Parkes Radiotelescope Correlator Guide

Parkes Technical Staff

Last Update: June 8, 2011

A PDF version of this document is available

Contents

• 1 Preface
• 2 Multibeam Correlator
  • 2.1 Single-beam High Resolution Modes
  • 2.2 Multibeam and Wide-band Correlator
  • 2.3 Multibeam Correlator Data location
  
  
• 3 Digital Filter Banks
  • 3.1 DFB main features
  • 3.2 DFB Observing Modes
  • 3.3 Pulsar Folding Mode
  • 3.4 Pulsar Search Mode
  • 3.5 Time-binning Mode
  • 3.6 Spectrometer Mode
  
  
• 4 Supported Correlator Configurations
• 5 BPSR
• 6 Analogue Filter Banks
• 7 APSR
• 8 Other pulsar observation resources
• 9 Starting Correlator GUIs
• 10 GUI description
• 11 Configuring the Correlator
• 12 Commands
• 13 Using the Correlator in Stand-Along Mode: Dummsy
• 14 Using MBTP/SPD
• 15 Troubleshooting
  • 15.1 GUI unresponsive
  • 15.2 SYNCCC: WARNING - Total Power TOO LOW or TOO HIGH

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
Single Beam	64	4	2	Full	1	16384	RPFITS
MB/WB	8	4	2	Full	2	4096	RPFITS

2.1 Single-beam High Resolution Modes

It is possible to use high-resolution spectral-line modes using the central-beam of the 20CM and 6GHz Multibeam receivers. Also, single-beam receivers are able to use high-resolution modes of the Multibeam correlator. Supported modes are shown below in Table 8.

2.2 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  below.

2.3 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

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.

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, or to use the second IF input for RFI excision. The available BW are 8 (available in the short term), 16, 32, 64, ...., up to 1024 MHz. The maximum number of channels depends both on the observing mode (e.g. pulsar folding, time-binning) and configuration (e.g. dual or single frequency), with a maximum of 16384 and 8192 for DFB3 and DFB4, respectively.

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	16384
DFB4	1024	8	2	Full	1	4096

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:
   • 2k bins, 2k channels, 1024 MHz BW:
     4.096 ms (DFB3)
     8.192 ms (DFB4)
   • 2k bins, 2k channels, 512 MHz BW:
     8.192 ms (DFB3)
     16.384 ms (DFB4)
   • 2k bins, 512 channels, 1024 MHz BW:
     1.024 ms (DFB3)
     2.048 ms (DFB4)
5. The max number of frequency channels is limited to 2048.
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/DFB4	1024	64	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 BW.
4. The minimum sampling rate is 100 $\mu$s.
5. The max number of frequency channels is 8192 (DFB3) and 4096 (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 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	1024	64	2	Full	1	8192	CFITS
DFB4	1024	64	2	Full	1	4096	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:
   • The minimum is 8;
   • The maximum depends on the configuration, but cannot exceed 2048 (e.g., with 8192 channels, the maximum number available is 32);
3. The number of frequency channels:
   • The minimum is 512
   • The maximum is 8192 for DFB3 when used single-frequency (4096 dual-frequency);
   • 4096 for DFB4;
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	16	2	Full	1	8192	RPFITS
DFB3 (2 IFs)	1024	16	2	Full	2	4096	RPFITS
DFB4	1024	16	2	Full	1	4096	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:
   • The maximum is 16384 for DFB3 when used; total power mode only (full Stokes not available). If no polarization data are required, it can offer 8192 channels in dual-frequency too;
   • The minimum is 512.
   • The maximum is 4096 for DFB4.
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	4096	RPFITS
DFB3 (2 IFs, no pol)	1024	8	2	no pol	2	8192	RPFITS
DFB4	1024	8	2	Full	1	4096	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
mb1	1	1	1025	64	2
mb13	1	13	1025	64	2
mb13_16	1	13	1025	16	2
mb13_4_1024_2p	1	13	1025	4	2
mb13_4_512_2p	1	13	513	4	2
mb13_8_1024_2p	1	13	1025	8	2
mb13_8_512_2p	1	13	513	8	2
mb13_fqsw	1	13	1025	64	2
mb1_4_1024	1	1	1025	4	2
mb1_4_2048	1	1	2049	4	2
mb1_64_1024_3p	1	1	1025	64	3
mb1_64_2048	1	1	2049	64	2
mb1_64_64_3p	1	1	65	64	3
mb1_8_2048	1	1	2049	8	2
mb7_16_2048	1	7	2049	16	2
mb7_4_1024	1	7	1025	4	2
mb7_4_2048	1	7	2049	4	2
mb7_64_1024_2p_2f	2	7	1025	64	2
mb7_64_1024_ab_2f	2	7	1025	64	1
mb7_64_2048	1	7	2049	64	2
mb7_64_2048_swap	1	7	2049	64	2
mb7_8_1024	1	7	1025	8	2
mb7_8_1024_3p	2	7	1025	8	3
mb7_8_1024_ab_2f	2	7	1025	8	1
mb7_8_2048	1	7	2049	8	2
mb_64_2048_2f	2	1	2049	64	2

Table 8: MB Correlator: High spectral resolution for one beam only.

Name	Bands	Beams	Chans	BW	Products
mbcc_16_16384_2p	1	1	16385	16	2
mbcc_16_2048_2p	1	1	2049	16	2
mbcc_16_4096_2p	1	1	4097	16	2
mbcc_16_8192_2p	1	1	8193	16	2
mbcc_16_8192_3p	1	1	8193	16	3
mbcc_32_4096_2p	1	1	4097	32	2
mbcc_32_8192_2p	1	1	8193	32	2
mbcc_4_16384_2p	1	1	16385	4	2
mbcc_4_4096_3p	1	1	4097	4	3
mbcc_4_8192_2p	1	1	8193	4	2
mbcc_4_8192_2p_fqsw	1	1	8193	4	2
mbcc_4_8192_3p	1	1	8193	4	3
mbcc_4_8192_3p_fqsw	1	1	8193	4	3
mbcc_64_1024	1	1	1025	64	2
mbcc_64_2048	1	1	2049	64	2
mbcc_8_16384_2p	1	1	16385	8	2
mbcc_8_4096_2p	1	1	4097	8	2
mbcc_8_8192_2p	1	1	8193	8	2
mbcc_8_8192_3p	1	1	8193	8	3

Table 9: DFB3/DFB4 Search modes

Name	Bands	Beams	Chans	BW	Products	nbins
srch_1024_512	1	1	513	1024	3	1
srch_256_1024	1	1	1025	256	3	1
srch_256_512	1	1	513	256	3	1
srch_512_512	1	1	513	512	3	1

Table 10: DFB3/4 Time-binning modes

Name	Bands	Beams	Chans	BW	Products	nbins
sdfb3_tb16_1024_512	1	1	513	1024	3	16
sdfb3_tb16_16_8192	1	1	8193	16	3	16
sdfb3_tb16_16_8192_off	1	1	8193	16	3	16
sdfb3_tb16_16_8192_on	1	1	8193	16	3	16
sdfb3_tb16_256_512	1	1	513	256	3	16
sdfb3_tb16_256_512_nfsw	1	1	513	256	3	16
sdfb3_tb16_2b2f_256_512	2	1	513	256	3	16
sdfb3_tb16_2f_256_512	2	2	513	512	3	16
sdfb3_tb16_2f_256_512_nfsw	2	2	513	512	3	16
sdfb3_tb16_2f_64_512	2	1	513	64	3	16
sdfb3_tb16_512_512	1	1	513	512	3	16
sdfb3_tb16_64_512	1	1	513	64	3	16
sdfb3_tb32_16_8192	1	1	8193	16	3	32
sdfb3_tb4_2b2f_256_512	2	1	513	256	3	4
sdfb3_tb8_2f2p_8_4096	2	1	4097	8	2	8
sdfb3_tb8_2f_8_4096	2	1	4097	8	3	8
sdfb3_tb8_64_8192	1	1	8193	64	3	8
sdfb4_tb16_256_512	1	1	513	256	3	16

Table 11: DFB3/4 Spectrometer Modes

Name	Bands	Beams	Chans	BW	Products	nbins
sdfb3_128_1024	1	1	1025	128	2	1
sdfb3_128_8192	1	1	8193	128	2	1
sdfb3_256_1024	1	1	1025	256	2	1
sdfb3_256_8192	1	1	8193	256	2	1
sdfb3_64_1024	1	1	1025	64	2	1
sdfb3_64_8192	1	1	8193	64	2	1
sdfb4_128_1024	1	1	1025	128	2	1
sdfb4_128_8192	1	1	8193	128	2	1
sdfb4_256_1024	1	1	1025	256	2	1
sdfb4_256_8192	1	1	8193	256	2	1
sdfb4_64_1024	1	1	1025	64	2	1
sdfb4_64_8192	1	1	8193	64	2	1

Table 12: DFB3/DFB4 Pulsar Fold modes

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

5 BPSR

The Berkeley Parkes Swinburne Recorder (BPSR) has been developed by the Pulsar Group of the Swinburne University, Melbourne. BPSR is a multibeam digital backend designed for pulsar searching and is normally used in combination with the 13-beam 20 cm receiver array (MB-20). It is also possible to use the centre beam only.

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

BPSR 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).

6 Analogue Filter Banks

The Analogue Filter Banks (AFB) is the former system for pulsar searching with the 20-cm multibeam receiver. It is an analogue system and it is still offered under request. It can also be used with single receivers.

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

7 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).

8 Other pulsar observation resources

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

9 Starting Correlator GUIs

Correlator GUIs need to be run on specific computers:

Correlator	Program	Runs On...
Multibeam	pkcor	PKCCC1
DFB3 (pulsar)	psrdfb3	PKCCC3
DFB3 (spectral)	sdfb3	PKCCC3
DFB4 (pulsar)	psrdfb4	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.

All correlator GUIs are usually displayed on BOURBON, which is the four-displays at eye level in the main Control Room. If the relevant correlator GUI is not running on BOURBON, 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)

psrdfb3/psrdfb4 (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 te 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.

10 GUI description

This section describes some of the features of the GUI.

• Cycle:

  Shows the number of cycles per integration (one cycle = 5 seconds).

• State:

  State of the correlator. Can be 'Awaiting Connection' or 'Connected'.

• File:

  Status of output (FITS) file. Can be 'OPEN' or 'CLOSED'.

• Avg:

  The number of cycles averaged before writing to file.

11 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.

12 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.

13 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/PSFDFBs 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 9) 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'.

14 Using MBTP/SPD

MBTP displays the total power 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 BOURBON and in an xterm, telnet to the appropriate machine:

Machine	Correlator
pkccc1	Multibeam
pkccc3	PSRDFB3/SDFB3
pkccc4	PSRDFB4/SDFB4

once in, at the prompt type: disps.

Two xterms with titles "MBTP" and "SPD" will appear. Now on 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.

15 Troubleshooting

15.1 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 PSRDFB 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 BOURBON xterm where PKCOR or PSRDFB 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.

Incorrect Calibration Control Unit Setup

The Calibration Control Unit (CCU) is a 12x12 LED unit in the upstairs control room where users can select different calibration inputs (noise doide, 11 Hz square wave, etc). It is located at about chest height in Rack #4 in the upstairs control room. To remote-control the CCU, use the PKMC software by typing pkmc from the command-line. Once the main GUI is up, 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 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 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).

About this document ...

Parkes Radiotelescope Correlator Guide

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