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BACKEND

    BACKEND  name      nPart resolution bandwidth fShift
                             receiverBand [polarization subband|sideband]

    BACKEND  /CLEAR

    Alternative short syntax (only for the backends shown here!):
    BACKEND  BBC   nPart           /REC receiverBand [polarization sideband]
    BACKEND  NBC   nPart           /REC receiverBand [polarization subband]
    BACKEND  4MHz  nPart           /REC receiverBand [polarization subband]
    BACKEND  WILMA nPart           /REC receiverBand [polarization subband]
    BACKEND  FTS   nPart           /REC receiverBand [polarization subband]
    BACKEND  FTS   nPart /FINE     /REC receiverBand [polarization subband]

    Set up backends for heterodyne receivers.

    Character :: name           ! name of backend
    Integer   :: nPart          ! (logical) number of backend part
    Real      :: resolution     ! [MHz]
    Real      :: bandwidth      ! [MHz]
    Real      :: fShift         ! frequency shift [MHz]
    Character :: receiverBand   ! receiver band      to connect to backend part
    Character :: polarization   ! EMIR: polarization to connect to backend part
    Character :: subband        ! EMIR: subband      to connect to backend part
    Character :: sideband       ! EMIR: sideband     to connect to backend part

    Choices for (backend) name are:
    BBC                         ! Broad  Band Continuum Backend
    NBC                         ! Narrow Band Continuum Backend
    4MHz                        ! filter spectrometers with fixed resolution
    WILMA                       ! autocorrelation spectrometers
    FTS                         ! Fourier Transform Spectrometer
    VESPA                       ! autocorrelator with variable resolution


    Choices for receiverBand are (compare RECEIVER command):
    E090 E150 E230 E330 HERA1 HERA2

    Choices for polarization are (for EMIR; compare RECEIVER command):
    Horizontal Vertical

    Choices for subband   |   sideband, when observing with EMIR, are:
            LO LI UI UO   |   LSB USB
    LSB and USB apply only to EMIR bands with 8 GHz bandwidth (E090, E230,
    and E330) and Backend BBC.

    fShift can be used to shift (offset) the backend band within the
    receiver band; this only applies to some backends, in particular
    VESPA. For VESPA, the range for fShift is much smaller than the 4GHz
    subbands of EMIR. For wide-bandwidth backends, fShift is fixed,
    corresponding to the frequency pattern of the EMIR subbands and
    backend bands. See EMIR and backend documentation.

    /CLEAR completely clears the backend setup.

    If option /CLEAR is present, all other parameters and options are ignored.

    NOTE: EMIR subbands, IF cables, and Backends

    The output signals from EMIR are transmitted to the spectrometers and
    NBC through 8 IF cables. Each IF cable carries one subband of bandwidth
    4 GHz. This subbands are LO, LI, UI, or UO.

    NBC, 4MHz, WILMA, and VESPA can only(!) be connected to IF cables 1 to 4.
    FTS parts 1 to 4 can also be connected to IF cables 1 to 4.

    The command options RECEIVER /HORIZONTAL and RECEIVER /VERTICAL allow
    to select up to 4 EMIR subbands that will be transmitted through IF
    cables 1 to 4 (compare HELP RECEIVER /HORIZONTAL and the EMIR user
    documentation). This selection can include Outer subbands.

    In addition, the IF cables 5 to 8 carry the 4 Outer subbands
    corresponding to the subbands selected for IF cables 1 to 4. E.g., if
    we select for IF 1 to 4:
    E230 ver UO    E090 ver UI    E230 hor UI   E090 hor UI
    then the IF cables 5 to 8 will transmit:
    E230 ver UO    E090 ver UO    E230 hor UO   E090 hor UO.

    Only FTS parts 5 to 8 can be connected to IF cables 5 to 8.

    BACKEND NBC|WILMA|FTS /DEFAULT will automatically set the maximum
    number of backend parts for all available subbands.

    BACKEND BBC is completely independant of the sub band selections for
    the IF cables.

    NOTES:
    - for some backends the resolution and/or bandwidth are fixed and the
      short syntax can be used. (The full syntax is supported for all backends).
    - for VESPA always use the full syntax!
    - after changing the receiver configuration: BACKEND /CLEAR is recommended
      followed by the backend setup for the new receivers; without that it is
      possible that pako will not accept BACKEND commands because of unresolved
      conflicts between the RECEIVER and BACKEND setups.
    - However, the backend command will automatically try to disconnect
      backends that were connected to receiver (sub)bands that are not
      connected anymore.


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Gildas manager 2023-06-01