Office-based support personnel need a modern tool for radio communications. Operations center personnel, desk officers, help desks, and other office workers need to send and receive voice communications to and from two-way radios using a standard personal computer (PC). A new tool for dispatch provides this capability using Radio over Internet Protocol (RoIP) technology, personal computers, and mobile radios or base stations to make the connection. This system links the PC to a mobile radio in the same geographic area as the field worker via the agency’s computer network. This revolutionary solution is called IP Network Based Desktop Dispatch.

Figure 1. Operations center worker communicates with field personnel using a standard PC

This unique access point to the radio system enhances operations center efficiency. Catalyst’s Desktop Dispatch provides a graphical user interface – a compact, user-friendly window to control the radio and reflect radio status. With the click of a mouse, an operator can reply to a field unit across town or in the next state. By leveraging the power of the personal computer, Desktop Dispatch provides key information to help the dispatcher initiate and respond to radio communications users and leverages personal computer database capabilities to enhance and improve dispatch operations. Desktop Dispatch provides a test tool for radio system maintenance personnel to exercise your radio network, end to end. Desktop Dispatch also provides powerful features such as:

• The ability to sum audio from different geographic regions, different types of radios, and different frequency bands.
• The ability to change privileged levels by logon name.
• The ability to transmit simultaneously to multiple locations.
• The ability to retrieve conversations that have been recorded and stored by Desktop Dispatch Recording.

This tool also provides many advanced features.  The Global View Window allows users to view the activity of multiple entities simultaneously and quickly switch between them.  The Call History Window allows the PC user to review a detailed list of recent calls, and retrieve the recording of that call.  Supervisors can change groups, channels, systems, and scan on each radio (depending upon the radio type), while standard users may only transmit to selected group.

Most importantly , this system saves money by reducing infrastructure costs.  No special switch is required for routing voice traffic from the different geographic regions to the operations center.  No dedicated telephone lines or other audio links are required to route voice traffic.  Instead, the messages flow over the existing computer network using Internet Protocol (IP).  The PC can also be used for other tasks such as word processing, email, and other information retrieval functions.  With the capability for a single Remote PC to communicate with up to 18 different regions, valuable desk space is saved.  Finally, installation and relocation costs are minimized at the operations centers since only a local or wide area network connection is required for each PC.

In addition to enhancing the efficiency of operations center personnel and reducing infrastructure costs, Desktop Dispatch can be used for many radio applications, including:

• Console Switch Backup:  Not only does Desktop Dispatch connect the agency's diverse users to a single dispatch point, it also offers a backup to the console switch and its links within each region.  These links are most vulnerable during a disaster, when you need the connection the most.
   
• Test Tool:  Desktop Dispatch can be used to place end-to-end calls through the radio network.  A technician can test the radio network right from the shop, saving hours of service time and speeding restoration of radio communications.
   
• RF Efficiency:  This tool can reduce the number of telephone interconnect calls by allowing office workers to make radio calls from their PCs.  Today, some office workers are able to make a telephone call to a field worker's radio.  Such calls consume the radio frequency (RF) channel for the duration of the conversation, wasting that precious resource.  Desktop Dispatch, on the other hand, allows the office worker to make an RF efficient group call that only use the channel while someone is talking.
   
• Dial-up Application:  Desktop Dispatch installed on a laptop or personal computer can be used to provide voice connectivity to radio users from any location that has dial-up telephone access.  Remote laptop and PC users gain connection to their agency intranet via the same dial-up connection used to retrieve email and transmit files.  Once connected, users activate Desktop Dispatch and can communicate to radio users via Desktop Dispatch Gateways.  Common audio compression allows clear communications to be established over dial-up circuits with as little as 19.2 kilobits per second of bandwidth.

INTRODUCTION

Desktop Dispatch™ (Desktop Dispatch) provides a communications and control path between a PC and a two-way radio, providing connectivity via  Local Area Network (LAN) or Wide Area Network (WAN).  The system allows office workers to communicate efficiently with field personnel who have two-way radios.

Catalyst Communications Technologies, Inc. (CCTI), a RoIP firm with extensive two-way radio and PC software experience, has created the technology to allow your organization to connect to multiple PCs to multiple radios for dispatch, help desk, and other office-based operations.

BENEFITS

Desktop Dispatch provides cost-effective wide-area communications for operations center personnel and other office workers.  The costs of leasing or installing dedicated telephone lines or microwave radio networks are eliminated.  Instead, the agency's LAN/WAN is used to link these office workers with the field.  Installation time and relocation costs are greatly reduced using this software-based solution.

Desktop Dispatch increases the efficiency of your work force.  By using the familiar windows-based PC, these tools facilitate rapid interaction between the office and the field.  New users can quickly be added to the system, often in a matter of minutes.  On-line help, tool tips (short explanation of controls), and graphics make the product easy to learn as you go.  This product can reduce radio system maintenance costs when it is used to test the radio network, end-to-end.  A technician can place test calls from a single location while monitoring other diagnostic equipment rather than traveling to the field.

Desktop Dispatch also increases the efficiency of your radio network.  When support personnel talk directly to their field counterparts, the message tends to be more concise.  When office users can contact the field with a RF efficient group call versus an RF inefficient telephone interconnect call, the radio network is freed up for other calls.

DESKTOP DISPATCH™ DESCRIPTION

Desktop Dispatch is a "Client/Server" application.  The server component runs on a Radio Gateway connected to a mobile radio or base station.  This processor controls the radio via PTT function, channel select, and other remote control capabilities and converse the audio to messages that can be sent over a LAN or WAN.  It is depicted below.

Figure 2.  Radio gateway provides voice and control interface to a two-way radio

The PC interface is extended to one or more other Remote PCs via a LAN or WAN as depicted below.  The Radio Gateway is co-located with the Fixed Radio and is dedicated to controlling it and managing requests from Remote PCs.  The Remote PCs are used by operations center personnel as well as other office workers and may be operated at remote locations that are connected to the Radio Gateway via the LAN/WAN.

Figure 3.  Remote PC connects to radio gateway and fixed radio via a WAN

With this connection, voice messages are sent back and forth between the Remote PC and the Jaguar radio.  The field radio user speaks into his two-way radio, transmitting audio to the fixed radio and the Radio Gateway (a server PC) via the radio system.  The Radio Gateway then converts the speech to a digital message and sends it over the WAN as IP packets to the Remote PC.  The Remote PC converts the speech to a digital message to analog voice and plays them through the computer's speakers.

The Remote PC user replies by clicking on the transmit button and speaking into the microphone connected to his computer.  The Remote PC converts his speech to a digital message and sends  it over the WAN to the Radio Gateway.  The Radio Gateway converts the digital messages to analog voice.  The Radio Gateway routes the audio to the two-way radio for transmission to the field portable or mobile radio.

Throughout this entire sequence, control messages are routed from the Radio Gateway to the Remote PC.  These messages control which Remote PC is allowed to talk and provide information such as the time of the last transmission.  When the Remote PC user wants to speak, his PC sends a control message via the WAN to the fixed radio, telling it to begin transmitting.

The Remote PC can multitask other Windows® applications with the Desktop Dispatch client software.  This capability allows the office worker to access information from this PC while interfacing with field radios.  It also allows the office worker to monitor radio traffic as a background task while he uses his PC for other tasks.  The Windows® operation systems have some inherent multitasking limitations.  Users should observe the same practices applied to other programs when multitasking the Desktop Dispatch application.

The Desktop Dispatch system will connect multiple Remote PCs with multiple Radio Gateways, allowing each Remote PC user to monitor and call each group of users, some of which may be in different geographic regions using different frequency bands or using different trunking protocols.  (Each Radio Gateway has a single radio attached.)

Figure 4.  Example system of three Remote PCs and two Radio Gateways

From this architecture, and the inherent scaling capabilities of IP networks, systems that include many radios and Gateways and many Remote Clients can be designed.