Packet Radio Long-Term Vision


It is generally accepted that communications in an emergency will not be equal to what is normally available. System overload or failure, as well as the need to work from temporary centres will all reduce communications capacity and availability. To be effective, emergency communications must provide some portion of normal communications capabilities. Up to the 1970s, information was moved by telephone, radio or as a physical package (Paper mostly). The world had a limited number of computers and computer networking was not generally available. Amateur radio HF and VHF radio was sufficient to provide a useful emergency communications solution.

Today, computers are everywhere and almost all are connected to a private network and/or the Internet in some way. The ability to create, store and forward large amounts of information as computer data has influenced emergency response, therefore also influencing emergency communications. In an emergency, voice communications is excellent for short tactical messages, especially if the sender or recipient is mobile or portable. For moving blocks of information such as lists of names or supplies, text messages using a computer and radio link are more efficient. With computers in widespread use, much of the information is managed as documents or spreadsheets, which allow special formatting and tables. Transporting these files over a radio link eliminates duplication of effort to re-type the information and presents the data in its native format for end users. In order to be effective and useful in the world we live in today, Amateur radio must provide more than HF and VHF voice communications.

Many amateurs view Packet Radio as a historical part of Amateur radio which died in the nineties with the rise of the Internet. While the Internet did lead to the demise of packet radio, the main failure of packet radio was the requirement for multiple hops to link locations and the low speed of these backbone links. With the Internet growth in the late nineties, packet radio could not compete.

The EMRG packet network is being specifically built to support emergency communications. This is not an attempt to bring the original packet networks back to life. The network will be open to all local amateurs when it is not in use for an emergency or EMRG exercise. Local amateurs are encouraged to use the network, to promote interest and skill in using the packet network.

Wireless Local Loop

Packet radio is still a viable solution for emergency communications as a 1200 and 9600 bps wireless "local loop", providing communications between end sites and the nearest wireless node. Several Nodes can be located across the City, interconnected using wired or wireless higher speed data links. While it is possible that wired communications across the entire City will fail or be destroyed in an emergency, there is a higher probability that only portions of the communications infrastructure will be impacted. Hybrid communications solutions that interconnect wireless and wired systems, will provide the most effective solutions.

Data Rates

The EMRG emergency packet network will support 1200 bps. Operation at 1200 bps is important because this is the speed that most amateur's TNCs support and because as the distance increases from the central node to the remote site, supporting higher speeds may not be possible. MFJ Enterprises sells a 1200/2400 baud TNC, which it says does not require radio modification. This may be an option if new TNCs must be purchased anyway, because it would provide a higher speed connection, using a standard VHF mobile radio.

Supporting 9600 bps in the future will allow higher speed transmission and the potential to support TCP/IP. The use of higher speed packet could be used to provide a faster connection between key sites such as the Red Cross ad EOC, as well as providing a backbone network if there are several nodes in the City. The use of TCP/IP, Internet type routing over packet radio links offers some exciting possibilities, where the radio system becomes transparent to the user, allowing use of applications that support TCP/IP and interconnection with wired networks such as the Internet. This allows a person with a text e-mail application to send messages which travel over a wired or wireless LAN connection to a packet radio gateway node. The gateway node sends the data across the packet network to its destination. Using TCP/IP on 1200 bps links is not effective because most of the bandwidth is consumed by the TCP/IP overhead.

Radio - Computer Interface

The original packet radio networks required a Terminal Node Controller (TNC) to interface between a computer serial port and the radio. In recent years, sound cards have become standard in computers and software has been written which can encode and decode packets through the sound card. Several manufacturers produce a Sound Card Interface to simplify the use of a computer sound card with a radio. The Sound Card Interface provides PTT from the computers serial port or in some cases a built in VOX, plus they provide electrical isolation between the radio and computer. Most of these sound card interfaces support multiple communications modes and can include additional connections for microphones and other equipment, so the installation does not need to be dismantled in order to use the radio for other purposes. West Mountain Radio is a well known Sound Card Interface company, with their RIGBlaster product line.

The EMRG packet network will not use Sound Card Interfaces, even for portable stations unless it can be proved effective. The advantage of a TNC over sound card interface, is packet routing for Nodes and Gateways, plus better packet decoding from poorer quality signals. The Sound Card interface also requires greater CPU processing to produce the packet audio signal.

One of the manufacturers of TNCs for many years, is Kantronics. The Kantronics KPC-9612+ TNC is a possibility for the Nodes and Gateways. The KPC-9612+ has built in support for 1200 and 9600 bps, plus KA-Net. The Kantronics TNC also supports Post Office Code Standardization Advisory Group (POCSAG) code, which has been used successfully by amateurs to build a paging network. This could be used for distributing short messages to selected personnel or sites, for people on the move.

Additional Opportunities

The initial packet radio network created by EMRG will provide basic data communications capabilities. From the experience of building and operating the network, amateurs can become more knowledgeable and look for opportunities to improve.


There are a couple printers available, but including a printer as part of the portable kits, would greatly enhance the communications capability by providing a printed copy of the message.

Additional Nodes

The central node will not be reachable from all locations in the City, without digital repeaters. Initially this function will be done by portable systems and through the use of beam antennas. Installing additional nodes or gateways can reduce the distance from the end site (shelter) to a node, allowing higher speed and less end user equipment.

High Speed Backbone

Adding more nodes will lead to congestion if the links between nodes are not larger than the links to end users. Wired and wireless links can be used to ensure that there is sufficient speed between nodes. The wired solution could be using dial up modems or piggybacking on City owned facilities. Wireless solutions include amateur radio high speed modems or using unlicensed wireless 802.11 LAN/WAN equipment which is now readily available.

High Speed Portable Systems

Amateur radio has an allocation within the wireless LAN/WAN spectrum and the LAN/WAN spectrum is unlicensed anyway, so there are opportunities to enhance the network by integrating high speed LAN/WAN links into the network. The West Carleton Amateur Radio club and numerous other groups across North America, are experimenting with the use of 802.11 wireless equipment for amateur radio communications. It may be possible to provide much higher speed remote links at end sites, allowing non text data transfers and information exchange.

Post Office Code Standardization Advisory Group (POCSAG) code

The POCSAG code is a synchronous paging format that allows pages to be transmitted to a text based pager or a computer with decoding software. Pagers are available that can operate in the Amateur bands, so it would be possible to use paging for delivery of one way messages to users who are mobile, such as within a shelter. There are limits on paging due to the power transmitted, so coverage would not include the entire City of Ottawa, but should cover the most densely populated portion.

Network Design

Basic Test Network

The EMRG Emergency Packet Radio network is based on an initial single site 1200 bps configuration, which can be enhanced through a series of future projects. The initial test network has one central node capable of wide area 1200 bps operation, three fixed sites at key emergency locations and several portable stations for deployment as required in an emergency.

The Test network will can be used in an emergency and provides a system on which to test hardware and software. While all of the hardware and software works, there are a lot of issues with how they are implemented, which options to set for optimized operation and which PC hardware and operating system will they work with.

The central node is capable of packet routing so with packet terminal software on each PC, text messages can be exchanged between stations.

220 MHz

The Amateur 1.35 m (220 MHz) band has a lot of potential for packet radio. The band is not well used today, will not interfere with 2m VHF and 70cm UHF communications. The band has reasonably good coverage, but slightly smaller antennas than 2m VHF.The 220 MHz band is not used by many amateurs and is not supported by many older scanners, making it less likely to be monitored in an emergency.

The down side for 220 MHz is the lack of used infrastructure (antennas and radios), plus the limited availability of new equipment. While EMRG would like to use 220 MHz for some communications, financial realities will limit this activity. In many cases there are VHF antennas existing, that just need to be used and there is used equipment readily available.

The EMRG Communications Centre and the Emergency Operations Centre at City Hall have Kenwood tri-band (144,220,440 MHz) radios allowing a dedicated 220 MHz channel between these two sites if required for voice or packet. The 220MHz option could be extended to the Red Cross in the future, making a dedicated core station network. The radios have not appeared in any of the sites with modifications to support 9600 baud packet, so only 1200 baud can be supported.

Future Network Options

In future projects, options include moving the core fixed stations to 220MHz, adding a high speed backbone using wireless licensed or unlicensed spectrum or wired links and adding TCP/IP support for routing to the Internet and within the EMRG network and POCSAG paging.

EMRG Packet Project

The project portion of getting a packet network going, is getting a few PCs together, loading software, building interfaces, getting everything to work, testing and defining a workable solution. It sounds easy until you try. Software and hardware don't always do what they should do on your machine, or with your OS or with your TNC, etc.

The first step is to get a couple stations on the air with basic 1200b packet and terminal software such as Winpack. This will provide a test network and will allow packet communications between the EOC at City Hall and the EMRG Communications Centre at Fire Dispatch. The main site is VE3OCE on 145.030 MHz.

Once the two station network is up and running, testing of other software and network design can take shape. Hopefully some of the original packet experts in Ottawa, will be able to provide some input.

One aspect is to install and evaluate AGWPE. This software is important for use in the Emergency Operations Centre and the EMRG communications centre, for three reasons, with #1 being the most important;

  1. ability to share TNCs with computers across a network
  2. ability to send TCP/IP over a radio link
  3. ability to interface to a radio through a sound card, instead of a TNC

Another important area is to design and build a node that can support multiple users and multiple locations. This will need to include the ability to gateway from connections on other frequencies and other speeds.

The most important ongoing and final activity is Document, Document, Document, then test documentation.

To be effective, the EMRG packet network must be built and maintained by a group of EMRG members, not just a couple dedicated, enthusiastic people who build a network that collapses when they are not available to maintain it. While there are many possibilities for the future of Amateur radio data communications, EMRG will only build what can and will be supported.