LIMBO Recorder

The code is used for recording data for LIMBO project.

Getting Start

1. compile the code

       make
       sudo make install
   

2. Set Environment Variables
   You need to set three environment variables:
   (1) LIMBO_DATA_DIR, which defines the spectra data path;
   (2) SPECTRA_ETH, which defines the ethernet port for spectra data;
   (3) VOLTAGE_ETH, which defines the ethernet port for voltage data.
   (The following values are the default vaules. If you're happy with them, you don't need to set them again.)

       export LIMBO_DATA_DIR=/home/obs/data
       export SPECTRA_ETH=enp3s0
       export VOLTAGE_ETH=enp136s0
   

3. Start the data Recorder

       restart_recorder.sh
   

   When you run this script, a "data" directory will be created defined by "LIMBO_DATA_DIR", which is used for storing spectra data. Voltage data files will be created in ramdisk(/mnt/ramdisk). A new file will be created every second. The max number of the voltage data files is 16 by default. The oldest file will be deleted automatically, when the file number reaches to the max. The max number of voltage file names is defined in databuf.h

       #define VOL_FILE_NUM            32
   

TO-DO: set port number dynamically.

3. Enable recording

       enable_record.sh
   

   When you run this script, a new data file will be created in the "data" directory, and it stores 4096 spectra data.

       enable_vol_record.sh
   

   When you run this script, a new voltage file will be created in /mnt/ramdisk. The max number of voltage files is define by VOL_FILE_NUM.

4. Disable recording

       disbale_record.sh
   

   This script will stop recording spectra data. Once you run enable_record.sh again, a new spectra data file will be created.

       disable_vol_record.sh
   

   This script will stop recording voltage data. Once you run enable_vol_record.sh again, a new voltage data file will be created.

5. Stop the data Recorder

       stop_recorder.sh
   

6. mount ramdisk

       mount_ramdisk.sh 
   

Normally, you just need to run this script one time. Then you can run df -h to make sure the ramdisk is created. ~$ df -h Filesystem Size Used Avail Use% Mounted on tmpfs 16G 0 16G 0% /mnt/ramdisk 7. umount ramdisk umount_ramdisk.sh

File Format

We will store two kinds of data: Spectra data and Voltage data.

Spectra data file

• file name
  The name of the spectra data file starts with "Spectra_", following the UTC time when the file is generated. For example "Spectra_20221110042101.dat" means the file was generated at 04:21:01 on 11/10/2022.

• file header
  We have several versions of file header:

  1. Ver-0.0.0
     The size of file header is 1024 bytes for now, which includes the fpg file we used, the UNIX time when we set the registers and the register vaules we used for the experiment. It's json format. For example:

      {
          "fpg": "dsa10_frb_2022-11-04_1844.fpg",
          "Time": 1668058079.2594,
      "SampleFreq": 500,
          "AccLen": 127,
  "AdcCoarseGain": 16,
      "FFTShift": 65535,
      "Scaling": 0,
      "DataSel": 1,
      "SpecCoeff": 7,
      "AdcDelay0": 5,
      "AdcDelay1": 5,
      "AdcDelay2": 5,
      "AdcDelay3": 5,
      "AdcDelay4": 5,
      "AdcDelay5": 5,
      "AdcDelay6": 5,
      "AdcDelay7": 5
      }
  

  2. Ver-0.0.1
     The size of file header is defined at the beginning of the file, which is an unsigned int value. You have to read the first 4 bytes out, and then you will know the size of file header( It doesn't include the first 4 bytes).
     Some other information are added to the file header, such as RA, DEC, AZ, EL and so on.

             SWVer: '0.0.1'
               fpg: 'limbo_500_m_2023-05-09_1203.fpg'
              Time: 1675998927.58758
        SampleFreq: 500
            AccLen: 127
     AdcCoarseGain: 4
          FFTShift: 2047
           DataSel: 1
           Scaling: 0
         SpecCoeff: 4
         AdcDelay0: 5
         AdcDelay1: 5
         AdcDelay2: 5
         AdcDelay3: 5
         AdcDelay4: 5
         AdcDelay5: 5
         AdcDelay6: 5
         AdcDelay7: 5
          RF_Lo_Hz: 1350000000
     Target_RA_Deg: '271:05:14.85'
     Target_EL_Deg: '-29:31:08.9'
       Pointing_AZ: 0
       Pointing_EL: 90
  Pointing_Updated: 1676526303.31059
  

  Note: To recognize the file version, you can read the first byte from the data file. If it's 123("{"), that's the ver-0.0.0 file.

  3. Ver-0.0.3
     We added Pol0EqCoeff and Pol1EqCoeff to the file header,which are used for voltage data. The new items in the file header is shown below:

             SWVer: '0.0.3'
               fpg: 'limbo_500_m_2023-05-09_1203.fpg'
       Pol0EqCoeff: 59904
       Pol1EqCoeff: 59904
  

  4. Ver-0.0.4 We added Source to the file header:

             SWVer: '0.0.4'
            Source: 'Crab'
  

• data in the file
  Each data frame contains three part:

1. The time when we received the packets, including second part and micro second part.

       uint64_t sec
       uint64_t usec
   

2. The counter value from FPGA, which counts the frame.

       uint64_t cnt
   

   Note: Only 56 bits are valid in the cnt value.

3. spectra data

       uint16_t spectra[2048]
   

   2048-channels spectra data are stored, and the data are in 16-bit format.

Voltage data file

• file name
  The name of the spectra data file starts with "VoltageV2_", following the UTC time when the file is generated. For example "VoltageV2_20221110042101.dat" means the file was generated at 04:21:01 on 11/10/2022.
• file header
  It's the same as the spectra data file header.
• data in file
  Each data frame also contains three parts:

1. The time when we received the packets, including second part and micro second part.

       uint64_t sec
       uint64_t usec
   

2. The counter value from FPGA, which counts the frame.

       uint64_t cnt
   

   Note: Only 56 bits are valid in the cnt value.

3. Voltage data

       int8_t voltage[4096]
   

   The voltage data contains I/Q ADC inputs(2048 channels x 2). Each channel contains 4-bit real data and 4-bit imaginary data.