RU2001104812A

RU2001104812A - Method for suppressing multipath errors in satellite navigation receivers

Info

Publication number: RU2001104812A
Application number: RU2001104812/09A
Authority: RU
Inventors: Юрий Сергеевич Дубинко; Татьяна Юрьевна Дубинко; Сергей Владимирович Карпань
Original assignee: Закрытое акционерное общество "Конструкторское бюро навигационных систем"; Государственное предприятие-"КБ Оризон-Навигация"
Filing date: 2001-02-21
Publication date: 2003-05-20

Claims

1. A method of suppressing multipath errors in satellite navigation receivers, which consists in performing operations of searching for navigation satellite signals by the carrier frequency and code delay, tracking the signals found by the tracking loops on the carrier and delay, measuring the radio navigation parameters, as well as the amplitude of the received signal, bit synchronization and separation of the service information transmitted by the satellite, characterized in that the operations for smoothing the amplitude are subsequently carried out sequentially, smoothing gave the formation of amplitude variations, the formation of range variations, the formation of covariances as the product of amplitude and range variations, the primary smoothing of covariances, the detection (detection) of the effect of multipath (comparison with a threshold), decision-making (when the threshold is exceeded), the secondary smoothing of covariances, calculation estimates range errors by dividing the said covariance by the current value of the amplitude variation and introducing amendments to the code and phase ranges, calculating the phase difference of the direct and reflected signals, calculating an estimate of the error of the current phase caused by multipath and introducing corrections in the measurements of the current phase, and calculating the phase difference of the direct and reflected signals (current phase angle Ψ _i ) is determined by the formula (1)

(1)

where t _i is the current time;

t _m - the moment closest to the current previous maximum amplitude;

T is the period of amplitude fluctuations caused by multipath interference (the interval between adjacent maxima accommodating t),

and the estimate of the error of the current phase caused by multipath is calculated by the formula (2)

(2)

where γ denotes the ratio of the amplitudes of the reflected and direct signals;

φ _i is the current error of the phase meter;

ψ _i is the phase difference of the direct and reflected signals;

as the amplitude of the direct signal take its current smoothed value, as the amplitude of the reflected signal is the half-difference of the maximum and minimum values of the amplitude closest to the current time t _i .

2. The method according to claim 1, characterized in that the said smoothing of the amplitude and covariance samples can be performed by any of the methods known in mathematical statistics, for example, by the formula (3)

_i = (1-a)

_i-1 + α

, (3)

Where

_i - updated estimate of the smoothed value;

_i-1 - previous rating;

- the sample element of the smoothed parameter newly received in processing;

parameter X after the arrival of the next i-th element of the smoothed sample X _i ;

α is the smoothing coefficient.

3. The method according to claims 1 and 2, characterized in that the said smoothing of the measured values of the ranges D _{i is} carried out recursively using information about the measured values of the Doppler integrals DIi, for example, by the formula (4)

= (

+ DIi) (1-α) + αDi,

Where

- An updated estimate of the smoothed range upon receipt of the next ith measurement;

- the same estimate in the previous step;

α is the smoothing coefficient;

Di is the newly measured range value.