TC Test #2 with SUBKTEMP and PTC control

OBSID 0x00002099-209D, 2009-07-01 (OD 49, Commissioning Phase)

1. Test Basics

Data were downloaded from ops_1@chesterfield on 2009 Jul 5 with the export utility from HIPE (BUILDNUM 229). Converted format was selected. The time ranges downloaded were:

"0x00002099": 17:57:25 to 20:38:45 UT
"0x0000209D": 21:25:55 to 21:56:48 UT

Photometer and PTC settings were:

bias voltages in NHK: 31.1, 31.3, 31.4, 127.6 mV (PSW, PMW, PLW, PTC)
bias frequency in NHK: 131.1 Hz
phases in NHK: 182.1, 182.1, 186.4, 204.7 deg (PSW, PMW, PLW, PTC) -- a little bit different from the past two tests (OD 17, OD 29)

Here is the test record in Word format.

2. Data Processing

Not much more than adding PHOTOFF/PHOTOFFxxx in to the PHOT/PHOTFARRAYxxx, using NHK/TIME, PHOT/TIME, and PHOTOFF/TIME to time coordinate.

3. Results

00002099.pdf, first part of test starting at 17:57 UT; "HCSPTCTE_50976753_0006.IPF" control starts at ~600 seconds; "HCSPTCTE_50976753_0007.IPF" control starts at ~3000 seconds; "HCSPTCTE_50976753_0008.IPF" control starts at ~5700 seconds, stops at ~6700 seconds; "HCSPTCTE_50976753_0009.IPF" control starts at ~8600 seconds;
0000209D.pdf, first part of test starting at 21:26 UT; "HCSPTCTE_50976753_0009.IPF" control starts at ~250 seconds, but performance looks different from end of 00002099.pdf

Here is a summary of key parameters for the various settings:

HCSPTCTE_50976753_0006.IPF:
- SUBKTEMP control
- set point: *change* of -150 ADU
- Kp = 7.5
- Ki = 0.2
- Kd = 0.0025
- low-pass filter gain, b1, b2: 1.565, -1.143, -0.413
HCSPTCTE_50976753_0007.IPF:
- PTC control (which one???)
- set point: *change* of +50 ADU
- Kp = -0.0625
- Ki = -0.05
- Kd = -0.0025
- low-pass filter gain, b1, b2: 1.565, -1.143, -0.413
HCSPTCTE_50976753_0008.IPF:
- SUBKTEMP control
- set point: *change* of -1000 ADU
- Kp = 7.5
- Ki = 0.2
- Kd = 0.0025
- low-pass filter gain, b1, b2: 1.565, -1.143, -0.413
HCSPTCTE_50976753_0009.IPF:
- SUBKTEMP control
- set point: *change* of -150 ADU
- Kp = 1.875
- Ki = 0.05
- Kd = 0.0025
- low-pass filter gain, b1, b2: 1.565, -1.143, -0.413

4. Conclusions

All control settings in this test are stable against runaway. There is some low-level oscillation in some thermometers for some of the settings, but maybe not a big deal.
During obsid 0x00002099, L0 drifted by 2 mK, which is clearly seen leaking through to the PTC thermometers and focal plane with the expected sign according to the thermal model.
Obsid 0x0000209D looked quite stable at the focal plane at the end of the test, but the evaluation time was short.
The "0009" parameters are getting close to the limit that negligible white noise is induced in the heater and PTC thermometers due to the noisy SUBKTEMP readout. The stabilization time for those parameters is approximately 700 sec.
There are no obvious PTC level jumps in the data this time.

CDD, 2009 Jul 5