DE102020200422A1 - Determination of propagation delays of satellite signals - Google Patents

Abstract

In order to create a method (60) for determining transit time delays (d) of satellite signals (S) by reflections on buildings (20), which is technically simple and reliable, it is proposed that at least one satellite signal (S ) to receive time information and position information by a receiver (40), based on the at least one received satellite signal (S), to determine a number (N) of receivable satellites (30) which communicate with the receiver (40), and using a quadratic model (50) from the number (N) of receivable satellites (30) to calculate an average propagation delay (dm) of satellite signals (S).

Description

The invention relates to a method for determining transit time delays of satellite signals due to reflections on buildings, a satellite-based method for calculating a position of a receiver and a receiver for satellite signals.

State of the art

For position determination in open or uncovered areas, GNSS (Global Navigation Satellite Systems) -based methods are usually used. For this purpose, several satellite signals are received and decoded by a receiver in order to determine the position of the satellites and the transit time of the satellite signals from the satellites to the receiver. The decoded distances between the receiver and the satellites are defined as so-called pseudo-distances, since these are to be understood as an approximation of the actual distance due to errors and measurement uncertainties.

By knowing the pseudo-distances, the navigation equation can be solved and the receiver can be located on the basis of the result of the navigation equation. The navigation equation can be solved, for example, by an extended Kalman filter.

In areas with tall buildings, such as city centers, the satellite signals can be reflected on the walls of buildings and then received by the receiver. Typically, a direct satellite signal and one or more reflected satellite signals can be received by a receiver in urban areas. Such reflections cause delays in the transit time of the satellite signals and falsify the determined pseudo-distances between the respective satellite and the receiver. Such delays also lead to an incorrectly determined position of the receiver as a result of the navigation equation.

The likelihood of reflections from satellite signals depends on various factors, such as building height, area and position of the receiver, surface of the building walls and the like. In particular, the estimation of delays in the transit times due to reflections can be faulty, which makes a correction of the determined position of the receiver more difficult.

Disclosure of the invention

The invention is based on the object of creating a method for the technically simple and reliable determination of transit time delays.

This object is achieved by the features specified in claim 1. Further advantageous refinements of the invention are described in the subclaims.

According to one aspect of the invention, a method for determining propagation delays of satellite signals by reflections on buildings is provided. The method can preferably be carried out by a device such as a receiver and can be based on a satellite-based system.

In a step, at least one satellite signal with time information and position information is received by the receiver from at least one satellite. The position information is designed here as a satellite position. The satellite signals can be transmitted by one or more satellites as required or on request or continuously.

A number of satellites which communicate with the receiver is determined based on the at least one received satellite signal. The satellites communicating with the receiver transmit satellite signals which can be received directly or indirectly by the receiver.

In a further step, an average transit time delay of satellite signals is calculated from the number of communicating satellites using a quadratic model.

The quadratic model makes it possible to provide a technically simple and robust approximation which enables the average propagation delay to be determined precisely. In particular, an average propagation delay of a propagation delay distribution can be determined, which can occur at different times of the day, different building heights surrounding the receiver and the like. To calculate the propagation delay using the quadratic model, the number of satellites that can be received is essentially decisive.

Based on such a simplified determination of the average transit time delay, a position determination of the receiver can be corrected and determined more precisely. It can according to one aspect of the invention receivers with a higher accuracy are provided.

Such a receiver can, for example, be a vehicle-mounted receiver. The receiver can receive satellite signals and is set up to carry out the method for determining transit time delays of satellite signals by reflections on buildings.

The determined average propagation delays can be used to determine a propagation delay distribution in which the average propagation delay and a number of reflections along buildings influence the shape.

According to an advantageous embodiment, the quadratic model is designed as a second order regression. The average propagation delay of satellite signals is preferably calculated using the following formula: $${\text{d}}_{\text{m}}=\text{c}2*{\text{N}}^2+\text{<figure-callout id="1" label="c" filenames="DE102020200422A1\_0011.png" state="{{state}}">c</figure-callout>}1*\text{N}+\text{<figure-callout id="0" label="c" filenames="DE102020200422A1\_0011.png" state="{{state}}">c</figure-callout>}0$$

verwendet.According to a further preferred embodiment, the formula $${\text{d}}_{\text{m}}=-0.23{\text{N}}^2+5.08\text{N}-4.08$$

used.

Here, d _m corresponds to the average propagation delay of an absolute or actual propagation delay d, which is designed as a propagation delay distribution. The number of satellites N that can be received by the receiver is decisive here.

The transit time delay can be taken into account particularly precisely when calculating the position if an absolute or actual transit time delay is calculated as a gamma distribution with the average transit time delay as a shape parameter and a scale parameter.

It should also be mentioned that no two-way communication is possible with the GNSS systems currently in operation. This is also questionable for data protection reasons.

In a further embodiment, the number is calculated as a percentage of the number of satellites received from a number of visible satellites. The number of visible satellites depends on the geographical position. For example, there are more satellites available at the equator than at the North Pole or South Pole. The number of visible satellites depends on the satellite-based system. The GPS has 31 satellites, for example, which can be expanded by a further 24 satellites when combined with GLONASS. Accordingly, satellites can be used for Galileo and BeiDou.

The satellites visible to the receiver are oriented relative to the receiver in such a way that at least theoretical communication is possible. Satellite signals can be exchanged directly between a visible satellite and the receiver, provided that there are no obstacles preventing the transmission of the satellite signals. The satellite signals can be transmitted unidirectionally or bidirectionally.

The receivable or communicating satellites correspond to satellites that enable direct or indirect transmission of satellite signals. This also includes satellite signals reflected off buildings.

According to a further exemplary embodiment, the scale parameter of the gamma distribution corresponds to a number of reflections of a satellite signal on buildings. A natural number between 0 and 3, including 0 and 3, is preferably used as the scale parameter. In particular, a dominant number of reflections can be used for the scale parameter, which can usually be one. Depending on the position of the receiver and the nature of the surroundings of the receiver, there can be any number of received satellites.

The number of receivable satellites can be determined based on the received satellite signals. Alternatively, the number of "visible" satellites for the receiver can be known.

According to a further aspect of the invention, a satellite-based method for calculating a position of a receiver is provided. Runtime delays of satellite signals caused by reflections on buildings are determined and used to correct the determined position. The transit time delays can be determined by the method according to the invention for determining transit time delays of satellite signals through reflections on buildings.

For example, both methods according to the invention can be carried out by the recipient. Alternatively or additionally, the correction of the determined positions can be based on an external server unit, such as a cloud implemented on determined transit time delays by at least one recipient.

The method enables the determined positions of receivers in urban areas to be corrected quickly and efficiently.

In a further advantageous embodiment, the average propagation delay (d _m ) of satellite signals ( S. ) used in a method for determining a detour length or a detour transit time of a navigation signal received via a detour. In the method for determining the detour length and / or detour transit time of a satellite signal received with a receiver via a detour caused by a reflection compared to a directly received satellite signal, the received signal or satellite signal detected by the receiver contains a superimposition of a first signal component from the directly received satellite signal and a second signal component from the satellite signal received via the detour. Preferably, at least two satellite signals of different transmission frequencies, which are broadcast by one and the same satellite, are received by the receiver, the signal powers of the at least two received satellite signals being evaluated to determine the detour length and / or detour transit time. The detour length or a detour transit time can correspond to the transit time delay. This makes it possible to calculate the detour length or the detour transit time based on the number of receivable satellites, whereby the method for determining a detour length or a detour transit time of a navigation signal received via a detour can be simplified.

• 1 eine schematische Darstellung einer Anordnung zum Veranschaulichen eines erfindungsgemäßen Verfahrens zum Ermitteln von Laufzeitverzögerungen von Satellitensignalen durch Reflektionen an Gebäuden gemäß einer Ausführungsform,
• 2 ein Diagramm eines quadratischen Modells zum Berechnen einer durchschnittlichen Laufzeitverzögerung,
• 3 schematische Diagramme zum Veranschaulichen von Gammaverteilungen als Laufzeitverzögerungen, und
• 4 ein schematisches Ablaufdiagramm eines satellitenbasierten Verfahrens zum Berechnen von einer Position eines Empfängers.

Several exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Show it:

• 1 a schematic representation of an arrangement for illustrating a method according to the invention for determining transit time delays of satellite signals by reflections on buildings according to an embodiment,
• 2 a diagram of a quadratic model for calculating an average propagation delay,
• 3 schematic diagrams to illustrate gamma distributions as propagation delays, and
• 4th a schematic flow diagram of a satellite-based method for calculating a position of a receiver.

In the 1 Figure 3 is a schematic representation of an arrangement 10 to illustrate a method according to the invention for determining transit time delays of satellite signals S. through reflections on buildings 20th shown according to one embodiment.

The propagation delays occur when satellite signals S. on buildings 20th reflected and thus cover a greater distance dR compared to direct signal transmission. In the 1 the additional distance dR is made clear, which results in a delay in transit time.

The satellite signals S. are from satellites 30th sent out continuously or at regular time intervals. The satellite signals S. can of recipients 40 can be received and evaluated. For example, a recipient can 40 on a vehicle 41 be mounted to determine a position of the vehicle. For this purpose, pseudo-distances E between the receiver 40 and satellites 30th from time-of-flight measurements of the satellite signals S. be determined.

In the illustrated embodiment, the receiver is 40 on a roof of the vehicle 41 arranged. The vehicle 41 can move at one speed or be parked immobile.

Depending on the position of the vehicle 41 in the world can use the satellite signals S. can be received at different reception angles θ. With decreasing angle θ and increasing height µ of buildings 20th a number of reflections, which also serves as a scale factor, can increase.

Recipient 40 of the vehicle 41 can be used independently or in combination with an optional control unit 42 the satellite signals S. receive and decode. For example, time information and position information from one or more satellites can be used 30th be received.

The 2 FIG. 13 shows a diagram of a quadratic model for calculating an average propagation delay d _m . The average propagation delay d _m can be determined by a regression 50 second order can be approximated. The following curve forms several measured average propagation delays 51 from. The respective measured transit time delays 51 were at a different number of for the recipient 40 visible satellites 30th in different environments U Recipient 40 and determined by the regression 50 second order approximated.

wobei bevorzugterweise folgende Werte angenommen werden können: $$\text{c}0=-\mathrm{4,08}$$

$$\text{c}1=\mathrm{5,08}$$

$$\text{c}2=-\mathrm{0,23}$$

The regression 50 second order can be used as a quadratic model and has the following equation: $${\text{d}}_{\text{m}}=\text{c}2*{\text{N}}^2+\text{<figure-callout id="1" label="c" filenames="DE102020200422A1\_0011.png" state="{{state}}">c</figure-callout>}1*\text{N}+\text{<figure-callout id="0" label="c" filenames="DE102020200422A1\_0011.png" state="{{state}}">c</figure-callout>}0$$

where the following values can preferably be assumed: $$\text{c}0=-4.08$$

$$\text{c}1=5.08$$

$$\text{c}2=-0.23$$

Using the equation, the average propagation delay d _{m can} be calculated solely on the basis of that for the receiver 40 known number N of visible satellites 30th be calculated.

In the 3 schematic diagrams are shown to illustrate gamma distributions dargestellt as propagation delays d or propagation delay distributions. For clarification, a scale factor of one was used in all diagrams, which is a reflection on a building 20th corresponds to.

The diagrams show exemplary gamma distributions ┌ for different average building heights µh in the area U Recipient 40 . The average building height µh takes into account all buildings 20th in the neighborhood U Recipient 40 and can for an environment U can be defined as a characteristic building height.

It can be seen that with increasing average building height µh in the area U Recipient 40 the average propagation delay d _m decreases.

The 4th shows a schematic flow diagram of a satellite-based method 60 for calculating a position of a receiver 40 . The procedure 60 is used to determine propagation delays d of satellite signals S. through reflections on buildings 20th and can be used to correct determined positions of the receiver 40 can be used.

In one step 61 is from at least one satellite 30th at least one satellite signal S. with time information and position information by the receiver 40 receive.

Based on the at least one received satellite signal S. will be in a further step 62 a number N of satellites 30th determines which one with the recipient 40 communicate.

Then a quadratic model or regression 50 second order from the number N of communicating satellites 30th an average propagation delay d _m of satellite signals S. calculated 63.

In a further step 64 can be based on the average propagation delay d _m of satellite signals S. the gamma distribution ┌ can be determined as the propagation delay distribution.

The gamma distribution ┌ can be carried out in a subsequent step 65 for correcting pseudoranges E between the receiver 40 and satellites 30th can be used.

The method shown can advantageously be compared with the method already registered in accordance with DE 10 2019 216 164.2 or can be combined with other methods for calculating the detour length in urban canyons, because this avoids ambiguities.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102019216164 [0049]

Claims (10)

Method (60) for determining transit time delays (d) of satellite signals (S) due to reflections on buildings (20), wherein - from at least one satellite (30) at least one satellite signal (S) with time information and position information by a receiver (40 ) is received, - based on the at least one received satellite signal (S), a number (N) of receivable satellites (30) is determined which communicate with the receiver (40), - by a square model (50) from the number ( N) of the receivable satellites (30) an average propagation delay (d _m ) of satellite signals (S) is calculated. Procedure according to Claim 1 , wherein the quadratic model (50) is designed as a second order regression and the average propagation delay (d _m ) of satellite signals (S) by the formula $${\text{d}}_{\text{m}}=\text{c}2*{\text{N}}^2+\text{c}1*\text{N}+\text{c}0$$

is calculated. Procedure according to Claim 2 , where the coefficients are defined as follows: $$\text{c}0=-4.08;\text{c}1=5.08;\text{c}2=-\mathrm{0.23.}$$

Procedure according to Claim 1 or 2 wherein the number (N) is calculated as a percentage of the number of received satellites (30) from a number of visible satellites (30). Method according to one of the Claims 1 to 3 , wherein a propagation delay (d) is calculated as a gamma distribution (┌) with the average propagation delay (d _m ) as a shape parameter and a scale parameter. Procedure according to Claim 4 , the scale parameter of the gamma distribution (┌) corresponding to a number of reflections of a satellite signal (S) on buildings (20), a natural number between 0 and 3, including 0 and 3, being used as the scale parameter. Method according to one of the Claims 1 to 5 , the average transit time delay (d _m ) of satellite signals (S) being used in a method for determining a detour length or a detour transit time of a navigation signal received via a detour. Method according to one of the Claims 1 to 7th , the method shown being advantageously combined with further methods for calculating the detour length of reflections in urban canyons. Satellite-based method for calculating a position of a receiver (40), wherein propagation delays (d) of satellite signals (S) caused by reflections on buildings (20) are determined by a method (60) according to one of the preceding claims and for performing a correction (65 ) of the determined position can be used. Receiver (40), in particular a vehicle-mounted receiver, for receiving satellite signals (S), the receiver (40) being set up to carry out a method according to one of the preceding claims.

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