GB2406453A

GB2406453A - Determination of velocity of remote targets

Info

Publication number: GB2406453A
Application number: GB0321548A
Authority: GB
Inventors: Geoffrey Robinson
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-09-13
Filing date: 2003-09-13
Publication date: 2005-03-30
Anticipated expiration: 2023-09-13
Also published as: GB0321548D0; GB2406453B

Abstract

Means for improvement in accuracy of determination of velocity of relatively moving objects transmitting radiowaves from consideration of time delay effects. In determining the velocity of remote objects it has been found that accuracy can be improved by compensating for previously unknown factors. There is a relativistic velocity effect from signal time delay and a misinterpretation of data when the otherwise very precise electromagnetic signal Doppler cycle count method is used. Velocity, and related positional information, measured remotely by any means will be improved in accuracy by applying compensation for relativistic velocity effect. The improved accuracy is particularly beneficial when object velocity is high and/or where extreme precision is required. Applications include; Remote objects in space; Communications via satellites; Location using Global Positioning Satellites (GPS); Prediction of position, monitoring and control of objects independent of GPS.

Description

1 2406453

TITLE

Improvements in determination of velocity of remote objects

DESCRIPTION

An apparent acceleration of spaceship Pioneer 10 had not been explained despite extensive study of possible causes. The paper by John D. Anderson, Philip A. Laing, Eunice L. Lau, Anthony S. Lui, Michael Martin Nieto and Slava G. Tureshev. Study of the anomalous acceleration of Pioneer 10 and 11. Physical Review D, vol 65, article 082004 (2002), provides details of a most comprehensive investigation of effects both internal and external to the spacecraft together with effects due to modelling and computation techniques. Radio Doppler data collection, data editing and data reduction are also covered.

In addition to measurement of target velocity by the well known successive distance measurements using electromagnetic (em) radiated signals, the monitoring of Pioneer 10 employed a very precise form of radio Doppler involving continuous cycle counting.

Indication of acceleration was a drift in residual Doppler cycles counted when compared to the model velocity. Model velocity is the expected relative velocity when all factors effecting it are taken into account, for example sinusoidal velocity changes due to Earth's movement in the Solar system.

A correct model velocity will exactly match the signal frequency received to yield a zero nett cycle count from the comparing and computing units. A constant velocity difference, model versus actual, must yield constant nett cycle count.

My probing theoretical evaluation of the methodology, data acquisition and interpretation in the John D Anderson et al paper detemmined that the acceleration was false. Apparent acceleration was found to be caused by a relativistic Doppler effect (RDE) that results in the model velocity being understated. The constant model velocity deficit was found to be misinterpreted as acceleration by the cycle count method.

The two unexpected and previously unsuspected factors: A relative velocity due to signal return time delay and a progressive accumulation of counted cycles deficit compared to count expected together explain the apparent acceleration.

Compensating the model velocity Vr for RDE from the relationship Vr = Vp(1 + Vplc) where Vp is the true (higher) velocity and c the speed of light (299792458m,-), was shown in the study to reduce the Doppler residuals and thus the false acceleration to near zero thus solving the Pioneer 10 problem.

Further, velocity measured remotely by any means that does not compensate for signal delay relativistic effect will be improved in accuracy by use of the relationship between the measured (relative) and actual velocities. For example, successive parallax measurements of distant objects to calculate their velocity.

Because position change is directly related to velocity the accuracy of position determination or prediction will also improve by use of the relationship between the measured (relative) and actual velocities.

Figure 1 is a velocity diagram showing an example of the relationship between the uncompensated measured velocity Vr and the actual true velocity Up, shown relative to signal source. By mathematical analysis the relationship is Vr = Vp(l + Vplc).

in figure I an em signal wave peak or pulse is transmitted at time It when the target is at point S1. The signal travels at speed c to reach the target at point A when it is instantly transponded back to be received at time tB. The signal received at time tB reflects the situation at an earlier time tA, point A, when it was transponded at speed c from the target.

By the time the signal is received the spaceship has travelled to point B. A succession of signals, for example the one shown at time in, yields the relative and lower velocity Vr instead of the true velocity Vp; a relativistic Doppler effect (RDE) to the receiver. A uniformly increasing range deficit is illustrated by the increasing separation of the velocity lines.

The expression Vr= Vp(1 + Vplc) can be rewritten as VplVr = (1 + Vplc). This is a ratio in classical Doppler form becoming (-vp/c) to include Special Relativity (SR).

The difference SR makes to the Doppler ratio VplVr (at Pioneer 10 velocity of 12200ms) is less than I part in a billion (8.28 x 10- ). By comparison RDE is very much greater than any SR effect.

In addition to resolving the Pioneer 10 problem the new approach could be useful in dealing with a similar situation for spaceship Ulysses. Other uses are in improving the accuracy of monitoring and control of any moving object. The relativistic effect is greater at high velocities but benefit can be obtained at lower velocities when extremely high precision is an advantage. Examples could include but are not limited to communication satellites: monitoring and control of trajectory of powered objects; between Earth base station or stations and space objects; between Earth base station or stations and spaceships and satellites; uni- directional or multi-directional combinations of em sources and receivers; determination and prediction of position.

Claims

1. Means for improvement in accuracy of determination of velocity of relatively moving objects from consideration of time delay effects.

2. Means according to claim 1 where the improvement is from the relationship between a uniform relative measured velocity Vr and a true uniform velocity Vp compensated for time delay effects in the form Vr = Vp(1 + Vplc) .

3. Means according to claim 1 where the improvement is from the relationship between a uniform relative measured velocity Vr and a true velocity Vp compensated for time delay effects in the form Vr = Vp(l + Vplc)- simplified to Vp = Vr(1 + Vrlc) where Vr is small in relation to c and sufficient improvement is obtained from the simpler processing of calculations.

4. Means according to claim I where the principle is extended to provide algorithms for relatively accelerating objects.

5. Means according to any preceding claim applied to the determination of velocity of relatively moving objects in order to obtain improved performance.

6. Means substantially as described herein.

6. Means according to any preceding claim applied to the determination of rate of change of velocity of relatively moving objects in order to obtain improved performance.

7. Means according to any preceding claim applied to determination and prediction of position.

8. Means substantially as described herein.

Amendments to the claims have been filed as follows 1. Improvement in accuracy of determination of velocity of relatively moving objects by compensating for a relative velocity effect in which the velocity of an object, computed from cycles counted dunug a period of the observers times the cycles being from Doppler modified frequency of electromagnetic radiation emitted or reflected by or transmitted from the object, is perceived as differing from the actual velocity of the object.

2. Means according to claim I where the improvement is obtained for receding objects by replacing the measured velocity K by a true velocity Vp from the relationship Vr = Vp(1 + Yp/c)-.

3. Means according to claim I where the improvement is obtained for receding objects by replacing the measured velocity Or by a true velocity Vp from the relationship Vr = Vp(1 + Vp/c) simplified to Up = Vr(l + Yr/c) when Vr is small in relation to c and sufficient improvement is obtained from the simpler processing of calculations.

4. Means according to claim 1 nowhere the improvement is obtained for approaching objects by replacing the measured velocity Fir by a true velocity Up Mom the relationship K= Vp(l- Yplc)-.

5. Means according to claim 1 where the improvement is obtained for approaching objects by replacing the measured velocity liar by a true velocity Vp from the relationship Vr= Yp(l - Vplc)t simplified to pip= Yr(1- lyric) when Vr is small in Amendments to the claims have been filed as follows relation to c and sufficient improvement is obtained from the simpler processing of calculations.