PTP 450 Configuration and User Guide
Wireless operation
1-12
pmp-0815 (August 2015)
Wireless operation
This section describes how the PTP 450 wireless link is operated, including modulation
modes, power control and security.
Time division duplexing
The system uses Time Division Duplexing (TDD) – one channel alternately transmits and
receives rather than using one channel for transmitting and a second channel for
receiving. To accomplish TDD, the BHM must provide sync to its BHS. Furthermore,
collocated BHMs must be synced together – an unsynchronized BHM that transmits during
the receive cycle of a collocated BHM can prevent a second BHM from being able to
decode the signals from its BHSs. In addition, across a geographical area, BHMs that can
“hear” each other benefit from using a common sync to further reduce self-interference
within the network.
Modules use TDD on a common frequency to divide frames for uplink (orange) and
downlink (green) usage, as shown in the figure below.
For more information on synchronization configuration options, see
location and using the OFDM Frame Calculator Tool
on page
Figure 7
TDD frame division
Time
