The pulsar digital filterbank

1.0 Current status

Prototype DFB system with 256 MHz of bandwidth installed at Parkes

2.0 Usage

The DFB system is run in a similar manner to the wide-band correlator. Up-to-date information on setting up cables, running tcs etc. is given in John Sarkissian's P456 folder (stored on the shelf in the control room).

2.1 Starting the observations

Details for the following are given in the P456 folder and are similar to the wide-band correlator setup.

Set up the wiring for the given receiver
Switch on the receiver if necessary
Switch the CAL to the DFB on the calibrator control box
On a solaris machine:
```
     cd losetup
     lorun xx
    
```
where xx is mb.cmd for the multibeam receiver or 1050fb.cmd for the 10-50 receiver.
If necessary produce a schedule file in /psr1/wbcorr (use P456_20cm_DFB.sch as an example)
Run tcs in DFB mode.

2.2 On-line monitoring

The on-line monitoring program is run on a linux machine

> psrdfb

This program sometimes crashes. However the archives are produced in /nfs/PKCCC2_1 and can be viewed using pav.

2.3 Setting the levels

The current recommended observing procedure is to set the levels to achieve 40 - 60 amplitude units on the spd display (type sel pp11). However, the lorun scripts are intended to set the levels at the commencement to approximately the correct value on cold sky. If the attenuation levels need to be changed then modify the "C12att (dB)" attenuators on LOGUI. (There are four of these: it's nearly always the first two, counting from the left, that you want.)

2.4 Common problems

2.4.1 CORDAT: Not keeping up

This seems to be a relatively common problem and occurs during long observations. It is caused by the FITS format requiring the software to write to the header (at the top of the file) and at the bottom of the file. When the time to get between the top and bottom of the file is long then this error occurs. It can be fixed by increasing the TSUB time in tcs. The online monitoring software psrcorr seems to fail to read such files and may need restarting.

2.4.2 CORDAT: Error in (Begin,End) times for integration (-1,-1)

Email from John Reynolds (28 Dec 05):

Your exprerience with the

        CORDAT: Error in (Begin,End) times for integration (-1,-1)

error sounds uncannily similar to problems experienced by Matthew Bailes
last week. As did you, he found that swapping back to 10 sec cycles
briefly seemed to cure the problem.

This is relatively new behaviour as far as I know - it makes no sense to
me. Your observation that every new config needs to be run at least once
with 10s cycle is new information.

3.0 Current configurations

The table provides the minimum pulsar spin-period (in milliseconds) for every possible combination of number of channels and phase bins. The number in parentheses is the value for only 2-channel output (instead of the standard 4 channel).

DFB channels			Phase bins
	256	512	1024	2048
128	0.8(0.5)	1.5(1.0)	3.1(2.0)	6.2(4.0)
512	2.6(1.5)	5.2(3.0)	10.4(6.1)	20.8(12.3)
2048	10.4(6.3)	20.8(12.5)	41.6(25.0)	83.0(50.0)

The full list of configurations are available from /nfs/online/local/tcs/cfg/DFBpsr.cfg and (as of 27/09/05) include

# Parkes Digital Filter Bank
#                                Primary               Alternate                                    Pulsar binning mode
#                         --------------------    --------------------                            -----------------------
#                         Conversion              Conversion                     BW  No  No  No    No   bins/    period
# Config file name          chain      Backend      chain      Backend     IF   MHz  bm pol chan  bins period  low   high
dfb2048_256_32_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3    33  2048  2048    0    999
dfb2048_256_32_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2    33  2048  2048    0    999
dfb2048_256_128_3p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   129  2048  2048  .0062  999
dfb2048_256_128_2p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   129  2048  2048  .0040  999
dfb2048_256_512_3p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   513  2048  2048  .0208  999
dfb2048_256_512_2p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   513  2048  2048  .0123  999
dfb2048_256_2048_3p         lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3  2049  2048  2048  .083   999
dfb2048_256_2048_2p         lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2  2049  2048  2048  .050   999
dfb1024_256_32_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3    33  1024  1024    0    999
dfb1024_256_32_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2    33  1024  1024    0    999
dfb1024_256_128_3p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   129  1024  1024  .0031  999
dfb1024_256_128_2p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   129  1024  1024  .0020  999
dfb1024_256_512_3p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   513  1024  1024  .0104  999
dfb1024_256_512_2p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   513  1024  1024  .0061  999
dfb1024_256_2048_3p         lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3  2049  1024  1024  .0416  999
dfb1024_256_2048_2p         lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2  2049  1024  1024  .0250  999
dfb512_256_32_3p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3    33   512   512    0    999
dfb512_256_32_2p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2    33   512   512    0    999
dfb512_256_128_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   129   512   512  .0015  999
dfb512_256_128_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   129   512   512  .0010  999
dfb512_256_512_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   513   512   512  .0052  999
dfb512_256_512_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   513   512   512  .0030  999
dfb512_256_2048_3p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3  2049   512   512  .0208  999
dfb512_256_2048_2p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2  2049   512   512  .0125  999
dfb256_256_32_3p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3    33   256   256    0    999
dfb256_256_32_2p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2    33   256   256    0    999
dfb256_256_128_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   129   256   256  .0008  999
dfb256_256_128_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   129   256   256  .0005  999
dfb256_256_512_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   513   256   256  .0026  999
dfb256_256_512_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   513   256   256  .0015  999
dfb256_256_2048_3p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3  2049   256   256  .0104  999
dfb256_256_2048_2p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2  2049   256   256  .0063  999
dfb128_256_32_3p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3    33   128   128    0    999
dfb128_256_32_2p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2    33   128   128    0    999
dfb128_256_128_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   129   128   128    0    999
dfb128_256_128_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   129   128   128    0    999
dfb128_256_512_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   513   128   128    0    999
dfb128_256_512_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   513   128   128    0    999
dfb128_256_2048_3p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3  2049   128   128    0    999
dfb128_256_2048_2p          lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2  2049   128   128    0    999
dfb64_256_32_3p             lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3    33    64    64    0    999
dfb64_256_32_2p             lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2    33    64    64    0    999
dfb64_256_128_3p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   129    64    64    0    999
dfb64_256_128_2p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   129    64    64    0    999
dfb64_256_512_3p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   513    64    64    0    999
dfb64_256_512_2p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   513    64    64    0    999
dfb64_256_2048_3p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3  2049    64    64    0    999
dfb64_256_2048_2p           lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2  2049    64    64    0    999
dfb16_256_512_2p            lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  2   513    16    16    0    999
NULL                        lo_rack     cpsr_l      lo_rack     cpsr_r      1   256   1  3   513  1024  1024    0    999

4.0 Installation tests

Tests carried out with the WBCORR and prototype DFB in August 2005

Installation of the DFB