Antenna System Monitoring - ASM Series
© Copyright RFI 2012
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INTRODUCTION
As a radio network operator, you know that radio networks
are at the heart of an ever expanding number of service
provision organisations. Emergency service, public safety
and commercial users rely heavily on radio communications
technology and are increasingly demanding higher levels of
network performance.
As a result, network operators are facing demanding KPIs
with performance penalties. To cope with this, Periodic
Maintenance Inspections (PMI) are performed to keep an
eye on systemperformance. Unfortunately, the staff required
to undertake this work puts budgets under pressure and
the network down-time to do the measurements may be
counted against the total network availability.
THE PROBLEM
So how do you meet your budget and minimise downtime
and outages without increasing costs or staff numbers?
The obvious answer is real-time, continuous system
performance monitoring. And where better to monitor
performance than right at the antenna? It’s the power leaving
the antenna that’s important. If the signal doesn’t leave the
antenna, the network can’t deliver a service to the users.
But as you know, monitoring performance at the antenna
on an operational system is not easy. By the time you get
to the antenna feeder cable, all the transmitters have been
combined. It is no longer possible to raise an alarm based on
a simple power level measurement. To detect a transmission
fault you really need a spectrum analyser. Measuring
antenna VSWR at this point while the system is operating
is also difficult. Using a communications site analyser is not
necessarily the answer as most expect to work with a single
carrier.
Inanycase, all thisequipment isexpensiveand itwouldbehard
to justify having one or more spectrum or communications
site analysers permanently installed at each site.
THE SOLUTION
The RFI Antenna System Monitor (ASM) is the inexpensive
solution to the real-time system performance monitoring
problem. The ASM can make per carrier power and VSWR
measurements at the antenna feeder and can generate
alarms based on preset high/low power and VSWR limits.
Because it has an Ethernet port, integrating the ASM into
your system is very easy.
THE NUMBERS
Let’s say you have 20 sites in your system and that you need
to do a PMI on each of these sites to check the power and
VSWR on each channel, twice a year. Let’s also assume the
sites have to come down for 5 hours to do the PMI and that
you need two technicians on site for that period. In addition,
there’s travel time, say 2 hours out, 2 hours back on average.
Finally, there’s the burden at the Network Operations Centre
(
NOC) to manage both the site unavailability over that period
and the PMI process (say another technician for the same 5
hour period).
All that adds up to 23 man-hours expended per site visit. So
the total effort for 20 sites, twice a year, is 920 man-hours or
115
man-days per year, plus the unavailability element - and
this is still not real time monitoring.
Even if we cost the technicians at only $50 per hour, the total
comes to 920 x $50 = $46,000 or
$2,300 per site, per year.
These figures assume all sites are within about 55 miles (90
km, 2 hours’ drive) of the service centre. Put a few sites in
more remote country areas and the costs can escalate very
quickly.
Compare this with an approximate $5,000 once-off capital
cost per site to provide real-time monitoring for up to
four antennas with a level of granularity you can’t hope to
replicate with PMI.
ANTENNA MONITORING:
MEET KPI’S, SAVE MONEY
AND REDUCE DOWNTIME
