eth2 > 150mhz_14122012.dat <br \>

The packet would consist of 512 channel of beam data with each channel having 32-bit precision. Gulp captures the data in 32-bit binary format. To plot it or convert it to 16-bit binary format, a de-packetization routine has been written (Refer next section). <br \>     

gmrt@ctrlpoco$ vim file_fast.c <br \>

Edit this 'C' file as per requirement. A brief explanation is given below. <br \>

fprintf(ha,"%u\n",v); <br \> Keep the above statement to make the output ASCII file plot able by  GNUPLOT. <br \>

fwrite(&v,sizeof(v),1,ha); <br \> This statement is required to make the output BINARY file compatible with Pulsar Monitor (PMON). PMON is a software developed at the GMRT for de-dispersion and folding of beam data to get pulsar profile. <br \>

After making these changes follow the steps below to create .exe file <br \> 

2antenna$ gcc ­-o file_fast.o file_fast.c <br \>

Usage : ./file_fast.o <Dump_filename> <OUTPUT_filename> <Packet_size>  <Scaling_factor> <br \>

This De-packetizes the *.data file in to *.out file with packet_size of 2K bytes and a desired scaling factor <br \>

2antenna$ ./file_fast.o 150mhz_14122012.dat1 150mhz_14122012.out 2048 1024 <br \>

2antenna$ ./file_fast.o 150mhz_14122012.dat1 150mhz_14122012.out 2048 1024 <br \>

Plot the De-packetized OUTPUT_file using GNUPLOT. <br \>

A detailed design document is available as a CASPER memo: https://casper.berkeley.edu/wiki/Pocket_Beamformer%28PoBe%29_on_FPGA