Motorola PTP 300 - Manual (Page 38)

PTP SOLUTIONS GUIDE 38
FAQs continued
17. What is Time Division Duplex (TDD) Synchronization?
Time Division Duplex (TDD) refers to a transmission scheme that times and synchronizes the flow of
transmissions as they are sent and received so that interference between signals is greatly reduced.
Motorola’s TDD capability in PTP 600 Series solutions uses a timing reference signal provided by a
Memorylink UltraSync™ GPS-100M synchronization unit. The UltraSync GPS-100M’s timing reference
originates from the atomic clocks on GPS satellites that orbit the earth.
18. What do you mean by near- and non-line-of-sight
A wireless connection between two points with obstructions that block the RF signal resulting in two
scenarios:
19. Do the pTp 300, 400, 500 and 600 Series support Virtual LANs (VLANs)?
Yes. All Ethernet frames tagged with a VLAN priority greater-than or equal-to a system-administrator-
configured threshold (set on the VLAN Configuration web page) will be prioritized for transmission over the
wireless link.
0. Why is it important to install the pTp Lightning protection Unit with pTp 300, 400, 500 and 600
Series wireless Ethernet bridges?
The radio units are frequently installed on high towers and masts, often with external antennas, making
them targets for nearby electro-magnetic surges (lightning) in the atmosphere. While 100% protection
is neither possible nor implied, PTP Lightning Protection Units can provide the radios the best possible
protection against damage resulting from sudden power surges induced in the cables by nearby lightning
strikes.
Near line-of-sight –
Optical line-of-sight between
the two points, but the Fresnel
zone is blocked
Fresnel Zone
Visual line of sight Clear line-of-sight
Blocked Fresnel
Non line-of-sight –
No optical line-of-sight between
the two points, plus the Fresnel
zone is blocked.
Fresnel Zone
Visual line of sight Blocked line-of-sight
Blocked Fresnel