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Why Packet Radio?www.tapr.org

• What is the history of packet radio ?• Data packet technology was developed in the mid-1960’s.

• Put into practical application in the ARPANET in 1969.

• Initiated in 1970, the ALOHANET, based at the University of Hawaii, was the first large-scale packet radio project.

• Amateur packet radio began in Montreal, Canada in 1978, the first transmission occurring on May 31st.

• This was followed by the Vancouver Amateur Digital Communication Group (VADCG) development of a Terminal Node Controller (TNC) in 1980.

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Why Packet Radio? (or APRS)www.tapr.org

• Sometimes Analog Voice communication can be difficult to understand due to background noise.

• Sometimes it takes too long to communicate long names and symbols using voice accurately.• How long would it take to communicate: “Bacitracin Ointment 15mg” in a noisy

environment?

• Why packet over other modes?Packet has several great advantages over other digital modes: • transparency • error correction • automatic control• Sometimes packet radio can get a signal through when analog modes don’t.

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What is Packet Radio?

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Three Basic Components (Experiment 1)1) Computer2) Radio3) TNC (Terminal Node

Controller)

Option (Experiment 2)Replace TNC with computer software and interface to radio

Decision –Options

• Choose Radio

1) Verify connection to TNC

2) Verify connection to Sound Card

• Choose Interface

• TNC – Stand-alone

• TNC – Custom dedicated

• Sound Card Interface

• Choose Computer (We choose Raspberry Pi)

• Choose Software

• Terminal Tool

• Outpost

• RMS Express

• Etc.

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• Basic Raspberry Pi Computer Complete

• 4 – USB2 Connectors

• BCM43438 WiFi and Bluetooth

• Low Energy (BLE) on board

• Runs on 5 volts through Micro-USB connector

• Video – built in HDMI

• 40pin extended GPIO

• 4 pole stereo output

• Software runs on SD Card

• Many options available –including color touch screens

• Software is a form of LINUX –no cost

• Starting cost – about $35

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My Three Experiments of Operation Using Raspberry Pi

Packet Radio or APRS

Experiment 1: Using Standard TNC

Experiment 2: Using Sound Card

Experiment 3: Using PCB -TNC

1. Radio2. TNC – Heathkit

HK-213. Interface Cable4. RS232 to

Raspberry PI interface or USB to RS232 Cable

5. Software

1. Radio2. Interface Cable3. USB Sound Card4. Interface Hardware5. Software

1. Radio2. Interface Cable3. PCB-TNC4. Software

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Future

First: Development (Make Sure Components Work)

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Check Radio on 145.01 MHz Simplex (Local Packet Frequency)

Add TNC (Heathkit HK-21) – Because I had one.

Build interface cable between TNC and Radio

Obtain microphone Pinout on radio

Obtain connector information on TNC: Input and RS232

See Appendix

Connect TNC to Laptop Computer

Repurposed old 386SX Laptop running Windows 3.1 because it had RS232 ports

Use software available Used “Terminal” software built in to Windows 3.1

First: Development

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1) Hardware Setup 2) Use Terminal Accessory Windows 3.1

3) Set up Serial Port for TNC

4) Turn on TNC Display

5) Connect to REX

6) HELP on REX

7) Stations Heard

First Stage – Fully Operational

Experiment 1: Using Standard TNC

1. Radio – checked and verified in Slide #9

2. TNC – Heathkit HK-21 – checked and verified in Slide #9

3. Interface Cable – checked and verified in Slide #9

4. Prepare Raspberry Pi – Setup: http://www.qrvtronics.com/CatHAM_Radio/files/MyRaspberryPi.pdf

5. RS232 to Raspberry PI interface: ended up using a USB to RS232 cable (easier to implement).

6. Software: used “gtkterm” for Raspberry Pi

7. See for set-up used: http://www.qrvtronics.com/CatHAM_Radio/files/MyPacketRadio_Experiment_1.pdf

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Experiment 1: Using Raspberry Pi

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• Discovered some useful tools built or loadable into the Raspberry Pi1) VNC software – allows remote control and viewing of the Raspberry Pi over

your local network.

2) Gtkterm – terminal for talking to the TNC. (GTKTerm on Raspbian as HyperTerminal alternative.)

3) Adding audio to listen to music on the Raspberry Pi (Ok this has nothing to do with the Experiment 1)

4) Change Screen on Raspberry Pi window

5) Adding a simple screen - display to the Raspberry Pi

Working TNC and Raspberry Pi

• TNC Advantage:

1) All inclusive box

2) Usually includes a mailbox

3) Easy to set up

• TNC Disadvantage:

1) Can be Expensive ($150+)

2) Can use a lot of power

3) Not always compact

Three Experiments of Operation Using Raspberry Pi

Packet Radio

Experiment 1: Using Standard TNC

Experiment 2: Using Sound Card

Experiment 3: Using PCB -TNC

1. Radio2. TNC – Heathkit

HK-213. Interface Cable4. RS232 to

Raspberry PI interface or USB to RS232 Cable

5. Software

1. Radio2. Interface Cable3. USB Sound Card4. Software

1. Radio2. Interface Cable3. PCB-TNC4. Software

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Experiment 2: Using Sound Card

1. Radio

2. Interface Cable

3. Get audio working on Raspberry Pi

4. USB Sound Card

5. Building a controller/interface adaptor

6. Software

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Sound Card Operation with Music

• Getting the music to work has been a bit of a challenge.• Much of the internet help has been old and outdated.

• Sudo apt-get install hamradiomenus was a help.

• Completed document for Audio: http://www.qrvtronics.com/CatHAM_Radio/files/MyRaspberryPiSettingUpYourAudio.pdf

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Basic Block Diagram

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Sound Card and Sound Card Interface Replace the TNCThe software creates the function that the TNC preforms

Working the Experiment

• Detailed information: http://www.qrvtronics.com/CatHAM_Radio/files/MyPacketRadio_Experiment_2.pdf

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End of Presentation -Questions?

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Books and Other Material Websites

• Books

• Raspberry Pi 2 Workshop Manual (Haynes)

• Raspberry Pi for Dummies (Wiley)

• Websites

• https://www.raspberrypi.org/learning/software-guide/quickstart/

• https://raspberrypihq.com/

• https://qrvtronics.com/Side_Left_B/MyPACKET_Experiments.htm

• RS232 Interface ($2.65): https://www.sunsky-online.com/product/default!view.do?subject.id=334804

• Raspberry Pi: ($35)• https://www.adafruit.com/product/3775?src=ra

spberrypi

• OR https://www.newark.com/raspberry-pi/rpi3-modbp/sbc-arm-cortex-a53-1gb-sdram/dp/49AC7637?src=raspberrypi

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Bibliography

• www.tapr.org

• M0HPA – for example

• http://www.g0hwc.com/raspberry-pi-ham-radio.html

• http://f6bvp.org/AX25_BBS_Node_RaspBerry_Pi_install.html

• New Raspberry Pi Zero W – Just $10 https://www.adafruit.com/product/3400

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Appendix

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HK-21 Pinout Schematic HK-21 Pinout Motorola Microphone Pinout

Appendix

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Puxing Wiring

Micro USB Connector

Baofeng and Puxing Cable

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