Multiple phase cal tones in experiment c1013 ($01JUN25XA)

Introduction

Experiment c1013 ($01JUN25XA) was observed with channel frequency band 8 MHz channel. Correlator extracted phase cal phases at frequencies 10KHz and 4010 KHz at X-band ant 10KHz, 6010 KHz at S-band. It was fringed two times, with using phase cal at 10KHz and with using phase cal phase at 4010 KHz for X-band and 6010KHz for S-band. (Exception: 6010 KHz tone at GILCREEK was used for both cases). Two databases were created, $01JUN25XA with 10KHz phase cal and $01JUN25X1 with 4010/6010 KHz.

Comparison of solutions

Two solutions were made, one with 10KHz phase calibration, another with 4010/6010 KHz phase calibration. Delay transfer technique was used for comparision of these two solutions in order to be sure that solution setup, weights, suppression flags etc were identical in both solutions.

Solution 1: with 10 KHz phase cal frequency 

 Delay        1371           37 ps

 Baseline Statistics
      Baseline      # W.Obs   W.RMS Del N.R.D. 
                  used/recov     ps            
 GILCREEK-HARTRAO   14/  14      78    1.15    
 GILCREEK-SESHAN25 127/ 131      47     .86    
 GILCREEK-TSUKUB32 366/ 383      30     .86    
 GILCREEK-WESTFORD 216/ 225      34     .83    
 HARTRAO -SESHAN25  52/  55      47     .75    
 HARTRAO -TSUKUB32  53/  53      44     .90    
 HARTRAO -WESTFORD  52/  53      31     .87    
 SESHAN25-TSUKUB32 316/ 331      42     .88    
 SESHAN25-WESTFORD  39/  40      54     .94    
 TSUKUB32-WESTFORD 136/ 141      45    1.01    

 Corrected Reduced Chi-Square    .9143

Full listing of the solution with 10KHz phase cal tones.

Solution 2: with 4010/6010 KHz phase cal frequency

It has exacatly the same parameterization, weights, suppressions status etc as solution 1. 
 Delay        1371           37 ps

 Baseline Statistics
      Baseline      # W.Obs   W.RMS Del N.R.D.
                  used/recov     ps           
 GILCREEK-HARTRAO   14/  14      68    1.01   
 GILCREEK-SESHAN25 127/ 131      46     .84   
 GILCREEK-TSUKUB32 366/ 383      30     .86   
 GILCREEK-WESTFORD 216/ 225      32     .79   
 HARTRAO -SESHAN25  52/  55      46     .74   
 HARTRAO -TSUKUB32  53/  53      44     .90   
 HARTRAO -WESTFORD  52/  53      30     .84   
 SESHAN25-TSUKUB32 316/ 331      41     .87   
 SESHAN25-WESTFORD  39/  40      55     .95   
 TSUKUB32-WESTFORD 136/ 141      43     .98   

 Corrected Reduced Chi-Square    .8780
Solution with 4010/6010 KHz phases is slightly better than the solution with 10KHz phase cal phases, but improvement is marginal.

Full listing of the solution with 4010/6010 KHz phase cal tones.

Solution 3: with 4010/6010 KHz phase cal frequency

It has slighly different parameterization and weights than solution 2. 
 GILCREEK-HARTRAO   14/  14      77     .88
 GILCREEK-SESHAN25 128/ 132      45     .93
 GILCREEK-TSUKUB32 366/ 383      30     .92
 GILCREEK-WESTFORD 216/ 225      31     .93
 HARTRAO -SESHAN25  52/  55      44     .82
 HARTRAO -TSUKUB32  53/  53      46     .85
 HARTRAO -WESTFORD  52/  53      30     .78
 SESHAN25-TSUKUB32 316/ 331      40     .93
 SESHAN25-WESTFORD  39/  40      54     .94
 TSUKUB32-WESTFORD 136/ 141      43     .94

Solution 4: with 4010/6010 KHz phase cal frequency and with calibration for spurious signals computed by Phase_Doctor:

It has exacatly the same parameterization, weights, suppressions status etc as solution 3. 
 GILCREEK-HARTRAO   14/  14      80     .91
 GILCREEK-SESHAN25 128/ 132      44     .93
 GILCREEK-TSUKUB32 366/ 383      30     .92
 GILCREEK-WESTFORD 216/ 225      31     .92
 HARTRAO -SESHAN25  52/  55      42     .78
 HARTRAO -TSUKUB32  53/  53      45     .82
 HARTRAO -WESTFORD  52/  53      29     .75
 SESHAN25-TSUKUB32 316/ 331      40     .93
 SESHAN25-WESTFORD  39/  40      54     .94
 TSUKUB32-WESTFORD 136/ 141      43     .94

Spurious signals at 10KHz phase cal tones

Normalized phase cal amplitude versus phase cal phase. (Units for phases at all plots are radians).

Spurious signals at 4010/6010 KHz phase cal tones

Normalized phase cal amplitude versus phase cal phase.

Differences in phase cal phases 4010/6010 KHz minus 10KHz tones tones

Conclusions

  1. Using 4010/6010 KHz phase cal marginally improved results of c1013 with respect to solution with 10KHz phases. Improvement is of about the same magnitude as removal of spurious phase cal signals as Phase_Doctor does it.

  2. Spurious signals in phase cal tones at 4010 KHz frequency is at about the same level as spurious signals at 10 KHz frequency.

  3. Variations in the differences in phase cal phases 4010 KHz minus 10 KHz are at the level 0.03 - 0.30 rad ( 2 - 20 degrees ). They depend on station and may show pattern and spikes. Points with spikes have a tendency to be outliers in our solutions.

  4. Re-fringing old experiments is not justified.

  5. More investigation how and why phase of phase cal varies within each individual channel is desirable. Extraction of all 8 phase cal frequencies in rdv22 experiment promises to substantially clarify situation.

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This page was prepared by Leonid Petrov

Last update: 12-DEC-2001 17:40:34