# Presentation: 203067

## CORS/OPUSFUTURE PROSPECTS

- Delivery of some CORS data in near real-time via Ntrip
- OPUS-RS to process 15 minute data sets
- OPUS projects

**Notes:**
NOTES for presentation at CORS forum Sep. 12, 2005

These are the three topics we will describe today

## Desired New Features

- Process multiple files as network
- Reduce occupation time to ~ 15 min
- Process single frequency (L1) data
- Publish OPUS results

**Notes:**
These were the objectives we had last year.

## Desired New Features

- Process multiple files as network
- Reduce occupation time to ~ 15 min
- Process single frequency (L1) data
- Publish OPUS results

-  OPUS Projects

- OSU Contract

-  PAT 22

**Notes:**
This was how we intended to accomplish them.

OPUS projects is operational for NGS and contractor field projects

OPUS Rapid Static, to reduce occupation time to 15 minutes, is now an operational prototype. All of its parts are  operational, but it needs some experience to become reliable and robust.

The idea of processing single frequency data withy OPUS is still a research question. It is not yet certain that tropospheric and ionospheric double difference delays can be reliably interpolated over the baseline distances typical of OPUS solutions (100-200 km)

OPUS-DB has already been described

## STREAMING CORS DATA WITH NTRIP

- What format?
- What stations?
- What software?
- What distance?
- What data rate?
- What latency?

**Notes:**
NGS has bought and installed the Ntrip software, and so is technically capable of streaming CORS data in near real-time. 

Now the question is “What data should be provided?” NGS wants to provide data streams that will be used.

When you came in, you were given a packet which contained a questionairre about possible uses of streamed CORS data. If you have an opinion on these matters, please take the time to answer the questions. You may join the breakout session on this subject, or you can send in yur answers later.

## Slide 5

**Notes:**
OPUS-RS is an operational prototype.

Note that the OPUS-RS home page looks just like regular OPUS. The only difference is the big red warning box.

## OPUS-RS

- Uses RSGPS program instead of PAGES
- 	(based on OSU MPGPS program)
- Uses P1 and P2 as well as L1 and L2 obs
- Resolves all ambiguities with LAMBDA
- Geometry free linear combination used to determine DD ionospheric delays

**Notes:**
Although the front page looks just like regular OPUS, OPUS-RS is actually a major new program. Internally it uses the RSGPS program rather than the PAGES program NGS has used for baseline processing for many years.

RSGPS is a new program, based on research done by the SPIN group at OSU (see paper on this subject at the ION meeting Friday afternoon).

NGS is still accumulating experience on its behavior.

Tgese are its major features

## RSGPS

- Observation  Equations

**Notes:**
These are the observation equations used by RSGPS.

RSGPS uses double difference equations. There are four observation equations for each epoch, baseline, and satellite.

The unknowns are the station positions, tropospheric delay parameters, double difference ionospheric delays, and ambiguities.

## RSGPS

- May be used in two modes :
- 		Network and Rover
- In network mode, only reference stations are used and to solve for ambiguities and double difference ionospheric delays
- In rover mode, ionospheric delays and troposphere parameters are interpolated from reference stations to rover.

**Notes:**
RSGPS has two modes.

When used in OPUS-RS, RSGPS is run first in the network mode, using selected nearby CORS (or IGS) stations as reference stations. This determines the behavior of the troposphere and ionosphere delays in the local area for the time span of the observations. 

RSGPS is then run in rover mode, where the observations from the rover station are now included. Tropospheric and ionospheric delays are now interpolated to the rover, and the data from all stations are adjusted simultaneously.

## OPUS-RS

- Expected to produce solution with 15 minutes of data (vs. 2 hours for current OPUS)
- Network solution (rather than individual baselines)
- Expected accuracy approx. 2 cm horizontal and 4 cm vertical

**Notes:**
These are some of the properties of OPUS-RS

## Methodology – Rapid-Static Algorithm

**Methodology – Rapid-Static Algorithm**

**Rover solution schemes**

**B**

**A**

**X**

**Network**

**C**

**A**

**X**

**Rover**

**C**

- AC

- AB

**XA**

- XB

- XC

**B**

- AB

- AC

**All three CORS stations contribute to the estimation of a single set of ambiguities **

**One unknown baseline**

**Notes:**
In the rover mode, RSGPS is able to apply contraints on quatities that were determined in the network mode run. These are the double differnence ambiguities and double difference ionospheric delays

In the network run, station A is the hub. Ambiguities and delays are determined for the baseline AB and AC.

In the rover run, station X is the hub. Ambiguities and delays on the baseline XA are the unknowns. The ambiguities and delays on XB, which enter the observation equations, are constrained by XB=XA+AB, where the ambiguities and delays on AB were determined in the network run. The ambiguities are integers, determined by LAMBDA, and the ionospheric delays are determined from the phase observations and the integer ambiguities using the geometry free linear combinations.

## OPUS-RS

- Interface will be almost identical to regular OPUS
- Output report will be similar to regular OPUS, but with quality indicators based on the W-ratio from the LAMBDA validation tests

**Notes:**
OPUS-RS will look a lot like regular OPUS

## OPUS-RS DATASHEET

**RINEX FILE: bkly118o.05o                            TIME: 12:09:34 UTC**
**  ****SOFTWARE:**** rsgps 0.6  RS22.prl****                    START: 2005/04/28  14:00:00**
** ****EPHEMERIS: igu13204.eph [ultra-rapid]              STOP: 2005/04/28  15:00:00**
**  ****NAV FILE: brdc1180.05n                        OBS USED:  2120 /  2173   :  98%**
**  ****ANT NAME: NONE                               ****QUALITY INDICATORS: 8.33 / 6.54**
**ARP HEIGHT: 0.0                              OVERALL RMS: 0.010(m)**
** ****REF FRAME: NAD_83(CORS96)(EPOCH:2002.0000)            ITRF00 (EPOCH:2005.3222)**
**         ****X:       776242.978(m)   0.002(m)            776242.306(m)   0.002(m)**
**         ****Y:     -4986708.281(m)   0.026(m)          -4986706.835(m)   0.026(m)**
**         ****Z:      3888159.007(m)   0.015(m)           3888158.876(m)   0.015(m)**
**       ****LAT:   37 47 52.09045      0.011(m)        37 47 52.11755      0.011(m)**
**     ****E LON:  278 50 52.04960      0.005(m)       278 50 52.03155      0.005(m)**
**     ****W LON:   81  9  7.95040      0.005(m)        81  9  7.96845      0.005(m)**
**    ****EL HGT:          692.689(m)   0.026(m)               691.398(m)   0.026(m)**
** ****ORTHO HGT:          723.765(m)   0.036(m) [Geoid03 NAVD88]**
**                        ****UTM COORDINATES    STATE PLANE COORDINATES**
**                         ****UTM (Zone 17)         SPC (4702 WV S)**
**Northing (Y) [meters]     4183392.127            88557.655**
**Easting (X)  [meters]      486599.893           586595.234**
**Convergence  [degrees]    -0.09328516          -0.09409456**
**Point Scale                0.99960221           0.99994831**
**Combined Factor            0.99949357           0.99983964**
**US NATIONAL GRID DESIGNATOR: 17SMB8660083392(NAD 83)**
**                              ****BASE STATIONS USED**
**PID       DESIGNATION                        LATITUDE    LONGITUDE DISTANCE(m)**
**DF4048 GALP GALLIPOLIS CORS ARP            N385039.148 W0821640.092  152255.7**
**DF5767 DOBS DOBSON CORS ARP                N362531.514 W0804311.711  157086.8**
**AI1571 BLKV BLACKSBURG CORS ARP            N371221.637 W0802452.276   92575.9**

**Notes:**
On the OPUS-RS datasheet, only two entries have changed:

The name and version of the processing program

The number of fixed ambiguities has gone away, since LAMBDA fixes all the ambiguities. In its place are the quality indicators from the network and rover runs of RSGPS. The quality indicator in each run is the average of the W-ratio at the last three epochs. The W-ratio is a statistical  measure of how well the best set of integer ambiguities is separated from the second best set. The W-ratio has been shown to be distributed as Student’s t. We like to see both of these numbers greater than 3.0. If the second number (the quality indicator for the rover solution) is less than 1.0, RSGPS may have been unable to find the correct integer ambiguities and the solution may be in error by many centimeters.

## Slide 13

**Notes:**
OPUS project starts with the registration of  a project

## Slide 14

**Notes:**
This is the result of registering an OPUS project

## Slide 15

**Notes:**
The user selects stations to be included in the project, and designates which are hub stations and which are the fixed stations

## OPUS Projects 

- Add project planning / monitoring
- Automated file management
- Review repeat measurements
- Network adjustment with GPSCOM
- Publish in NGS Integrated Data Base

**Notes:**
These are some of the properties of OPUS Projects

## Front of Room

- Real-Time Group

- Iono/Tropo
- Group

- Guidelines
- Group

- OPUS
- Group