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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.
Subsections
Gildas manager
2024-03-28