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Analog Filter Rack

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       The Analog Filter Rack consists of eight 1.6 GHz Sampler/Filter modules, sixteen 100 MHz Converter/Filter modules and some supporting modules that provide power and reference frequencies derived from the master hydrogen maser in the GB Site Timing Center.  The filter modules are fed from the sixteen 1-8 GHz Converter modules in Converter Racks A and B.  The 1.6 GHz Sampler modules choose from one of two 1-8 GHz Converter module outputs or one of two inputs designed for future use and filter the signal to an 800-1600 MHz range, an 800-1000 MHz range or ranges set by one of two other possible filters, one via external rear panel connections, the other installed inside the module.  Each of the sixteen 100 MHz Converters takes an output from one of the sixteen 1-8 GHz Converter modules, down converts the signal to a 15-350 MHz range and filters to 50-100 MHz range, a 25-38 MHz range, an externally added filter range or a range set by a future digital filter that will follow the 25-38 MHz filter.  All Sampler and Converter modules in the Filter Rack send an RF output to the sampler section of the Spectrometer, all eight Sampler modules and eight of the sixteen 100 MHz Converter modules send a frequency stream proportional to the RF power level detected at the output of each of the modules to the Digital Continuum Receiver via optical fiber.  The RF power level  is determined by coupling the signal to a square law detector.  That detected voltage is indicated on the Filter Module CLEO pages under 'SG Power (V)' or 'CF Power (V)', on meters on the front panel of each filter module and sent to a voltage to frequency converter to generate the proportional frequency stream for the DCR.  Each RF detector is measured to determine its individual voltage versus power characteristics and the data from those measurements is available here.
 
 
 

Initial CLEO Analog Filter Rack Screen:
 


 

The initial CLEO Analog Filter Rack screen has the Menu Bar common to most CLEO screens, three tabs that access the Converter tabs, 1.6 GHz Sampler tabs and the Power Supplies tab.  At the bottom of the screen is a Quit button and the State/Status frame common to CLEO device and manager screens.

100 MHz Converters Tab:

The Analog Filter Rack Screen will open with the 100 MHz Converters Tab active. Each of the Converter Pair Tabs under the 100 MHz Converter tab opens a page with the following parameters for each of the two Converters: Blue Buttons explained in a following section,  A  Select button to activate the module with an indicator for the State of the module, a selector for one of four filters, one of which can be installed external to the module in a short amount of time and a filter marked 'spare' which is reserved for a proposed digital filter, and an indicator for the voltage produced by an RF power level square law detector.  This voltage is exponentially proportional to the RF power level at the module output, a voltage of 0.1 volts is approximately -10 dBm, 1 volt is approximately 0 dBm and 10 volts approximately +10 dBm, better accuracy can be obtained from the individual module detector's calibration data.  For optimal Spectrometer operation a level of 1.0 volts is preferable.  This voltage is also sent to a voltage to frequency converter and the resulting frequency stream  from odd numbered converters is sent via optical fiber to the Digital Continuum Receiver.

All Converters Tab:
 


 

This is the CLEO page for All Converters which performs the same functions for all sixteen Converter/Filter modules that the module pair pages perform but without a signal flow diagram for the modules.  The Red Outline of the power in CF7 indicates that parameter is out of its recommended range.

1.6 GHz Sampler Tab:
 

Pressing a tab for a pair of 1.6 GHz sampler modules opens the CLEO page above, allowing (after unlocking the module) the user to view and adjust the parameters of a pair of Sampler modules.  Each module has a Select button to activate the module with an indicator for the State of the module, a selector for one of four inputs from the Converter Rack, a selector for one of four filters, one of which can be installed external to the module in a short amount of time, and an indicator for the voltage produced by an RF power level square law detector.  This voltage is exponentially proportional to the RF power level at the module output, a voltage of 0.1 volts is approximately -10 dBm, 1 volt is approximately 0 dBm and 10 volts approximately +10 dBm, better accuracy can be obtained from the individual module detector's calibration data.  For optimal Spectrometer operation a level of 1.0 volts is preferable.  This voltage is also sent to a voltage to frequency converter and the resulting frequency stream is sent via optical fiber to the Digital Continuum Receiver.

All Samplers Tab:
 

This is the CLEO page for All Samplers which performs the same functions for all eight Sampler/Filter modules that the module pair screens performs but without a signal flow diagram for the modules.

Blue Buttons:
On each of the pages for specific modules there are blue buttons next to function selections that will open the IF Manager screen information box on that particular function.  On screens controlling all the particular modules the blue button opens a sub menu from which a specific input, output or function information screen can be chosen.  Information such as where the signal on that particular input or output is coming from or going to, frequency, bandwidth, polarization of that signal and the manager controlling that function is available on a screen like this one:


 
 

Power Supplies Tab:

  On this page are samplers that monitor the power supply voltages for the Analog Filter Rack.

 

 


Copyright 2000 Associated Universities, Inc. Washington D.C., USA
Modified: 23 October, 2001 by Ronald J. Maddalena