User's Manual

PT30 Postal Tag RFID-LSCAN
Page: 5 of 6
Programmer UP23 box. If a tag enters LF field but the valid excitation pattern can not be recognized (i.e. overlapping fields or
interference), the tag does not transmits anything.
4 REGULATORY COMPLIANCE
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may
not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause
undesired operation.
This equipment has been tested and found to comply with the limits for Class B digital devices, pursuant to Part 15 of the FCC
Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This
equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the
instruction manual, may cause harmful interference to radio communications. However, there is no guarantee that interference
will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which
can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one of more of
the following measures:
• Reorient or relocate the receiving antenna
• Increase the separation between the equipment and receiver
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.
Warning: Changes or modifications not expressly approved by the party responsible for compliance could void the user’s
authority to operate the equipment.
4.1.1 Maximum Transmission Time
To comply with 15.231(a) of FCC regulations, the maximum transmission time of PT30 in Excitation mode must not exceed 5
seconds.
To minimize collisions in an application, PT30 tags are programmed with random values for the WSD parameter, which ensures
that inter-message durations are randomized differently for individual tags. To ensure sufficient transmission redundancy in an
application a certain optimum number of transmitted messages is selected and programmed into the WIP+WRC parameters. The
sum of both parameters represents the number of messages transmitted in a burst and this affects the overall transmission
duration.
In our typical application WIP + WRC = 20 and WSD = 7 and the resulting average transmission time is around 2s. If we set
maximum values for these parameters WIP + WRC = 30 and WSD = 30 the resulting transmission time is 4.3s so PT30 still
complies with the FCC requirements for maximum transmission time.
4.1.2 Maximum Duty Cycle
To comply with 15.231(a) of FCC regulations from average transmitted power point of view, the maximum transmission Duty
Cycle for PT30 must not exceed 24% in any 100ms time window.
The maximum value of duty cycle in PT30 is achieved when 100ms window falls on the Excitation transmission bursts. The table
below shows the best estimate of the duty cycle in 100ms for different combinations of WEP = WIP+WRC and WSD. As we
can see as long as WEP = WIP+WRC > 3 and WSD ≥ 7 the duty cycle in any 100ms window varies between 8% and 16% so
there is margin compared with the maximum value of 24%.