amateur radio digital modes l.
Skip this Video
Loading SlideShow in 5 Seconds..
Amateur Radio Digital Modes PowerPoint Presentation
Download Presentation
Amateur Radio Digital Modes

Loading in 2 Seconds...

play fullscreen
1 / 60

Amateur Radio Digital Modes - PowerPoint PPT Presentation

  • Uploaded on

Amateur Radio Digital Modes. Western Washington Medical Services Team Brian Daly, WB7OML EC, King County. History. March, 1980 Federal Communications Commission approved the transmission of ASCII for Amateur Radio in the United States

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

Amateur Radio Digital Modes

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
amateur radio digital modes

Amateur Radio Digital Modes

Western Washington Medical Services Team

Brian Daly, WB7OML

EC, King County

  • March, 1980
    • Federal Communications Commission approved the transmission of ASCII for Amateur Radio in the United States
    • Year and a half after Canadian hams had been authorized to transmit digital "packet radio“
  • Doug Lockhart, VE7APU, of Vancouver, British Columbia
    • Developed a device that he called a terminal node controller (TNC)
    • It worked with a modem to convert ASCII to modulated tones and convert the demodulated tones back to ASCII
  • 1981  group of hams in Tucson, Arizona, founded the Tucson Amateur Packet Radio Corporation (TAPR)
    • Developed a modified version of the commercial X.25 protocol called Amateur X.25 (AX.25)
  • November, 1983, TAPR released the first TNC in kit form, the TAPR TNC1
  • 1984
    • a great deal of packet experimentation was done, software for packet bulletin board systems was developed, and packet radio started becoming more and more popular all across the U.S. and Canada
so what is this packet stuff
So What is this Packet Stuff?
  • Data that is to be transmitted is collected in the TNC and sent as bursts, or packets, of information
  • Each packet has:
    • The callsign or address of who it's going to
    • Who it's coming from
    • The route between the two stations
    • Data and error checking
packet characteristics
Packet Characteristics
  • Packet is an error-detecting mode, which means that it is capable of communicating error-free information, including binary data (for images, software applications, etc)
  • The problem with packet is that it requires strong, “quiet” signals at both ends of the path to function efficiently
    • Packet doesn’t tolerate signal fading, noise or interference, which makes it a poor choice for the chaotic world of HF
  • HF packet is still used for long-distance traffic forwarding between some VHF packet networks (although much of this data is now traveling via the Internet)
    • You’ll also find HF packet in use as part of the APRS (Automatic Position Reporting System) network.
osi layers for packet
OSI Layers for Packet
  • Network layer
    • No network services above the data link layer are required for direct, keyboard-to-keyboard connections between stations
    • To provide automated routing of data between stations (important for the delivery of electronic mail), several network layer protocols have been developed for use with AX.25
      • Most prominent among these are NET/ROM, ROSE, and TexNet
    • Any network layer protocol may be used, including the ubiquitous Internet Protocol
  • Data link layer: AX.25
    • AX.25 defines both the physical and data link layers of the OSI model
  • Physical layer: modem and radio
digital modulation
Digital Modulation
  • Transfer a digital bit stream over an analog bandpass channel
  • Analog carrier signal is modulated by a digital bit stream of either equal length signals or varying length signals
what are digital modes
What are Digital Modes??
  • TOR
    • Teleprinting Over Radio
  • AMTOR - Amateur Teleprinting Over Radio
    • FSK mode
      • hardly used in the 21st Century
    • 5 bits (as did RTTY)
    • Cannot transfer extended ASCII or any binary data
    • Combines the best aspects of packet (the ability to pass binary data, for example) and the robust error-free nature of AMTOR.
    • FSK mode
    • Standard on modern Multi-Mode TNCs
    • 200 baud operating rate
    • Huffman compression technique
    • True binary data transfer capability
digital modes
Digital Modes
    • Sophisticated data coding, coupled with complex modulation schemes and digital processing technology, in an effort to overcome the vagaries of HF
    • Impressive performance even in the face of weak signals and terrible band conditions
    • Proprietary mode developed by HAL
  • G-TOR
    • Incorporates a data inter-leaving system that assists in minimizing the effects of atmospheric noise and has the ability to fix garbled data
    • Tries to perform all transmissions at 300 baud but drops to 200 baud if difficulties are encountered and finally to 100 baud
    • Proprietary mode developed by Kantronics
  • PSK31
    • PSK31 could be viewed as a “high octane cousin of RTTY”
    • Casual keyboard-to-keyboard operating
    • It has also been embraced enthusiastically by the QRP community
Dual port 1200/9600 bps operation, standard

Port 1 supports 1200 bps

Port 2 supports 4800, 9600, 19200, 38400 bps with DFSK modulation

"NEWUSER" mode provides a quick start for packet newcomers

Large capacity internal mailbox and mail forwarding feature

Multiple user mailbox flashes Mail lamp for up to 10 call signs

GPS operation mode allows use with APRS® or other geolocation software

Telemetry functions and Remote Control with two A/D inputs and two control line outputs

Paging transmit/receive capability -- POCSAG compatible

Digital audio drive control -- set from keyboard or by remote control


"Online" HELP feature

128k memory standard; 512k optional

modes of operation
Modes of Operation
  • TNCs can operate in several different modes of operation:
    • Terminal Mode
      • Allows you to communicate with your TNC using a 'dumb' RS-232 serial terminal, or a terminal emulation software program running on your PC
      • Allows you to communicate with your TNC with "English-like" command strings
      • AX.25 is run in the TNC
    • KISS Mode
      • The normal AX.25 communication protocol that is built into the TNC's firmware is essentially bypassed
      • It is done when a more advanced communication protocol is to be used (such as Tcp/Ip), or because of limitations of the built in AX.25 firmware
      • TNC essentially turns into a simple modem device, transmitting and receiving raw HDLC packets
Use the PC Soundcard DSP as a modem

Interface from computer to radio

RIGblaster example

Benefit: supports many different digital modes via software

what do i need for vhf packet
What Do I Need for VHF Packet?
  • 2 meter transceiver
    • There is packet activity on 220, 440 and HF, but 2 meters is where most of the action is
  • TNC - a terminal node controller
  • Cable for connecting the TNC to the radio
    • Appropriate mic and speaker jack connectors for the radio you're going to use
  • Cable for connecting the TNC to the computer
what is a digipeater
What is a Digipeater?
  • Digipeater = packet radio digital repeater
  • Most digipeaters operate on simplex and do not receive and transmit simultaneously
    • Receive the digital information, temporarily store it
    • Then turn around and retransmit it
packet bulletin board systems bbs
Packet Bulletin Board Systems (BBS)
  • Most cities have one or more packet Bulletin Board Systems, or BBS
  • BBSs do two main things:
    • send and receive personal messages for their local users
    • send and receive messages or bulletins intended for people locally or around the world.
  • BBS is part of a national system of other BBSs, it has the ability to pass information or messages to any other BBS in the US or the world
    • This allows you to send messages locally, to someone located in the next state, or to someone on the other side of the world
  • BBSs pass local and national bulletins, which are messages intended to be read by everyone.
    • In this way, amateurs can read the latest messages about the ARRL, AMSAT, TAPR, propagation, DX, and other bulletins on varied topics
nws bbs
  • National Weather Service
    • Transmits current flood and weather watches, warnings, and advisories, as well as the latest public and marine forecasts and conditions to a West Seattle Bulletin Board System (BBS) via packet radio
    • Amateurs can then receive this information via packet at 145.010 MHz
  • Worldwide network of participating amateur stations bound together through the use of the Internet
  • By linking with any Winlink station – using HF PACTOR or VHF/UHF packet – Amateur radio Operators can exchange e-mail messages and attachments) with other Winlink-participating hams, or with anyone with a standard Internet e-mail address
  • CMS
    • The Common Message Servers (CMS) are the common coordinating server engines central to the Winlink 2000 "star" Network configuration
    • They coordinate the traffic between the participating network stations (PMBOs) as well as serving as the e-mail, bulletin and position reporting interface
    • All this is done over the Internet in order to make the amateur radio spectrum more efficient, leaving these radio frequencies available for end-users
    • Each of the existing Common Message Servers is a mirror image of the other, providing continual redundancy should one of these servers become inoperative
  • TELNET (TELecommunication NETwork)
    • Network protocol used on the Internet or local area network (LAN) connections
  • TELPAC (TELnet-PACket Bridge)
    • Allows the Winlink 2000 user to employ VHF/UHF Packet mode with the B2F protocol to take advantage of "last mile" coverage
    • Telpac efficiently links conventional AX.25 packet to Winlink 2000's Telnet Servers
    • Allows the connection of a VHF/UHF modem either directly or via the AGW Packet Engine with a Paclink or Airmail user application, and converts the AX.25 Packet to Internet Telnet for connection to a Winlink Participating Station' s(PMBO) Telnet Server
  • PMBO
    • A Winlink 2000 participating network mailbox (MBO)
    • PMBOs or Radio Message Servers , communicate with each other through the CMS's in a "star" network configuration via the Internet, and with the end-users over radio or Internet via Telnet or WEB Browser Access
map of pmbos
Map of PMBOs



email via amateur radio




Email via Amateur Radio



By connecting to the VHF packet Telpac Node the ham station may be linked to the internet to send and receive e-mails.












Internet E-mail

paclink agw
Paclink AGW
  • Paclink AGW
    • Easily configured Winlink 2000 (WL2K) radio E-mail client that interfaces with most popular E-mail client programs such as Microsoft Outlook Express
    • Paclink AGW adds packet radio and Telnet channels for WL2K connectivity to Outlook Express
  • Paclink utilizes the AGW Packet Engine to drive Packet modems, including computer sound cards
    • With one single Paclink application, in front of a firewall and behind a router, multiple computers may be enabled with radio email when used with the Winlink 2000 network system
  • Airmail (mainly for HF Pactor) is a messaging program (similar to Microsoft Outlook in appearance) specifically designed for connection to an HF radio Winlink participating station
    • Developed specifically for sending messages via HF radio and optimized for low-speed links, not an adaptation of an ordinary email
  • Airmail may be used for VHF/UHF Packet under limited circumstances
  • Airmail is required for a radio user to connect to Winlink over HF radio
  • AirMail can be used to exchange messages with another ham station, which is also using AirMail, without using the internet
  • AirMail handles Attachments
  • On VHF/UHF Airmail would access a Winlink Gateway which would have Telpac installed and running, or one of the Winlink “RMS” Stations
so what does this all mean
So what does this all mean?
  • MST Use Cases for Packet
    • Ability to Send Forms from Hospitals to NCS
      • HICS-213 Forms
      • Medical Supply Lists
      • SITREPS and Damage Assessment Forms
      • Patient Tracking Forms
    • Internet Last Mile Replacement?
packet model
If we are using packet to just send forms, we don’t necessarily need email or Winlink

Simpler packet file transfers

Simplex point-to-point


Packet Model?

Simplex Packet

File Transfers

Airmail Client?