Low Energy Tests Running a Script in Standard Mode
7-44 PN: 13000-00205 Rev. N MT8852B Operation Manual
Carrier & Drift Test
The carrier drift test performs a frequency drift measurement over the length of the packet
received. The carrier frequency offset is measured in the same manner as basic rate initial
carrier test, but on the eight preamble bits in the low energy reference packet.
There are differences in the measurement method for 2LE packets because of the 2 Mbps data
rate, and for BLR (S=8) packets because the encoding method used is not capable of
generating a 10101010 pattern.
When measuring 2LE packets, the maximum drift rate applies to the difference between any
two 20-bit groups separated by 50 s (BLE uses 10-bit groups).
When measuring BLR (S=8) packets, the payload type used for testing consists of a repetitive
sequence of ‘11111111’ octets. When passed through the S=8 encoder, this sequence becomes
a repeating ‘00111100’ pattern. The measurement is carried out as follows:
From the start of the preamble field the average frequency is measured in groups of 16 bits. A
similar process is carried out throughout the payload of the packet. The instrument then
checks the drift rate over any 48 s interval in the payload and also the drift rate over two
specified 48 s intervals in the preamble.
Figure 7-61. Low Energy Carrier & Drift Test - BLE Packets
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