Agilent Technologies E4438C - Page 23

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Packet types
The three different packet types that can be chosen for the dirty transmitter test are DH1,
DH3, and DH5. The payload for all packet types is a PN9 data sequence. The PN9 data
sequence is truncated after the maximum amount of PN9 data has been placed in the
packet. Since this is truncated data, these packets cannot be used with the ESG’s option
UN7 BER analyzer, which requires a continuous PN sequence. The payload length of
each packet type is as follows:
• DH1=27 bytes
• DH3=183 bytes
• DH5=339 bytes
Each impairment set consists of two to four packets. The sequence bit in the header field
is toggled for the second and fourth packet to indicate to the Bluetooth device that the
incoming packet is not a re-transmitted packet.
Poll period
In Bluetooth systems, master and slave devices exchange information by alternating
packet transmission in TDD mode. The poll period is used to simulate the time period
when the other Bluetooth device would be transmitting its packets. The omit poll period
section allows for verification setups where the Bluetooth TDD mode can be ignored;
instead the ESG will create Bluetooth packets for every time slot. This selection will be
beneficial when comparing results against normal TDD mode to determine the effects of
LO switching, or for comparing other state machine transitions. In characterizing receiver
performance, or for high-speed verifications, we recommended you omit the poll period.
Figure 28 shows the timing diagram for each of the three packet types. The poll period is
625 microseconds long, and data is not transmitted during this period. The poll period is
transmitted before each packet type, unless omit period is enabled. The amount of poll
period(s) for each packet type is as follows:
• DH1=1 poll period
• DH3=3 poll periods
• DH5=5 poll periods
Creating Signals
12.50 ms
DH5 DH5
5 poll periods
Amplitude
7.50 ms
DH3 DH3
3 poll periods
2.50 ms
t
t
t
DH1 DH1
1 poll period
Figure 28. Timing diagram for test set for each packet type. Use with External
Frame Sync not selected. When Use with External Frame Sync is selected, the
DH1 impairment set consists of four packets.