KOKB00USA Site Information Form (site log) International GNSS Service See Instructions at: https://files.igs.org/pub/station/general/sitelog_instr.txt 0. Form Prepared by (full name) : Tatevik Shakhbandaryan Date Prepared : 2023-03-13 Report Type : UPDATE If Update: Previous Site Log : kokb_20210805.log Modified/Added Sections : 3.20,3.21 1. Site Identification of the GNSS Monument Site Name : Kokee Park Geophysical Observatory Four Character ID : KOKB Monument Inscription : 3028-S IERS DOMES Number : 40424M004 CDP Number : Monument Description : 'Dinardo'-type steel plate Height of the Monument : Monument Foundation : CONCRETE ROOF OF 4 m TOWER Foundation Depth : 4 m Marker Description : Date Installed : 1987-01-01T00:00Z Geologic Characteristic : Bedrock Type : Bedrock Condition : Fracture Spacing : Fault zones nearby : Distance/activity : Additional Information : Geological Province: Hawaiian Archipelago : Local Geology: The islands probably originated : as the result of motion of the Pacific Plate : over a fixed hot spot. The hot spot has been : releasing magma from fractures as the plate : moved northwest. : Geological information from "NASA Space Geodesy : Program: Catalogue of Site Information", : Technical Memorandum 4482, March 1993, p248. : 'Dinardo'-type plate on old satellite tracking : base. 2. Site Location Information City or Town : Kokee Park, Waimea, State or Province : Kauai, Hawaii Country : United States of America Tectonic Plate : PACIFIC Approximate Position (ITRF) X coordinate (m) : -5543838.3609 Y coordinate (m) : -2054586.6103 Z coordinate (m) : 2387810.1225 Latitude (N is +) : +220734.5496 Longitude (E is +) : -1593953.7472 Elevation (m,ellips.) : 1167.5216 Additional Information : The site is in Kokee Park, Waimea, Kauai. Kauai : is the northern-most island of the eight major : islands of the State of Hawaii. : Site information from "NASA Space Geodesy : Program: Catalogue of Site Information", : Technical Memorandum 4482, March 1993, p248. : Approximate positions updated 2004-05-21. : Approximate positions updated 2005-01-14. 3. GNSS Receiver Information 3.1 Receiver Type : ROGUE SNR-8 Satellite System : GPS Serial Number : 10 Firmware Version : 5.6 Elevation Cutoff Setting : 4 deg Date Installed : 1990-10-05T00:00Z Date Removed : 1992-05-14T00:00Z Temperature Stabiliz. : none Additional Information : 3.2 Receiver Type : ROGUE SNR-8 Satellite System : GPS Serial Number : 10 Firmware Version : 7.0 Elevation Cutoff Setting : 4 deg Date Installed : 1992-05-14T00:00Z Date Removed : 1992-11-09T00:00Z Temperature Stabiliz. : none Additional Information : 3.3 Receiver Type : ROGUE SNR-8 Satellite System : GPS Serial Number : 10 Firmware Version : 7.2 Elevation Cutoff Setting : 4 deg Date Installed : 1992-11-09T00:00Z Date Removed : 1993-02-17T00:00Z Temperature Stabiliz. : none Additional Information : 3.4 Receiver Type : ROGUE SNR-8 Satellite System : GPS Serial Number : 10 Firmware Version : 7.3 Elevation Cutoff Setting : 4 deg Date Installed : 1993-02-17T00:00Z Date Removed : 1993-05-29T00:00Z Temperature Stabiliz. : none Additional Information : 3.5 Receiver Type : ROGUE SNR-8 Satellite System : GPS Serial Number : 10 Firmware Version : 7.4 Elevation Cutoff Setting : 4 deg Date Installed : 1993-05-29T00:00Z Date Removed : 1993-10-16T00:00Z Temperature Stabiliz. : none Additional Information : 3.6 Receiver Type : ROGUE SNR-8 Satellite System : GPS Serial Number : 10 Firmware Version : 7.5 Elevation Cutoff Setting : 4 deg Date Installed : 1993-10-16T00:00Z Date Removed : 1994-05-05T00:00Z Temperature Stabiliz. : none Additional Information : 3.7 Receiver Type : ROGUE SNR-8 Satellite System : GPS Serial Number : 10 Firmware Version : 7.8 Elevation Cutoff Setting : 4 deg Date Installed : 1994-05-05T00:00Z Date Removed : 1996-01-10T22:00Z Temperature Stabiliz. : none Additional Information : 3.8 Receiver Type : ROGUE SNR-8000 Satellite System : GPS Serial Number : T139 Firmware Version : 0.9 link 01/05/96 (3.2 with GPSMet Code) Elevation Cutoff Setting : 4 deg Date Installed : 1996-01-10T22:00Z Date Removed : 1999-07-23T00:00Z Temperature Stabiliz. : none Additional Information : 3.9 Receiver Type : AOA SNR-8100 ACT Satellite System : GPS Serial Number : R137-U Firmware Version : 3.3.32.2 Elevation Cutoff Setting : 4 deg Date Installed : 1999-07-23T00:00Z Date Removed : 2000-04-26T00:00Z Temperature Stabiliz. : none Additional Information : 3.10 Receiver Type : AOA SNR-8100 ACT Satellite System : GPS Serial Number : R137-U Firmware Version : 3.3.32.2 1s soc2rnx Elevation Cutoff Setting : 4 deg Date Installed : 2000-04-26T00:00Z Date Removed : 2002-01-08T19:00Z Temperature Stabiliz. : none Additional Information : samplerate - 1s : offload format - soc : conversion to 30s - soc2rnx 3.11 Receiver Type : AOA SNR-8100 ACT Satellite System : GPS Serial Number : R137-U Firmware Version : 3.3.32.2 Elevation Cutoff Setting : 4 deg Date Installed : 2002-01-08T19:00Z Date Removed : 2002-04-02T20:00Z Temperature Stabiliz. : none Additional Information : samplerate - reverted to 30s 3.12 Receiver Type : AOA SNR-12 ACT Satellite System : GPS Serial Number : R255-U Firmware Version : 3.3.32.5 Elevation Cutoff Setting : 4 deg Date Installed : 2002-04-02T20:00Z Date Removed : 2002-09-24T23:18Z Temperature Stabiliz. : none Additional Information : samplerate - 1s : offload format - soc : conversion to 30s - soc2rnx 3.13 Receiver Type : ASHTECH UZ-12 Satellite System : GPS Serial Number : ZR220014901 Firmware Version : CJ10 1s soc2rnx Elevation Cutoff Setting : 4 deg Date Installed : 2002-09-24T23:18Z Date Removed : 2004-12-22T23:00Z Temperature Stabiliz. : none Additional Information : 3.14 Receiver Type : ASHTECH UZ-12 Satellite System : GPS Serial Number : UC2200436003 Firmware Version : CN04 1s soc2rnx Elevation Cutoff Setting : 4 deg Date Installed : 2004-12-22T23:05Z Date Removed : 2008-03-27T00:01Z Temperature Stabiliz. : none Additional Information : 3.15 Receiver Type : ASHTECH UZ-12 Satellite System : GPS Serial Number : IR2200722003 Firmware Version : CQ00 Elevation Cutoff Setting : 4 deg Date Installed : 2008-03-27T00:06Z Date Removed : 2019-03-29T21:45Z Temperature Stabiliz. : none Additional Information : 3.16 Receiver Type : SEPT POLARX5TR Satellite System : GPS+GLO+GAL+BDS+QZSS Serial Number : 3013927 Firmware Version : 5.2.0 Elevation Cutoff Setting : 0 deg Date Installed : 2019-03-29T21:46Z Date Removed : 2019-09-11T23:32Z Temperature Stabiliz. : none Additional Information : 3.17 Receiver Type : SEPT POLARX5TR Satellite System : GPS+GLO+GAL+BDS+QZSS Serial Number : 3013927 Firmware Version : 0.0.0-181002 Elevation Cutoff Setting : 0 deg Date Installed : 2019-09-11T23:32Z Date Removed : 2020-01-03T01:00Z Temperature Stabiliz. : none Additional Information : 3.18 Receiver Type : SEPT POLARX5TR Satellite System : GPS+GLO+GAL+BDS+QZSS Serial Number : 3013927 Firmware Version : 5.3.0 Elevation Cutoff Setting : 0 deg Date Installed : 2020-01-03T01:00Z Date Removed : 2020-01-31T21:21Z Temperature Stabiliz. : none Additional Information : 3.19 Receiver Type : SEPT POLARX5TR Satellite System : GPS+GLO+GAL+BDS+QZSS Serial Number : 3013927 Firmware Version : 5.3.2 Elevation Cutoff Setting : 0 deg Date Installed : 2020-01-31T21:21Z Date Removed : 2021-02-03T23:15Z Temperature Stabiliz. : none Additional Information : 3.20 Receiver Type : SEPT POLARX5TR Satellite System : GPS+GLO+GAL+BDS+QZSS Serial Number : 3013927 Firmware Version : 5.4.0 Elevation Cutoff Setting : 0 deg Date Installed : 2021-02-03T23:15Z Date Removed : 2023-03-06T22:44Z Temperature Stabiliz. : none Additional Information : 3.21 Receiver Type : SEPT POLARX5TR Satellite System : GPS+GLO+GAL+BDS+QZSS Serial Number : 3013927 Firmware Version : 5.5.0 Elevation Cutoff Setting : 0 deg Date Installed : 2023-03-06T22:44Z Date Removed : CCYY-MM-DDThh:mmZ Temperature Stabiliz. : none Additional Information : 3.x Receiver Type : (A20, from rcvr_ant.tab; see instructions) Satellite System : (GPS+GLO+GAL+BDS+QZSS+SBAS) Serial Number : (A20, but note the first A5 is used in SINEX) Firmware Version : (A11) Elevation Cutoff Setting : (deg) Date Installed : (CCYY-MM-DDThh:mmZ) Date Removed : (CCYY-MM-DDThh:mmZ) Temperature Stabiliz. : (none or tolerance in degrees C) Additional Information : (multiple lines) 4. GNSS Antenna Information 4.1 Antenna Type : JPLD/M_R JPLA Serial Number : 10 Antenna Reference Point : BCR Marker->ARP Up Ecc. (m) : 0.093 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : JPLA Radome Serial Number : Antenna Cable Type : Antenna Cable Length : Date Installed : 1990-11-05T00:00Z Date Removed : 1991-04-17T00:00Z Additional Information : 4.2 Antenna Type : JPLD/M_R JPLA Serial Number : 10 Antenna Reference Point : BCR Marker->ARP Up Ecc. (m) : 0.093 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : JPLA Radome Serial Number : Antenna Cable Type : Antenna Cable Length : Date Installed : 1991-04-17T00:00Z Date Removed : 1996-01-10T22:00Z Additional Information : Available records do not indicate the : reason for this April 17, 1991 update. 4.3 Antenna Type : AOAD/M_T JPLA Serial Number : 282 Antenna Reference Point : BPA Marker->ARP Up Ecc. (m) : 0.0614 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : JPLA Radome Serial Number : Antenna Cable Type : Antenna Cable Length : Date Installed : 1996-01-10T22:00Z Date Removed : 1996-08-01T20:00Z Additional Information : 4.4 Antenna Type : AOAD/M_T JPLA Serial Number : 202 Antenna Reference Point : BPA Marker->ARP Up Ecc. (m) : 0.0614 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : JPLA Radome Serial Number : Antenna Cable Type : Antenna Cable Length : Date Installed : 1996-08-01T20:00Z Date Removed : 2002-04-02T20:00Z Additional Information : 08-JAN-2002 19:20 UT : dome removed temporarily : cleaned and re-centered 4.5 Antenna Type : AOAD/M_T JPLA Serial Number : 451-U Antenna Reference Point : BPA Marker->ARP Up Ecc. (m) : 0.0614 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : JPLA Radome Serial Number : Antenna Cable Type : Antenna Cable Length : Date Installed : 2002-04-02T22:00Z Date Removed : 2002-09-24T23:18Z Additional Information : (mulitiple lines) 4.6 Antenna Type : ASH701945C_M NONE Serial Number : CR620004604 Antenna Reference Point : BPA Marker->ARP Up Ecc. (m) : 0.0614 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : NONE Radome Serial Number : Antenna Cable Type : Antenna Cable Length : Date Installed : 2002-09-24T23:18Z Date Removed : 2004-05-18T21:30Z Additional Information : (mulitiple lines) 4.7 Antenna Type : ASH701945G_M NONE Serial Number : CR6200342010 Antenna Reference Point : BPA Marker->ARP Up Ecc. (m) : 0.0614 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : NONE Radome Serial Number : Antenna Cable Type : Andrew Corporation 1/2" heliax Antenna Cable Length : 76 m Date Installed : 2004-05-18T21:30Z Date Removed : 2008-09-24T20:00Z Additional Information : New antenna cable installed during : antenna swap. 4.8 Antenna Type : ASH701945G_M NONE Serial Number : CR6200342010 Antenna Reference Point : BPA Marker->ARP Up Ecc. (m) : 0.0614 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : NONE Radome Serial Number : Antenna Cable Type : Andrew Corporation 1/2" heliax Antenna Cable Length : 76 m Date Installed : 2008-09-24T20:00Z Date Removed : 2021-03-25T00:00Z Additional Information : No antenna change. Powered GPS signal : splitter installed for second receiver. 4.9 Antenna Type : ASH701945G_M NONE Serial Number : CR6200342010 Antenna Reference Point : BPA Marker->ARP Up Ecc. (m) : 0.0614 Marker->ARP North Ecc(m) : 0.000 Marker->ARP East Ecc(m) : 0.000 Alignment from True N : 0 deg Antenna Radome Type : NONE Radome Serial Number : Antenna Cable Type : Times Microwave LMR-600 Antenna Cable Length : 91 m Date Installed : 2021-03-25T00:00Z Date Removed : CCYY-MM-DDThh:mmZ Additional Information : No antenna change. RF Cable and powered GPS : signal splitter were replaced. 4.x Antenna Type : (A20, from rcvr_ant.tab; see instructions) Serial Number : (A*, but note the first A5 is used in SINEX) Antenna Reference Point : (BPA/BCR/XXX from "antenna.gra"; see instr.) Marker->ARP Up Ecc. (m) : (F8.4) Marker->ARP North Ecc(m) : (F8.4) Marker->ARP East Ecc(m) : (F8.4) Alignment from True N : (deg; + is clockwise/east) Antenna Radome Type : (A4 from rcvr_ant.tab; see instructions) Radome Serial Number : Antenna Cable Type : (vendor & type number) Antenna Cable Length : (m) Date Installed : (CCYY-MM-DDThh:mmZ) Date Removed : (CCYY-MM-DDThh:mmZ) Additional Information : (multiple lines) 5. Surveyed Local Ties 5.1 Tied Marker Name : KOKB 1311 Tied Marker Usage : Tied Marker CDP Number : 1311 Tied Marker DOMES Number : 40424S001 Differential Components from GNSS Marker to the tied monument (ITRS) dx (m) : -7.941 dy (m) : 23.616 dz (m) : 4.407 Accuracy (mm) : Survey method : Date Measured : (CCYY-MM-DDThh:mmZ) Additional Information : 5.x Tied Marker Name : Tied Marker Usage : (SLR/VLBI/LOCAL CONTROL/FOOTPRINT/etc) Tied Marker CDP Number : (A4) Tied Marker DOMES Number : (A9) Differential Components from GNSS Marker to the tied monument (ITRS) dx (m) : (m) dy (m) : (m) dz (m) : (m) Accuracy (mm) : (mm) Survey method : (GPS CAMPAIGN/TRILATERATION/TRIANGULATION/etc) Date Measured : (CCYY-MM-DDThh:mmZ) Additional Information : (multiple lines) 6. Frequency Standard 6.1 Standard Type : EXTERNAL H-MASER Input Frequency : 5 MHz Effective Dates : 1990-10-05/2002-09-24 Notes : clock steering off 6.2 Standard Type : INTERNAL Input Frequency : Effective Dates : 2002-09-24/2002-10-14 Notes : clock steering on 6.3 Standard Type : EXTERNAL H-MASER Input Frequency : 5 MHz Effective Dates : 2002-10-14/2006-10-31 Notes : Drifting, switched to backup H-Maser 6.4 Standard Type : EXTERNAL H-MASER Input Frequency : 5 MHz Effective Dates : 2006-10-31/2007-07-18 Notes : Backup Maser (NR-1) online at 20:00Z : Backup Maser (NR-1) taken off at 23:58:35Z 6.5 Standard Type : EXTERNAL H-MASER Input Frequency : 5 MHz Effective Dates : 2007-07-18/2009-10-18 Notes : Primary H-Maser online at 23:59:04Z 6.6 Standard Type : EXTERNAL H-MASER Input Frequency : 5 MHz Effective Dates : 2009-10-18/2009-10-27 Notes : H-Maser failure ~15:00Z 6.7 Standard Type : EXTERNAL H-MASER Input Frequency : 5 MHz Effective Dates : 2009-10-27/2010-05-12 Notes : H-Maser returned to service ~21:00Z 6.8 Standard Type : EXTERNAL H-MASER Input Frequency : 5 MHz Effective Dates : 2010-05-12/2013-09-09 Notes : Removed -1.56e-13 frequency offset at 17:11UTC 6.9 Standard Type : INTERNAL Input Frequency : Effective Dates : 2013-09-09/2013-09-18 Notes : 6.10 Standard Type : EXTERNAL H-MASER Input Frequency : 5 MHz Effective Dates : 2013-09-18/2019-03-29 Notes : 6.11 Standard Type : EXTERNAL H-MASER Input Frequency : 10 MHz Effective Dates : 2019-03-29/CCYY-MM-DD Notes : 10MHz external frequency and 1PPS. 6.x Standard Type : (INTERNAL or EXTERNAL H-MASER/CESIUM/etc) Input Frequency : (if external) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Notes : (multiple lines) 7. Collocation Information 7.x Instrumentation Type : (GPS/GLONASS/DORIS/PRARE/SLR/VLBI/TIME/etc) Status : (PERMANENT/MOBILE) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Notes : (multiple lines) 8. Meteorological Instrumentation 8.1.x Humidity Sensor Model : Manufacturer : Serial Number : Data Sampling Interval : (sec) Accuracy (% rel h) : (% rel h) Aspiration : (UNASPIRATED/NATURAL/FAN/etc) Height Diff to Ant : (m) Calibration date : (CCYY-MM-DD) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Notes : (multiple lines) 8.2.x Pressure Sensor Model : Manufacturer : Serial Number : Data Sampling Interval : (sec) Accuracy : (hPa) Height Diff to Ant : (m) Calibration date : (CCYY-MM-DD) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Notes : (multiple lines) 8.3.x Temp. Sensor Model : Manufacturer : Serial Number : Data Sampling Interval : (sec) Accuracy : (deg C) Aspiration : (UNASPIRATED/NATURAL/FAN/etc) Height Diff to Ant : (m) Calibration date : (CCYY-MM-DD) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Notes : (multiple lines) 8.4.x Water Vapor Radiometer : Manufacturer : Serial Number : Distance to Antenna : (m) Height Diff to Ant : (m) Calibration date : (CCYY-MM-DD) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Notes : (multiple lines) 8.5.x Other Instrumentation : (multiple lines) 9. Local Ongoing Conditions Possibly Affecting Computed Position 9.1.x Radio Interferences : (TV/CELL PHONE ANTENNA/RADAR/etc) Observed Degradations : (SN RATIO/DATA GAPS/etc) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Additional Information : (multiple lines) 9.2.x Multipath Sources : (METAL ROOF/DOME/VLBI ANTENNA/etc) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Additional Information : (multiple lines) 9.3.x Signal Obstructions : (TREES/BUILDINGS/etc) Effective Dates : (CCYY-MM-DD/CCYY-MM-DD) Additional Information : (multiple lines) 10. Local Episodic Effects Possibly Affecting Data Quality 10.1 Date : 2007-10-01/2007-10-01 Event : Surevy work around antenna 18:30-23:00z 10.2 Date : 2007-10-03/2007-10-03 Event : Surevy work around antenna 00:10-01:15z 10.3 Date : 2007-10-04/2007-10-04 Event : Surevy work around antenna 01:15-02:15z 10.4 Date : 2008-09-23/2008-09-24 Event : Work around antenna for a five hour period : ~20:00-01:00 Z 10.5 Date : 2008-09-24/2008-09-25 Event : Work around antenna for a five hour period : ~20:00-01:00 Z 10.6 Date : 2012-02-01/2012-02-01 Event : Transition from .soc to .ash data types. : For soc data types used soc2rnx to do the : conversion to RINEX data. For ash data types : using teqc directly to do the conversion to : RINEX data. 10.7 Date : 2012-11-26/2012-11-26 Event : The railings at the periphery of the concrete : vault/tower where antenna is mounted were : raised at 23:10 UTC and lowered at 23:33 UTC. 10.8 Date : 2015-01-14/2015-01-14 Event : The railings at the tower where antenna is : mounted were raised at 18:45 UTC and lowered : at 19:54 UTC. 10.9 Date : 2021-07-27/2021-07-29 Event : Safety railings were raised on the Verlort : tower at the Kokee Park Geophysical : Observatory, and there was personnel activity : in the vicinity during this time, affecting : the GNSS antenna signal that services KOKB. 10.x Date : (CCYY-MM-DD/CCYY-MM-DD) Event : (TREE CLEARING/CONSTRUCTION/etc) 11. On-Site, Point of Contact Agency Information Agency : Jet Propulsion Laboratory Preferred Abbreviation : JPL Mailing Address : 4800 Oak Grove Drive : Pasadena, CA 91109 USA Primary Contact Contact Name : David A. Stowers Telephone (primary) : 818-354-7055 Telephone (secondary) : Fax : 818-393-4965 E-mail : dstowers@jpl.nasa.gov Secondary Contact Contact Name : UNAVCO Network Engineer Telephone (primary) : 303-381-7500 Telephone (secondary) : Fax : 303-381-7451 E-mail : ggn-ops@postal.unavco.org Additional Information : 12. Responsible Agency (if different from 11.) Agency : Preferred Abbreviation : Mailing Address : Primary Contact Contact Name : Telephone (primary) : Telephone (secondary) : Fax : E-mail : Secondary Contact Contact Name : Telephone (primary) : Telephone (secondary) : Fax : E-mail : Additional Information : 13. More Information Primary Data Center : JPL Secondary Data Center : CDDIS URL for More Information : Hardcopy on File Site Map : Y Site Diagram : Y Horizon Mask : N Monument Description : Y Site Pictures : Y Additional Information : Antenna Graphics with Dimensions ASH701945B_M ASH701945C_M ASH701945D_M ASH701945E_M ASH701945G_M +-------+ / + \ <-- 0.1280 L2 | + | <-- 0.1100 L1 +-----------------+-------------+------------------+ <-- 0.1006 TCR | | | | | | | | +-+--------------------------------------------------+-+ <-- 0.0376 +-------------------+-------------+--------------------+ <-- 0.0346 BCR | | | | +------x------+ <-- 0.0000 BPA=ARP <-- 0.3794 --> ARP: Antenna Reference Point BPA: Bottom of Preamplifier L1 : L1 Phase Center L2 : L2 Phase Center TCR: Top of Chokering BCR: Bottom of Chokering