UHF (450MHz) was never an option, but 700MHz
was considered. There was a period where the FCC
reconsidered the future of the 700MHz spectrum.
Would they make it all data? Would they make it
6.25kHz modulation? That industry “chatter” made this
spectrum option seem uncertain at the time. We already
had uncertainty with our VHF frequency because some
channels were licensed as “secondary”. In addition,
Region 43 (Washington State) is classified a border state
within the 800MHz re-banding process and there was
plenty of risk with regard to licensing. Each frequency
band option had positives and negatives, but we had to
MACC considered purchasing multi-band radios, but
the main reason we didn’t go ahead was their high cost.
However, this was not the sole reason:
• We wanted to ensure complete operations among our
users, meaning we wanted all radios to perform and
behave the same, even in failure mode.
• We identified subtle differences in certain feature sets.
• We purchased a complete system from our vendor
and needed to verify the performance of the radios,
infrastructure and consoles together. We weren’t in a
position to vet other brand radios and their functions
in the timeline we had.
• We discovered limitations on multi-band radios. For
instance, we discovered not all multi-band vendors
had LSM technology, and that when scanning in
multi-band mode, certain priorities were limited.
Finally, we chose 800MHz as a platform for a P25
We knew this decision would come with challenges. Our
state agencies and eight bordering counties are all VHF
narrowband analog, so we faced interoperability hurdles.
We have fire agencies using Minitor V analog pagers
and Knox Boxes in the field. What were we going to do
about state wide mobilizations for fire or to support
law enforcement in multi-jurisdictional pursuits? We
knew coverage would experience changes but we were
under-prepared for them. Every decision we made had
trade-offs and we under estimated the magnitude of the
cultural changes required.
Timescales were one of our biggest concerns. We knew
with our frequency situation it would take longer to
implement a 800MHz P25 trunked simulcast system.
There were complex design and interoperability issues to
resolve and there was trunked fleet-mapping required.
With the narrowband clock ticking and a need for
some level of VHF analog interoperability we decided
to move forward with a parallel VHF analog simulcast
system replacement. During the migration to the new
narrowband system, we built a number of sites to
improve coverage and make the transition relatively
smooth. There was no culture change required initially,
no new features, just more VHF coverage. So everybody
was happy, until the transition to 800MHz P25 trunking
Before we transitioned users onto the new trunked
system, we took great care to ensure it was ready. We
conducted comprehensive testing of all functions,
features, failure modes and coverage. We involved users
throughout this process.
We made many improvements during that testing,
but we still experienced user complaints during the
migration. In hindsight, we used a relatively small
sample group of test users and the environment was
highly controlled. When we started rolling out radios
in the real world, even after we trained users, issues
emerged. The radios were operating in areas and ways
we had not tested. Users were not used to the radios
behavior and there was a magnitude of cultural change
required that we had underestimated.
MIGRATING TO A P25 TRUNKED NETWORK – LESSONS LEARNED >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>