sigloc (version 0.0.4)

locate: Estimation of a Radio Telemetry Signal

Description

The function locate estimates the location of a transmitter signal from radio telemetry studyies using the maximum likelihood estimation (MLE) approach. as.data.frame can be used to convert an object inheriting the class transmitter into a data.frame. plot allows a graphical display of the calculated transmitter signal locations.

Usage

locate(x)
"plot"(x, add, errors, pch, cex, col, badcolor, ...)
"print"(x, ...)
"as.data.frame"(x, row.names=NULL, optional=FALSE, ...)

Arguments

x

An object inhering the class receiver containing the X and Y location of the receiver, the bearing of the transmitter signal, and the identification of the point groupings. If data inherits the class data.frame or table, it should contain these columns under the headings 'Easting', 'Northing','Bearing', and 'GID' respectively

add

A logical specification for whether to plot locations onto an existing plot window.

errors

A logical specification for whether error ellipses should be plotted alongside estimated locations.

pch

Either an integer specifying a symbol or a single character to be used as the default in plotting points.

cex

A numerical value giving the amount by which plotting locations should be magnified to the default.

col

A specification for the default plotting color.

badcolor

A logical specification for whether non-MLE-derived locations should be idenitfied.

row.names

NULL or a character vector giving the row names for the data frame. Missing values are not allowed.

optional

Logical. If TRUE, setting row names and convering column names is optional.

...

Additional parameters to be passed to the generic function plot, print, and as.data.frame.

Value

locate returns an object belonging to the S4 class transmitter

Details

This function uses data from radio telemetry studyies to compute the location of a transmitter signal using the maximum likelihood estimation (MLE) approach described in Lenth (1981). If the MLE approach fails to provide a reasonable estimate of the transmitter signal location, the function will provide a warning message and instead use the midpoint of the intersections to estimate the location. This will also appear in the resulting object as a '2' under the BadPoint heading and can be displayed in the plot function by setting the input parameter badcolor to TRUE.

References

Lenth, R.V. (1981). On Finding the Source of a Signal. Technometrics, 23(2), 149-154.

See Also

as.receiver for additional information on the class receiver. findintersects for additional information on the class intersect

Examples

## Load the data and convert to desired format
data(bear)
bear<-as.receiver(bear)

## Estimate location of transmitter signal
(loc<-locate(bear))

## Display results with a different color for bad points
plot(loc,badcolor=TRUE,xlab="Easting",ylab="Northing")