Specifications

ETSI
Final draft ETSI EN 300 328 V1.8.1 (2012
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04)
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5.3.7.2.1.4 Generic test procedure for measuring channel/frequency usage
This is a generic test method to evaluate transmissions on the operating (hopping) frequency being investigated. This
test is performed as part of the procedures described in clause 5.3.7.2.1.1 up to clause 5.3.7.2.1.3.
The test procedure shall be as follows:
Step 1:
• The analyzer shall be set as follows:
- Centre Frequency: Equal to the hopping frequency or centre frequency of the channel
beinginvestigated
- Frequency Span: 0 Hz
- RBW: ~ 50 % of the Occupied Channel Bandwidth (if the analyser does not support
this setting, the highest available setting shall be used)
- VBW:
RBW (if the analyser does not support this setting, the highest available
setting shall be used)
- Detector Mode: RMS
- Sweep time: > the Channel Occupancy Time. It shall be noted that if the Channel
Occupancy Time is non-contiguous (for non-LBT based Frequency Hopping
Systems), the sweep time shall be sufficient to cover the period over which
the Channel Occupancy Time is spread out.
- Number of sweep points: see note
NOTE: The time resolution has to be sufficient to meet the maximum measurement uncertainty of 5 % for the
period to be measured. In most cases, the Idle Period is the shortest period to be measured and thereby
defining the time resolution. If the Channel Occupancy Time is non-contiguous (non-LBT based
Frequency Hopping Systems), there is no Idle Period to be measured and therefore the time resolution can
be increased (e.g. to 5 % of the dwell time) to cover the period over which the Channel Occupancy Time
is spread out, without resulting in too high a number of sweep points for the analyzer.
EXAMPLE 1: For a Channel Occupancy Time of 60 ms, the minimum Idle Period is 3 ms, hence the minimum
time resolution should be < 150 µs.
EXAMPLE 2: For a Channel Occupancy Time of 2 ms, the minimum Idle Period is 100 µs, hence the minimum
time resolution should be < 5 µs.
EXAMPLE 3: In case of a system using the non-contiguous Channel Occupancy Time approach (40 ms) and
using 79 hopping frequencies with a dwell time of 3,75 ms, the total period over which the
Channel Occupancy Time is spread out is 3,2 s. With a time resolution 0,1875 ms (5 % of the
dwell time), the minimum number of sweep points is ~ 17 000.
Trace mode: Clear / Write
Trigger: Video
In case of Frequency Hopping Equipment, the data points resulting from transmissions on the hopping frequency being
investigated are assumed to have much higher levels compared to data points resulting from transmissions on adjacent
hopping frequencies. If a clear determination between these transmissions is not possible, the RBW in step 1 shall be
further reduced. In addition, a channel filter may be used.
Step 2:
• Save the trace data to a file for further analysis by a computing device using an appropriate software
application or program.