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%META:TOPICINFO{author="PaulMarganian" date="1119957621" format="1.0" version="1.1"}%
Balancing the Power Levels for the GBT
To optimize an observing session, GBT users need the capacity to readily set the power levels in the GBT hardware to their optimum values. Due to the complexity of the GBT and the wide variety of observations which are undertaken on it, this is an extremely complicated issue. This document is an attempt to explore all issues related to optimizing the power levels in the GBT hardware an will serve as the launching document for any MRs or hardware projects which may be necessary to implement the balancing procedures. Note while this documents makes no attempt to describe the implementation details of the balancig schemes, any software modifications listed in this document are intended to be used within Astrid, and the ability to utilize any software modifications outside of astrid is left to the design within an individual MR.
The details in this document have arisen from discussions of the Observing Issues group, the discussions of which are summarized in the first BalancingDescription document.
GBT Devices
There are 8 different devices on the GBT which a user needs to be able to balance individually - the Prime Focus receivers, IF Rack, converter rack, analog filter rack, spectrometer, spectral processor, spigot, & BCPM. In general, each of these devices needs a command which will set the attenuators to acheive the ideal balance for the hardware.
This balance command should be able to sample the voltage (power) levels multiple times to avoid issues with RFI. Ideally, the number of times a the voltage sampler is read should be configurable by the observer, with a default value of three. The observer should also be able to turn the noise diodes on or off during a balance session (with the default being off). A message should be sent to the observing log reporting the success or failure of any balance command, with the offset from ideal (in dB or V) reported inthe case of failure. Additionally, the observer should have the ready ability to change the target power levels and add or subtract attenuation from any of these devices. Finally, each of these commands should be able to be called both from an observing script and also during an observing session (when a scan is running).
A MR has already been written for the Prime Focus receivers, and is found at ModificationRequest4C804
-- KarenONeil - 28 Jun 2005 |