Measuring the cband cal  values.


 Links to the plots:

Measuring the hcorcal
The spectra of (calon/caloff -1).
The power levels during the measurements.


    New diodes were installed on the cband system on 22apr03. On 25apr03 the cals were measured using absorber and tracking blank sky. The correlator was configured as 25 Mhz by 1024 lags by 4 sbc.  4000 to 6000 MHz  was covered in 100 Mhz chunks (20 steps). At each step a 3 second integration with the hcorcal on was followed by a 3 second integration with the cal off. The frequency range 4000 to 6000  was covered 9 times on absorber and 9 times on the sky.  See  measuring cals on the telescope using sky and absorber for a more detailed description.


    After taking the data, the spectrum of the cal showed a ripple in polA. This turned out to be a loose cable in the cal box. On 05may03 the problem was found and corrected. The cal values measured here were installed because of a calibration run on 25apr03. There was no other cband data taken between 22apr03 and 05may03.

Measuring the hcorcal: (

The temperatures used for cband were:
Temperatures Used
Trcvr from amplifiers 8 K
Tomt orthmode transducer 4 K
Tabs absorber temperature 302 K
Tsky sky + scattered ground radiation 3 + 15=18K
Trcvr Tamp+Tomt 8 + 4 = 12K

The hcorcal measured values:

    This shows the results of the measurements.

The spectra of (calon/caloff -1):

     The spectra for the  cal (calOn/caloff -1) for the data taken on the sky is shown in the plots. Each color is a different pass through the frequency range 4000 to 6000 Mhz (9 in total).  Offsets have been added to each pass for plotting purposes. A 1 Mhz ripple is a delay of 1 usec or a down and back distance of 150 meters. The 90 MHz ripple in polA would be  150/90. * .6 = 1 meter (.6 is the velocity of light in the cables). Since the ripple is in polA and not polB (using the correlated cal), the loose cable is after the power splitter for diode1.
The cable was tightened 05ma03 and the cals were remeasured.

The power levels during the measurements:

    The power levels during the measurements are shown. Black is pola and red is polB.
processing: x101/030425/