MeqAzEl.py

# A Python TDL script to test the AzEl node# standard preamblefrom Timba.TDL import *from Timba.Meq import meqfrom Timba.Meq import meqdsfrom numarray import *# Timba.TDL.Settings.forest_state is a standard TDL name.# This is a record passed to Set.Forest.State.Settings.forest_state.cache_policy = 100;def _define_forest (ns):  """define_forest() is a standard TDL name. When a forest script is  loaded by, e.g., the browser, this method is automatically called to  define the forest. The 'ns' argument is a NodeScope object in which  the forest is to be defined, usually this is simply the global scope.  """;# set up a sequence of nodes for testing of the AzEl node# first define an RA and DEC (in radians)  ra = 0.0  dec = 0.57595865  ns.ra0 << Meq.Parm(ra,node_groups='Parm')  ns.dec0 << Meq.Parm(dec,node_groups='Parm')# then create a MeqComposer containing ra dec children  ns.RADec <<Meq.Composer(ns.ra0, ns.dec0)# station positions for one of the VLA telescopes - gets converted# into an aips++ MVDirection object in the AzEl node;# (units are metres)  X_pos = -1597262.96  Y_pos = -5043205.54  Z_pos = 3554901.34  ns.x_pos << Meq.Parm(X_pos,node_groups='Parm')  ns.y_pos << Meq.Parm(Y_pos,node_groups='Parm')  ns.z_pos << Meq.Parm(Z_pos,node_groups='Parm')# create a  MeqComposer containing X_pos, Y_pos, Z_pos children  ns.XYZ <<Meq.Composer(ns.x_pos, ns.y_pos, ns.z_pos)# we should now be able to create an AzEl node with X,Y,Z station positions  ns.AzEl << Meq.AzEl(radec=ns.RADec, xyz=ns.XYZ)# we should also be able to specify the VLA position directly  ns.AzEl1 << Meq.AzEl(radec=ns.RADec, observatory='VLA')# create a ReqSeq node to call the two AzEl nodes  ns.reqseq <<Meq.ReqSeq(ns.AzEl,ns.AzEl1)def _test_forest (mqs,parent):  """test_forest() is a standard TDL name. When a forest script is  loaded by, e.g., the browser, and the "test" option is set to true,  this method is automatically called after define_forest() to run a  test on the forest. The 'mqs' argument is a meqserver proxy object.  """;##### time and frequency domain# time - cover one day  t0 = 0.01;  t1 = 86400.01;# any old frequency####  f1 =  299792458.0;  f0 = 0.9*f1;# Make cells array - we will compute Azimuth and Elevation over a period# of one day divided into 120 segments  cells = meq.cells(meq.domain(f0,f1,t0,t1),num_freq=1,num_time=120);# define request  request = meq.request(cells,rqtype='e1')# execute request  a = mqs.meq('Node.Execute',record(name='reqseq',request=request),wait=True);# The following is the testing branch, executed when the script is run directly# via 'python script.py'if __name__ == '__main__':  Timba.TDL._dbg.set_verbose(5);  ns = NodeScope();  _define_forest(ns);  # resolves nodes  ns.Resolve();```