JPL/DSN Meetings Re MEX BSR Configuration JPL 303-419 (7 April 2004, 9:30-11:30 AM) 1400 Shamrock, Monrovia (7 April 2004, 1:30-3:30 PM) DSS 14/SPC 10 (8 April 2004, 8:30 AM - 3:30 PM) Participants: Larry Bracamonte (Thurs) Art Freiley (all) Doug Hofhine (Thurs) Dwight Holmes (all) Kamal Oudrhiri (Thurs) Dick Simpson (all) Jose Valencia (Weds PM, Thurs) Jesse Velasco (Weds PM, Thurs) Ram ??? (Weds PM) Steve ??? (Thurs PM) Wednesday (AM and PM): Simpson explained science experiment geometry, overview of expected execution, measurement goals (accurate measurement of surface echo power in X- RCP, X-LCP, S-RCP, and S-LCP), and currently identified high-level implementation questions. He illustrated analysis with data from 21 January experiment. Success depends on precise measurement of echo signal power relative to background noise, precise comparison of background noise against 15K noise diodes during the track, and precise calibration of the noise diodes against cold sky and ambient loads during both pre-cal and post-cal in all four channels. Microwave and I/F Configurations: Bracamonte had provided operator directives in an e-mail to Velasco about a week before. These establish microwave links and ensure that radio science and closed-loop receivers (RSR and CLR, respectively) are connected to the proper feeds. Fleshed out during discussion, these are: OD# Operator Directive Explanation 1 UG14 CNF SRDA1C1O2 S-RCP via diplexer to LNA1, Channel 1, Output 2 2 UG14 CNF SLLA2C2O1 S-LCP low-noise path to LNA2, Channel 2, Output 1 3 UG14 CNF SA1A1C1O2 S-band A1 ambient load to LNA1, Channel 1, Output 2 4 UG14 CNF SA2A2C2O1 S-band A2 ambient load to LNA2, Channel 2, Output 1 5 UG14 CNF XRA1O1 X-RCP to LNA1, Output 1 6 UG14 CNF XLA2O2 X-LCP to LNA2, Output 2 7 UG14 CNF XA1A1O1 X-band A1 ambient load to LNA1, Output 1 8 UG14 CNF XA1A2O2 X-band A1 ambient load to LNA2, Output 2 9 UG14 MOD 102 A Sets dichroic reflector to EXTENDED position 10 R1B IFS 14_S_RCP Connects RSR 1B to logical S-RCP 11 R2A IFS 14_S_LCP Connects RSR 2A to logical S-LCP 12 R1A IFS 14_X_RCP Connects RSR 1A to logical X-RCP 13 R2B IFS 14_X_LCP Connects RSR 2B to logical X-LCP 14 DC01 DISC Disconnect CLR1 from previous connection 15 DC01 CONN DSS14XO1 Connect CLR1 to X microwave Output 1 (RCP) 16 DC02 DISC Disconnect CLR2 from previous connection 17 DC02 CONN DSS14SO2 Connect CLR2 to S microwave Output 2 (RCP) Notes on 1/2: This choice of paths should yield S-RCP and S-LCP signals with very similar background Tsys. Since S-RCP is already through the diplexer, it also allows for the unlikely possibility of an S-band uplink. Notes on 3/4: If #4 is executed before #3, LNA1 is still connected to S- RCP. If #3 is executed first, there is no input to LNA2 until #4 is executed. Notes on 7/8: Either #7 or #8 will connect both X-band LNAs to the ambient load; both commands should be issued so that each is recorded in the log file. Notes on 10-13: The system will make the required connections to ensure that S-RCP is actually routed to R1B, S-LCP to R2A, etc. Non-standard connections in the microwave system may result in errors, however. The RSR assignments above are the ones used in the 21 January bistatic radar observations; they can be changed. IF Configuration Options: Bracamonte also provided insight into path options at the RF/IF Downconverter (RID), IF Channel Assembly (ICA), Full Spectrum Processor/IF Switch (FSP IFS), and IF Switch (IFS) levels. This is too complicated to summarize here in text. Noise Diode Control: A CLR is required to set the noise diode level, to set its modulation frequency (pulse mode or continuous), to enable it (actually turn it on), and to disable it (turn it off). Ordinarily these diodes run continuously in pulse mode at the 0.25K level. Following (nominal) diode levels are available: 50, 12.5, 8, 4, 2, 1.5, 1, and 0.25K. In pulsed mode, the diode is ON 50% of the time, so half the nominal level will be seen with long time averages (more than 1 second). Levels can be changed while the diode is ON. NB: Mitek(?) diodes inject noise even when disabled, an apparent design defect. In worst case, this can be at -10 dB compared with the enabled state; more typical is -13 dB. Best strategy in these cases is to set the level to 0.25K at the same time they are disabled. But this should not be an issue for MEX bistatic radar because Mitek diodes are not among the choices. Bracamonte recommends the following procedure for controlling the noise diodes. Although GUI selections are not always captured in the log, these are. Operator should: To turn noise diode ON: Configure a CLR for the proper band and polarization (e.g., OD #14/15 to control X-RCP diode) Bring up the NAR display for that CLR Pull down menu to set level to 12.5K Set Modulation Frequency to ON Select ENABLE To turn noise diode OFF (assumes CLR configured and NAR display up): Select DISABLE Optionally: can set level to 0.25K if not expecting to use again soon Alternatively, Bracamonte said operator directives can be used. These were not fleshed out, but are something like the following (enable and disable commands are liners 3 and 4, respectively): DC01 set nds=12.5 DC01 MFQ=ON DC01 set snt E DC01 set snt D Tests (Thursday PM): Steve was operator during tests of configurations. Test results follow on three separate pages. We did not have time to test S-LCP, judging it the least promising option once the Fort Irwin RFI appeared on S-RCP. Oudrhiri assisted with the RSR, which was a little difficult to start because there were no predicts. The predicts eventually used placed both RSR's at frequencies which were not optimium. The operator can introduce offsets (FRO), but these are limited to about 7 MHz, not enough to correct the tuning completely; but we used them at both S- and X-band. Following recommendations from Andre Jongling, we used the DIG ATT Auto feature on the RSR with ambient loads connected to LNA inputs in each test. During previous tests, we have set ATT using cold sky; with the ambient load connected, the RSR front end A/D conversion may have been non-linear. Hofhine and Holmes assisted Freiley with parallel measurements at the Noise Instrumentation rack. Hofhine will provide a procedure documenting the steps. Freiley will analyze results from this test independently for comparison against RSR results next week. Freiley recommended that the procedure be carried out during pre-cal and post-cal for each bistatic radar experiment; it provides independent calibration of the noise diodes and Tsys when the antenna is stowed. Freiley recommended that the following be used in noise calculations: Tamb = 273.15 + Tphys + TLNA + TFOLLOWUP where Tphys be as noted above TLNA = 4.11K TFOLLOWUP = 0.04K Dick Simpson original: 9 April 2004 S-RCP Test: Rotated through four states: UG14 CNF SRDA1C1O2 S-RCP via diplexer to LNA1, Channel 1, Output 2 cold sky, with and without noise diode UG14 CNF SA1A1C1O2 S-band A1 ambient load to LNA1, Channel 1, Output 2 ambient load, with and without noise diode Following applied throughout the test: UG14 CNF SLLA2C2O1 S-LCP low-noise path to LNA2, Channel 2, Output 1 R2A IFS 14_S_RCP Connects RSR 1B to logical S-RCP R2B IFS 14_S_LCP Connects RSR 2A to logical S-LCP DC02 DISC Disconnect CLR2 from previous connection DC02 CONN DSS14SO2 Connect CLR2 to S microwave Output 2 (RCP) -----------+---+---+---+-------+-------------------------------------------- ERT (UTC) SKY ND AMB RCP RMS COMMENT -----------+---+---+---+-------+-------------------------------------------- 21:22:00 X RSR has been recording for some time 21:22:45 X X 21:23:30 X X 21:23:50 X 8 21:26:35 X 28 21:29:25 X X 29 21:31:40 X X 10 21:33:50 X 8 Holmes reports RFI (Fort Irwin source?) 21:37:00 X 28 21:38:55 X X 29 21:42:42 X X 10 21:44:18 X 21:48:00 RSR HALT -----------+---+---+---+-------+-------------------------------------------- Freiley reported later that ambient load physical temperature (Tphys) was 18.7C. X-RCP Test: Rotate through four states: UG14 CNF XRA1O1 X-RCP to LNA1, Output 1 cold sky, with and without noise diode UG14 CNF XA1A1O1 X-band A1 ambient load to LNA1, Output 1 ambient load, with and without noise diode Following applied throughout the test: UG14 CNF XLA2O2 X-LCP to LNA2, Output 2 R2A IFS 14_X_RCP Connects RSR 2A to logical X-RCP R2B IFS 14_X_LCP Connects RSR 2B to logical X-LCP DC01 DISC Disconnect CLR1 from previous connection DC01 CONN DSS14XO1 Connect CLR1 to X microwave Output 1 (RCP) -----------+---+---+---+-------+-------+------------------------------------ ERT (UTC) SKY ND AMB RCP RMS LCP RMS COMMENT -----------+---+---+---+-------+-------+------------------------------------ 22:00:35 X RSRs recording 22:03:25 X X 30 22:05:50 X X 11 7 22:08:35 X 8 8 22:11:10 X 29 29 22:11:53 X X 30 29 22:12:35 X X 12 8 22:13:22 X 8 8 -----------+---+---+---+-------+-------+------------------------------------ Big cloud spotted over DSS 14 Freiley reported the following later: Physical temperature of X1 ambient load (Tphys): 11.5C and 11.8C Derived Top: 21.4K and 24.8K Derived Noise Diode temperature (TND): 19.5K and 18.0K X-LCP Test: Rotate through four states: UG14 CNF XLA2O2 X-LCP to LN21, Output 2 cold sky, with and without noise diode UG14 CNF XA1A2O2 X-band A1 ambient load to LNA2, Output 2 ambient load, with and without noise diode Following were set during X-RCP test and were not changed: UG14 CNF XRA1O1 X-RCP to LNA1, Output 1 R2A IFS 14_X_RCP Connects RSR 2A to logical X-RCP R2B IFS 14_X_LCP Connects RSR 2B to logical X-LCP Following were issued at the beginning of this test and were not changed: DC01 DISC Disconnect CLR1 from previous connection DC01 CONN DSS14XO2 Connect CLR1 to X microwave Output 2 (LCP) -----------+---+---+---+-------+-------+------------------------------------ ERT (UTC) SKY ND AMB RCP RMS LCP RMS COMMENT -----------+---+---+---+-------+-------+------------------------------------ 22:26:00 X 29 RSRs continuing to record 22:27:55 X X 29 30 22:29:50 X X 7 10 22:31:40 X 7 7 22:34:23 X 29 29 22:37:50 X X 29 30 22:38:55 X X 7 10 22:40:48 X 7 7 Big cloud may be dissipating 22:42:15 RSRs HALT -----------+---+---+---+-------+-------+------------------------------------ Freiley reported the following later: Physical temperature of X2 ambient load (Tphys): 12.5C and 12.9C Derived Top: 16.9K and 17.0K Derived Noise Diode temperature (TND): 15.5K and 15.0K