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).