Transcript Orange County Real Time Network

Orange County Real Time
Network
OCRTN
County of Orange, California
Presented by Arthur R. Andrew III
OCRTN


OCRTN is a sub-network of California Real Time
Network (CRTN)
Consists of 10 CGPS-RT stations
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
9 Ashtech Z-XII3 and 1 Trimble NetRS receivers
10 Choke-Ring Antennas
OCRTN was declared 100% operational at the
February 20th, 2003.
California Real Time Network
(CRTN)

San Diego County
(SDCRTN) – 18 CGPS-RT

Imperial County
(ICRTN) – 5 CGPS-RT

Orange County
(OCRTN) – 10 CGPS-RT
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Riverside County
(RCRTN) – 19 CGPS-RT

Los Angeles County
(LACRTN) – 12 CGPS-RT
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Parkfield
(PRTN) – 14 CGPS-RT
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Central Valley
(CVSRN) – 5 CGPS-RT
CRTN
SDCRTN
CRTN
ICRTN
CRTN
RCRTN
CRTN
OCRTN
CRTN
LACRTN
CRTN
PCRTN
CRTN
CVSRN
Northern California CGPS-RT
OCRTN
Baselines
Lengths
(Avg: 15km or 10 miles)
Telemetry
Connections:
Data streamed at
1 second using
Spread Spectrum
radios (900 MHz)
(very reliable with the
exception of SACY)
Telemetry Connections:
BLSA:
Stream data at 1 second
rate using CDMA modem
(some latency issues)
Typical OCRTN Site
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Ashtech Z-XII/Micro-Z receiver w/ Choke Ring antenna
FreeWave Spread Spectrum Radio w/ Yagi antenna
Real Time
Data Flow:
PC#1 – RTD – Archive and Positioning
PC#2 – RTD – RTCM Server
CRTN/OCRTN - Current RTK Solution

Single Base Station Mode:
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RTK rover picks which base station to use by dialing the IP and port address.
This method allows rover to compute multiple positions from multiple base
stations on a single point.
Rover must have ability to control wireless modem (choose different port
assignments)
Nearest Base Station Mode:

Server picks the closest base station to the rover position. Does not have the
ability to pick and choose different base stations.

Rover must sends NMEA GGA autonomous position (latitude, longitude, height)
to network software via Internet.
Server streams RTCM version 2.2, message types 3, 18, 19, and 22
from selected base station to rover.
Data Streams and Epochs
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OCRTN – OCS Server
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IP: 206.194.127.187
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Port 8000s RTCM V2.2
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CRTN – CSRC Server
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IP: 132.239.152.74
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Port 7000s RTCM V2.2
Port 8000s RTCM V2.3
(V2.3 supports antenna models)
NAD83 - 1991.35 Epoch
NAD83 - 2004.0 Epoch
Differ by 1.75’ NW
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Hours:
RTD Server RTCM Usage
OCRTN RTCM Stream - Client Connection Time
250
200
150
100
50
0
Geomatics has 7 Leica SR530 RTK Rovers
“Voodoo”
Stick
Types of Surveys
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Reconnaissance
Aerial Target Control
Landfill Quantities
Monument Location
Verification
Construction
GIS Inventory
Topographic
Monument Verification
Aerial Control Densification
Airport Crew
OCRTN RTK
How does it work?
It works no different than standard
RTK. The standard RTK radios that
are restricted by line-of-sight are
replaced with wireless data
modems that use the cellular
provider’s cell site network.
Wireless Internet Modems
allows access to Internet data (TCP/IP)

CDMA/1XRTT - Code Division Multiple Access
Static and Dynamic IP, uses TCP/IP
Cost around $200 - 800 per modem
In Orange County, Verizon and Sprint are the providers.
Service charge is $79.99 per month, unlimited use.
Operates @ 50 – 70 Kbps

GSM/GPRS – General Packet Radio Service
Access
Dynamic IP, uses TCP/IP
Cost around $200 - 800 per modem
In Orange County, AT&T / Cingular are some of the the
providers. Service charge is $79.99 per month,
unlimited use.
Operates @ 50 Kbps
OCRTN – Address/Ports
OCRTN IP Address: 206.194.127.187
The site port assignments are as follows:
8000
8001
8011
8002
8013
8012
8015
8014
8017
8016
8018
– Nearest Base Station
– BLSA
- WHYT
- CAT2
- MJPK
– SACY
- SBCC
– OEOC
– SCMS
– TRAK
– FVPK
8010 - Geodetics Smart RTCM Client
OCRTN
Network RTK
How well does it work?
It works only as good as the GPS
receiver you’re using works.
Some receivers may do better on
longer lines.
Some receivers may fix the
ambiguities (TTF) quicker than
others.
Santa Ana River – EDM
Baseline.ppt
Base Station Characteristics

Each Base Station has
its own characteristics
related to:
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Geology - Subsidence
Sky Visibility
Obstructions
May 2002 to Present - Horizontal Time Series
Issues effecting RTK Heights
SACY CCCS TRAK
CCCS
LBC1
SACY
FVPK
Long-term subsidence area
TRAK
May 2002 to Present - Time Series
Horizontal - N
Horizontal - E
Vertical
www.ocgeomatics
http://sopac.ucsd.edu/projects/realtime/