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LINE

        [PDBI\]LINE Name Frequency Band [Lock [Center [Harm]]]

    Define  and  plot the receiver frequency coverage of the Plateau de Bure
    Interferometer (with the receivers installed in winter 2006/2007).   The
    command syntax is identical to that of the corresponding command in OBS:
        Name      is a line name to label the plot
        Frequency is the rest frequency in GHz
        Band      should be USB or LSB
        Lock      is LOW or HIGH [optional, default LOW]
        Center    is the IF1 frequency in MHz [optional, default 6500]
        Harm      is the harmonic number [optional]

    o  The receiver band to be used (1 to 4) will be determined by the soft-
    ware.

    o Since 2015, NOEMA observations are preferentially  performed  using  a
    limited  number  of  LO frequencies for which receiver performances have
    been optimized. Those frequencies are distributed all over the  receiver
    bands  every  500MHz. For latest states of NOEMA (from 2015 on), this is
    taken into account in the ASTRO\LINE command. The  command  checks  that
    the LO frequency is located on this grid. When this is not the case, the
    command returns an error and a new IF center frequency  is  proposed  to
    ensure a tuning frequency that matches the grid.  The option /ONGRID can
    be used in order to let the command use  this  suggested  frequency  and
    avoid  to  return an error.  The tuning frequency is computed using only
    the source LSR velocity. With the Doppler tracking,  the  actual  LO  is
    slightly different from the tuning frequency.  Both tuned and tracked LO
    frequencies are given in output when the LINE  command  arguments  match
    the  tuning  grid.  With the option /FIXED_FREQ, the command ignores the
    tuning grid.

    o The center frequency is expressed in the first IF (4-8 GHz = 4000-8000
    MHz). WARNING: it is highly not recommended to center the line frequency
    at 6 GHz. This is because the correlator analyses quarters of the 4  GHz
    bandwidths,  and  6  GHz is very precisely at the limit between two such
    adjacents quarters.

    o The plot displays the four "quarters" Q1...Q4 that can be selected  as
    input for the correlator (see NARROW_INPUT command):
      Q1 = 4.2-5.2 GHz, Q2 = 5.0-6.0 GHz
      Q3 = 6.0-7.0 GHz, Q4 = 6.8-7.8 GHz

    o  Commands  NARROW and SPECTRAL are available to setup the IF processor
    and the spectral units of the narrow-band  correlator  (see  the  corre-
    sponding help). A typical ASTRO session would look like:

    line toto 100 usb           ! choice of rx tuning
    narrow q1 q3                ! choice of the correlator windows
    spectral 1  20 320 /nar 1   ! correlator unit 1
    spectral 2 320 200 /nar 2   ! correlator unit 2
    spectral 2 320 210 /nar 2   ! new def. of unit 2 --> plot is updated

    o  Command  PLOT can be used to plot the full receiver coverage, that of
    the NARROW band correlator, or that or the WIDEX correlator.

    o LINE can also be used to produce plots of the  frequency  coverage  of
    the  old receivers (replaced in 2006/2007). The command OBSERVATORY PDBI
    year allows one to select the instrument as of the selected year:
    - 1995: 3 and 1.3 mm receivers, 500 MHz bandwidth
    - 2000: 3 and 1.3 mm receivers, 580 MHz bandwidth
    - 2006: new generation receivers (NGR: 4 GHz bandwidth, 2 polar.)
    - 2010 NGR +  modifications in the LO system
    - 2013 = 2010 + additional slight modification in the LO system
    - 2015 = 2013 + Optimized tuning on a LO grid [default]
    For the OLD receivers (years 1995 & 2000), the  commands  NARROW,  SPEC-
    TRAL,  PLOT are not active. Please enter HELP LINE OLD for a description
    of the behaviour of the LINE command in that case.


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Gildas manager 2018-08-20