[daip] Fringe, exhaustive baseline search gives wrong solution

[Thomas Krichbaum]

Hi Eric,

I have run FRING on 3 other datasets. Now I do not see any problem with 
exhaustive baseline search. If I enable exhaustive baseline search (aparm(9)=1 and set the 
search parameter) I obtain more 'good' solutions than with ap9=0.  This is as expected and
very good.

The main difference to the previous FRING runs of last September is that I now use 'older'
data which where correlated with the MK4 correlator and that these older data sets did not contain
any subarraying.

I am now wondering if a possible reason for the previous problems with the exhaustive baseline search
may be related to either (i) DiFX (probably less likely) or (ii) to the existence of two subarrays.  

I am using FRING in version TST. Did you eventually modify FRING between Sep. 2011 and now (Dec. 12th) ?

best regards, Thomas


On Wednesday 14 September 2011, Thomas Krichbaum wrote:
> Hi,
> 
> I use FRING in version 'new' and 'tst'. I run it in the exhaustive baseline search mode using ap5=1 and ap7=1. 
> This is necessary since the data have low SNR (3mm-VLBI). 
> 
> The parms are set like this:
> REFANT        5   
> SEARCH       12   11 3 4 13 2 0
> SOLINT          4
> SOLSUB        2
> SOLMIN         1
> APARM 2 0 0 0 1 2 4 0 1 0 
> DPARM 2 500 500 1 0 0 1 0
> 
> As in some earlier versions, I again encounter 'wrong' solutions, which appear occassionally.
> I thought that bug was fixed some time ago. 
> 
> In the coarse search I see phases above 360 deg or even with "****". 
> 
> The POSSM plot shows that the delays on some baselines come out wrongly. 
> 
> When I switch off exhaustive mode (set aparm9=0) the effect seems to dissappear. However
> that mode gives too few solutions, since FRINGE does not cycle through the full antenna list.
> 
> Here the prtmsg output for a particular scan:
> 
>    1    3   14-SEP-2011  19:12:29     FRING     IF number =    1 Poln. =   1
>    1    3   14-SEP-2011  19:12:29     FRING     Fitted phases, rates, delays and SNR: [ P = phase(deg),
>    1    3   14-SEP-2011  19:12:29     FRING       R = rate(mHz), D = Single-Band Delay(nsec), S = SNR ]
>    1    3   14-SEP-2011  19:12:29     FRING       R = rate(mHz), D = Single-Band Delay(nsec), S = SNR ]
>    1    3   14-SEP-2011  19:12:29     FRING     Ant(01): Phas=-959.6 rate=     -1.81 delay=      2.86 SNR=  20.4
>    1    3   14-SEP-2011  19:12:29     FRING     Ant(03): Phas=****** rate=     27.16 delay=    -11.47 SNR=  21.6
>    1    3   14-SEP-2011  19:12:29     FRING     Ant(04): Phas=****** rate=      0.74 delay=      3.06 SNR=  21.4
>    1    3   14-SEP-2011  19:12:29     FRING     Ant(07): Phas=****** rate=     17.50 delay=      2.02 SNR=  20.2
>    1    3   14-SEP-2011  19:12:29     FRING     Ant(08): Phas=-958.2 rate=    -24.19 delay=     -0.23 SNR=  18.6
>    1    3   14-SEP-2011  19:12:29     FRING     Ant(10): Phas=****** rate=     -2.38 delay=      1.83 SNR=  21.5
>    1    3   14-SEP-2011  19:12:29     FRING     Ant(11): Phas=****** rate=      2.69 delay=      2.66 SNR=  22.1
>    1    3   14-SEP-2011  19:12:29     FRING     Ant(12): Phas=****** rate=     -4.39 delay=      3.46 SNR=  22.1
>    1    3   14-SEP-2011  19:12:29     FRING     Standard RMS errors (deg, mHz, nsec):
> 
> 
> Is this a bug ?
> 
> 
> best regards, Thomas
> 
>  
> 
> -- 
> Thomas P. Krichbaum                       
> Max-Planck-Institut für Radioastronomie 
> Auf dem Hügel 69                        
> D-53121 Bonn / Germany
> 
> Tel. :  (Germany +49)-228-525-295
> Fax :  (Germany +49)-228-525-229
> e-mail: tkrichbaum at mpifr-bonn.mpg.de
> URL:   http://www.mpifr-bonn.mpg.de/staff/tkrichbaum
> 
> 



-- 
Thomas P. Krichbaum                       
Max-Planck-Institut für Radioastronomie 
Auf dem Hügel 69                        
D-53121 Bonn / Germany

Tel. :  (Germany +49)-228-525-295
Fax :  (Germany +49)-228-525-229
e-mail: tkrichbaum at mpifr-bonn.mpg.de
URL:   http://www.mpifr-bonn.mpg.de/staff/tkrichbaum