OTF Testing of Phased Array
B. Shillue
2013-10-04
These notes were assembled after a meeting with R. Fisher, A. Roshi, B. Simon, B.
Shillue, prior to the NRAO Shutdown of 10-04-13. The test protocols described here
apply to PAF testing meant to take place after the NRAO re-opens.
Testing Schedule:
Day 1: Test #1
Day 2: Test #2,3,4
Day 3: Test #5,6
Day 4: Cleanup of previous days with Test #7, #8 at night
Day 5, 6: Test #9,10
1. Re-assemble, pump, and cool receiver
Test Description: After the LNA reconfiguration and measurement, the receiver needed
to be reassembled. This is completed, as Bob reports the receiver is now re-assembled
and ready for pumping. However, vacuum pumping will not take place until NRAO
reopens. After the receiver is pumped and cooled, the hardware testing will begin.
Length of test: 4 days. 3 days for reassembly, 1 day for cooldown.
Hardware Needed for Test: Various hand tools needed for reassembly. Vac pump,
Refrigerator power supply, helium compressor
Software Needed for Test: None
Test Output: Record temperature of cold stage(s)
2. Connect Receiver to Test System
Test Description: Dipole installation and connection to fiber in OTF.
Length of test: 2 hours
Hardware Needed for Test: Hand tools needed for dipole installation
Software Needed for Test: None
Test Output: None
3. Signal Connectivity
Test Description: Establish that there is end-to-end system connectivity. In tape room,
check the power spectrum of the received analog output of the fiber modem for each of
38 channels. Hot Load in place.
Length of test: 2 hours
Hardware Needed for Test: Spectrum analyzer
Software Needed for Test: None
Test Output: Record power level at 1500 MHz for each channel. Note any spectrum
anomalies.
4. Receiver Noise Temperature Spot Check
Test Description: Measure at least 4 channels receiver noise temperature at the output of
the receiver (in the OTF).
Length of test: 2 hours
Hardware Needed for Test: Green Bank custom receiver noise temperature test set.
(Details to be filled in later). OTF facility for moving between hot and cold loads.
Software Needed for Test: Custom Labview software (part of Testset)
Test Output: Swept frequency measurement of receiver noise temperature
5. Optimize Signal Power Levels
Test Description: Optimize uniformity of the signal levels at the input of the
downconverters by swapping fiber modem pairs. (This requires data previously taken on
the modem gains). Hot load in place.
Length of test: 4 hours
Hardware Needed for Test: Power meter with band limiting filter? Or spectrum
analyzer?
Software Needed for Test: None
Test Output: Record Power level for each channel before and after hardware swaps.
Record the serial numbers of the fiber modems, and associated receiver channel, before
and after the swaps.
6. Optimize Channel Dynamic Range
Test Description: This test is mean to be done for several channel, so that a repeatable
result can be established. The idea is to add an attenuator at the input of the
downconverter to increase the dynamic range of the measurement system as seen by the
backend. For a particular channel, disconnect the RF input to the fiber modem. Then
measure the noise floor at the output of the downconverter. Add attenuation at the input
of the downconverter until the power measured at the output of the downconverter is no
longer reduced dB-for-dB. Reprat for several channels and choose an attenuator value
that works best for all channels.
Length of test: 2 hours
Hardware Needed for Test: Power meter with band limiting filter? Or spectrum
analyzer?
Software Needed for Test: None
Test Output: Record each power level measured at the downconverter outputs, including
channel # and attenuator value.
7. Receiver Noise Temperature RF measurement
Test Description: Measure each channel noise temperature at the output of the receiver.
This test must be done on quiet RF conditions, clear quiet night sky.
Length of test: 4 hours
Hardware Needed for Test: Green Bank custom receiver noise temperature test set.
(Details to be filled in later). OTF facility for moving between hot and cold loads.
Software Needed for Test: Custom Labview software (part of Testset)
Test Output: Swept frequency measurement of receiver noise temperature, for each of
38 channels.
8. Receiver Noise Temperature IF measurement
Test Description: Measure all channels noise temperature with the system data
acquisition. This test must be done on quiet RF conditions, clear quiet night sky.
Length of test: 1 hour
Hardware Needed for Test: Front End, Back End, Data Acquisition, OTF hot/cold
Software Needed for Test: ADLink Data Monitor and Displays (list other?)
Test Output: Swept frequency measurement of receiver noise temperature, plots and
data. Table which identifies cross reference between plot, data, channel, time of
measurement, and conditions of test (this could be a notebook).
9. Receiver Noise Temperature IF measurement Repeatability/StabilityTesting
Test Description: Measure all channels noise temperature with the system data
acquisition. Repeat of receiver noise temperature to check repeatability and stability.
This test must be done on quiet RF conditions, clear quiet night sky.
Length of test: 2 days
Hardware Needed for Test: Front End, Back End, Data Acquisition, OTF hot/cold
Software Needed for Test: ADLink Data Monitor and Displays (list other?)
Test Output: Swept frequency measurement of receiver noise temperature, plots and
data. Table which identifies cross reference between plot, data, channel, time of
measurement, and conditions of test (this could be a notebook).
10. Receiver Noise Temperature IF measurement Channel Disconnect Test
Test Description: With the hot load in place, with a single channel disconnected at the
dewar output, run a single frequency scan. Repeat for all 38 channels varying which one
is disconnected. This test will confirm the mapping between front end channel and
software channels.
Length of test: 2 hours
Hardware Needed for Test: Front End, Back End, Data Acquisition, OTF hot/cold
Software Needed for Test: ADLink Data Monitor and Displays (list other?)
Test Output: Single frequency measurement of receiver noise power. Table which
identifies cross reference between data, channel disconnected, and time of measurement
(this could be a notebook).