1. Your name
  2. The project  number (as on the schedule, with lower-case letter)
  3. The type of observation (in this case, click on ``Pulsar'' button)
In what follows, the setup might seem to be a bit strange. This happens because CIMA is in a state of flux. There are several new features (like the "NEW AND IMPROVED IF/LO SETUP") which are a) guaranteed to work for any frequency and b) will soon become the basis of CIMA. So you should become acquainted with these as soon as possible.

The setup occurs in three phases; that will eventually converge in three relevant widgets: Pointing, IF/LO setup and Back-end setup. Telescope setup should occur in this order.




IF/LO setup:

image of IF/LO control widget

Image of ew Improved IF/LO control widget

  1. The receiver
  2. The polarization (for a few receivers, like L-wide, one can choose between linear and circular polarizations, for other receivers this is not available)
  3. The front-end filterbank (for L-wide, I normally choose the 1120-1220, 1320-hipass filters; this creates a notch between 1220 and 1320 MHz which excludes a lot of very strong RFI from radars like Punta Salinas). Again, a front-end filterbank is not available for all receivers.
  4. The IF path from the Gregorian to the control room (for new projects, this should be chosen as 10GHz to 1500; this has several advantages, like keeping the LOs of the band being observed, and a very large bandwidth). Until now, the 750 MHz path was used for L-wide and 750-MHz narrow was used to the low-frequency receivers. Now, the 750-narrow is still strongly recommended for the receivers below 1 GHz, for Lband and above, we recommend 10GHz ro 1.5.
  5. Select destination. The WAPP is the normal destination. However, one might want to use the WAPP in parallel with other backends. Details here.
  6. The central frequencies for the 4 WAPPs
  7. The bandwidths for the 4 WAPPs.
  8. Optional: Press the "Show these Choices" button. This will show you a screen like that produced by "rxview". You can see in that screen if LOs are in your passbands, and other useful information.
  9. Press button that says "Apply this setup". You should be ready to go. The view given by "rxview" will become similar to what you saw in the previous line.
The reason why the WAPP bandwidths have to be chosen at this point is the following: If the bandwidth selection is 100 MHz, the WAPPs accept incoming signals at 250 MHz. If the bandwidth selected is 50 MHz or smaller, then the WAPPs accept incoming signals at 275 MHz. This information is needed to calculate the LO frequencies.
  1. If you like the present configuration, and if it takes time to setup and if you have taken time testing it, then you might want to save it. You can do this by clicking on the "Save Configuration" button.
  2. You can recover this later by clicking on the "Load configuration" button.

Back-end setup:

Important: The ratio between number of lags and number of microseconds in the sampling time should not exceed 4 (for 3-level, no polarization mode)! Otherwise, the data rate is too fast, and the machine becomes unstable.
IF everything is alright, go to the next step.
IF one of the WAPPs is not responding, open another xterm, slogin to the wapp that is not responding as "wapp"
> slogin wapp2 -l wapp
type in the password (wappme), and then type ``start_wapp''.
To be able to ``monitor'' the signal, you must have the WAPPs on ``search'' mode. If you swicth to ``timing'' or ``sampler'' (a mode that can do baseband sampling), you can no longer monitor the signal.
In the lower plot of ``snap'', you can select the total power or ``bandpass''. The right plot is a waterfall plot, showing time in the horizontal axis and frequency in the vertical axis for the two polarizations.

Image of Advanced IF power control widget

End of setup stage. Now do observation in "search mode", "timing mode" or "sampler mode".

IF/LO setup for simultaneous observations with the WAPP and other backends:

Last updated: Nov.2 2004
Paulo Freire