User's Manual
User Manual V5 CT23 Container Tag RFID-LSCAN
Page: 8 of 8
5.1.3 Predetermined Transmissions Timing
To comply with 15.231(e) of FCC regulations, the following rules must be met:
a) total transmission (burst) length must be less than 1 second;
b) Inter-beacon duration must be 30 or more times longer than transmission duration;
c) Inter-beacon duration must be more than 10 seconds.
CT23 pattern of predetermined transmissions depends on the combination of three different programming parameters: number of
messages in a beacon, inter-beacon duration and inter-message (within a beacon transmission) randomization. Different applications
may require different combination for optimum performance.
To ensure compliance with the regulations, special software was designed to calculate actual values for the restricted criteria (green fields
in the table below) based on the CT23 parameters. Below is a sample of the application with typical setting for CT23 and we can see that
the resulting transmission pattern complies with the regulations. The last condition of less than 20% during 100ms window comes from
the averaging factor used for transmitted power testing.
Beacon Mode
FCC 15.231 (e) conditions
WBP
3
0.27
<= 1s
Total transmission (burst) length must be less than 1 second.
WEB
0
10.00
>= 10s
Inter-beacon duration must be more than 10 seconds.
WMB
3
36.58
>= 30 times
Inter-beacon duration must be 30 or more times longer than transmission duration.
WR1
1
WIS
0
WIM
120
FCC 15.231 (a-e) conditions - transmitted power averaging factor
WEI
60
0.12
<=20%
Maximum duty cycle must be less than 20% within any 100ms time window.
WMI
10
5.2 CT23 Declaration for ETSI EN 300 220-1 [8.10.3]
When operating in Excitation mode CT23 will transmit messages less than 20 times a day, whenever it will pass through a valid
125 kHz excitation field with a special modulation pattern. The range of receiving this field is about 5m around a Lyngsoe
Systems exciter. Each typical transmission has up to 40 messages of 5ms each so total transmission time is 200ms. Assuming the
20 transmissions are spread around a typical postal work day of 16 hours get a typical duty factor of 20*0.2/3600/16=0.0069%.
When operating in Beaconing mode CT23 can be programmed to transmit three messages 5ms long each every 10s. This would
give a total tx time of 15ms every 10,000 ms so a duty factor of 0.15%.
When operating in Motion mode, in a typical scenario, the transmitter may transmit 10 times / hour five messages each time. This
would give a total tx time of 10*5*5 ms every 3,600,000 ms so a typical duty factor of 0.0069%. However, for example during
transportation using trucks, if the transmitter will be continuously shaken and if this feature is enabled, it will start transmitting
periodic messages - three messages 5ms long each every 10 seconds. This means 0.15% duty factor for the worst case motion
scenario.
If we add all these duty factors in the very unlikely case that they will all occur within one hour, we get
0.0096+0.15+0.15=0.31% duty factor over one hour interval so the transmitter fits in Class 2 – less than 1% channel
occupancy.