Dismiss
Surety is performing system maintenance this weekend. Electronic date stamps on new Prior Art Database disclosures may be delayed.
Browse Prior Art Database

Process for Accurately Identifying Blind Speed Intervals for Use of Range Rate Information in a Track-while-scan System

IP.com Disclosure Number: IPCOM000108245D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 84K

IBM

Related People

Hammer, JB: AUTHOR

Abstract

The process consists of a single step; this step is to calculate the input estimate for the blind speed decision process using the two most recent range measurements for a track and the time that has elapsed between them. The process is described by Equation 1 below: P1se(tk) = {Psm(tk) - Psm(tk-1)} : WT (1) where Psm(tk) = the present slant range position measurement for the track (nmi); Psm(tk-1) = the previous slant range position measurement for the track (nmi); WT = the time interval (seconds) between the two range measurements; P1se(tk) = the estimated radial velocity of the track in knots.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Process for Accurately Identifying Blind Speed Intervals for Use of Range Rate Information in a Track-while-scan System

The process consists of a single step; this step is to
calculate the input estimate for the blind speed decision process
using the two most recent range measurements for a track and the time
that has elapsed between them.  The process is described by Equation
1 below:
P1se(tk) = {Psm(tk) - Psm(tk-1)} : WT (1)
where  Psm(tk)   =    the present slant range position measurement
for the track (nmi);
Psm(tk-1) =    the previous slant range position measurement
for the track (nmi);
WT        =    the time interval (seconds) between the two
range measurements;
P1se(tk)  =    the estimated radial velocity of the track in
knots.

Choosing correct "blind speed intervals" is an important key to
using Doppler (Range Rate) measurements which are provided in some
surveillance sensors.  Prior techniques used track state estimates to
determine an input range rate estimate for use in a "blind speed
decision process."  However, the presence of low blip-scan rations on
the Doppler measurements makes the use of prior track state estimates
unreliable.

Doppler measurements can consist of two or more statistically
independent phase angle measurements, each varying between 0 and 360
degrees.  The phase angles are derived from different pulse
repetition frequencies (PRFs). The phase angles represent the
aircraft range rate being measured modulo N(k) knots for each of the
k PRFs used in the sensor.  We call the N(k) "blind speeds" and their
integer multiples the "blind speed intervals."

In order to use the two Doppler measurements, it must be
determined in which pair of blind speed intervals the aircraft is
travelling.  The process of determining between which pair of blind
speed intervals an aircraft is travelling is called th...