compatibility of receiver types for glonass widelane ambiguity resolution simon banville, paul...

Compatibility of Receiver Types for GLONASS Widelane Ambiguity

Resolution

Simon Banville, Paul Collins and François LahayeGeodetic Survey Division, Natural Resources Canada

Presented at the PPP Workshop, 12-14 June 2013, Ottawa, Canada

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Outline

GLONASS inter-frequency phase biases

Calibration vs estimation of phase biases

Characterization of GLONASS inter-frequency code biases

Application to the Melbourne-Wübbena combination

Summary and future work

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Inter-frequency phase biases

Carrier-phase biases are only “apparent” biases:

Computing the reference ambiguity using [phase – code] can cause an apparent frequency-dependent bias due to a misalignment between phase and code observables.

[Sleewaegen et al. 2012]

Between-receiver phase observation

Receiver-clock parameter

DD ambiguity

Reference ambiguity

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Inter-frequency phase biases

From Sleewaegen et al. (2012).

Apparent carrier-phase biases:

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Calibration vs estimation

GLONASS inter-frequency phase biases can be calibrated [Wanninger 2012]:

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GLONASS inter-frequency phase biases can also be estimated on the fly [Banville et al. 2013]:

A system of n observations and n unknowns can be defined.

DD ambiguities will be integers if reference satellites have adjacent frequency numbers.

Reference

satellites

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From Banville et al. (2013).

UNBN (NovAtel) – UNBJ (Javad) baseline

Ambiguities naturally converge to integers.

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Inter-frequency code biases

For long-baseline ambiguity resolution (or PPP), use of the Melbourne-Wübbena combination is often made.

Need to deal with inter-frequency code biases (IFCB)…

Application of the phase-bias estimation strategy can absorb the linear component of IFCB.

Do IFCB have a linear dependency on the frequency channel number? If so: no calibration needed! If not: are they consistent for a given receiver type?

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Test network: 145 stations from EUREF on 2013-03-01

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Pre-analysis using ionosphere-free code observations

Based on code residuals from PPP (GPS+GLONASS).

If ionosphere-free IFCB have a linear dependency on the frequency channel number, so will the narrowlane IFCB used in the Melbourne-Wübbena combination.

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Trimble [C1/P2] (32) Leica [C1/P2] (68)

Ionosphere-free IFCB (from PPP)

Leica antennas without domes

Ashtech antenna

Older firmware

Ashtech antenna

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NovAtel [C1/P2] (6) Septentrio [C1/P2] (4)


PolarX4

PolarX3

14 hours of data missing

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Javad [C1/P2] (16) Javad Legacy [P1/P2] (7)


AOAD/M_T OSOD

Note: Javad Legacy receivers show a certain compatibility. Sampling was not sufficient to draw significant conclusions for other Javad models.

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Topcon [C1/P2] (19) Topcon NetG3 [P1/P2] (5+8)


???

Note: There is a certain consistency between models for Topcon receivers, although there are “outliers” and a dependency on antenna type.

From NRCan

“Outliers”

Non-linear

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Summary

Most receivers show a quasi-linear dependency of the IFCB with respect to the frequency channel number.

For a given receiver make, IFCB can be affected by: Antenna type and domes Receiver model (and firmware version)

Residuals effects will propagate into clock/bias estimates and could create inconsistencies if not accounted for: calibration is required.

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Application to Melbourne-Wübbena

Methodology:

Estimate one set of daily satellite M-W biases (1/satellite) for Leica receivers.

Estimate one set of daily satellite M-W offsets (1/satellite) per receiver type (to check for receiver compatibility).

Estimate each station M-W bias, reference ambiguity and a widelane ambiguity per arc.

Fix ALL ambiguity parameters to closest integer and look at residuals.

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Internal consistency

Leica (68 stations)

92.8% < 0.15 cycles

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Internal consistency Offset w.r.t. Leica

Trimble (32 stations)

90.6% < 0.15 cycles

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NovAtel (6 stations)

97.7% < 0.15 cycles

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Septentrio (4 stations)

98.9% < 0.15 cycles

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Javad (14 stations)

78.7% < 0.15 cycles

Notes:

• Javad Legacy and Javad Delta don’t seem compatible.

• Javad Legacy only (7) [P1/P2]:

91.9% < 0.15 cycles

• Larger sampling needed to analyze Javad Delta.

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Topcon (19 stations)

64.6% < 0.15 cycles

Notes:

• Topcon NetG3, NetG3A, EGG_D and Odyssey don’t seem compatible.

• Dependency on antenna type and “outliers”.

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Application of the phase-bias estimation strategy to the (undifferenced) Melbourne-Wübbena combination: Removes the linear trend of the narrowlane IFCB. Residual IFCB effects are estimated as a part of the M-W

satellite biases. One set (or more) of biases is needed per receiver type

(unless compatible). Not all receiver/antenna combinations can be

accommodated by this approach at this point... The method can still allow GLONASS widelane ambiguity

resolution on a rather large subset of stations.

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Future work

For ION GNSS 2013: Apply M-W GLONASS biases to processing of long

baselines. What is the stability of GLONASS satellite M-W

biases?

Generate ionosphere-free GLONASS satellite clocks.

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References

Banville, S., P. Collins and F. Lahaye (2013). “GLONASS ambiguity resolution of mixed receiver types without external calibration,” GPS Solutions. Published online.

Sleewaegen, J.M., A. Simsky, W. de Wilde, F. Boon and T. Willems (2012). “Demystifying GLONASS inter-frequency carrier phase biases,” InsideGNSS, Vol. 7, No. 3, pp. 57-61.

Wanninger, L. (2012). “Carrier-phase inter-frequency biases of GLONASS receivers,” Journal of Geodesy, Vol. 86, No. 2, pp. 139-148.

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Questions

[email protected]

mailto:[email protected]

compatibility of receiver types for glonass widelane ambiguity resolution simon banville, paul...

Documents

phase code

interfrequency code

frequency channel number

code residuals

code observables

adjacent frequency numbers

narrowlane ifcb

linear component of