Parkes Radiotelescope Correlator Guide

Parkes Technical Staff

Last Update: June 12, 2014

A PDF version of this document is available

Contents

1 Preface

This guide outlines the Multibeam and Digital Filterbank correlators currently available at Parkes.

2 Multibeam Correlator

The digitiser units provide 2-bit, 4-level digital data at a sample rate of 128 $\times$ 10$^6$ samples s$^{-1}$ from an input signal covering the frequency range 128 to 192 MHz. They include automatic control of the sampler decision levels aimed at reducing any zerolevel offset and maintaining the magnitude levels at the point which gives optimum signaltonoise ratio. They also include total power detectors and synchronous demodulators which are used in conjunction with the switched noise source injected in the input waveguides to measure the system temperature. The correlator uses the NASA SERC High Performance Correlator chip. This chip is a 1024 lag, 3-level correlator. The data are converted from four levels to three at the correlator input. The correlator board contains two of these chips and is capable of forming two 1024 lag autocorrelations or one 1024 lag crosscorrelation. Thirteen of these boards are required to form up to a 2048 channel autocorrelation spectrum for each of the 26 sampled data streams.

Configurations are of the type "mbX_BW_CH" where X = number of beams and BW the bandwidth (MHz), and CH the number of frequency channels. A "2p" indicates two polarizations and "3p" indicates full Stokes with the third product is the cross product of the two polarisations, and therefore is complex. The real and imaginary parts give the third and fourth Stokes. A "2f" indicates two input IFs. Table 2 reports a summary of the Multibeam Correlator's main futures and standard configurations are shown in Table 7.


Table 1: Multibeam Correlator
Backend BW (max) BW (min) # pol Stokes # IF channels file format
  [MHz] [MHz]       (max)  
Multiple Beams 64 4 2 Full 1 1024 RPFITS
MB/WB 8 4 2 Full 2 4096 RPFITS

2.1 Multibeam and Wide-band Correlator

The Multibeam Correlator has the capability to merge with the Wideband Correlator to provide a two-IF input and an autocorrelation function of 4096 channels. Supported configurations in this mode are listed in Table 8 below.

2.2 Multibeam Correlator Data location

The user interface to the correlator is normally TCS, available on any control-room workstation. The correlator hardware is controlled by PKCOR which runs on the correlator control computer PKCCC1. Data files are stored on /data/PKCCC1_1/corr/ on PKCCC1. Real-time data monitoring and analysis are provided by LIVEDATA which must be run under any Linux or Solaris machine. The PKCCC1_1/corr/ data disk is mounted as /nfs/PKCCC1_1 on the Linux/Solaris platform.

3 Digital Filter Banks (DFB)

The Digital Filter Banks mark 3 and 4 (DFB3 and DFB4) are the digital backends offered for single- and dual-receiver systems of the Parkes Observatory . These units are digital correlators for spectral, continuum and pulsar observations and provide both the power spectrum of each polarisation (Total Intensity) and the complex cross-spectrum (polarization).

The correlator is of the FX type and before the spectral processing the signal is prefiltered in sub-bands by a polyphase filter for high isolation and low RFI contamination into the next bands.

NOTE: It is NOT possible to perform dual-IF observations in frequency-switching mode (e.g., for spectral-line work). The options in this case are to use a single IF and use frequency-switching for each line seperately, or use position-switching with dual IFs. The latter means double the time spent on source, plus some overhead in moving the telescope between the ON and OFF positions.

3.1 DFB main features

The samplers are 8-bit units for high dynamic range. This gives high robustness against RFI saturation and a better tolerance of the input power level. The maximum input bandwidth (BW) is 1024 MHz . The main difference between DFB3 and DFB4 is the number of input frequency bands that can be processed: two for DFB3 (dual polarization each) and one for DFB4. DFB3 can thus serve either dual receivers, a double IF from a single receiver (not with frequency-switching), or to use the second IF input for RFI excision. The available BW are 8, 16, 32, 64, ...., up to 1024 MHz. The maximum number of channels depends on the observing mode (e.g. pulsar folding, time-binning), the bandwidth, and configuration (e.g. dual or single frequency), with a maximum of 8192.

Table 2 reports a summary of the DFBs' main futures.


Table 2: Main features of the two DFBs.
Backend BW (max) BW (min) # pol Stokes # IF channels (max)
  [MHz] [MHz]        
DFB3 1024 8 2 Full 2 8192
DFB4 1024 8 2 Full 1 8192


3.2 DFB Observing Modes

The DFBs can be used in four observing modes:

  1. Pulsar folding mode (pulsar observations);
  2. Pulsar search mode (pulsar observations);
  3. Time binning mode (spectral line/continuum observations at high time resolution);
  4. Spectrometer mode (spectral line/continuum observations at low time resolution).

3.3 Pulsar Folding Mode

Spectra are folded on the pulsar period. Used to observe pulsars of known period. Relevant configuration parameters are:

  1. The number of time-bins the folding period is divided in;
  2. The number of frequency channels;
  3. The BW.
  4. The minimum folding time depends on the configuration. Examples are:
  5. The max number of frequency channels is limited to 4096 (DFB3) and 2048 (DFB4).
  6. File format is "CFITS".
  7. The program to run DFB3 (DFB4) in this mode is "pdfb3" ("pdfb4") on the computer "pkccc3" ("pkccc4").

Main features of the pulsar folding mode are summarised in Table 3. Configurations are of the type "pdfbX_YYY_BW_CH" where X = 3,4 (for DFB3 and DFB4, respectively), YYY is the number of time-bins per folding period, BW the bandwidth (MHz), and CH the number of frequency channels. See Table 12 for supported modes.


Table 3: Pulsar Folding Mode
Backend BW (max) BW (min) # pol Stokes # IF channels file format
  [MHz] [MHz]       (max)  
DFB3 1024 8 2 Full 1 4096 CFITS
DFB4 1024 8 2 Full 1 2048 CFITS


3.4 Pulsar Search Mode

Spectra are dumped to file unfolded and the output is the spectrum as a function of time. Used to search for new pulsars. Relevant configuration parameters are:

  1. The number of time-bins the dump time is divided in;
  2. The number of frequency channels;
  3. The bandwidth (BW);
  4. the number of bits (2, 4, or 8).
  5. the number of polarizations (1, 2, or full Stokes).
Some of the major features are:
  1. The minimum sampling rate depends on the configuration and the computing power required. A typical value is 100 $\mu$s.
  2. The max number of frequency channels is 8192.
  3. File format is "CFITS".
  4. The program to run DFB3 (DFB4) in this mode is "pdfb3" ("pdfb4") on the computer "pkccc3" ("pkccc4").

Main features are reported in Table 4. Configurations are of the type "srch_BW_CH" where BW is the bandwidth (MHz) and CH the number of frequency channels. See Table 9 for supported modes.


Table 4: Pulsar Search Mode
Backend BW (max) BW (min) # pol Stokes # IF channels file format
  [MHz] [MHz]       (max)  
DFB3/DFB4 1024 64 2 Full 1 8192 CFITS

3.5 Time-binning Mode

It is used for spectral line and continuum observations, especially when observations require scans or, more in general, sampling times of 2 sec or shorter. Spectra are integrated in time bins (sampling time). Data are dumped every time-cycle, which is a set of time-bins. Relevant configuration parameters are:

  1. The time-cycle: 4-s or longer;
  2. Number of time-bins in each time-cycle:
  3. The number of frequency channels:
  4. The BW.
  5. File format is "RPFITS".
  6. The program to run DFB3 (DFB4) in this mode is "sdfb3" ("sdfb4") on the computer "pkccc3" ("pkccc4").

Main features of the time-binning mode are summarised in Table 5. Configurations are of the type "sdfbX_tbYY_BW_CH" where X = 3,4 (for DFB3 and DFB4, respectively), YY is the number of time-bins, BW the bandwidth (MHz), and CH the number of frequency channels. A "2b2f" stands for dual-frequency. See Table 10 for supported modes.


Table 5: Time-Binning Mode
Backend BW (max) BW (min) # pol Stokes # IF channels file format
  [MHz] [MHz]       (max)  
DFB3 (1 IF) 1024 8 2 Full 1 4096 RPFITS
DFB3 (2 IFs) 1024 8 2 Full 2 4096 (2048 at 1024 MHz) RPFITS
DFB4 1024 8 2 Full 1 4096 (2048 at 1024 MHz) RPFITS

3.6 Spectrometer Mode

It can be used for spectral line and continuum observations when sampling times of 4-s or longer are required. It is like the time-binning mode but with one time-bin a time-cycle. Relevant configuration parameters are:

  1. the time-cycle: 4-s or longer;
  2. the number of frequency channels:
  3. the BW.
  4. File format is "RPFITS".
  5. The program to run DFB3 (DFB4) in this mode is "sdfb3" ("sdfb4") on the computer "pkccc3" ("pkccc4").

Main features are reported in Table 6. Configurations are of the type "sdfbX_BW_CH" where X = 3,4 (for DFB3 and DFB4, respectively), BW the bandwidth (MHz), and CH the number of frequency channels. A "2bm" stands for dual-frequency. See Table 11 for supported modes.


Table 6: Spectrometer Mode
Backend BW (max) BW (min) # pol Stokes # IF channels file format
  [MHz] [MHz]       (max)  
DFB3 (1 IF) 1024 8 2 Full 1 8192 RPFITS
DFB3 (2 IFs) 1024 8 2 Full 2 8192 RPFITS
DFB4 1024 8 2 Full 1 8192 RPFITS

4 Supported Correlator Configurations

The configurations below are those currently supported. If your configuration is not listed, please contact Parkes Operations (parkes-operations[at]csiro.au).


Table 7: MB Correlator: Using standard MB samplers.
Name Bands Beams Chans BW Products
mb13_4_512_2p 1 13 513 4 2
mb7_4_1024 1 7 1025 4 2
mb1_4_1024 1 1 1025 4 2
mb1_4_2048 1 1 2049 4 2
mb7_4_2048 1 7 2049 4 2
mb13_4_1024_2p 1 13 1025 4 2
mb7_8_1024_3p 2 7 1025 8 3
mb7_8_1024_ab_2f 2 7 1025 8 1
mb7_8_1024 1 7 1025 8 2
mb1_8_2048 1 1 2049 8 2
mb13_8_512_2p 1 13 513 8 2
mb7_8_2048 1 7 2049 8 2
mb13_8_1024_2p 1 13 1025 8 2
mb7_64_2048 1 7 2049 64 2
mb7_64_2048_swap 1 7 2049 64 2
mb7_64_1024_2p_2f 2 7 1025 64 2
mb1 1 1 1025 64 2
mb1_64_1024_3p 1 1 1025 64 3
mb1_64_2048 1 1 2049 64 2
mb7_64_1024_ab_2f 2 7 1025 64 1
mb13 1 13 1025 64 2
mb_64_2048_2f 2 1 2049 64 2
mb13_fqsw 1 13 1025 64 2
mb1_64_64_3p 1 1 65 64 3


Table 8: Wideband/Multibeam Correlator
Name Bands Beams Chans BW Products
mbwb7_4_2048_2f 2 7 2049 4 2
mbwb2_4_2048_2f 2 2 2049 4 2
mbwb7_4_2048 1 7 2049 4 2
mbwb7_8_4096_2p 1 7 4097 8 2
mbwb13_8_2048_2p 1 13 2049 8 2
mbwb7_8_2048_2f 2 7 2049 8 2
mbwb7_8_2048 1 7 2049 8 2


Table 9: DFB3/DFB4 Search modes
Name Bands Beams Chans BW Products nbins      
srch_16_512 1 1 513 12 3 1      
srch_64_512 1 1 513 64 3 1      
srch_64_256 1 1 257 64 3 1      
srch_256_512 1 1 513 256 3 1      
srch_256_1024 1 1 1025 256 3 1      
srch_256_128 1 1 129 256 3 1      
srch_512_512 1 1 513 512 3 1      
srch_512_128 1 1 129 512 3 1      
srch_1024_512 1 1 513 1024 3 1      


Table 10: DFB3/4 Time-binning modes
Name Bands Beams Chans BW Products nbins      


Table 11: DFB3/4 Spectrometer Modes
Name Bands Beams Chans BW Products nbins      
sdfb3_8_8192_fqsw 1 1 8193 8 3 1      
sdfb3_2f2p_8_4096 2 1 4097 8 2 1      
sdfb3_tb8_2f_8_4096 2 1 4097 8 3 8      
sdfb3_8_8192 1 1 8193 8 3 1      
sdfb4_8_8192 1 1 8193 8 3 1      
sdfb3_2f_8_4096 2 1 4097 8 3 1      
sdfb3_tb8_2f2p_8_4096 2 1 4097 8 2 8      
sdfb3_2f_8_8192 2 1 8193 8 3 1      
sdfb3_tb16_2f_8_4096 2 1 4097 8 3 16      
sdfb3_2f2p_8_8192 2 1 8193 8 2 1      
sdfb3_tb16_16_8192_off 1 1 8193 16 3 16      
sdfb3_2p_16_4096_fqsw 1 1 4097 16 2 1      
sdfb3_tb16_16_8192_on 1 1 8193 16 3 16      
sdfb3_2f_16_8192 2 1 8193 16 3 1      
sdfb3_2p_16_4096 1 1 4097 16 2 1      
sdfb3_16_8192 1 1 8193 16 3 1      
sdfb3_tb32_16_8192 1 1 8193 16 3 32      
sdfb3_16_8192_fqsw 1 1 8193 16 3 1      
sdfb3_tb16_16_8192 1 1 8193 16 3 16      
sdfb3_32_8192_fqsw 1 1 8193 32 2 1      
sdfb3_64_8192 1 1 8193 64 2 1      
sdfb3_2f2p_256_8192_64_8192 2 1 8193 64 2 1      
sdfb3_64_2048 1 1 1025 64 3 1      
sdfb3_tb8_64_8192 1 1 8193 64 3 8      
sdfb3_2f2p_64_8192 2 1 8193 64 2 1      
sdfb3_tb16_2f_64_512 2 1 513 64 3 16      
sdfb4_64_1024 1 1 1025 64 2 1      
sdfb3_64_1024 1 1 1025 64 2 1      
sdfb3_64_8192_fqsw 1 1 8193 64 2 1      
sdfb3_tb16_64_512 1 1 513 64 3 16      
sdfb3_2bm_64_2048 1 2 2049 64 2 1      
sdfb4_64_8192 1 1 8193 64 2 1      
sdfb3_128_8192 1 1 8193 128 2 1      
sdfb4_128_8192 1 1 8193 128 2 1      
sdfb4_128_8192_fqsw 1 1 8193 128 2 1      
sdfb3_128_1024 1 1 1025 128 2 1      
sdfb4_128_1024 1 1 1025 128 2 1      
sdfb3_128_8192_fqsw 1 1 8193 128 2 1      
sdfb3_tb16_256_512 1 1 513 256 3 16      
sdfb3_2bm_256_4096 1 2 4097 256 2 1      
sdfb4_256_8192 1 1 8193 256 2 1      
sdfb3_tb4_2b2f_256_512 2 1 513 256 3 4      
sdfb3_tb16_2b2f_256_512 2 1 513 256 3 16      
sdfb4_256_1024 1 1 1025 256 2 1      
sdfb3_2bm_256_8192 1 2 8193 256 2 1      
sdfb3_2bm_256_2048 1 2 2049 256 2 1      
sdfb3_256_1024 1 1 1025 256 2 1      
sdfb3_256_8192_fqsw 1 1 8193 256 2 1      
sdfb3_256_8192 1 1 8193 256 2 1      
sdfb4_tb16_256_512 1 1 513 256 3 16      
sdfb3_tb16_2f_256_512 2 2 513 512 3 16      
sdfb3_512_8192_fqsw 1 1 8193 512 2 1      
sdfb3_tb16_512_512 1 1 513 512 3 16      
sdfb3_1024_1024 1 1 1025 1024 3 1      
sdfb3_1024_8192_fqsw 1 1 8193 1024 2 1      
sdfb3_tb16_2f_1024_512 2 1 513 1024 3 16      
sdfb3_tb16_1024_512 1 1 513 1024 3 16      


Table 12: DFB3/DFB4 Pulsar Fold modes
Name Bands Beams Chans BW Products nbins      
pdfb3_512_64_2048 1 1 2049 64 3 512      
pdfb3_512_64_512 1 1 513 64 3 512      
pdfb3_256_64_2048 1 1 2049 64 3 256      
pdfb4_256_64_1024 1 1 1025 64 3 256      
pdfb4_512_64_1024 1 1 1025 64 3 512      
pdfb4_128_64_512 1 1 513 64 3 128      
pdfb4_512_64_512 1 1 513 64 3 512      
pdfb4_128_64_1024 1 1 1025 64 3 128      
pdfb3_512_64_1024 1 1 1025 64 3 512      
pdfb3_256_64_512 1 1 513 64 3 256      
pdfb3_128_64_512 1 1 513 64 3 128      
pdfb3_256_64_1024 1 1 1025 64 3 256      
pdfb3_128_64_2048 1 1 2049 64 3 128      
pdfb4_256_64_512 1 1 513 64 3 256      
pdfb3_128_64_1024 1 1 1025 64 3 128      
pdfb4_512_128_1024 1 1 1025 128 3 512      
pdfb4_512_128_512 1 1 513 128 3 512      
pdfb4_512_128_2048 1 1 2049 128 3 512      
pdfb4_512_256_1024 1 1 1025 256 3 512      
pdfb4_256_256_1024 1 1 1025 256 3 256      
pdfb3_512_256_2048 1 1 2049 256 3 512      
pdfb3_512_256_512 1 1 513 256 3 512      
pdfb3_512_256_1024 1 1 1025 256 3 512      
pdfb4_512_256_512 1 1 513 256 3 512      
pdfb3_256_256_2048 1 1 2049 256 3 256      
pdfb4_512_256_2048 1 1 2049 256 3 512      
pdfb4_256_256_512 1 1 513 256 3 256      
pdfb3_256_256_1024 1 1 1025 256 3 256      
pdfb4_256_256_2048 1 1 2049 256 3 256      
pdfb3_512_512_512 1 1 513 512 3 512      
pdfb4_512_512_512 1 1 513 512 3 512      
pdfb4_512_512_2048 1 1 2049 512 3 512      
pdfb4_512_512_1024 1 1 1025 512 3 512      
pdfb3_512_512_2048 1 1 2049 512 3 512      
pdfb4_512_1024_2048 1 1 2049 1024 3 512      
pdfb3_512_1024_2048 1 1 2049 1024 3 512      
pdfb4_512_1024_512 1 1 513 1024 3 512      
pdfb3_512_1024_512 1 1 513 1024 3 512      
pdfb4_256_1024_1024 1 1 1025 1024 3 512      
pdfb3_256_1024_2048 1 1 2049 1024 3 256      
pdfb4_512_1024_1024 1 1 1025 1024 3 512      
pdfb4_256_1024_512 1 1 513 1024 3 512      
pdfb3_512_1024_1024 1 1 1025 1024 3 512      
pdfb4_256_1024_2048 1 1 2049 1024 3 512      

5 HIPSR

The HI Parkes Swinburne Recorder (HIPSR) has been developed by a collaboration of: the Pulsar Group of the Swinburne University, Melbourne; ICRAR University of Western Australia, Perth; University of Oxford; CASS. HIPSR is a multibeam digital backend designed for pulsar searching and limited spectral-line modes; currently only the "wide-band" mode of 400MHz/8192 channels is available, with a "narrow-band" 200MHz/16k channel configuration in progress. HIPSR is used in combination with the 13-beam 20 cm receiver array (MB-20).

General background information can be found at the following link: HIPSR documentation

A PDF guide is availble on how to observe using the Multibeam receiver and HIPSR in 400GHz/8192chans spectral-line mode, with a focus on HI observations. It is available here.

HIPSR has limited support and is currently offered on a shared-risk basis. Enquiries about its use in proposals should be directed to Ettore Carretti (Ettore.Carretti[at]csiro.au).

6 APSR

The ATNF Parkes Swinburne Recorder (APSR) has been developed by the Swinburne University as a coherent dedispersion backend for searching and timing pulsar observations with single receivers. It uses the ATNF's DFB3 samplers to digitise the signal.

The user guide can be found at the following link: APSR User Guide

APSR is as yet unsupported and is offered on a shared-risk basis. Enquiries about its use in proposals should be directed to Ettore Carretti (Ettore.Carretti[at]csiro.au).

7 Other pulsar observation resources

More information on using Pulsar backends is available from the ATNF Pulsar site.

8 Starting Correlator GUIs

Correlator GUIs need to be run on specific computers:

Correlator Program Runs On...
Multibeam pkcor PKCCC1
DFB3 (pulsar) pdfb3 PKCCC3
DFB3 (spectral) sdfb3 PKCCC3
DFB4 (pulsar) pdfb4 PKCCC4
DFB4 (spectral) sdfb4 PKCCC4
   

The GUI displays information about the configuration of the correlator (i.e. bandpass, number of channels etc.), integration cycle, name of the current data file and diagnostic information about the correlator activity. It is handy during observations for changing the configuration file and for checking whether or not a file is open.

Generally, the GUI for each correlator is essentially the same as shown in Figure 1, showing that of MBCORR as example.

PKCOR GUI at startup

All correlator GUIs are usually displayed on joffrey (bourbon, before the remote observing era starts), which is the four-displays at eye level in the main Control Room. If the relevant correlator GUI is not running on joffrey (bourbon, before the remote observing era starts), move the cursor across to DISPLAY2 and open an xterm window (using the left mouse button to select 'xterm'), type:

ssh pkccc1 (Multibeam)

ssh pkccc3 (DFB3)

ssh pkccc4 (DFB4)

The login and password are available from staff. You start the relevant correlator program by typing the following:

pkcor (Multibeam correlator)

pdfb3/pdfb4 (DFB3/4 in pulsar mode)

sdfb3/sdfb4 (DFB3/4 in spectral-line mode)

This will start a number of iconised xterms, CFG (CONFIG), CD (CORDAT) and XF (XFER), which you can ignore, plus the main correlator GUI. In the State box, the message:

Awaiting Connection

should be in yellow. From the xterm you started the program in you should also see the message:

SYNCCC: WAIT for CONNECTION from TCS .........

You are now in a position to start TCS. It is preferable that PKCOR or the DFB GUI are up and running before TCS is started. If they should exit for any reason, you will need to exit from TCS and get the correlator GUI going again before restarting TCS. Once TCS has started, the State box should show: Connected In general you will not need to interact further with the correlator GUI. All the necessary control commands will be sent by TCS.

9 GUI description

This section describes some of the features of the GUI.

10 Configuring the Correlator

Occasionally you may need to manually reconfigure the correlator. This can be done by clicking the CONFIG button. This button is active only when a scan/track has stopped. The CONFIG xterm, which logs the progress of the reconfiguration, will appear briefly and display a 'bubble race', showing the configuration taking place.

11 Commands

On the bottom right hand corner, there is a Command: entry box where you can enter commands. Note that many of the possible commands do not have any meaning for the Parkes correlator. For completeness, a listing of these commands is available here. It should be noted not ALL commands will be compatible with ALL correlator GUIs.

12 Using the Correlator in Stand-Along Mode: Dummsy

By using the program 'DUMMSY', it is possible to bypass the dependency of TCS to display spectral information for a particular receiver. The PKCOR/DFBs command starts all the essential processes, including the main GUI. However to actually run the correlator a client has to connect to it. This is usually TCS, but there is a simplified client on pkccc1 itself called 'dummsy', which can also be used. However the main correlator processes have to be running already before you start dummsy. There can also be only one client at a time, so starting a second copy of dummsy, or failing to kill TCS first will also cause errors.

To use dummsy, telnet to the relevant correlator computer (see Table 8) and startup two xterms:

xterm &
xterm &

Now in one xterm, type the relevant command to start up the correlator GUI. In the other xterm, enter dummsy. The GUI will resize itself and the state will go from "Awaiting connection" (yellow) to just "STOPPED" (grey). Entering the "GO" command changes the state to "GO" (grey). Commands are passed to the correlator via the '}' prompt (press the ENTER/RETURN key a few times until you see it). If you haven't done so already, you will also need to start up the SPD (Spectral Display) display (see the Online Programs section of the Parkes User Guide). Commands for using DUMMSY can be found here.

Note there is also a GUI for dummsy: tkdummsy (or tkds). Instead of passing commands on the command line, with tkds, commands are passed to the correlator via an entry widget at the bottom of the GUI labelled 'Command'.

13 Using MBTP/SPD

MBTP displays the total power (MBCOR only) for each beam in use. SPD displays data from the correlator, either in the lag domain - the correlation function as measured directly by the correlator - or in the frequency domain - the spectrum which results from the Fourier transform of the correlation function. The user can select which of the products contained within the correlator configuration to display and in what form to display them. Go to joffrey (bourbon, before the remote observing era starts) and in an xterm, telnet to the appropriate machine:

Machine Correlator
pkccc1 Multibeam

once in, at the prompt type: disps.

Two xterms with titles "MBTP" and "SPD" will appear. Now on joffrey (bourbon) in the xterm titled "MBTP", type the following (press $<$CR$>$ after each):

  mbtp
  /xs
  sel 1-13a

In the other xterm titled "SPD", type:

  spd
  /xs
  sel mb

You won't get anything meaningful out of them until you start observing. Online documentation for SPD is available here. Other commands for both SPD and MBTP are available from sheets in the control room.

14 Using SPD with DFBs

SPD displays data from the correlator, either in the frequency domain - the spectrum which results from the products of the Fourier transforms of the two polarization signals (DFBs are FX correlators), or in the time domain - all frquency channels in the selected range binned together and plotted versus the time bin within the last time cycle acquired (time-binning mode only). The user can select which of the products contained within the correlator configuration to display and in what form to display them. Go to joffrey (bourbon, before the remote observing era starts) and in an xterm, ssh to the appropriate machine (user "corr", passwd to be enquired to the project support):

Machine Correlator
pkccc3 PDFB3/SDFB3
pkccc4 PDFB4/SDFB4

once in, at the prompt type: spd,

and then type the following (press $<$CR$>$ after each):

  /xs
  sel *          (to plot all available spectra -- all polarizations, all IFs)
  on aa, bb, ab  (to plot auto and cross-products)
  bins x-y       (to plot spectra of bins x to y of a time-cycle)
  ch LL HH       (to plot only channels LL to HH)
  ch             (to plot all channels)
  scale a XX YY  (to scale amplitude in the range XX YY)
  scale a        (to auto-scale)
  sel pp11       (to set time-domain plotting)
  sel 11         (to set back to frequency-domain)

You won't get anything meaningful out of it until you start observing. Online documentation for SPD is available here. Other commands for both SPD and MBTP are available from sheets in the control room.

15 Troubleshooting

15.1 Incorrect Calibration Control Unit Setup

The Calibration Control Unit (CCU) is a 12x12 LED unit available via PKMC, where users can select different calibration inputs (noise doide, 11 Hz square wave, etc). Click the "Show->" button associated with the "Cal Control Unit". On the top are INPUTS and to the left are OUTPUTS (i.e., 10cm, MULTI...).

For Multibeam Observing (non-pulsar), you must select the LED which intesects the MBCor and Multi (20CM) labels. To do this, select the radiobutton which intersect these two labels on the pkmc GUI. In order to see if the calibration unit is working and you have selected the right input noise source, perform a calibration (with TCS) on a strong source like Hydra A, or 1934-638. If you see reasonable fluxes after the calibration is done (look in the TCS log window), you are okay to proceed.

15.2 Block Control Computers

For reference, the location of each block control computer (bcc) is summarised below:

15.3 MBCORR

15.3.1 GUI unresponsive

If the GUI is still up but it is not responding to buttons, particularly the QUIT button, a CTRL C in the xterm from which you started PKCOR or DFB then answer the "Exit from Glish (y/n) ?" question with y.

If you experience problems restarting after an abnormal exit there are probably "rogue" processes still running which must be killed manually. On the joffrey (bourbon) xterm where PKCOR or DFB was started, type:

corkill

This will kill processes with a command name containing any of the words cor, tksynccc, config, cordat, xfer. PKCOR will not restart until all such processes have been killed.

15.3.2 SYNCCC: WARNING - Total Power TOO LOW or TOO HIGH

With 20cm Multibeam observing, you might see this message when a GPS satellite at 1380MHz (10-15 Jy) appears in one or more beams. Strong Galactic sources have also been a culprit. Look at the MBTP display on joffrey (bourbon) to see the response of each beam. Check the Tsys values on the PKCOR GUI. If these are OK (around 20K), some attenuation may be needed. This can be done via the buttons on the "multibeam cable equaliser" module on rack G (the farthest to the left) in the upstairs control room. This is usually done on a regular basis by observatory technical staff. Note that for the Multibeam receiver, some beams have low total powers due to wear-and-tear on some LNAs (low noise amplifiers).

15.3.3 CONFIG: ER_ETDQueueOverflow from blk 7

It is usually best to stop observing and try recofiguring the correlator using the CONFIG button on the PKCOR GUI. If you need to restart the block control computer(s), they are 'standard' diskless PCs with the familiar white reset button. Occasionally the EVG (Event Generator) cards in the BCCs get into an error state with a red LED showing, indicating loss of clock frame. It is usually necessary to power-cycle the BCCs, not just reboot them, to clear this red LED indication. (This can also occur with the EVG card in @scpkdesk). @strongAny reset of a BCC requires a manual reprogramming of the associated correlator, by clicking on the CONFIG button of the correlator GUI.

15.4 DFBs

15.4.1 GUI unresponsive or corrupt spectra

If you have issues getting DFB3 or DFB4 going, follow the procedures below.

  1. Try reconfiguring the DFB (click CONFIG button on DFB GUI);

    Try this at least 2 times before moving to #2.

  2. If #1 is not sufficient, quit and restart DFB GUI (pdfb3/sdfb3, or pdfb4/sdfb4 according to the observing mode)

    Try this at least 2 times before moving to #3;

  3. If #2 is not sufficient, use the bcckill and corkill procedures:

    Try this at least 2 times before moving to #4

  4. If #3 is not sufficient, reboot the two l-bcc06 (DFB3 only) and l-bcc11 boards:

    Try this 2 times before moving to #5

  5. If #4 has been unsuccessful, power cycle the DFB (very last resort!):

About this document ...

Parkes Radiotelescope Correlator Guide

This document was generated using the LaTeX2HTML translator Version 2008 (1.71)

Copyright © 1993, 1994, 1995, 1996, Nikos Drakos, Computer Based Learning Unit, University of Leeds.
Copyright © 1997, 1998, 1999, Ross Moore, Mathematics Department, Macquarie University, Sydney.

The command line arguments were:
latex2html -init_file latex2html-init -show_section_numbers -split +0 -no_footnode -no_subdir correl.latex

The translation was initiated by Stacy Mader on 2014-06-12

Stacy Mader
2014-06-12