MADR00ESP Site Information Form (site log v2.0)
     International GNSS Service
     See Instructions at:
       https://files.igs.org/pub/station/general/sitelog_instr_v2.0.txt


0.   Form

     Prepared by (full name)  : UNAVCO Network Engineer
                              : (ggn-ops@postal.unavco.org)
     Date Prepared            : 2023-01-09
     Report Type              : UPDATE
     If Update:
      Previous Site Log       : madr00esp_20210720.log
      Modified/Added Sections : 3.17, 3.18, 11


1.   Site Identification of the GNSS Monument

     Site Name                : Madrid Deep Space Tracking Station
     Nine Character ID        : MADR00ESP
     Monument Inscription     : None
     IERS DOMES Number        : 13407S012
     CDP Number               : 115
     Monument Description     : 2 Brass brackets
       Height of the Monument : 0.203 m
       Monument Foundation    : Roof mounted
       Foundation Depth       : 5.15 m
     Marker Description       : DIVOT
     Date Installed           : 1989-01-01T00:00Z
     Geologic Characteristic  : (BEDROCK/CLAY/CONGLOMERATE/GRAVEL/SAND/etc)
       Bedrock Type           : (IGNEOUS/METAMORPHIC/SEDIMENTARY)
       Bedrock Condition      : (FRESH/JOINTED/WEATHERED)
       Fracture Spacing       : (0 cm/1-10 cm/11-50 cm/51-200 cm/over 200 cm)
       Fault zones nearby     : (YES/NO/Name of the zone)
         Distance/activity    : (multiple lines)
     Additional Information   : The subsurface is composed of granite and thin
                              : layers of sandy soil. Solid granite bedrock
                              : occurs at depths of three to nine meters.
                              : Varying layers of soft granite and fractured
                              : granite occur between surface material and
                              : bedrock. The area is undergoing a phase of
                              : active erosion.
                              : Geological information from "NASA Space Geodesy
                              : Program Memorandum 4482" p277.


2.   Site Location Information

     City or Town             : Robledo
     State or Province        : N/A
     Country or Region        : ESP
     Tectonic Plate           : EURASIAN
     Approximate Position (ITRF)
       X coordinate (m)       : 4849202.394
       Y coordinate (m)       : -360328.993
       Z coordinate (m)       : 4114913.186
       Latitude (N is +)      : +402544.98
       Longitude (E is +)     : -0041458.77
       Elevation (m,ellips.)  : 829.5
     Additional Information   : Site is located on JPL's Madrid Tracking
                              : station which is south of Madrid, Spain near
                              : Robledo
                              : The reference frame is ITRF2000.
                              : The epoch is January 1, 2004.


3.   GNSS Receiver Information

3.1  Receiver Type            : ROGUE SNR-8
     Satellite System         : GPS
     Serial Number            : UNKN
     Firmware Version         : 4.1
     Elevation Cutoff Setting : 4 deg
     Date Installed           : 1989-12-15T00:00Z
     Date Removed             : 1992-04-15T00:00Z
     Temperature Stabiliz.    : none
     Additional Information   : Date Removed is an approximate and
                              : will need to be verified.

3.2  Receiver Type            : ROGUE SNR-8
     Satellite System         : GPS
     Serial Number            : UNKN
     Firmware Version         : 6.9
     Elevation Cutoff Setting : 4 deg
     Date Installed           : 1992-04-15T00:00Z
     Date Removed             : 1992-06-15T00:00Z
     Temperature Stabiliz.    : none
     Additional Information   : Date Removed is an approximate and
                              : will need to be verified.

3.3  Receiver Type            : ROGUE SNR-8
     Satellite System         : GPS
     Serial Number            : UNKN
     Firmware Version         : 7.1
     Elevation Cutoff Setting : 4 deg
     Date Installed           : 1992-06-15T00:00Z
     Date Removed             : 1994-02-04T00:00Z
     Temperature Stabiliz.    : none
     Additional Information   : Date Removed is an approximate and
                              : will need to be verified.

3.4  Receiver Type            : ROGUE SNR-8
     Satellite System         : GPS
     Serial Number            : UNKN
     Firmware Version         : 7.6
     Elevation Cutoff Setting : 4 deg
     Date Installed           : 1994-02-04T00:00Z
     Date Removed             : 1996-10-03T00:00Z
     Temperature Stabiliz.    : none
     Additional Information   : Date Removed is an approximate and
                              : will need to be verified.

3.5  Receiver Type            : ROGUE SNR-8
     Satellite System         : GPS
     Serial Number            : UNKN
     Firmware Version         : 7.8
     Elevation Cutoff Setting : 4 deg
     Date Installed           : 1996-10-03T00:00Z
     Date Removed             : 1999-08-18T07:00Z
     Temperature Stabiliz.    : none
     Additional Information   : Rogue receiver has been permanently turned off.

3.6  Receiver Type            : ASHTECH Z-XII3
     Satellite System         : GPS
     Serial Number            : LP03574
     Firmware Version         : CC00
     Elevation Cutoff Setting : 4 deg
     Date Installed           : 2000-06-30T00:00Z
     Date Removed             : 2014-01-15T19:14Z
     Temperature Stabiliz.    : none
     Additional Information   : samplerate - 1s
                              : offload format - soc
                              : conversion to 30s - soc2rnx

3.7  Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO
     Serial Number            : 01326
     Firmware Version         : 3.5.3
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2014-01-15T19:15Z
     Date Removed             : 2014-03-20T20:50Z
     Temperature Stabiliz.    : none
     Additional Information   : (multiple lines)

3.8  Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO
     Serial Number            : 01326
     Firmware Version         : 3.5.5
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2014-03-20T20:52Z
     Date Removed             : 2014-10-27T16:00Z
     Temperature Stabiliz.    : none
     Additional Information   : L1 center = 1573

3.9  Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO
     Serial Number            : 01326
     Firmware Version         : 3.5.7b0
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2014-10-27T16:30Z
     Date Removed             : 2015-01-22T18:03Z
     Temperature Stabiliz.    : none
     Additional Information   : L1 center = 1573
                              : SBAS off

3.10 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO
     Serial Number            : 01326
     Firmware Version         : 3.5.8b0-12-52e9
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2015-01-22T18:04Z
     Date Removed             : 2015-09-01T16:30Z
     Temperature Stabiliz.    : none
     Additional Information   : L1 center = 1573
                              : SBAS off

3.11 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO
     Serial Number            : 01326
     Firmware Version         : 3.6.3
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2015-09-01T16:31Z
     Date Removed             : 2016-03-23T17:23Z
     Temperature Stabiliz.    : none
     Additional Information   : L1 center = 1573
                              : SBAS off

3.12 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO
     Serial Number            : 01326
     Firmware Version         : 3.6.4
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2016-03-23T17:30Z
     Date Removed             : 2018-08-23T19:33Z
     Temperature Stabiliz.    : none
     Additional Information   : L1 center = 1573
                              : SBAS off
                              : QZSS off

3.13 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO+GAL+BDS
     Serial Number            : 01326
     Firmware Version         : 3.7.2
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2018-08-23T19:45Z
     Date Removed             : 2019-05-28T19:19Z
     Temperature Stabiliz.    : none
     Additional Information   : (multiple lines)

3.14 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO+GAL+BDS
     Serial Number            : 01326
     Firmware Version         : 3.7.6
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2019-05-28T19:19Z
     Date Removed             : 2020-04-07T00:20Z
     Temperature Stabiliz.    : none
     Additional Information   : (multiple lines)

3.15 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO+GAL+BDS
     Serial Number            : 01326
     Firmware Version         : 3.7.9
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2020-04-07T00:20Z
     Date Removed             : 2021-03-23T20:52Z
     Temperature Stabiliz.    : none
     Additional Information   : (multiple lines)

3.16 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO+GAL+BDS+QZSS
     Serial Number            : 01326
     Firmware Version         : 4.0.02
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2021-03-23T20:52Z
     Date Removed             : 2021-07-15T22:34Z
     Temperature Stabiliz.    : none
     Additional Information   : (multiple lines)

3.17 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO+GAL+QZSS
     Serial Number            : 01326
     Firmware Version         : 4.1.01
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2021-07-15T22:34Z
     Date Removed             : 2021-09-27T23:59Z
     Temperature Stabiliz.    : none
     Additional Information   : Disabled BDS tracking.

3.18 Receiver Type            : JAVAD TRE_G3TH DELTA
     Satellite System         : GPS+GLO+GAL
     Serial Number            : 01326
     Firmware Version         : 4.1.01
     Elevation Cutoff Setting : 0 deg
     Date Installed           : 2021-09-28T00:00Z
     Date Removed             : CCYY-MM-DDThh:mmZ
     Temperature Stabiliz.    : none
     Additional Information   : (multiple lines)

3.x  Receiver Type            : (A20, from rcvr_ant.tab; see instructions)
     Satellite System         : (GPS+GLO+GAL+BDS+QZSS+IRNSS+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        DOME
     Serial Number            : UNKN
     Antenna Reference Point  : BCR
     Marker->ARP Up Ecc. (m)  :   0.0000
     Marker->ARP North Ecc(m) :   0.0000
     Marker->ARP East Ecc(m)  :   0.0000
     Alignment from True N    : 0 deg
     Antenna Radome Type      : DOME
     Radome Serial Number     : 
     Antenna Cable Type       : (vendor & type number)
     Antenna Cable Length     : (m)
     Date Installed           : 1989-12-15T00:00Z
     Date Removed             : 1996-09-25T00:00Z
     Additional Information   : Antenna is mounted on the Roof of the SPC-60
                              : Date Removed is an approximate and
                              : will need to be verified.

4.2  Antenna Type             : AOAD/M_T        NONE
     Serial Number            : 404-B
     Antenna Reference Point  : BPA
     Marker->ARP Up Ecc. (m)  :   0.0254
     Marker->ARP North Ecc(m) :   0.0000
     Marker->ARP East Ecc(m)  :   0.0000
     Alignment from True N    : 0 deg
     Antenna Radome Type      : NONE
     Radome Serial Number     : 
     Antenna Cable Type       : (vendor & type number)
     Antenna Cable Length     : (m)
     Date Installed           : 1996-09-25T00:00Z
     Date Removed             : 2003-09-10T00:00Z
     Additional Information   : (multiple lines)

4.3  Antenna Type             : AOAD/M_T        NONE
     Serial Number            : 4046
     Antenna Reference Point  : BPA
     Marker->ARP Up Ecc. (m)  :   0.0254
     Marker->ARP North Ecc(m) :   0.0000
     Marker->ARP East Ecc(m)  :   0.0000
     Alignment from True N    : 0 deg
     Antenna Radome Type      : NONE
     Radome Serial Number     : 
     Antenna Cable Type       : (vendor & type number)
     Antenna Cable Length     : (m)
     Date Installed           : 2003-09-10T00:00Z
     Date Removed             : 2003-10-29T00:00Z
     Additional Information   : model number: 7490575
                              : Date Removed is an approximate and
                              : will need to be verified.

4.4  Antenna Type             : AOAD/M_T        NONE
     Serial Number            : 404-B
     Antenna Reference Point  : BPA
     Marker->ARP Up Ecc. (m)  :   0.0254
     Marker->ARP North Ecc(m) :   0.0000
     Marker->ARP East Ecc(m)  :   0.0000
     Alignment from True N    : 0 deg
     Antenna Radome Type      : NONE
     Radome Serial Number     : 
     Antenna Cable Type       : (vendor & type number)
     Antenna Cable Length     : (m)
     Date Installed           : 2003-10-29T00:00Z
     Date Removed             : 2003-11-11T13:30Z
     Additional Information   : model number 7490575

4.5  Antenna Type             : AOAD/M_T        NONE
     Serial Number            : 451-U
     Antenna Reference Point  : BPA
     Marker->ARP Up Ecc. (m)  :   0.0254
     Marker->ARP North Ecc(m) :   0.0000
     Marker->ARP East Ecc(m)  :   0.0000
     Alignment from True N    : 0 deg
     Antenna Radome Type      : NONE
     Radome Serial Number     : 
     Antenna Cable Type       : (vendor & type number)
     Antenna Cable Length     : (m)
     Date Installed           : 2003-11-11T13:30Z
     Date Removed             : CCYY-MM-DDThh:mmZ
     Additional Information   : model number 7490582-2

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         : MADR 1665
     Tied Marker Usage        : VLBI
     Tied Marker CDP Number   : 1565
     Tied Marker DOMES Number : 13407S010
     Differential Components from GNSS Marker to the tied monument (ITRS)
       dx (m)                 : -134.246 m
       dy (m)                 : 159.664 m
       dz (m)                 : 164.275 m
     Accuracy (mm)            : 
     Survey method            : CONVENTIONAL SURVEY
     Date Measured            : 2003-05-22T00:00Z
     Additional Information   : https://itrf.ign.fr/ties/13407.tie
                              : 34m antenna DSS65

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        : 1989-12-15/2000-06-27
       Notes                  : presumed dates

6.2  Standard Type            : INTERNAL
       Input Frequency        : (if external)
       Effective Dates        : 2000-06-27/2004-08-04
       Notes                  : (multiple lines)

6.3  Standard Type            : EXTERNAL H-MASER
       Input Frequency        : 5 MHz
       Effective Dates        : 2004-08-04/2004-08-06
       Notes                  : (multiple lines)

6.4  Standard Type            : INTERNAL
       Input Frequency        : (if external)
       Effective Dates        : 2004-08-06/2014-01-29
       Notes                  : (multiple lines)

6.5  Standard Type            : EXTERNAL H-MASER
       Input Frequency        : 5 MHz
       Effective Dates        : 2014-01-29/CCYY-MM-DD
       Notes                  : (multiple lines)

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

7.1  Instrumentation Type     : VLBI
       Status                 : PERMANENT
       Effective Dates        : 1987-01-01/CCYY-MM-DD
       Notes                  : 34m antenna DSS-65,
                              : year of construction
                              : IERS notes 1990-03-21

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

9.1.1  Radio Interferences    : Wi-Fi antenna system (2.4GHz)
       Observed Degradations  : None
       Effective Dates        : 2011-11-01/2012-02-07
       Additional Information : located around 45 degrees north and
                              : near enough to produce multipath effects.

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)

9.2.1  Multipath Sources      : Safety Metallic Roof Handrail
       Effective Dates        : 2011-02-01/2011-02-01
       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                    : 2003-09-10/2003-10-30
      Event                   : failed antenna splitter and subsequent
                              : troubleshooting efforts resulted in
                              : loss of data during this period.

10.2  Date                    : 2003-11-11/2003-11-11
      Event                   : continued intermittent tracking until
                              : this date, both antenna and splitter
                              : were replaced. splitter is now AC
                              : powered, rather than depending on the
                              : DC output from either receiver.
                              : GPS Networking, Inc. P/N -
                              : NH1ALDCBS1x2-N/15/110

10.3  Date                    : 2012-02-08/CCYY-MM-DD
      Event                   : Wi-Fi antenna located at Building 300 roof
                              : has been disconnected and removed on
                              : 2012-02-08T14:30 HS Madrid,Spain time.
                              : This is in response to finding the source
                              : of Madrid GPS signal multipath.

10.4  Date                    : 2012-02-21/CCYY-MM-DD
      Event                   : Part of the handrail nearest to GPS antenna
                              : was removed. This appears to have solved
                              : the Madrid GPS multipath degradation problem.

10.5  Date                    : 2014-01-23/2014-01-23
      Event                   : L1 center frequency is 1573, SBAS is off.

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          : Oak Grove Drive 4800
                              : CA 91109 Pasadena
                              : United States of America (the)
     Primary Contact
       Contact Name           : UNAVCO Network Engineer
       Telephone (primary)    : +1 303-381-7500
       Telephone (secondary)  : 
       Fax                    : +1 303-381-7451
       E-mail                 : ggn-ops@postal.unavco.org
     Secondary Contact
       Contact Name           : 
       Telephone (primary)    : 
       Telephone (secondary)  : 
       Fax                    : 
       E-mail                 : 
     Additional Information   : (multiple lines)




12.  Responsible Agency (if different from 11.)

     Agency                   : (multiple lines)
     Preferred Abbreviation   : (A10)
     Mailing Address          : (multiple lines)
     Primary Contact
       Contact Name           : 
       Telephone (primary)    : 
       Telephone (secondary)  : 
       Fax                    : 
       E-mail                 : 
     Secondary Contact
       Contact Name           : 
       Telephone (primary)    : 
       Telephone (secondary)  : 
       Fax                    : 
       E-mail                 : 
     Additional Information   : (multiple lines)


13.  More Information

     Primary Data Center      : JPL
     Secondary Data Center    : CDDIS
     URL for More Information : 
     Hardcopy on File
       Site Map               : (Y or URL)
       Site Diagram           : Y
       Horizon Mask           : Y
       Monument Description   : Y
       Site Pictures          : Y
     Additional Information   : (multiple lines)
     Antenna Graphics with Dimensions

AOA/M_T

                         -----
                     /     +     \                        <--  0.128  L2
                    |      +      |                       <--  0.110  L1
  +--------------------------------------------------+    <--  0.102  TCR
  |                                                  |
  |                                                  |
  |                                                  |
  |                                                  |
+-+--------------------------------------------------+-+  <--  0.038
+-------------------+-------------+--------------------+  <--  0.035  BCR
                    |             |
                   =|             |
                    +------x------+                       <--  0.000 BPA=ARP


   ARP: Antenna Reference Point           BPA: Bottom of Preamplifier
   L1 : L1 Phase Center                   L2 : L2 Phase Center
   TCR: Top of Chokering                  BCR: Bottom of Chokering