Page | 1 January 31, 2017
APN-075 Rev 1
APN-075:
STEADYLINE
®
Page | 2 January 31, 2017
Contents
STEADYLINE ................................................................................................................................................... 3
What does STEADYLINE do? ......................................................................................................................... 3
MAINTAIN ................................................................................................................................................. 4
TRANSITION .............................................................................................................................................. 5
PREFER ACCURACY .................................................................................................................................... 6
UAL (USER ACCURACY LEVELS) ................................................................................................................. 7
What does STEADYLINE not do? ................................................................................................................... 9
In what applications should STEADYLINE not be used? ................................................................................ 9
Under what conditions can STEADYLINE be used? ....................................................................................... 9
When is the use of STEADYLINE not recommended? ................................................................................. 10
STEADYLINE 1.0 ........................................................................................................................................... 11
Configuring a Receiver ............................................................................................................................ 11
TRANSITION Example .......................................................................................................................... 12
MAINTAIN Example ............................................................................................................................. 14
PREFER ACCURACY Example ............................................................................................................... 15
UAL Example ....................................................................................................................................... 16
DISABLE STEADYLINE ........................................................................................................................... 17
STEADYLINE 2.0 & New Position Type Reporting ....................................................................................... 18
What is new in STEADYLINE 2.0? ............................................................................................................ 18
Example 1 – STEADYLINEDIFFERENTIALTIMEOUT > RTKTIMEOUT ..................................................... 19
Example 2 – RTKTIMEOUT > STEADYLINEDIFFERENTIALTIMEOUT ..................................................... 21
Example 3 – Emulating STEADYLINE 1.0 Operation Using STEADYLINE 2.0 ........................................ 22
Using STEADYLINE 2.0 in Maintain and Transition Modes ..................................................................... 23
Using STEADYLINE 2.0 in UAL Mode ....................................................................................................... 23
Where to go for Support ............................................................................................................................. 24
Page | 3 January 31, 2017
STEADYLINE
Supported Firmware Versions:
STEADYLINE 1.0 – 6.600, 6.620, 6.700
STEADYLINE 2.0 – 6.710, 6.720 or later for OEM6
– 7.200 or later for OEM7
Supported Hardware:
STEADYLINE 1.0 – OEM615, OEM628, SMART6, SMART6-B, SMART6-T, SMART6-TB, SMART6-L
STEADYLINE 2.0 – OEM628, SMART6-L
– All OEM7 Products
What does STEADYLINE do?
NovAtel’s STEADYLINE technology reduces position jumps that can occur when a GNSS receiver changes
positioning modes.
A receiver will change its positioning mode depending upon the solution it is able to compute. The type
of positioning solution the receiver can compute depends upon:
1. Number of satellites tracked by the receiver
2. Quality of the signals from those satellites
3. Availability of correction signals
4. Positioning types supported by the software model activated on the receiver
This effect is especially evident when a receiver transitions from a high accuracy RTK position solution to
a lower accuracy solution such as PPP, DGPS, GLIDE+SBAS or even autonomous GLIDE™ as shown in
Figure 1 below:
Figure 1 - Positioning Change without STEADYLINE
Smooth transitions are extremely important for precision steering applications where sudden jumps are
disruptive.
Page | 4 January 31, 2017
STEADYLINE provides 4 different modes for smoothing the positioning jumps which are:
• MAINTAIN
• TRANSITION
• PREFER ACCURACY
• UAL
Each of these modes is described in more detail below:
MAINTAIN
When the receiver transitions to a different positioning mode and MAINTAIN mode is selected, it
maintains the position offset calculated to limit a potential real position jump. The receiver continues to
apply the position offset to all positions calculated in the new positioning mode as shown in Figure 2
below.
Figure 2 – STEADYLINE MAINTAIN Mode Operation
MAINTAIN is useful for relative positioning throughout the field because it maintains the last position at
the time the position mode has changed. It will not return back to the absolute accuracy of the original
position mode. This means that when the RTK position is once again available, the offset created by the
last used position type will remain in the reported position.
In Figure 3 below, two positioning engines are running on the GNSS receiver: RTK and GLIDE. The
BESTPOS log output by the NovAtel receiver will provide the highest accuracy position available by the
receiver. At the beginning of the graph, the highest accuracy position available comes from the RTK
engine and that position is output in the BESTPOS log. When RTK corrections are lost, the RTK engine
will drop out of its fixed integer solution based upon the current RTK Timeout. STEADYLINE MAINTAIN
mode switches over to the GLIDE position engine but eliminates the jump in position. The BESTPOS log
provides a GLIDE position output without the discontinuity and jump. As the RTK outage progresses,
STEADYLINE ramps up towards the position provided by the GLIDE engine. When the corrections are
again received and the RTK position engine provides a fixed integer solution, STEADYLINE switches over
to the RTK position solution and BESTPOS log provides the RTK position but with a position offset based
upon the last position output by the GLIDE engine. The jump is removed but a position offset remains.
Page | 5 January 31, 2017
Figure 3 – STEADYLINE MAINTAIN Mode Expanded View
TRANSITION
When the receiver transitions to a different positioning mode using TRANSITION mode, the position
offset is applied to the calculated position to limit a potential real position jump. The position then
slowly transitions to the new position type over a user specified period of time as shown in Figure 4
below.
Figure 4 – STEADYLINE Transition Mode Operation
In Figure 5 below, two positioning engines are running on the GNSS receiver: RTK and GLIDE. The
BESTPOS log output by the NovAtel receiver will provide the highest accuracy position available by the
receiver. At the beginning of the graph, the highest accuracy position available comes from the RTK
engine and that position is output in the BESTPOS log. When RTK corrections are lost, the RTK engine
drops out of its fixed integer solution. BESTPOS will continue to report the position type as the RTK
position type until RTKTIMEOUT expires after which it will report a PDP position type. STEADYLINE
TRANSITION mode ramps up towards the position provided by the GLIDE engine based upon the user-
specified transition time and this position is reported in the BESTPOS log. When the corrections are
again received and the RTK position engine provides a fixed integer solution, STEADYLINE ramps back to
Page | 6 January 31, 2017
the RTK position solution based upon the user-specified time and the BESTPOS log reports an RTK
position type.
Figure 5 – STEADYLINE TRANSITION Mode Expanded View
PREFER ACCURACY
In PREFER ACCURACY mode, the positioning mode change depends on the accuracy level of the
positioning modes. When the position mode changes from a more accurate to a less accurate mode the
receiver uses the MAINTAIN mode. When the position mode changes from a less accurate to a more
accurate mode the receiver uses the TRANSITION mode as shown in Figure 6 below.
Figure 6 – STEADYLINE PREFER ACCURACY Mode Operation
In Figure 7 below, two positioning engines are running on the GNSS receiver: RTK and GLIDE. The
BESTPOS log output by the NovAtel receiver will provide the highest accuracy position available by the
receiver. At the beginning of the graph, the highest accuracy position available comes from the RTK
engine and that position is output in the BESTPOS log. When RTK corrections are lost, the RTK engine
will drop out of its fixed integer solution after the RTK timeout. STEADYLINE MAINTAIN mode switches
over to the GLIDE position engine but reduces the jump. The BESTPOS log provides a GLIDE position
output but reports an RTK position type without the discontinuity and jump. As the RTK outage
progresses, STEADYLINE ramps up towards the position provided by the GLIDE engine. When the
RTKTIMEOUT expires, the position type reported changes from RTK to PDP. When the corrections are
Page | 7 January 31, 2017
again received and the RTK position engine provides a fixed integer solution, STEADYLINE uses
TRANSITION mode to ramp back to the RTK position solution based upon the user-specified time and
the BESTPOS log reports an RTK position type.
Figure 7 – STEADYLINE PREFER ACCURACY Mode Expanded View
UAL (USER ACCURACY LEVELS)
User accuracy levels can be set, using the UALCONTROL command, to change the solution type in the
GPGGA and BESTPOS messages. When UALCONTROL is used along with STEADYLINE, the accuracy mode
is adjusted based on the current estimated accuracy (standard deviation).
Using the UALCONTROL command, the user can set the standard deviation limits for operational and
warning limits. Using STEADYLINE in UAL mode uses these operational and warning limits to control the
STEADYLINE behavior and requires UALCONTROL to be set.
The operational limit is the standard deviation range in meters when STEADYLINE will use the MAINTAIN
mode to minimize jumps when changing from higher accuracy to lower accuracy position solution. The
warning limit is the standard deviation range specified in meters when STEADYLINE will reset. These
limits also control the reported position type in the BESTPOS log output. When the position accuracy is
within the operational limit, the BESTPOS message outputs the position type as OPERATIONAL. When
the position accuracy is between the operational and warning limits, the position type is reported as
WARNING. When the position accuracy is outside of the warning limit, the position type is reported as
OUT_OF_BOUNDS and STEADYLINE resets. When going from OUT_OF_BOUNDS to WARNING or
OPERATIONAL, a jump in position will occur.
UALCONTROL can also be used independently from STEADYLINE. This means that the user can generate
OPERATIONAL, WARNING and OUT_OF_BOUNDS position types in the BESTPOS and GGA logs based
upon the limits set by the UALCONTROL command.
Page | 8 January 31, 2017
In Figure 8 below, the user has set operational and warning limits using the UALCONTROL command. At
point A, higher accuracy corrections are lost and the receiver changes to a lower accuracy solution.
When the position reported by the receiver is within the operational limits, the solution type reported in
the BESTPOS message is OPERATIONAL and the receiver will always use the MAINTAIN accuracy mode.
When the position reported is between the operational and warning limits (B), the receiver uses the
PREFER_ACCURACY mode and reports the position type as WARNING in the BESTPOS message. When
the position reported by the receiver returns to below the operational limit (C), the solution type
reported is OPERATIONAL but the receiver continues to use the PREFER_ACCURACY mode until the
position offset is removed. After the offset is removed (D), the receiver transitions to the MAINTAIN
accuracy mode.
Figure 8 – STEADYLINE User Accuracy Level (UAL) Mode Operation
In the Figure 9 below, the position reported exceeds the operational limit (B) and STEADYLINE changes
to TRANSITION mode and the position type changes to WARNING. If the position reported continues to
drift off beyond the Warning Limit (C), the position type will be reported as OUT_OF_BOUNDS and
STEADYLINE will be automatically reset.
Position Type: OPERATIONAL
Position Type: WARNING
Position Type: WARNING
Position Type: OUT_OF_BOUNDS
Position Type: OUT_OF_BOUNDS
Page | 9 January 31, 2017
Figure 9 – STEADYLINE USER ACCURACY LEVEL (UAL) Mode Operation – Out of Bounds
What does STEADYLINE not do?
STEADYLINE is NOT a bridging technology in the true sense in that it will not continue to provide you
positions when you lose all GNSS signals. It will bridge short RTK correction outages, but the accuracy of
the position solution will be that of the next best positioning mode available.
In an example where RTK corrections are lost and the position switches from an RTK position type
(NARROW_INT) to standalone (SINGLE_POINT), the receiver accuracy level also changes from RTK
(centimeter) to standalone (meter or sub-meter accuracy). Although STEADYLINE smoothed the jump
between the centimeters to sub-meter solution, the transition to the sub-meter solution still means sub-
meter accuracy. Using GLIDE with STEADYLINE will further smooth the position, but the longer the
receiver is providing a sub-meter solution, the more the error will grow.
In what applications should STEADYLINE not be used?
STEADYLINE should not be used as a long duration high accuracy bridging solution if GLIDE is the only
other positioning type supported on the receiver.
STEADYLINE should not be used if GLIDE is the only positioning type supported on the receiver.
Under what conditions can STEADYLINE be used?
STEADYLINE needs to be used with a high-accuracy GNSS position type such as RTK or TerraStar-C.
STEADYLINE works best when used in open sky conditions where there is a clear view of the sky and no
trees or obstacles at the headlands.
Position Type: WARNING
Position Type: OUT_OF_BOUNDS
Position Type: OUT_OF_BOUNDS
Position Type: WARNING
Page | 10 January 31, 2017
When is the use of STEADYLINE not recommended?
STEADYLINE is not recommended for use near tree lines or at treed headlands unless a secondary high
accuracy position solution is also available such as TerraStar-C. This would mean that RTK and TerraStar-
C should be active on the receiver.
When using STEADYLINE near obstacles and during loss of RTK corrections, STEADYLINE will fall back to
the next most accurate positioning mode. If that positioning mode is GLIDE, then the user may
experience positioning jumps while running on the GLIDE engine as the vehicle moves in and out of the
tree lines.
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STEADYLINE 1.0
Supported Firmware Versions:
STEADYLINE 1.0 – 6.600, 6.620, 6.700
Supported Hardware:
STEADYLINE 1.0 – OEM615, OEM628, SMART6, SMART6-B, SMART6-T, SMART6-TB, SMART6-L
Configuring a Receiver
The format of the STEADYLINE command is:
STEADYLINE mode [transition_time]
Example:
STEADYLINE PREFER_ACCURACY 100
The transition_time parameter is the time over which the position solution will transition in seconds.
The minimum rate of change is 0.005 m/s regardless of this parameter. The transition_time parameter
is only valid with TRANSITION, PREFER_ACCURACY and UAL modes.
Page | 12 January 31, 2017
TRANSITION Example
Receiver Commands:
STEADYLINE TRANSITION 100
RTKTIMEOUT 60
PDPFILTER ENABLE
PDPMODE GLIDE AUTO
This will enable STEADYLINE in TRANSITION mode with a transition time of 100 seconds. This means
that when STEADYLINE will take 100 seconds to transition between a high and low accuracy solution.
In Figure 10 below, let’s assume that our receiver supports RTK as the high accuracy position solution
and GLIDE is the next available best accuracy solution.
Figure 10 – STEADYLINE Transition Mode Example
When RTK is lost at point A, STEADYLINE will make a 100 second transition to the GLIDE accuracy
solution (from point A to C) assuming that RTK is lost for more than 100 seconds. During that time the
position will ramp towards the position reported by GLIDE (shown in red). The position accuracy at the
end of the transition period from high accuracy to low accuracy will be that of the GLIDE solution as
shown in the accuracy envelope, however STEADYLINE will continue to report a position type of
NARROW_INT until the RTKTIMEOUT expires at 60 seconds (point B). After RTKTIMEOUT expires, the
position type reported will change to PDP. When RTK returns at point D, STEADYLINE will transition
back to the high accuracy solution over 100 seconds until RTK accuracy is restored at point E.
If RTK returns before the transition between the high and low accuracy is complete (e.g. Transition set
to 100 seconds but RTK comes back after 55 seconds and before RTKTIMEOUT), the receiver will
immediately transition back to the high accuracy position using the programmed transition time as
100 s
100 s
TRANSITION MODE transition_time = 100
Accuracy
Envelope
Desired Path
Vehicle Path
GLIDE
NARROW_INT
Reported Position Type:
A
B C
D
60 s
RTKTIMEOUT
E
NARROW_INT
AVAILABLE
CORRECTIONS LOST
RTK Corrections:
AVAILABLE
Page | 13 January 31, 2017
shown in Figure 11 below. The reported position type will continue to be NARROW_INT because RTK
corrections returned before the expiry of RTKTIMEOUT.
Figure 11 – RTK returns before RTKTIMEOUT Expires
Reported Position Type:
A
B C
55 s
100 s
TRANSITION MODE transition_time = 100
Accuracy
Envelope
Desired Path
Vehicle Path
NARROW_INT
NARROW_INT
60 s
RTKTIMEOUT
AVAILABLE
LOST
RTK Corrections:
AVAILABLE
Page | 14 January 31, 2017
MAINTAIN Example
Receiver Commands:
STEADYLINE MAINTAIN
RTKTIMEOUT 60
PDPFILTER ENABLE
PDPMODE GLIDE AUTO
This will enable STEADYLINE in MAINTAIN mode which will try to maintain accuracy based upon the last
position at each accuracy transition.
Figure 12 – STEADYLINE Maintain Mode Example
Referring to Figure 12 above, let us assume that our receiver supports RTK as the high accuracy position
solution and GLIDE is the next available best accuracy solution. When RTK is lost at point A, STEADYLINE
will apply the RTK position bias when it transitions to the GLIDE accuracy solution. STEADYLINE will
continue to report the NARROW_INT position type until the RTKTIMEOUT expires (from point A to B).
The rate of transition is determined by the standard deviation of the GLIDE position. After the
switchover to the GLIDE position, the GLIDE position may drift within the accuracy envelope (as shown
in red) but will maintain the RTK bias so that it never ramps up to the GLIDE position. If the difference
between RTK and GLIDE standard deviations is great, the ramp up rate between reported standard
deviations will be fast. The position reported by GLIDE may be anywhere within the accuracy envelope
which will be centered around the last RTK position.
When RTK is back at point C, MAINTAIN mode maintains the position reported by GLIDE and applies this
offset to the RTK position. In MAINTAIN mode, there is no guarantee that the reported RTK position will
be accurate. It will always have an offset based upon the last position at the time of the transition. This
offset may accumulate on successive transitions as shown at point D and F. MAINTAIN is useful to
Page | 15 January 31, 2017
maintain trajectory if pass-to-pass accuracy is not important (i.e. when using a “nudge” feature
commonly available on agricultural steering controllers).
PREFER ACCURACY Example
Receiver Commands:
STEADYLINE PREFER_ACCURACY 100
RTKTIMEOUT 60
PDPFILTER ENABLE
PDPMODE GLIDE AUTO
This will enable STEADYLINE in PREFER ACCURACY mode with a low to high accuracy transition time of
100 seconds. The ramp time of the low to high accuracy mode will be dependent upon the difference in
standard deviation between the high and low accuracy solution.
Figure 13 – STEADYLINE PREFER ACCURACY Mode Example
Referring to Figure 13 above, let’s assume that our receiver supports RTK as the high accuracy position
solution and GLIDE is the next available best accuracy solution. When RTK is lost at point A, STEADYLINE
will apply the RTK position bias when it transitions to the GLIDE accuracy solution. The reported
position type will be NARROW_INT until the RTKTIMEOUT expires (from point A to B). The rate of
transition is determined by the standard deviation of the GLIDE position. If the standard deviation is
high, the ramp time will be short. After switching over to GLIDE, the position can ramp further towards
the position reported by GLIDE (as shown in red) the longer we remain on the GLIDE position. The
position accuracy at the end of the transition period from high accuracy to low accuracy will be that of
the GLIDE solution as shown in the accuracy envelope. When RTK returns at point C, STEADYLINE will
transition back to the high accuracy solution over 100 seconds until back to full RTK accuracy at point D.
NARROW_INT
GLIDE
NARROW_INT
Reported Position Type:
A
B
C
100 s
PREFER ACCURACY MODE transition_time = 100
Accuracy
Envelope
Ramp time varies
with Std. Dev.
Desired Path
Vehicle Path
RTKTIMEOUT
D
AVAILABLE
CORRECTIONS LOST
RTK Corrections:
AVAILABLE
Page | 16 January 31, 2017
UAL Example
Using STEADYLINE with UAL requires the user to set the STEADYLINE mode to UAL and also set the
operational and warning limits using the UALCONTROL command. The following commands will set
STEADYLINE to UAL mode with a transition time of 100 seconds and the operational range of +/-8 cm
and warning range of +/-15 cm:
Receiver Commands:
STEADYLINE UAL 100
UALCONTROL ENABLE UAL 0.08 0.15
PDPFILTER ENABLE
PDPMODE GLIDE AUTO
Figure 14 – STEADYLINE USER ACCURACY LEVEL (UAL) Mode Example
Referring to Figure 14 above, let’s assume that our receiver supports RTK as the high accuracy position
solution and GLIDE is the next available best accuracy solution. The position is within the operational
range of +/- 8 cm standard deviation specified in the UALCONTROL command and the BESTPOS and
GPGGA logs indicate the position type as OPERATIONAL.
When RTK corrections are lost at point A, STEADYLINE in UAL mode will use the MAINTAIN mode and
apply the RTK position bias when it changes to the GLIDE accuracy solution. The rate of transition is
determined by the standard deviation of the GLIDE position. If the standard deviation is high, the ramp
time will be short. After switching over to GLIDE, the position can ramp further towards the position
reported by GLIDE (as shown in red) the longer we remain on the GLIDE position. The position accuracy
WARNING
NARROW_INT
GLIDE
NARROW_INT
UAL transition_time = 100
Ramp time varies
with Std. Dev.
Desired Path
Reported Position Type:
OPERATIONAL
OUT_OF_BOUNDS
UALCONTROL
OPERATIONAL RANGE
UALCONTROL
WARNING RANGE
STEADYLINE Disabled
100 s
OPERATIONAL
WARNING
A
B C
D
Accuracy Envelope
Vehicle Path
UALCONTROL
WARNING RANGE
Actual Position Type:
GLIDE
AVAILABLE
CORRECTIONS LOST
RTK Corrections:
AVAILABLE
CORRECTIONS LOST
Page | 17 January 31, 2017
at the end of the transition period from high accuracy to low accuracy will be that of the GLIDE solution
as shown in the accuracy envelope. As long as the receiver accuracy is within the Operational Range
Limit, the STEADYLINE will use the MAINTAIN mode.
When the position exceeds the standard deviation set by Operational Limit of +/-8 cm, the position type
output by the BESTPOS and GGA logs changes to WARNING. When the position is within the
UALCONTROL Warning Range, STEADYLINE will use the PREFER_ACCURACY mode which means that it
will continue to use the MAINTAIN accuracy mode until a higher accuracy solution is available, after
which it uses the TRANSITION mode to return to higher accuracy.
At point B, RTK returns, and STEADYLINE will transition back to the high accuracy solution over 100
seconds. Once the position is less than the specified +/-8 cm Operational Range, the BESTPOS and
GPGGA logs indicate the position type again as OPERATIONAL.
At point C, RTK is lost again and STEADYLINE again applies the RTK position bias and transitions to the
GLIDE position solution. Unfortunately, RTK corrections never return and the reported position exceeds
the +/-8 cm Operational Limit and the position type changes to WARNING. In this example the position
may continue to drift until the +/-15 cm Warning Range is exceeded after which the reported position
type changes to OUT_OF_BOUNDS and STEADYLINE is disabled.
DISABLE STEADYLINE
To disable STEADYLINE use the command:
Receiver Command:
STEADYLINE DISABLE
Page | 18 January 31, 2017
STEADYLINE 2.0 & New Position Type Reporting
Supported Firmware Versions:
– 6.710, 6.720 or later for OEM6
– 7.200 or later for OEM7
Supported Hardware:
– OEM628, SMART6-L
– All OEM7 Products
What is new in STEADYLINE 2.0?
NovAtel’s STEADYLINE 2.0 incorporates three new features:
1. New Position Type Reporting Features
• STEADYLINE can extend the reporting of RTK position types after transition to GLIDE mode
using the new STEADYLINEDIFFERENTIALTIMEOUT function.
2. Ability to propagate position during brief satellite outages
3. Improved smoothing to remove position spikes within position engines
When using STEADYLINE 1.0, the RTKTIMEOUT value would be used to change the position type
reported when using STEADYLINE. In FW versions 6.710 and later, the new
STEADYLINEDIFFERENTIALTIMEOUT has been added that is also used to control the reporting of position
types. This means that current STEADYLINE users will have to change their configurations when using
STEADYLINE 2.0 if they want it to operate similarly to STEADYLINE 1.0 (See Example 3 – Emulating
STEADYLINE 1.0 Operation Using STEADYLINE 2.0).
The STEADYLINEDIFFERENTIALTIMEOUT specifies how long STEADYLINE will report RTK or PPP solutions
after a loss of corrections. However, this new timeout is also logically OR’d with the RTKTIMEOUT &
PPPTIMEOUT. This means that STEADYLINE will report an RTK or PPP position type based upon the
longest timeout: either STEADYLINEDIFFERENTIALTIMEOUT or PPPTIMEOUT or RTKTIMEOUT.
With STEADYLINE 2.0, as soon as STEADYLINE is enabled, the STEADYLINEDIFFERENTIALTIMEOUT is (by
default) enabled and set to 300 seconds on firmware version 6.710, and 7.200. Firmware versions 6.720
and later have a default of 60 seconds. For example, when using RTK and corrections are lost,
STEADYLINE will transition to the GLIDE engine but will continue to report an RTK fixed position type
(NARROW_INT) for up to 300 seconds as long as it is the most available position type available.
If the RTKTIMEOUT is set to longer that the STEADYLINEDIFFERENTIALTIMEOUT, the solution type will be
reported as NARROW_INT after the transition to the GLIDE solution until the RTKTIMEOUT expires.
Page | 19 January 31, 2017
This new STEADYLINEDIFFERENTIALTIMEOUT was incorporated to allow STEADYLINE to extend the time
an RTK position type is reported. This benefits those integrators who want to continue to report an RTK
solution to their customers while STEADYLINE is being used as a fall back solution. This new
functionality reduces the back and forth switching in position types and offers more flexibility when
using STEADYLINE.
The following examples describe how the new STEADYLINEDIFFERENTIALTIMEOUT command works in
STEADYLINE 2.0 using the PREFER_ACCURACY mode.
Example 1 – STEADYLINEDIFFERENTIALTIMEOUT > RTKTIMEOUT
In this example, STEADYLINE is enabled to use the PREFER_ACCURACY mode and
STEADYLINEDIFFERENTIALTIMEOUT is set to a value higher than the RTKTIMEOUT.
Receiver settings:
STEADYLINE PREFER_ACCURACY 100
STEADYLINEDIFFERENTIALTIMEOUT 300
RTKTIMEOUT 60
PDPFILTER ENABLE
PDPMODE GLIDE AUTO
At point A in Figure 15 below, RTK corrections are lost and the differential age increases. STEADYLINE
switches over to use the GLIDE solution at point B when RTKTIMEOUT expires, but the receiver will
continue to report a position type of NARROW_INT for the duration of the
STEADYLINEDIFFERENTIALTIMEOUT (e.g. 300 seconds) as long as it is the most accurate position type
available. When the STEADYLINEDIFFERENTIALTIMEOUT expires at point C, the reported position type
will change to GLIDE. Note that even though the RTKTIMEOUT will expire at point B this timeout is
shorter than STEADYLINEDIFFERENTIALTIMEOUT, and the position type reported will continue to be
NARROW_INT as long as it is the most accurate position type available.
When RTK corrections return at point D and the receiver fixes to an RTK position, the NARROW_INT
position type will be reported again and STEADYLINE will smoothly transition back over 100s (in this
example) from the GLIDE position to the RTK position.
It should be noted that the standard deviations will increase up to those reported by the GLIDE engine
even though the reported position type is NARROW_INT.
Page | 20 January 31, 2017
Figure 15 – STEADYLINE 2.0 PREFER ACCURACY Example (STEADYLINEDIFFERENTIALTIMEOUT > RTKTIMEOUT)
If RTK corrections return before the STEADYLINEDIFFERENTIALTIMEOUT expires, the NARROW_INT
position type will continue to be reported as long it is the most accurate position type available as
shown in Figure 16 below. When corrections return at point B, STEADYLINE will smoothly transition
back to the RTK accuracy solution over 100 seconds.
GLIDE
NARROW_INT
NARROW_INT
Prefer Accuracy Mode = 100
Ramp time varies with Std. Dev.
Desired Path
Reported Position Type:
STEADYLINEDIFFERENTIALTIMEOUT
(e.g. 300s)
A B C
D
Accuracy Envelope
Vehicle Path
RTK Timeout (e.g. 60s)
Actual Position Type:
New STEADYLINE 2.0 Position Type Reporting
Example: STEADYLINEDIFFERENTIALTIMEOUT > RTK TIMEOUT
100 s
AVAILABLE
CORRECTIONS LOST
RTK Corrections:
AVAILABLE
NARROW_INT
NARROW_INT
GLIDE
Page | 21 January 31, 2017
Figure 16 – STEADYLINE 2.0 PREFER ACCURACY Example (RTK Corrections Returns Before Timeout)
Example 2 – RTKTIMEOUT > STEADYLINEDIFFERENTIALTIMEOUT
In this example, STEADYLINE is setup to use the PREFER_ACCURACY mode and RTKTIMEOUT is set to a
value higher than the STEADYLINEDIFFERENTIALTIMEOUT.
Receiver settings:
STEADYLINE PREFER_ACCURACY 100
STEADYLINEDIFFERENTIALTIMEOUT 30
RTKTIMEOUT 120
PDPFILTER ENABLE
PDPMODE GLIDE AUTO
At point A, as shown in Figure 17 below, RTK corrections are lost and the differential age begins to
increase. STEADYLINE switches over to use the GLIDE solution after RTKTIMEOUT expires, but the
receiver will continue to report a position type of NARROW_INT for the duration of the RTKTIMEOUT
(e.g. 30 seconds) as long as it is the most accurate position type available. At point C, the RTKTIMEOUT
expires and the reported position type changes to PDP. Note that even though the
STEADYLINEDIFFERENTIALTIMEOUT expired at point B, this timeout is shorter than RTKTIMEOUT, and
Prefer Accuracy Mode transition_time = 100
Ramp time varies with Std. Dev.
Desired Path
Reported Position Type:
NARROW_INT
STEADYLINE
Differential Timeout
A
B
Accuracy Envelope
Vehicle Path
NARROW_INT
NARROW_INT
GLIDE
NARROW_INT
Actual Position Type:
New STEADYLINE 2.0 Position Type Reporting
Example: RTK Corrections Return before STEADYLINEDIFFERENTIALTIMEOUT expires
100 s
AVAILABLE
CORRECTIONS LOST
RTK Corrections:
AVAILABLE
Page | 22 January 31, 2017
the position type reported will still be NARROW_INT as long as it is the most accurate position type
available.
When RTK corrections return at point D and the receiver fixes to an RTK position, the NARROW_INT
position type will be reported again and STEADYLINE will smoothly transition back over 100s (in this
example) from the last reported PDP position to the RTK position.
It should be noted that the standard deviations will increase up to those reported by the GLIDE engine
even though the reported position type is NARROW_INT.
Figure 17 - STEADYLINE 2.0 PREFER ACCURACY Example (RTKTIMEOUT>STEADYLINEDIFFERENTIALTIMEOUT)
Example 3 – Emulating STEADYLINE 1.0 Operation Using STEADYLINE 2.0
To make STEADYLINE 2.0 behave similarly to STEADYLINE 1.0 requires that the user set the
STEADYLINEDIFFERENTIALTIMEOUT to the minimum value of 5 seconds. By doing so, the RTKTIMEOUT
value will be used to switch the reported position type to PDP as soon as the RTKTIMEOUT expires.
Receiver settings:
STEADYLINE PREFER_ACCURACY 100
STEADYLINEDIFFERENTIALTIMEOUT 5
RTKTIMEOUT 60
PDPFILTER ENABLE
PDPMODE GLIDE AUTO
Prefer Accuracy Mode = 100
Ramp time varies
with Std. Dev.
Desired Path
Reported Position Type:
STEADYLINEDIFFERENTIALTIMEOUT
A
B
C
D
Accuracy Envelope
Vehicle Path
New STEADYLINE 2.0 Position Type Reporting
Example: RTKTIMEOUT longer than STEADYLINEDIFFERENTIALTIMEOUT
GLIDE
NARROW_INT
RTK Timeout
GLIDE
NARROW_INT
Actual Position Type:
100 s
AVAILABLE
AVAILABLE
CORRECTIONS LOST
RTK Corrections:
NARROW_INT
NARROW_INT
Page | 23 January 31, 2017
Figure 18 – STEADYLINE 2.0 – Emulating STEADYLINE 1.0 Operation
Using STEADYLINE 2.0 in Maintain and Transition Modes
STEADYLINE 2.0 works similarly in Maintain and Transition modes in that the
STEADYLINEDIFFERENTIALTIMEOUT command will also extend the reporting of RTK or PPP position
types until the timeout expires.
Using STEADYLINE 2.0 in UAL Mode
UAL mode operation remains the same when using STEADYLINE 2.0.
Prefer Accuracy Mode = 100
Ramp time varies
with Std. Dev.
Desired Path
Reported Position Type:
NARROW_INT
STEADYLINEDIFFERENTIALTIMEOUT= 5
A
B
C
Accuracy Envelope
Vehicle Path
New STEADYLINE 2.0 Position Type Reporting
Example : Emulating STEADYLINE 1.0 Operation
GLIDE
NARROW_INT
RTK Timeout
NARROW_INT
GLIDE
NARROW_INT
Actual Position Type:
100 s
AVAILABLE
AVAILABLE
CORRECTIONS LOST
RTK Corrections:
Page | 24 January 31, 2017
Where to go for Support
To help answer questions and/or diagnose any technical issues that may occur, the NovAtel Support
website is a first resource: www.novatel.com/support/
Remaining questions or issues, including requests for test subscriptions or activation resends, can be
directed to NovAtel Support by visiting www.novatel.com/support/contact/
. To enable the online form
and submit a ticket, first select a "Product Line" and then an associated "Product" from the list.
However, before contacting Support, it is helpful to collect data from the receiver to help investigate
and diagnose any performance-related issues. In those cases, if possible, collect the following list of logs
(the LOG command with the recommended trigger and data rate is included):
LOG VERSIONA ONCE
LOG RXSTATUSA ONCHANGED
LOG RAWEPHEMB ONCHANGED
LOG ALMANACB ONCHANGED
LOG IONUTCB ONCHANGED
LOG GLORAWEPHEMB ONCHANGED
LOG GLORAWALMB ONCHANGED
LOG GLOCLOCKB ONCHANGED
LOG TRACKSTATB ONTIME 10
LOG SATVIS2B ONTIME 60
LOG RANGEB ONTIME 1
LOG BESTPOSB ONTIME 1
LOG MATCHEDPOSB ONCHANGED
LOG PASSTHROUGHB ONCHANGED
LOG RXCONFIGA ONCE
The data described above can be collected using a terminal program that supports binary data logging,
or NovAtel’s CONNECT utility can be downloaded and installed from the NovAtel website:
www.novatel.com/support/info/documents/809
.