Real-time Menu

The Real-time menu contains entries that deal with real-time functionality.

Attach Camera attaches the RTD to the current CCD (see Set Camera below) via the rtdServer daemon process. Any images received by the server from the CCD will then be forwarded to and displayed on the RTD.

Detach Camera detaches the RTD from the currently attached CCD.

Set Camera brings up a simply entry dialogue to allow the user to enter the name of the current CCD camera. This is not attached to until Attach Camera is invoked.

The Rapid Frame entry lets you create a rapid frame either in the canvas window or in a separate popup window. This sets the drawing mode in the canvas containing the main image and displays a left button cursor to indicate that you should drag out an area on the image with mouse button 1.

The Preview Mode item is useful when in real-time mode. It makes a local copy of the shared memory image from a camera, so that it will not be overwritten or destroyed. This is a toggle button, so selecting it again will return you to real-time mode. If no camera is running, this button does nothing.

The Record/Playback Images... item allows the recording of images from a camera to file, and the playback of images from file to the RTD. The images are recorded as a FITS cube; thus this tool can be used to replay FITS cubes produced by other applications.

In `Record' mode, the tool allows the user to select a maximum size for the output file (the default being set to 5 Mb). In addition, the `cycle mode' can be toggled on or off: this indicates whether the recording should automatically loop round to the beginning of the file when the file is at its maximum size. It is also possible to select a specific sub-region of the incoming images to record; this could be useful when the incoming images are very large or the area of interest is small.

In `Playback' mode, the cycle mode still allows the user to select whether the playback will operate in a continuous loop. The speed of the playback is also variable, with the user able to specify slow, fast, or real-time updates. The real-time update (i.e. images re-displayed at the same rate as they were received) is only available on FITS cubes produced using the recorder tool; if the option is selected on another cube file, the playback speed defaults to `slow'.

It is also possible to playback images in reverse order and to single-step through the image file (return one image to the RTD at a time).

When the dialogue is invoked initially, the camera name specified is the current default RTD camera. When recording is commenced, the recorder tool will connect to the camera named in the `Camera Name' field. When playback of images is started, the parent RTD automatically attaches to the camera `RTDRPTOOL' and receives images in the usual manner. When playback finishes, the RTD detaches from this camera and reattaches to its original camera.

The Performance... menu item pops up a dialogue containing interactive performance data. These data refer to parameters that relate to the amount of processing carried out within the RTD on certain chores. These chores are: Tcl code interpretation, memory management, X function calls, and general processing.

The performance data can be displayed in three ways; as absolute time per image event, as percentage of total time per image event, or as normalised time. In the latter case, the X function calls and memory management processes are divided through by the size of the image (in kB) to allow comparison of performance across platforms for different image types and sizes. The normalised format is not applicable to general processing and Tcl code interpretation.

Support for a "benchmarking performance tester" has been added to the RTD release. See the reference section, RtdPerfTester(n) for more information.

The Rtd Simulation Control pops up a window to control the real-time simulation used for testing the RTD display and real-time functionality when no camera interface is available. To start the application, go to the demos directory and type rtdctrl .

To start the simulation, you load a FITS file in the dialogue and press the start button to notify the rtdServer to start sending images. Then select Attach Camera from the File menu of the RTD to tell the rtdimage to start listening for real-time image events. Detach Camera stops the application from accepting images from the rtdServer.

rtdctrl allows also the locking system to be tested explicitly by first inducing image jitter in the RTD and then removing this by applying semaphore locking to the shared memory areas. Load a suitable FITS file (avoiding floating-point formats as these can produce floating-point exceptions when they jitter) and unlock the server by invoking the Unlock button. After this, send the images to the server by invoking Send and adjust the update rate until image jitter is obtained. If the server is currently multi-buffered, it may be necessary to change the number of buffers to 1 in the source code for rtdImgEvt and rtdimage libraries: see the entry for rtdlock(1) in the reference section for instructions on how to do this.

The RTD and server daemons should be transparent in the absence of implementation of the locking. When the Lock button is invoked, locking should be implemented on the shared memory area, and the image jitter should vanish (albeit at a slower update rate).