Mission Planning and SP1
Outline of Session
 Standards
 Errors
 Planning
 Network
Design
 Adjustment
ICSM
Standards and Practices for
Control Surveys
‘SP1’
Positional Uncertainty
95% circle of uncertainty (metres)
 Independent of the nearby network
 SP1 ‘the uncertainty, in metres, at the
95% confidence level, with respect to
the defined reference frame (in our case
GDA94)’
 Order is relative – PU is absolute
 From 2005, PU replaces Order

Assigning Positional Uncertainty

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Formula in SP1 by Leenhouts, 1985
C = b/a
K = q0 + q1C + q2C2 + q3C3
Radius = aK
Where:
a = semi-major axis of the standard error ellipse
b = semi-minor axis of the standard error
ellipse.
q0 = 1.960790
q1 = 0.004071
q2 = 0.114276
q3 = 0.371625
Local Uncertainty
95% confidence level
 Average relative uncertainty with
respect to adjacent points
 Similar to Order which refers to 1s
 Same formula as PU but error ellipse
refers to ‘relative’ average between
adjacent points

Class and Order
Quality Indicators
 Determined by

 The
field and reduction procedures of the
survey.
 The quality of the origin data

Adjustments are an important element
of verifying Class and Order
Class
“CLASS is a function of the precision of a
survey network, reflecting the precision of
observations as well as suitability of
network design, survey methods,
instruments and reduction techniques used
in that survey. Preferably the CLASS is
verified by an analysis of the minimally
constrained least squares adjustment of
the network.”
Class is determined by
The network design.
 Observing procedures and
practices.
 Reduction of observations.
 The results of a minimally
constrained adjustment.

Testing Class

The semi major axis of each relative
error ellipse is tested against:r = c(d + 0.2)
r = Maximum allowable semi-major axis in mm
c = Factor to relate Distance to Error
d = Distance between stations in km
C Values for Each Class
3A
C Value
(for 1
sigma)
1
2A
3
A
7.5
B
15
C
30
D
50
Special high
precision projects
High precision
National Geodetic
Surveys
National and State
geodetic surveys
Densification of
geodetic surveys
Survey coordination
projects
Lower class surveys
E
100
Lower class surveys
Class
Typical Applications
r = c (d + 0.2)
e.g. Class A 1km GPS Line ~ r = 9mm
Relative Error Ellipse
<r
Order
“ORDER is a function of the class of a
survey, the conformity of the new data set
AND the precision of any transformation
process required to convert the results
from one datum to another”
Order
Order is determined in the same way as
class but AFTER a fully constrained
adjustment
 The same formula for ‘r’ is used

Some Order and C values
ORDER
C
(For one s)
00
0
1
2
3
4
5
1
3
7.5
15
30
50
100
Significance of Class and Order
1st Order
4th Order
1st Order 4th Order
1st Order
Class A
Class A
4th Order
1st Order
Class A
1st Order 4th Order
1st Order
GPS Surveying
Observations in SP1
 Static
Surveying
 Quick Static Surveying
 Pseudo-kinematic Surveying
 Kinematic Surveying
 Real
Time Kinematic Surveying (RTK)
General Requirements

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
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Use of Manufacturer’s Instructions
Ancillary Equipment
Geodetic Receivers and Software
Satellite Geometry, Number and Elevation
Need for closure in work and connection
to existing geodetic network
Connection to GDA and AHD as
appropriate
Warning on site Dependent Errors
GPS Calibration
SP1 now deals with GPS calibration
before starting GPS campaigns!
GPS Field Techniques Vs Class
Independent Occupations
Occupy the mark another time and
gather another data set
 Ideally separated in time with
observations to different set of satellites
 Ideally occupied from different base
station in the case of RTK
 Back to back but with a new set up of
the antenna is the minimum
 Enables detection of Errors

Errors in GPS
Surveying
Avoiding Errors
Specifications and Recommended
Practices have been designed to
minimize errors
 GPS Errors can be put in 2 groups...

 Factors
which affect Phase data and
thus the GPS Processing
 Factors external to Processing which
can affect the final result
Factors Affecting Processing

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

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Observation Time
Number and Geometry of Satellites
Quality of Starting Coordinates
Broadcast vs Precise Ephemeris
Ionospheric and Tropospheric delay
Site Specific Errors such as Multipath
All affect ability to correctly solve for
ambiguities and / or resulting precision
SP1 Covers Processing
CLASS
3A
2A
A
B
C
D
E
c-Values
(one
sigma)
1
3
7.5
15
30
50
100
< 8km
D*,DD,
FX
D*,DD,
FX
S,DD,FX
S,DD,FX
S,DD,FX
S,DD,FT
S,DD,FT
8-25kms
D,DD,FX
D,DD,FX
D,DD,FX
S,DD,FX
S,DD,FX
S,DD,FT
S,DD,FT
2550kms
D,DD,
FX(25)FT(50
D,DD,FX(
25)FT(50)
D,DD,FXFT
D,DD,FXFT
D,DD,FXFT
D, T
D, T
5090kms
D,DD,FT
DD or
**,
T D,FT
DD or
**,
T D,FT
DD or
**,
T D,FT
DD or
**,
T D,FT
D,T,NCP
D,T,NCP
> 90kms
D,T
D,T
D,T
D,T
D,T
D,T
D,T
S = Single Frequency.
D = Dual Frequency.
DD = Double difference.
FX = Fixed Ambiguity solution.
FT = Fixed ambiguity with repaired cycle slips.
T = Triple Difference.
NCP = Narrow correlation ie DGPS.
Factors External to Processing
Centring Error
 Antenna Height Error
 Number of repeat occupations of sites
 Quality of existing control to which
GPS survey is being fitted
 Datum Transformation
 For Heights - quality of Geoid
Ellipsoid Separation

GPS Survey Planning
Survey Planning
Station Marking
 Station Naming
 Manpower
 Funding
 GPS Equipment Available
 Other Resources

 key
maps, access information, program
sheets, booking forms, ancillary equipment
Reconnaissance
 Office
Preparation
 Site Selection
Visibility
Accessibility
Multipath
Permanency
Future
Use
Reconnaissance

Station Documentation
 Speedo
Traverse
 Travel Times
 Special Requirements
 Field Records

Logistics
 Travel
time
 Setup
 Observation
time
 Optimum Times
Observation
and Network
Design
Networked Observation
2
2
PSMs to be
Coordinated
Existing
Control
2
4
1
1
Networked Observation
2
2
PSMs to be
Coordinated
Existing
Control
2
2
2
2
Observation Design
PSMs to be
Coordinated
Existing
Control
Radiations are not closed - no check
Second Set - Checks Control and New Marks
Direct Measurement - extra check - little extra time
with GPS - or - Traversed during Cadastral Survey
Connections to Control
Network Mode
Connections to Control
Base Station Mode
Base 3
2
Base 1
Used for RTK and covered in SP1
Adjustment
Minimally Constrained
Adjustment





Only sufficient constraints in order to
achieve a solution.
Confirms internal accuracy of data.
Computed on ellipsoid of GPS
computation.
No “N” values are included.
Used to assign CLASS to coordinates.
Fully Constrained
Adjustment




All constraints are included.
GPS baselines may have to be
transformed (say to AGD) as part of
the adjustment process.
Include ‘N’ Values in this adjustment.
Used to assign ORDER to
coordinates.
Adjustment Analysis
Essential to verify Class and Order
 Variance factor should pass Chi Square test
 Standardized residuals inspected

RTK
Questions?