Afar AR-24010E, Operator'S Manual

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pulsAR radio Operator's Manual
T x R x T x R x T x R x
R x T x R x T x R x T x
T i m e
( A )
( B )
N x G 2
S y n c
R a d i o
2 ( A )
N x G 3
S y n c
R a d i o
3 ( A )
t d d s y n c = m a s t e r
N x G 1
S y n c
R a d i o
1 ( A )
N x G 4
S y n c
R a d i o
4 ( B )
t d d s y n c = o f f
N x G 5
S y n c
R a d i o
5 ( B )
N x G 6
S y n c
R a d i o
6 ( B )
N x G 9
S y n c
R a d i o
9 ( A )
t d d s y n c = a u t o t d d s y n c = o f f
R a d i o
7 ( B )
R a d i o
8 ( B )
N x G 1 0
S y n c
R a d i o
1 0 ( A )
t d d s y n c = o f f
Figure 2.6 – Synchronization with NetCrossing Gateways
The site on the left shows three gateways, each one connected to a respective radio. These radios are
co-located and therefore their TDD cycles need to be synchronized to avoid self-interference. Since
their LAN ports are not connected to each other the synchronization is achieved through the SYNC
ports of the gateways. You must connect all the SYNC ports together in a daisy-chain manner, and
configure the gateways tdd sync-mode to
master . In master mode each gateway keeps a cycle timer
running, synchronized to the other gateways. This synchronization is shared , i.e. no single gateway
is the synchronization source. In fact any gateway can be added or dropped without affecting the
cycle timers of the remaining gateways.
You must configure the three left radios as the “hub” for their RF links. Each of these three radios
detects the presence of the respective gateway, which becomes the source of its heartbeat over the
Ethernet. In this way, all three radios run their cycle times synchronized and following timeline A in
the figure.
The middle site in the figure illustrates another way in which the gateways participate in the cycle
synchronization. At this site radio 5 is a “remote” with its cycle synchronized to radio 2 across the
RF link. Radio 5 therefore becomes the source of the heartbeat at this site. It sends heartbeat packets
over the Ethernet, which synchronize the cycle timer of gateway 5. As shown in the figure you must
connect gateway 5 and 6 SYNC ports together and configure their tdd sync-mode to
auto . In this
mode the gateways propagate the heartbeat between the Ethernet WAN port and the SYNC port.
Gateway 5, which receives heartbeat packets from the radio, drives the SYNC port. Gateway 6
synchronizes its cycle timer to the SYNC port and sends heartbeat packets to radio 6. The two co-
located radios at this site have their cycle times synchronized, following timeline B. At this same site
you could have more pairs of gateways and radios. You would connect the SYNC lines of all the
gateways together and configure their tdd sync-mode to auto.
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