CN113552606B - Method for determining bit ambiguity - Google Patents
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
- G01S19/43—Determining position using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
- G01S19/44—Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method
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Abstract
There is provided a method of determining bit ambiguities, the method comprising: acquiring the satellite-ground distance of the epoch successfully positioned; obtaining a pseudo-range observation value of a current epoch; calculating bit ambiguity to be estimated including receiver clock error according to the difference value of the satellite-earth distance of the last successfully positioned epoch and the pseudo range observation value of the current epoch; acquiring a receiver clock error; and calculating the bit ambiguity according to the difference between the bit ambiguity to be estimated containing the receiver clock error and the receiver clock error.
Description
Technical Field
The present disclosure relates generally to the field of navigation technologies, and in particular, to a method for determining bit ambiguity.
Background
In a severe environment, the GNSS receiver has an error in counting the whole cycle of the satellite, that is, the output pseudorange observation contains bit ambiguity, so that the number of pseudorange observations available for a positioning calculation module is reduced, and even the positioning cannot be performed in a severe case.
Disclosure of Invention
An embodiment of the present application discloses a method for determining bit ambiguity, including:
acquiring the defense distance of the epoch successfully positioned;
obtaining a pseudo-range observation value of a current epoch;
calculating bit ambiguity to be estimated including receiver clock error according to the difference value of the satellite-to-ground distance of the last successfully positioned epoch and the pseudo-range observation value of the current epoch;
acquiring a receiver clock error;
and calculating the bit ambiguity according to the difference between the bit ambiguity to be estimated containing the receiver clock error and the receiver clock error.
In a preferred embodiment, the step of obtaining the receiver clock error further includes:
obtaining a plurality of groups of the satellite-to-earth distances and pseudo-range observation values through a plurality of tracking channels of a receiver, calculating a plurality of corresponding bit ambiguities to be estimated containing receiver clock errors, and respectively taking remainders of bit time lengths to be estimated containing the receiver clock errors as remainder difference values;
and averaging the plurality of remainder difference values to be used as an estimated value of the receiver clock error, and using the estimated value of the receiver clock error as the clock error of the receiver.
In a preferred embodiment, the method further comprises the following steps:
for the receiverThe estimated value of the clock error is checked, wherein the check formula is
δt r Representing the prior clock difference, t, of the receiver b Which represents the length of time of one bit,
an estimate value, q, representing the clock error of said receiver i Representing a bit ambiguity corresponding to a difference between the receiver prior clock offset and an estimated value of the receiver clock offset;
bit ambiguity q corresponding to the difference i Rounding to obtain the correction quantity round (q) i ) According to the correction quantity round (q) i ) Estimate of said receiver clock error
Correcting;
and taking the corrected estimated value of the receiver clock difference as the clock difference of the receiver.
In a preferred embodiment, the bit ambiguity q corresponding to the difference value is i Rounding to obtain the correction quantity round (q) i ) An estimate of the receiver clock error based on the correction
The step of performing a correction further comprises:
when the bit ambiguity q corresponding to the difference value i And the correction amount round (q) i ) Is less than or equal to a first threshold value, an estimated value of the receiver clock difference based on the correction amount
Correcting;
when the bit ambiguity q corresponding to the difference value i And the correction amount round (q) i ) Is greater than a first threshold, discarding the bit ambiguity q corresponding to the difference i The corresponding pseudorange observations.
In a preferred embodiment, the method further comprises the following steps:
checking the estimated value of the receiver clock error, wherein the checking formula is
δt r Representing the receiver a priori clock difference, t b Which represents the length of time of one bit,
an estimate value, q, representing the clock error of said receiver i Representing a bit ambiguity corresponding to a difference between the actual receiver clock error and the estimated receiver clock error;
bit ambiguity q corresponding to the difference i The correction quantity round (q) is obtained by rounding i ) When the bit ambiguity q corresponding to the difference value i And the correction quantity round (q) i ) When the difference value of (2) is less than or equal to a second threshold, the receiver a-priori clock difference is taken as the clock difference of the receiver.
In a preferred embodiment, the receiver prior clock difference is derived from a receiver native result, a sum of a clock difference of an epoch in which a last positioning is successful and a millisecond-level clock quantity, or a difference of a receiver signal receiving time and a whole second.
In a preferred example, the receiver a-priori clock difference is taken as the receiver clock difference, wherein the receiver a-priori clock difference is derived from receiver native results.
In a preferred embodiment, the method further comprises the following steps:
and repairing the pseudo-range observation value and the satellite signal transmission time according to the bit ambiguity.
In a preferred embodiment, the one-bit time length t b It was 0.02 s.
In a preferred example, the satellite distance of the last positioning successful epoch
Wherein,
and
the satellite positions under the geocentric geostationary coordinate system of the epoch which is successfully positioned,
and
the positions of the receivers under the geocentric geostationary coordinate system of the epoch in which the positioning succeeds are respectively.
Compared with the prior art, the method has the following beneficial effects:
according to the method and the device, firstly, the estimation process of the satellite position and the receiver position is simplified, the satellite range can be conveniently estimated, secondly, the estimated value of the receiver clock error is verified, the bit ambiguity can be efficiently and correctly solved, the pseudo range observed quantity and the signal transmission time can be restored, and further the positioning capability of the receiver in a severe environment is guaranteed.
A large number of technical features are described in the specification, and are distributed in various technical solutions, so that the specification is too long if all possible combinations of the technical features (namely, the technical solutions) in the application are listed. In order to avoid this problem, the respective technical features disclosed in the above summary of the invention of the present specification, the respective technical features disclosed in the following embodiments and examples, and the respective technical features disclosed in the drawings may be freely combined with each other to constitute various new technical solutions (which should be regarded as having been described in the present specification) unless such a combination of the technical features is technically impossible. For example, in one example, feature a + B + C is disclosed, in another example, feature a + B + D + E is disclosed, and features C and D are equivalent technical means that serve the same purpose, technically only one feature is used, but not both, and feature E may be technically combined with feature C, then the solution of a + B + C + D should not be considered as already described because the technology is not feasible, and the solution of a + B + C + E should be considered as already described.
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Non-limiting and non-exhaustive embodiments of the present application are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.
Fig. 1 is a flowchart of a method for determining bit ambiguities according to an embodiment of the present disclosure.
Detailed Description
In the following description, numerous technical details are set forth in order to provide a better understanding of the present application. However, it will be understood by those of ordinary skill in the art that the claimed embodiments may be practiced without these specific details and with various changes and modifications based on the following embodiments.
Description of partial concepts:
bit ambiguity: in the GNSS receiver, parameters such as a computed pseudo range and a satellite transmission time contain errors due to bit counting errors, and these errors are usually integral multiples of a bit time length, and are called bit ambiguities.
Receiver clock error: signal reception time measurement errors caused by receiver clock instability.
Receiver native results: besides opening the original observation quantity for downstream manufacturers to develop a positioning algorithm, the manufacturers of the chip of the receiver can also independently perform positioning calculation by utilizing the original observation quantity, wherein the result is a native result and usually comprises information such as the position, the speed, the clock error and the clock drift of the receiver.
Adjusting the clock volume: the difference between the receiver clock differences of the previous epoch and the next epoch.
Part of the innovation of the application lies in:
the method comprises the steps of simplifying satellite position and receiver position estimation processes when calculating the bit ambiguity, calculating the bit ambiguity to be estimated containing the receiver clock error by using the difference between the satellite range of the epoch with the successful previous positioning and the pseudo range observed value of the current epoch, and calculating the bit ambiguity to be estimated containing the receiver clock error by using the difference between the bit ambiguity to be estimated containing the receiver clock error and the estimated value of the receiver clock error. In addition, the estimated value of the receiver clock error is also checked, and the bit ambiguity can be efficiently and correctly solved, so that the pseudo-range observed quantity and the signal transmission time are restored, and the positioning capability of the receiver in a severe environment is further ensured.
To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
An embodiment of the present application discloses a method for determining bit ambiguity, and fig. 1 shows a flowchart of the method for determining bit ambiguity in the present embodiment. The method comprises the following steps:
102, acquiring a pseudo-range observation value of a current epoch;
103, calculating bit ambiguity to be estimated, which contains receiver clock error, according to the difference between the satellite-earth distance of the last successfully positioned epoch and the pseudo-range observed value of the current epoch;
and 105, calculating the bit ambiguity according to the difference value between the bit ambiguity to be estimated containing the receiver clock error and the receiver clock error.
In an embodiment, the step of obtaining the receiver clock error further includes:
obtaining a plurality of groups of the satellite-to-earth distances and pseudo-range observation values through a plurality of tracking channels of a receiver, calculating a plurality of corresponding bit ambiguities to be estimated containing receiver clock errors, and respectively taking the remainder of bit time length to be estimated of the plurality of bit ambiguities to be estimated containing receiver clock errors as remainder difference values;
and averaging the plurality of remainder difference values to be used as an estimated value of the receiver clock error, and using the estimated value of the receiver clock error as the clock error of the receiver.
In an embodiment, the method further comprises:
checking the estimated value of the receiver clock error, wherein the checking formula is
δt r Representing the receiver a priori clock difference, t b Which represents the length of time of one bit,
an estimate value, q, representing the clock error of said receiver i Representing a bit ambiguity corresponding to a difference of the receiver prior clock offset and the estimated value of the receiver clock offset. In this embodiment, the receiver is a known amount of the prior clock difference. The receiver a priori clock differences are, for example, the sum of the clock difference of the epoch in which the last positioning was successful and the millisecond-level clock quantity, or the difference of the receiver signal reception time and the second integer.
Bit ambiguity q corresponding to the difference i The correction quantity round (q) is obtained by rounding i ) According to the correction quantity round (q) i ) Estimate of said receiver clock error
And (6) correcting.
In one embodiment, when the difference value corresponds to a bit ambiguity q i And the correction amount round (q) i ) Is less than or equal to a first threshold value, based on the estimated value of the correction amount to the receiver clock difference
Correcting, and taking the corrected estimated value of the receiver clock error as the clock error of the receiver; when the bit ambiguity q corresponding to the difference value i And the correction amount round (q) i ) When the difference is greater than the first threshold value, the threshold value is setDiscarding the bit ambiguity q corresponding to the difference i The corresponding pseudorange observations. In one embodiment, the first threshold is, for example, 0.1.
In another embodiment, when the difference corresponds to a bit ambiguity q i And the correction quantity round (q) i ) When the difference value of (2) is less than or equal to a second threshold, the receiver a-priori clock difference is taken as the clock difference of the receiver. In this embodiment, the receiver a priori clock difference is derived from the receiver native result, the sum of the clock difference of the last epoch in which the positioning was successful and the millisecond level clock amount, or the difference between the receiver signal reception time and the whole second. In an embodiment, the second threshold is, for example, 0.1.
Specifically, the receiver a priori clock differences may have the following three sources: 1) if the receiver is successfully autonomously positioned, the prior clock error of the receiver is the clock error of the current epoch given by the native result of the receiver; 2) if the receiver can not successfully position by itself, when the clock volume is in millisecond level, the prior clock difference of the receiver is the sum of the clock difference of the last successfully positioned epoch and the difference value of the signal receiving time of the current epoch and the last successfully positioned epoch; 3) and when the clock difference of the receiver is less than millisecond, the prior clock difference of the receiver is the difference between the signal receiving time of the current epoch and an integer second. The priority of the three sources of the receiver prior clock difference is 1), 2) and 3), especially the clock difference prior knowledge of the 1) source has higher precision, and can be considered as the true value of the receiver clock difference.
In another embodiment, if the receiver prior clock error is derived from the native result of the receiver, the receiver prior clock error is taken as the clock error of the receiver, that is, the receiver prior clock error of the source is considered as a true value, and the bit ambiguity is obtained by directly subtracting the receiver prior clock error from the bit ambiguity to be estimated, which includes the receiver clock error.
In an embodiment, the method further comprises: and restoring the pseudo-range observation value and the satellite signal emission time according to the bit ambiguity. Wherein, a formula is adopted
To the abovePseudo-range observed value ρ i ' repair, p i Expressing the repaired pseudo range observed value on the ith tracking channel by adopting a formula
Repair of signal emission time, t s，i Represents the signal emission time, t 'after repair on the ith channel' s，i Representing the time of transmission of the signal on said ith channel at the output of the receiver.
In an embodiment, said one bit time length t b It was 0.02 s.
In a preferred example, the satellite distance of the last positioning successful epoch
Wherein,
and
the satellite positions under the geocentric geostationary coordinate system of the epoch which is successfully positioned,
and
the positions of the receivers under the geocentric geostationary coordinate system of the epoch in which the last positioning is successful are respectively.
In order to better understand the technical solution of the present specification, the following description is given with reference to a specific example, in which the listed details are mainly for understanding and are not intended to limit the protection scope of the present application.
First, the pseudorange is defined as the difference between the signal reception time and the signal transmission time multiplied by the vacuum light speed, i.e.:
ρ(t)＝c·[t r (t)-t s (t-τ)]
wherein c is the vacuum light velocity t r (t) is the signal reception time corresponding to GPS time t, and τ is the time when the signal is propagated, t s (t-tau) is the signal emission time corresponding to the GPS time t-tau, and rho (t) is the pseudo range. In practice, t is because neither the receiver clock nor the satellite clock may be exactly equal to GPS time r (t) and t s (t- τ) can be written as:
t r (t)＝t+δt r (t)
t s (t-τ)＝t-τ+δt s (t-τ)
wherein, δ t r (. cndot.) and δ t s (. cndot.) is the receiver clock offset and satellite clock offset, respectively, for the corresponding GPS time. Thus, the pseudorange ρ (t) may, in turn, be expressed as:
ρ(t)＝cτ+c[δt r (t)-δt s (t-τ)]
consider τ to have the following form:
wherein r (t- τ, t) represents the geometrical distance between the satellite position at time t- τ and the receiver position at time t, i.e. the satellite distance, and i (t) and t (t) represent the time delay caused by the influence of the ionosphere and the troposphere, respectively, when the signal propagates in the atmosphere. Thus, the pseudorange ρ (t) can also be expressed as:
ρ(t)＝r(t-τ，t)+c[δt r (t)-δt s (t-τ)+I(t)+T(t)]+ε(t)
where ε (t) is the sum of the remaining errors. In the above formula, the terms in parentheses can reach the millisecond level and only the receiver clock difference deltat is usually achieved r (t) of (d). This is because the inside of the receiver generally adopts a quartz clock, and as the measurement is performed, the clock offset will gradually drift and the drift amount will be large, and in order to ensure the synchronization with the GPS time, the receiver will generally adjust the clock offset periodically by inserting the clock offset to ensure that it has a certain accuracy. Obviously, whether the receiver clock error will reachTo the millisecond level, depending on the specific way of the clock, the clocks can be divided into the following two types, depending on the clock cycle and the level: 1) if the receiver clock difference is adjusted every second, the clock quantity is usually less than microsecond magnitude, and the receiver clock difference can not be accumulated to millisecond magnitude; 2) if the amount of clock inserted is on the order of milliseconds, the clock cycle is longer and the receiver clock difference will also accumulate to the order of milliseconds.
Under harsh environments, bit ambiguities may appear in pseudorange observations output by some receivers. At this time, signal transmission time t s Millisecond-level deviation occurs, namely, millisecond-level deviation occurs in the pseudo-range observed quantity. Because these receivers use a millisecond-level clocking scheme, in order to correctly estimate bit ambiguities and repair pseudoranges while clocking occurs, the pseudoranges ρ (t) are first simplified to:
ρ(t)≈r(t-τ，t)+cδt r (t)+ε(t)
partial sub-terms on the order of much less than milliseconds are ignored in the above equation. In addition, since the maximum operating speed of the satellite is only 927m/s and its component in the satellite distance direction is smaller, the earth rotation correction is no longer performed, and the pseudo range ρ (t) is further simplified as follows:
ρ(t)≈r(t，t)+cδt r (t)+ε(t)
in actual operation, the pseudorange r (t, t) at the current time is an unknown quantity, and can be replaced by the last time r (t ', t') of successful positioning, while ignoring time scale and noise, and expressing the pseudorange ρ as:
wherein,
the satellite positions in the geocentric geostationary coordinate system at the time t' respectively,
the receiver position under the geocentric geostationary coordinate system at the moment t 'is respectively, and t' is the GPS time of the last successful positioning. Considering all m tracking channels, the pseudo range ρ of the ith tracking channel i Can be expressed as:
ρ i ≈r i +cδt r ≈ρ i ′+c·0.02·n i
wherein ρ i ' pseudo-range observations, which are the actual outputs of the ith tracking channel, contain n i One bit ambiguity, i ═ 1, 2., m. Obviously, there are:
r i -ρ i ′＝c(0.02·n i -δt r )
wherein r is i -ρ i ' is a known quantity, n i And δ t r Is to be measured. Then, the above formula is rewritten as:
let l i ＝(r i -ρ i ')/c, the value of li integrated into 0.02s and l i The difference is
Obtaining a single variable data set
Obviously, L has better gathering property, and when the standard deviation std (L) is smaller than the set threshold value, the estimated value of the clock error is obtained
Comprises the following steps:
wherein avg (L) represents an average value of L.
Further, according to the concept that the pseudorange is the difference between the signal receiving time and the signal transmitting time multiplied by the vacuum light speed, the pseudorange definition in discrete form in practical case is written as:
ρ＝c·[(t r +δt r )-(t s +δt s )]
ignoring satellite clock differences of smaller magnitude, the formula is abbreviated as:
ρ＝c·[(t r +δt r )-t s ]
namely:
the equation reflects the inherent relation of the receiver clock error and three known quantities, namely pseudo-range observed quantity, signal receiving time and signal transmitting time, in millisecond order. Further, the check quantity q can be calculated by the following equation i Performing clock error detection:
wherein ρ' i Is defined as previously mentioned, t' s，i For the signal transmission time actually output by the ith channel, 0.02s is one bit time length.
If q is i About 0, the estimated value of the clock error is equal to or close to the prior value of the clock error, and the bit ambiguity n is directly calculated according to the formula i Is estimated by
If q is i If the clock is not 0 but is close to an integer, the estimated value of the clock error and the prior value of the clock error do not completely match but differ by an integer multiple of the time length of the bit, and the clock is considered to be presentThe estimated value of the difference is wrong, the prior value can be trusted, the estimated value of the clock difference needs to be adjusted to be consistent with the prior value, and then the bit ambiguity n is calculated according to the formula (5) i Is estimated by
If q is i If the estimated value of the clock difference or the prior value of the clock difference is not 0 and is not close to an integer, the estimated value of the clock difference or the prior value of the clock difference is possible to be wrong, and the bit ambiguity is abandoned and the corresponding pseudo range observed quantity is abandoned.
Two specific examples are given below as examples:
example 1
1. Assuming a certain epoch in a bad scene, the receiver has 9 tracking channels outputting pseudo range observations, i.e., m is 9.
2. And acquiring the satellite position and the receiver position saved in the last successful positioning, and calculating the estimated value of the satellite-to-ground distance of the current epoch.
3. Calculating l i Data set L ═ (0.02-0.028), (0.04-0.048), (0.06-0.068), (0.08-0.088), (0-0.008), [ -0.02- (-0.012)]，[-0.04-(-0.032)]，[-0.06-(-0.052)]And [ -0.08-0.072)]-0.008, -0.008, -0.008, -0.008, -0.008, -0.008, -0.008, -0.008, -0.008. The-0.008 in the above data set is the remainder difference obtained by taking the remainder to 0.02.
4. Obtaining an estimate of receiver clock error from a data set L
5. The prior value of the clock error is about-0.008 s and can be obtained by a check formula
Namely round (q) i ) Estimated value of clock error as 0
No adjustment is required.
6. According to l i And
obtaining an estimate of bit ambiguity, i.e. from the formula
To obtain
7. And repairing the originally received pseudo-range observed quantity and signal emission time on the basis of the obtained bit ambiguity estimated value, and then completing subsequent positioning calculation.
Example two
1. Assuming a certain epoch in a bad scene, the receiver has 7 tracking channels outputting pseudo range observations, i.e., m is 7.
2. And acquiring the satellite position and the receiver position saved in the last successful positioning, and calculating the estimation value of the current epoch satellite-earth distance.
3. Calculating l i Data set L ═ 0.007, (0.02-0.027), (0.04-0.047), [ -0.02- (-0.013)]，[-0.04-(-0.033)]，[-0.06-(-0.053)]，[-0.08-(-0.073)]-0.007, -0.007, -0.007, -0.007, -0.007, -0.007, -0.007, -0.007. -0.007 of the above datasetIs the remainder difference obtained by taking the remainder of 0.02.
4. Obtaining an estimated value of clock error from a single-variable data set
5. The prior information of the clock error is about 0.013s and can be obtained by a check formula
Namely round (q) i ) When the difference between the estimated value of the clock skew and the prior information is not 0 but is close to an integral multiple of the bit length, the estimated value of the clock skew is adjusted to be equal to the prior information.
6. According to l i And
obtaining an estimate of bit ambiguities, i.e. from
To obtain
7. And repairing the originally received pseudo-range observation quantity and signal emission time by using the obtained bit ambiguity estimated value, and then completing subsequent positioning calculation.
The clock error detection is also utilized, when the clock error of the receiver reaches more than half bit length, the correct restoration of the bit ambiguity can be ensured, and the subsequent positioning calculation is ensured to be carried out smoothly.
As can be seen from the above example, if the absolute value of the clock difference prior is greater than half a bit length, i.e. greater than 10ms,
and δ t r It will happen that they differ by an integer number of bits, if the absolute value of the clock difference prior is less than half a bit length,
and δ t r And (5) the consistency is achieved.
It should be noted that, in the present patent application, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, the use of the verb "comprise a" to define an element does not exclude the presence of another, same element in a process, method, article, or apparatus that comprises the element. In the present patent application, if it is mentioned that a certain action is performed according to a certain element, it means that the action is performed at least according to the element, and includes two cases: performing the action based only on the element, and performing the action based on the element and other elements. The expression of multiple, etc. includes 2, and more than 2, more than 2.
All documents mentioned in this specification are to be considered as being integrally included in the disclosure of this specification so as to be able to be a basis for modifications as necessary. It should be understood that the above description is only a preferred embodiment of the present disclosure, and is not intended to limit the scope of the present disclosure. Any modification, equivalent replacement, improvement or the like made within the spirit and principle of one or more embodiments of the present disclosure should be included in the protection scope of one or more embodiments of the present disclosure.
In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
Claims (9)
1. A method for determining bit ambiguities, comprising:
acquiring the satellite-ground distance of the epoch successfully positioned;
obtaining a pseudo-range observation value of a current epoch;
calculating bit ambiguity to be estimated including receiver clock error according to the difference value of the satellite-to-ground distance of the last successfully positioned epoch and the pseudo-range observation value of the current epoch;
acquiring a receiver clock error; the step of obtaining the receiver clock error further comprises: obtaining a plurality of groups of the satellite-to-earth distances and pseudo-range observation values through a plurality of tracking channels of a receiver, calculating a plurality of corresponding bit ambiguities to be estimated containing receiver clock errors, and respectively taking remainders of bit time lengths to be estimated containing the receiver clock errors as remainder difference values; averaging the plurality of remainder difference values to obtain an estimated value of the receiver clock error, and taking the estimated value of the receiver clock error as the clock error of the receiver
And calculating the bit ambiguity according to the difference between the bit ambiguity to be estimated containing the receiver clock error and the receiver clock error.
2. The bit ambiguity determination method of claim 1, further comprising:
checking the estimated value of the receiver clock error, wherein the checking formula is
δt r Representing the receiver a priori clock difference, t b Which represents the length of time of one bit,
an estimate representing said receiver clock error, q i Representing bit ambiguities corresponding to a difference between the receiver prior clock offset and the estimated value of the receiver clock offset;
bit ambiguity q corresponding to the difference i Rounding to obtain the correction quantity round (q) i ) According to the correction quantity round (q) i ) Estimate of said receiver clock error
Correcting;
and taking the corrected estimated value of the receiver clock difference as the clock difference of the receiver.
3. The method for determining bit ambiguities of claim 2, wherein said bit ambiguities q corresponding to said difference values i The correction quantity round (q) is obtained by rounding i ) An estimate of the receiver clock error based on the correction
The step of performing a correction further comprises:
when the bit ambiguity q corresponding to the difference value i And the correction quantity round (q) i ) Is less than or equal to a first threshold value, an estimated value of the receiver clock difference based on the correction amount
Correcting;
when the bit ambiguity q corresponding to the difference value i And the correction quantity round (q) i ) Is greater than a first threshold, discarding the bit ambiguity q corresponding to the difference i The corresponding pseudorange observations.
4. The method for determining bit ambiguities of claim 1, further comprising:
checking the estimated value of the receiver clock error, wherein the checking formula is
δt r Representing the prior clock difference, t, of the receiver b Which represents the length of a bit time of,
an estimate value, q, representing the clock error of said receiver i Representing a bit ambiguity corresponding to a difference between the actual receiver clock offset and the estimated value of the receiver clock offset;
bit ambiguity q corresponding to the difference i Rounding to obtain the correction quantity round (q) i ) When the bit ambiguity q corresponding to the difference value i And the correction amount round (q) i ) When the difference value of (2) is less than or equal to a second threshold value, the receiver prior clock difference is taken as the clock difference of the receiver.
5. The method according to any of claims 2-4, wherein the receiver a priori clock difference is derived from a receiver native result, a sum of a clock difference of an epoch of a last successful positioning and a millisecond-level clock amount, or a difference of a receiver signal reception time and a whole second.
6. The method of determining bit ambiguities of claim 1, wherein the receiver a priori clock differences are taken as clock differences of the receiver, wherein the receiver a priori clock differences are derived from receiver native results.
7. The method for determining bit ambiguities of claim 1, further comprising:
and restoring the pseudo-range observation value and the satellite signal emission time according to the bit ambiguity.
8. The method for determining bit ambiguities of any of claims 2-4, characterized in that said one bit time length t b It was 0.02 s.
9. The method of determining bit ambiguities of claim 1, wherein the last-fix successful epoch has a range from a guard to a ground
Wherein,
and
the satellite positions under the geocentric geostationary coordinate system of the epoch which is successfully positioned,
and
the positions of the receivers under the geocentric geostationary coordinate system of the epoch in which the positioning succeeds are respectively.
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