# Frontend operations¶

WARNING:

• It is necessary to manually select the observing focus using the hardware IF switch located in the control room. The figure below illustrates this rack.

## General rules¶

To change the frontend Local Oscillator frequency, use the following command:

> setLO=[freq1];[freq2];…;[freqN]


Notice the semicolon. Ideally, different values could be assigned to different IFs, thus tuning each IFs to a different sub-band. For the present hardware, though, this is not possible, so a single value must be specified:

e.g. > setLO=4900

Remember that the actually observed band begins at a frequency which is usually different from the LO one (see Initial setup)

The temperature of the calibration mark in use is recorded in the logfile whenever a Tsys is measured. It is also stored in the FITS/MBFITS output files. The calibration mark can be manually switched on and off respectively with:

> calOn
> calOff


WARNING:

• Even if the calibration diode is a device included in the frontend, it is controlled through the TotalPower backend. As a consequence, the “calmux” must be properly configured - see details in the backend section.

If the user wants to perform the setup for the frontend only (without affecting the mount, the minor servo or the backend), the command is:

> receiversSetup=[code]   (CCC, MMC, KKC, QQC)