[daip] Fringe, exhaustive baseline search gives wrong solution

[Thomas Krichbaum]

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