WSDA
®
-2000 User Manual
6.1 System Bandwidth in Synchronized Sampling
When using synchronized sampling all nodes in the wireless network are queried and given time
slots of various lengths based on their configuration (# of channels, sample rate, etc.). Nodes will
only transmit data during these time slots, therefore eliminating over-the-air data collisions. The total
time available for node transmissions is defined by the system bandwidth. Because the system
bandwidth is finite, only a fixed number of nodes can be supported when using synchronized
sampling. The number of nodes is largely dependent on node configuration, as each consumes part
of the bandwidth. Use the online network bandwidth calculator to determine the bandwidth capacity
for a particular system configuration: http://www.microstrain.com/configure-your-system
6.2 Synchronized Sampling with Multiple Gateways
If there are multiple gateways in the system, a Global Positioning System (GPS) time source can be
used to synchronize time between the gateways. Only gateways with attached GPS devices, such
as a LORD Sensing GPS or GNSS- enabled inertial sensor, will have this option (
see
Recommended Sensors on page 1
). The gateway-to-gateway synchronization for systems using
the GPS time source is on the order of micro-seconds.
Another option available on the WSDA-1500 gateway is to use an NTP time reference from the
internet. As there is lag inherent to using the internet to get a NTP time, it is not recommended for
synchronizing multiple gateways. This option would have a gateway-to-gateway synchronization on
the order of 10’s of milliseconds. A good compromise would be to use of a local NTP time reference.
This would reduce the gateway-to-gateway lag to milliseconds. For information on how to adjust the
times settings
see Time Options on page 39
.
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