5
USAGE GUIDELINES
The Model 6000 RF Barcode Reader communicates to the RF Host using a
radio frequency (RF) data link. The radio’s typical range is about 150 feet in an
unobstructed line-of-sight environment. Factors that effect the M6000 radio’s
performance in any given environment are related to the physics of radio wave
(electromagnetic wave) transmission, and include: distance, reflection,
cancellation, interference, and energy absorption.
Distance effects signal strength in that signal power diminishes rapidly
with the “inverse square rule”, which means as you go twice as far away there is
only one-fourth of the total signal strength present, and so on. The M6000
provides long battery life, but if there seems to a notable decrease in range, try
replacing the battery with a new, fresh one.
Reflection from metal objects effects radio waves in the same way that a
mirror reflects light; radio waves typically do not pass through metal objects.
When using the M6000 near metal objects, allow a sufficient distance of two feet
or so to allow radio waves to propagate. Using an M6000 radio when directly
separated from the RF Host by a metal wall would reduce transmission range or
perhaps block the signal.
A side effect of reflection is wave cancellation, in which the signal strength
coverage is dependent on the exact position in a room; this effect is associated
with “peaks” of strong signal and “nulls” of weak signal. You may have heard
the effect of static “nulls” on your car’s stereo when stopped at a traffic signal,
but when moving again the sound quality improves because both “peaks” and
“nulls” are being received. Moving the M6000 unit by an inch or two to find a
stronger wave “peak” can compensate for the occasional “nulls” when scanning.
Interference from other equipment may also be present in an
environment. The radio’s 916.5 MHz frequency is located near the center of the
FCC allocated Industrial, Scientific, and Medical (ISM) 902-928 MHz frequency
band. Interference in this frequency band is not common and not effected by
cellular telephones or pagers. The 900 MHz cordless telephones typically
operate at each end of this ISM frequency band, and so would not likely interfere
with the M6000.
Absorption is the final factor affecting the performance of the M6000
radio. The M6000 transmits a safe level of radio frequency energy, however, any
radio signal is to some degree absorbed by human body mass. When using the
M6000 at long range, the user’s body may disrupt the line-of-sight path to the RF
Host. The user will likely find satisfactory use from wearing the M6000 at one’s
waist, but to minimize the effect of body mass, for better reception, wear the
M6000 higher up on the body, such as in a chest pocket or on the arm using an
armband. For best reception, the M6000 can be affixed to the top of some lasers
or CCD’s using Velcro strips, thereby keeping the radio at arm’s length.
