PMP 400 and PTP 200 Series
Canopy User Guide Supplement
Issue 3, January 2009
Page 14 of 45
The best practice for channel planning for APs is to conduct extensive site RF surveys before
choosing channels. For those with the equipment and expertise, use commercial and industrial
spectrum analysis equipment. The PMP 400 and PTP 200 Series APs and SMs do not provide a
spectrum analyzer in the first release (planned for a subsequent release), but standard 5.4 GHz
FSK SMs can be used to give useful information on the RF environment in the planned PMP 400
and PTP 200 Series AP deployment location.
3.2
DOWNTILT
The standard AP antenna produces a 3 db beam elevation (up and down) of 5°, with near-in null
fill that allows good coverage of close-in SMs that otherwise would be affected by the narrow
pattern. This is a narrower pattern than operators may be used to with standard Canopy’s 60° 3
dB beam, and may require downtilt on the antenna. The standard antenna has provision for
measured downtilt. The operator should estimate downtilt based on antenna height above the
service area and using one of the many radio analysis and mapping tools or on-line calculation
tools for calculating downtilt.
3.3
WEATHER RADAR
Spectrum between 5600 and 5650 MHz (sometimes called the “weather notch”) is used by some
weather radar and is not allowed for use by regulations in some regions, including Canada and,
for new equipment, Europe. When the Canopy module is set to one of those regions (configured
on the “Configuration => General” page of the module), it will not allow configuration of the
appropriate frequencies, as shown in Table 3. Even in regions where use of the spectrum
between 5600 and 5650 MHz is allowed, such as the US, the best practice is to not use these
channels if there are any other usable channels available. Only use the channels in this “weather
notch” after performing long-term site surveys (minimum of a week) to ascertain the spectrum is
clear and that there don’t appear to be any weather radar in the area that will cause interference
to your Canopy system.
3.4
RANGE AND THROUGHPUT PLANNING
PMP 400 and PTP 200 Series modules provide up to 21 Mbps aggregate throughput at distances
of 1.25 mi (~1 km) (1.7 mi for 4.9 GHz systems) in RF environments with clear line-of-sight and
low background interference levels. Additional performance details are shown in Table 2 on page
12. RF environments with occluded Fresnel zones or higher background interference levels may
give lower, but still very good, performance, depending on the specifics of the environment.
Similar to standard Canopy, at any given instant, any radios operating at 1X or 2X take more “air
time” to transmit a given amount of data than if they were running at 3X. Similar to standard
Canopy, PMP 400 and PTP 200 Series modules may see reduced total throughput when
handling traffic with a high percentage of small packets.
The effect of this, again similar to standard Canopy, is that at any given instant total throughput
depends on
•
Mix of links running at 3X, 2X, and 1X
•
Mix of packet sizes
3.5
SPECTRUM ANALYZER
A spectrum analyzer is available on the SM at Tools => Spectrum Analyzer. The spectrum
analyzer is also available on an AP by temporarily converting it to an SM by setting the
Device
Type
to
SM
on the AP’s Configuration => General page. The spectrum analyzer works like the
spectrum analyzer in classic FSK SMs.
Spectrum analyzer uses include
