Cross Band Operating

Cross Band Operating
Options for Wide Area Only and
Wide Area and Local Area
Mike Duff
[email protected]
What is Cross Band Operation?
• Cross Band Operation is a function of a
Dual Band Radio wherein the two radios
are tied together such that a signal
received on the first radio is re-transmitted
by the second radio and vice versa.
Why Cross Band?
• Cross Band Operation creates a gateway
for other radios accessing the Cross Band
Radio to utilize frequencies, modes or
power not available on the native radio.
Examples of Cross Banding
• A Mobile Rig may be put in Cross Band
Operation with a Handie-Talkie to allow
the driver to access a repeater
unreachable from the Handie-Talkie when
he / she is out of the vehicle.
• A HF Base Station Rig may be put in
Cross Band Operation with a VHF Mobile
Rig to allow access to a HF net while
operating from a vehicle.
Why Are We Cross Banding ?
• We are Cross Banding because the Hospital Radios are
not in the Command Post or Logistical / Communications
• The radios are in penthouses and odd offices / closets.
• The Radio Operators need to be in an area where they
can pick up and deliver messages to Incident Command
• Since the Radio Operators and their radios are
separated, a link needs to be established between the
two. This link will be via Handie-Talkies which will not
have the power for Wide Area Simplex Communications.
• If the Radio Operators and their Base Station radios
were together, there would be no need for Cross Band
Wide Area Only Via Simplex
• If the only concern is to enable Radio
Operators to connect to each other over a
Wide Area circuit, then the following
scheme can be used.
• UHF or VHF can be used on the HandieTalkies as desired.
• VHF would be preferred for the long haul
Wide Area Only Via Duplex
• If a repeater is available, it can be
substituted for the long haul VHF Simplex
• The Handie-Talkies operate in Simplex
mode while the Cross Band Radios
operate in both Simplex and Duplex
• In a severe situation, repeaters may be
Wide & Local Area Via Simplex
• If the Local Area of operation for each hospital is
too large to support direct local communications
between Handie-Talkies, then the HandieTalkies may be operated in a Dual Band
configuration to provide reception of the Cross
Band radio’s Wide Area transmit signal.
• This makes the Cross Band radio function as a
Wide Area link and a Local signal booster
Wide & Local Via Simplex
• Local in range conversations can be conducted strictly
on the local area VHF channel.
• Wide area communications use the cross band radios to
access the wide area UHF channel.
• Users in the same local area that are out of range of
each other can communicate by monitoring the local
cross band radio’s wide area UHF channel.
• Reception of the UHF channel should be muted during
VHF transmit to avoid a feedback loop.
• If simultaneous reception of the VHF and UHF
frequencies presents a problem, the VHF channel can
be permanently muted. In this case, local
communications are made over the local cross band
radio’s “boost” channel but local HTs must be able to
hear the distant cross band radio’s UHF channel to
receive distant users.
Wide & Local Area Via Duplex
• The wide area circuit can also be a made via a repeater
by setting one side of the cross band radios to duplex
• We come to a difficulty though if simultaneous reception
of the VHF and UHF frequencies presents a problem.
• In the Wide & Local via Simplex scenario we could mute
the VHF channel permanently and receive both local and
wide area communications over the UHF channel.
• In this duplex scenario though, the local UHF “boost”
channel is different from the incoming UHF wide area
channel. Muting the VHF channel would block incoming
wide area communications.
• Therefore, if simultaneous reception presents a problem
then the local “boost” option must be abandoned in
duplex wide area applications.
Which is Best?
• Each of the preceding scenarios may have
benefits in different circumstances.
• A good strategy would be to program each
of the four scenarios into your particular
radios and then test each one to verify
expected operation.
• A cross band radio with “Hyper” memories
could then be used to call up any
particular scenario.
A Few Words of Caution
• Whenever cross banding to another system,
protect the input channels on the cross band
radio with CTCSS or DCS control tones.
• Be careful of power settings and duty cycles on
the cross band radio. It is not a commercial
• Stay in local control of the cross band repeater
as remote control of a repeater requires a
separate third channel which is not available on
simple cross band radios.
Questions and Answers
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