Telecoms Circuits; Lowest Telecoms Modulation Mode; Fixed Frequency Operation - Motorola PTP 600 series User Manual

User Guide: PTP 600 Series

Telecoms circuits

The PTP 600 link provides native support for one or two E1 links, or one or two T1
links. The link relays unstructured E1 or T1 data and provides accurate timing
transfer.

Lowest telecoms modulation mode

In narrow channel bandwidth and lower modulation modes, the link may have
insufficient capacity to relay the E1/T1 payload; in this case, the wireless link
continues to carries timing information in order to maintain accurate clock
synchronization. The relay of telecoms data resumes automatically when the link
reaches a suitable modulation mode.
Links that are able to operate consistently in a high modulation mode can take
advantage of lower link latency. This option is configured by setting the "Lowest
Telecoms Modulation Mode" during installation. Appropriate settings for this control
may be determined by using the Link Planner tool. The reduction in latency is achieved
by disabling the relay of telecoms data in lower modulation modes, and this
necessarily results in somewhat lower availability for the telecoms circuit. The loss of
availability can be estimated using the Link Planner.
The unit will override the user setting of Lowest Telecoms Modulation Mode if the
selected mode has insufficient capacity to carry the telecoms data, or if the mode
demands very high latency and requires more buffering than the link can provide.
When the effective mode differs for Single and Dual Payload operation two modes will
be displayed: "Lowest Dual Payload Modulation Mode" and "Lowest Single Payload
Modulation Mode".

Fixed frequency operation

In the PTP 600 link, data errors may occur during channel changes on an operational
link. It may be appropriate to minimize channel-change-related errors in a link
carrying Telecoms traffic by preventing channel changes initiated by i-DFS. This can
be achieved by barring all channels except one in the Spectrum Management page, or
alternately by selecting Fixed Frequency mode. These steps unavoidably disable
interference avoidance mechanisms, and should not be taken if the risk of errors due
to interference is more severe than the risk due to channel changes.
Fixed frequency operation is not available when radar detection requirements exist in
the frequency band.
phn-0896_012v000
Jul 2010
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Telecoms circuits
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