Responsible: Effland |
| *************************************************************************************** |
| RID 1712 |
| Doc. Title | | Specification, Section 5.7.1 | Originator: James Lamb | Date: 2007-09-09 |
| Description: | | This specification is a bit vague in what its intent is. Since the design has presumably be |
| verified with reference to the overall ALMA aperture efficiency and spillover specifications, |
| the goal should be to check that there are no manufacturing or assembly errors. Is the 90 |
| % efficiency from a theoretical calculation or prototype measurements and how much lower |
| than the the optimum is it. (I'd think that the theoretical value was closer to 95 %, so this |
| is a big difference). |
| |
| The edge taper is specified without any limits or frequency. The value could vary by 0.5 dB |
| over the band. Since a beam pattern measurement is presumably made to determine this, |
| why not provide provide a pattern Pass/Fail template? |
Suggested Solution: |
| *************************************************************************************** |
| RID 1713 |
| Doc. Title | | Band 6 Cartridge Test Procedure: IF | Originator: James Lamb | Date: 2007-09-09 |
| Output Power |
| Description: | | Sec 2 |
| ----- |
| |
| This section is inconsistent with the specifications (Sec. 5.3.2 IF power |
| variations) which specify the power variation, not the gain variation. In the |
| specifications it is not clear what the cartridge input should be for the |
| specified limits on power variation. |
| |
| Discrepancy needs to be resolved. |
Suggested Solution: |
| *************************************************************************************** |
| RID 1714 |
| Doc. Title | | Band 6 Test Procedure: RF Beam | Originator: James Lamb | Date: 2007-09-09 |
| Efficiency |
| Description: | | The efficiency is specified at the secondary mirror, but the measurement is made in the |
| near-field. Meeting the specification in the near-field does not guarantee that it is met at |
| the secondary. Equality of the two is only assured if the beam behaves according to the |
| calculation, but errors in the beam can result in the specification being met in the near |
| field, but not in the far field (and this is not just theoretical, I have seen this |
| experimentally). |
| |
| Consider an alternative. E.g., integrate the beam pattern measurement |
Suggested Solution: |
------------------------------------------------------------------------------------------------------------- |
Printed 2007-09-18 16:52:38 | Page 4 of 8 |