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VHF3000 - Digital Communication System
VHF3000 is a modular computer based communication system. We refer to it as a communication system and not only a VHF system because it seamlessly integrates VHF, mobilephones, fixed line telephones and software telephones.

Key features
The key features of the system are:

  • Advanced Tx/Rx muting
  • All communication including voice is over IP
  • Simplex and duplex VHF
  • Using position from AIS to locate suitable basestation
  • Automatic VHF call setup to vessel with DSC
  • Automatic Outbound Telphone call setup to vessel with DSC
  • Automatic Inbound Telphone call setup from vessel with DSC
  • Recording and playback

Modular structure
The system is available as modules. A full Coastal VHF Chain will integrate all the modules, while a small port may only need a Simplex Radio and remote Operator Display. Modules are: Simplex or Duplex Radios, DSC, AIS Integration and Telephony.

Simple VHF example
The following illustration shows an example of the most basic system. Server software runs as services on the operator pc. In this configuration the operator pc is shared with other software like Traffic Display or CCTV. Radio is Simplex only, with no DSC, therefore only one antenna.

Coastal VHF Chain example
The following illustration shows an example of a Coastal VHF Chain setup. It receives AIS data from an external AIS chain. It has a Telephony gateway to interface to PSTN - Public Switched Telephony Networks. The operator has access to Traffic Display with AIS target data, Telephony features from the pc, DSC sending and receiving, instant recording and playback and ofcourse simplex/duplex VHF audio on all configured frequencies.

What is the difference between VHF3000 and traditional remote operated VHF systems?
Most of the other remote operated VHF systems are single point-to-point systems where one or more VHF transceivers are operated from a central location. This means that there is no integration between the transceivers. If the transceivers are placed in the same location or near each other and operating on the same channel, there will be problems operating the system. A vessel calling will be heard over more than one receiver. Manual selection of station to answer the call requires evaluation of signal strength or knowledge of vessel position. When the Operator is transmitting to answer the call, he will hear his own voice coming back over the other transceivers.

The traditional way of solving this problem has been to use different channels for different areas. This means that the mariners have to change channel several times throughout the VTS area. Vessels crossing from one zone to another may be on different channels, and the VTS centre will often have to “hand over” vessels from one area (channel) to another.

In the VHF3000 system all these functions are integrated using advanced muting systems. If more than one Base Station receives the signal, the one receiving the best signal will be selected, and the others will be automatically muted during the vessels transmission. When the Operator is answering the call, the other Base Stations will be muted for the duration of the transmission to avoid feedback

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