Radio Networks


All Monitors operate on the UHF CB band, providing monitoring services on the government allocated emergency channels, and in some areas on highway channels and local repeaters.

In regions where a 5/35 repeater is in operation Monitors will listen to channel 5. You should use repeater or duplex mode to ensure your signal goes through the repeater, ensuring your transmission will be heard over a wider area.

In regions where no 5/35 repeater is in operation, or where the 5/35 repeater is inoperable, Monitors will listen to channel 5 in simplex mode. Turn OFF your repeater or duplex mode to operate on channel 5 simplex.

Channel 35 is not always monitored in regions where repeaters are operational as any signal on channel 35 will be heard on the repeater output, channel 5.

In some regions channel 40 and other locally used road channels, and local repeaters may also be monitored.

Range of UHF equipment is line of sight. Repeaters extend range because they are located on a high location, extending the line of sight.

HF (27MHz) CB

Some Monitors maintain a listening watch on 27MHz CB channel 9 (on 23 or 40 channel sets, channel 5 on 18 channel sets). Monitors will listen to the Upper Sideband or USB mode, although AM signals will be heard also.

If you only have 27MHz CB you should check with local Monitors to be certain this channel is monitored in your chosen area.

Range for 27MHz is greater than UHF, especially using SSB modes. 27MHz is not as affected by line of sight or obstacles as UHF is, so can be a good choice for bushland regions.

Medium/High Frequency (MF/HF)

Medium and High Frequency utilises frequencies between 2 and 30 MHz for very long range communications. It is used by the Royal Flying Doctor Service (RFDS) to communicate with remote stations.

HF frequencies can communicate hundreds or even thousands of kilometres. They are very long range, although they are greatly affected by atmospheric conditions, solar flares, seasons and even day and night. HF transceivers can be expensive, up to $3,000 or more, but they are invaluable for outback travellers as they can summon help across vast distances.

ACREM operates three HF frequencies that are used to maintain communications across Australia. Although we do not offer a service for travellers, ACREM Members are able to utilise these HF frequencies for communications while travelling, upon application. This is not the primary function of these frequencies, and any such use will always be secondary to their primary function of providing long range communications during emergencies and disasters.

Outpost Stations

The RFDS operate the Outpost Station network. This service provides emergency and safety communications for remote properties and mobiles operating in remote locations. To operate on this band you will need an Outpost non-assigned licence from the ACMA, plus a HF transceiver capable of operating on the RFDS frequencies.

Please note that the RFDS is the ONLY organisation authorised to provide emergency and safety services for the Outpost service. Claims by other organisations that they will/can offer an Outpost emergency/safety service are illegal. RFDS is the only organisation authorised to operate “control stations” in the Outpost service, and individual Outpost stations are only authorised to communicate with the RFDS control stations.

Australian 4WD Network (VKS737)

The Australian National 4WD Radio Network operates a HF service for 4WD enthusiasts and outback travellers. Members are able to communicate with VKS737 bases as well as RFDS bases, or other VKS737 members. Only mobile stations are authorised for membership and use of the VKS737 HF network.


ACREM operates several frequencies in the VHF-Hi band. There are three types of networks used:

  • Australia wide simplex network
  • State wide transportable repeater networks
  • Local simplex and repeater networks

The Australia wide simplex network is primarily used for events and field operations, or local short range use. For slightly longer range there is also a state wide transportable repeater allocation that can be set up at a convenient site to extend coverage.

There are also several local repeater systems that are used within that area for routine communications as well as events and field operations.

Once again, although these frequencies are not intended for use by travellers, ACREM Members are able to utilise the VHF frequencies for their own communications with other members, provided the frequency is not being used for its primary purpose.