====== Heterodyne Systems ======

Instructions for [[observing]].

Heterodyne systems at the CSO permit high resolution spectroscopy in the atmospheric windows from 177 to 920 GHz. 

===== Receivers  =====

^  Characteristics  ^^^^^^^^ 
^  Receiver  ^^  Range  ^  IF BW  ^  //T//<sub>rx</sub>  ^  Tuning  ^  Remarks  ^  Status  ^
| :::     |  :::   |  [GHz]    |  [GHz]  |  DSB [K]  | ::: | ::: | ::: |
| |||||||
| Sidecab  |  230   |  177-210  |  4-8  |  40  |  auto.  | Low freq. subband requires\\ add'l LO filter. Consult staff. |  operational  |
|:::|  :::   |  210-286  |  :::  |  :::  |  :::  |  | ::: | 
|:::|  345   |  315-380  |  1-2  |   90  |  manual  |  |  :::  |
|:::|  460   |  382-532  |  4-8  |   40  |  auto.   |  |  :::  |
|:::|  650   |  620-730  |  1-2  |  230  |  manual  |  |  :::  |
| |||||||
| Cassegrain |  Barney  |  300-410  |  4-8  |  50  |  manual  |  | //limited availability// |
|:::|  850     |  810-900  |  1-2  |  350-450  |  manual  | or Nasymth  | //limited availability// |
| |||||||
| |  <del> Zrex </del>  |  <del> 200-290 </del>  |  <del> 4-12 </del>  |  <del> 160-50 </del>  |  <del>manual</del>  | <del> aka Frank's receiver </del> | //decommissioned// |


^  Measured Performance  ^^^^^^^^^^
^  Receiver  ^^   Line  ^  Freq.  ^ SB ^  //Y//  ^  //T//<sub>sys</sub>  ^  //τ//<sub>225</sub>  ^  ZA  ^  Date  ^
| :::     ||  :::   |  [GHz]  | |  |  SSB [K]  | |  [deg]  | ::: |
| ||||||||||
| Sidecab  |  230  |  <sup>12</sup>CO(2-1)  |  230.5 |  Up  | |  220  | 0.126  |  15°  | 2013-03-05  |
|:::|  345   |  <sup>12</sup>CO(3-2)  |  345.8  |  Up  | 1.9  |  815  | 0.111  |  33°  | 2013-04-04  |
|:::|  461  |  <sup>12</sup>CO(4-3)  |  461.0  |  Lo  | |  1240  | 0.059  |  17°  | 2013-03-06  |
|:::|  650  |  ||||||||
| ||||||||||
| Cassegrain |  Barney  |  ||||||||
|:::|  850  |  ||||||||


==== Notes ====

  * All receivers are single polarization and double side band.
  * Measured //T//<sub>sys</sub> at indicated zenith angle (ZA).

  * [[sidecab_rxb]]
  * [[.:tuning:barney]]
  * [[obstime]] estimate
  * [[http://cso.caltech.edu/atm/tuning.html|Receiver tuning diagram]]
  * [[calibration]]

  * [[http://www.submm.caltech.edu/cso/receivers/|Existing and New Balanced Receiver Development]] 
    * [[http://www.submm.caltech.edu/cso/receivers/instructions.html|Tuning Instructions]] (Narrow band sidecab and 850 GHz receivers)
  * [[http://www.submm.caltech.edu/cso/receivers/beams.html|CSO Beam Efficiency Measurements]]

=== Maintenance ===

  * [[cryogenfills]]

===== Spectrometers  =====

^  ID     ^  //N//<sub>chan</sub>  ^  spacing  ^  BW  ^Remarks  ^
|                     ||  [kHz]  |  [GHz]  | |
|  |||||
|  [[FFTS1|FFTS1]]  |  8192      |  61     |  0.5    |tunable across 4-8 GHz IF  |
|  :::    |  :::       |  122    |  1      |::: |
|  [[FFTS2|FFTS2]]  |  4 x 8192  |  268.6  |  4 x 2  | |
|  [[AOS5|AOS5]]    |  4 x 2048  |  650    |  4 x 1  |four overlapping sections, 4 GHz usable BW  |

  * [[FFTS1]] \\ Available with all receivers.
  * [[FFTS2]] \\ Only available with the wide band (4-8 GHz) receivers.
  * [[AOS5]] \\ Only available with the narrow band (1-2 GHz) 345 GHz and 650 GHz sidecab receivers, the 850 GHz receiver, and the wide band (4-8 GHz) 345 GHz receiver (Barney).