SPS1M
−
EVK
5
Read Counts
An individual measurement consists of multiple Sensor or
Temperature Code reads. Taking multiple readings corrects
for channel
-
frequency dependence in the Sensor Code and
reduces random noise in the sensor and temperature
measurements
.
It is possible for some of the reads in a measurement to
fail
.
The reader will report a result if only some reads
succeed, but the accuracy of the result may be reduced. If
fewer than half of the read attempts in a measurement are
successful
,
a warning triangle will appear with the message
“Few reads” (Figure 9). The Dashboard can be used to
determine how many reads succeeded in a measurement.
Figure 9. The “Few reads” Warning
Making Measurements
Antenna Orientation
The reader antenna must extended (folded out from the
reader body) before reading tags. The RF beam is directed
outward and perpendicular to the face of the antenna
.
The
reader antenna should be aimed at the sensor tag
,
and the tag
oriented such that its long axis is perpendicular to the RF
beam (Figure 10).
Figure 10. Proper Reader Antenna and Tag
Orientation
Read Time
The read process begins when the yellow read button on
the touch screen or keypad is pressed
.
A progress bar will
appear on the screen to indicate the progress of the read
.
The
read process can take up to several seconds to complete. The
reader should be held still during the read process
.
Click the
Cancel button to stop the read process before it completes
(Figure 11).
Figure 11. The Read Progress Bar and Cancel Button
Maximum Read Range
The maximum distance at which a tag can be read depends
on the design of the tag and the surface it is placed upon
.
Also
,
nearby objects can reflect the reader signal and cause
multipath interference
.
Because of factors like these, the
maximum read range cannot be precisely predicted in
advance
.
In general
,
the handheld reader is designed to read
tags from a distance of 1 to 2 meters
.
