rmode command

This page is part of the ING document INS-DAS-29: Operations manual for UltraDAS

Function:

Rmode sets the readout mode for subsequent observations. It determines when and how many times the detector reads out for each run.
 

Usage:

    rmode [<camera>] <mode> <n-coadds|n-reads> <n-cycles>
where
mode is {"simple" | "mndr" | "ramp" | "spec" | "video"}
n-coadds is the number of readouts co-added before or after readout in one MNDR cycle
n-cycles is the number of cycles co-added.

where
mode is "spec", and the n-reads is the number of readouts to be performed for a fast spectroscopy run

where
mode is "video", and the n-reads is the number of frames to be read out for a video sequence (see note)

 

Examples:

    rmode simple
sets the camera up to read out like a CCD. One readout is made per run, after the integration. 
    rmode mndr 1 1
sets up the most basic MNDR (Multiple Non Destructive Read) mode. One readout is made before the integration and one after it; both are written to the output file. 
    rmode mndr 3 1
sets up an MNDR operation with co-averaging. Three readouts are made before integration and three more after integration. The pre-integration readouts are co-averaged, as are the post-integration readouts. The output file contains two images, the first holds the pre-integration co-average and the second the post-integration co-average. 
    rmode cds 3 10
extends the basic MNDR operation by co-averaging 10 MNDR cycles. Each cycle is itself a co-average of three pre-integration readouts and three post-integration readouts, as in the previous example. 
    rmode ramp
sets up the camera for read-up-the-ramp mode. The readouts are stored in the output FITS file in a manner determined by the setting of the storemode parameter. See the storemode command for details. 
    rmode spec 360
sets up the camera for fast spectroscopy mode. Each readout of the fast spectroscopy observation are stored in extensions in the output FITS file.
    rmode video 512
sets up the camera for video mode. Each frame is stored in an image extension in the output FITS file.
   

Notes and caveats:

Wherever there is co-addition in the MNDR mode, it is turned into co-averaging by dividing the co-added pixel by the number of readouts co-added.

CCD cameras default to simple 1 1 on start-up and reset. IR cameras default to mndr 1 1.


Fast Spectroscopy mode using "rmode spec" - only available on certain cameras (QUCAM)

To enable the rapid spectroscopy readout mode for the camera, the command 'rmode spec <n_reads>' is used. For example to set the camera up to perform 360 readouts:

    rmode qucam2 spec 360

Once the readout mode is set, the normal run commands (run, glance, scratch etc.) are used to perform exposures. The time specified in the run command is then used as the integration time for each readout in the readout sequence e.g.

    run qucam2 5 - perform a sequence of 5 second exposures, with the number of exposures determined by the n_reads parameter used in the 'rmode spec <n_reads>' command.

The time taken to perform a rapid spectroscopy run will be approximately:

t = n_reads * (exposure_time + readout_time)

To disable the rapid spectroscopy readout mode for the camera, set the readout mode back to simple:

    rmode qucam2 simple

Image sequences obtained using 'rmode spec' are stored in a single fits file with extensions.

NOTE:  zero second exposures are not permitted. 1ms is the minimum requested exposure time.


Video mode using "rmode video" - only available on certain cameras (ANDOR)

To enable video mode on the camera, the command 'rmode video <n_reads>' is used. The time specified in the run command is then used as the integration time for each frame in the video sequence. For example, to set the camera up to perform a 512 frame video sequence:

    rmode andor1 video 512

To disable video mode, set the readout mode back to 'simple':

    rmode andor1 simple