1 october 15-17, 2004 quarter century wireless association what's that racket?- hf digital...

QUARTER CENTURY WIRELESS ASSOCIATION

1October 15-17, 2004

What's That Racket?- HF Digital Modes

Ken W. Asmus VA3KA

Rick Bandla VE3CVG


2October 15-17, 2004

Table of Contents

Introduction Common HF Modes include RTTY, TOR modes

(AMTOR, PACTOR), CLOVER, HELL, MFSK, MT63, Packet, SSTV, PSK-31

Hardware Software Getting started Internet Resources Acknowledgments Discussion, questions and demo


3October 15-17, 2004

INTRODUCTION

Thanks to the generosity of radio hams with programming knowledge, the World Wide Web and the availability of personal computers, new and powerful communications tools are available to all hams.

We can all participate in the revolution by trying out these modes and judging their performance on all of the HF bands.

This presentation will provide a summary of the most common digital modes in use today and how you can get on the air with only a little effort!


4October 15-17, 2004

RTTY

“Radio Teletype" is an FSK (Frequency Shift Keying) mode that has been in use longer than any other digital mode

RTTY is a very simple technique which uses a five-bit code to represent all the letters of the alphabet, the numbers, some punctuation and some control characters

45 baud (typically) corresponds to a typing speed of 60 WPM. There is no error correction provided in RTTY; noise and

interference can have a seriously detrimental effect Recent resurgence due to use of sound cards and DSP software Very popular contesting mode


5October 15-17, 2004

AMTOR

AMateur Teleprinting Over Radio Derived from the commercial SITOR system (Simplex

Telex Over radio) developed primarily for Maritime use in the 1970s.

In the early 1980's, Peter Martinez, G3PLX, made several minor changes to the SITOR protocol and called it AMTOR

AMTOR improves on RTTY by incorporating a simple Error Detection technique


6October 15-17, 2004

AMTOR

AMTOR performs well even in poor HF conditions and the result is quite tolerable for normal text mode conversations

There are two modes used in AMTOR: ARQ and FEC Data is sent in groups of 3 characters (ARQ) The receiver responds to each 3 character group by sending either

an ACK (ACKnowledge) code (if OK) or a NAK (Negative AcKnowledge). Each time the transmitting station gets a NAK, that 3 character group is sent again.

In FEC mode (Forward Error Correcting), sometimes called Mode B, the sending station sends each character twice so this mode provides a means of transmitting to several stations at once. The receiving station does not acknowledge the data received

AMTOR systems are still limited to the technology of the 60s and maximum transmission rate (100 baud)


7October 15-17, 2004

PACTOR

FSK mode and is a standard on modern TNCs Combination of packet and AMTOR Techniques The most popular ARQ digital mode on amateur HF

today 200 baud operating rate, Huffman compression

technique and true binary data transfer capability makes this mode suitable for HF data file transfers

Many RF/INTERNET gateways worldwide using PACTOR and the WinLink Network


8October 15-17, 2004

WinLink

Winlink 2000 provides a full-featured radio digital message transfer system, worldwide

Email transfer with attachments, map & text-based position reporting, graphic & text-based weather bulletin services, and emergency communications are now available to the Amateur radio community by linking radio to the Internet using PACTOR on the HF Bands

The mobile user, whether on the high seas, jungles of a remote region, or traveling in an RV, has the ability to provide family and friends with the state of their safety and well-being along with the joys of their travels.

The Winlink 2000 system is currently used for emergency communications where local or regional communications are disrupted, including the the loss of the Internet, and where accuracy of information is paramount.


9October 15-17, 2004

PACTOR II

Robust and powerful PSK mode which operates well under varying conditions

Uses strong logic, automatic frequency tracking; it is DSP based

As much as 8 times faster then Pactor 1 Both PACTOR and PACTOR-2 use the same

protocol handshake, making the modes compatible


10October 15-17, 2004

PACTOR III

Proprietary mode used for message and traffic handling over an HF radio circuit

Use of Pactor-III protocol is limited for NA hams and some other countries due to the very wide bandwidth

Only the embedded hardware (modem) from the German company that owns the rights to this mode, is capable of operating Pactor-III.

No software solution available EXPENSIVE modems!


11October 15-17, 2004

CLOVER

PSK mode which provides a full duplex simulation Suited for HF operation (especially under good

conditions) Clover’s key characteristics are band-width efficiency

with high error-corrected data rates Clover adapts to conditions by constantly monitoring

the received signal Hardware based mode and limited use


12October 15-17, 2004

HELLSCHREIBER

A method of sending and receiving text using facsimile technology This mode has been around a long time; the recent use of PC

sound cards as DSP units has increased the interest in Hellschreiber

The single-tone version (Feld-Hell) is the method of choice for HF operation

35 WPM text rate, with a narrow bandwidth (about 75 Hz). Text characters are "painted" on the screen, as apposed to being

decoded and printed As a "fuzzy mode" it has the advantage of using the "human

processor" for error correction.


13October 15-17, 2004

MFSK16

An advancement to the THROB mode and encodes 16 tones Uses Fast Fourier Transform technology to decode the ASCII

characters, and Constant Phase Frequency Shift Keying to send the coded signal. Continuous Forward Error Correction (FEC) sends all data twice with an interleaving technique to reduce errors from impulse noise and static crashes

The relatively wide bandwidth (316 Hz) for this mode allows faster baud rates (typing is about 42 WPM) and greater immunity to multi path phase shift

Becoming a standard for reliable keyboard to keyboard operation and is available in several popular programs


14October 15-17, 2004

MT63

New DSP based mode for sending keyboard text over paths that experience fading and interference

Complex scheme to encode text in a matrix of 64 tones over time and frequency

Error correction at the receiving end while still providing a 100 WPM rate

Wide bandwidth (1Khz for the standard method) makes this mode less desirable on crowded ham bands such as 20 meters

A fast PC (166 Mhz or faster) is needed to use all the functions of this mode.


15October 15-17, 2004

HF PACKET

HF Packet is an FSK mode that is an adaptation of the very popular Packet radio used on VHF FM

The HF version of Packet Radio maintains the same protocols and ability to "node" many stations on one frequency

Even with the reduced bandwidth (300 baud rate), this mode is unreliable for general HF ham communications and is mainly used to pass routine traffic and data between areas where VHF repeaters may be lacking


16October 15-17, 2004

PSK-31

Developed by Peter Martinez G3PLX in 1995 Integration between computers and ham radio. Replacement for RTTY? Software uses DSP processing of computer soundcards Software is free (Digipan, HamRadio Deluxe, etc) Great for late night QSO’s and ideal for QRP Uses phase shift keying (BPSK or QPSK) - very spectrum efficient. Narrower than CW. Up to 80 PSK31 signals in bandwidth of 1 SSB signal. Better than CW under weak signal conditions PSK31 more susceptible to frequency changes than CW or RTTY Throughput is 31 baud and bandwidth is 31Hz Varicode – all 128 ASCII characters are represented Operation centred around specific frequencies on each band


17October 15-17, 2004

PSK-31 – Technical Info

By comparing the 31Hz bandwidth of PSK31 against a CW filter of 500 Hz; 10 * log (500/31) dB = 12 dB, reveals that a CW transmitter must put out 15 to 18 times more power than a PSK31 transmitter, to achieve the same S/N ratio at the Rx

phase shift keying (bpsk or qsk) – 2 pure tones 31Hz apart 0 bit in the data stream generates a 180 audio phase shift, but 1

does not Decoding uses Viterbi decoder – 5 bit pipeline for 32 parallel

functions QPSK mode is very accurate but requires 4 Hertz freq stability


18October 15-17, 2004

SSTV

MMSSTV – software solution that has made hardware obsolete

By JE3HHT Makoto Mori and it’s freeware MMSSTV supports numerous subsets of the following

modes: Robot, AVT90, Scottie, Martin, SC2, PD, P3, P5, P7, MP,MR,ML

Uses the same soundcard + computer setup as PSK31, etc.

There are other software packages but this is the ultimate


19October 15-17, 2004

HARDWARE

Computer 486 with 16 bit soundcard at least Almost every Creative Labs or clone works ok Faster computers are better + Windows 98 or above is better

Interface – provides elegant connectivity between computer and radio Rigblaster – Cadillac – $60+ USD MFJ Sound Card to Rig Interface – Cadillac- $60+ USD Rascal by Buxcom (Buck Rogers) - $30 USD simple kit Homebrew - $10 in parts

Commercial boxes PSK80, PSK-40, PSK-20, PSK-10 by Small Wonder Labs for PSK-31 IC756Pro is RTTY Rx capable Pactor III modem - proprietary Some multimode TNCs


20October 15-17, 2004

PSK- 80 Warbler

Transceiver on a card for PSK-31 For 80m 3.580.5MHz +/- 500Hz >3w PEP PSK31 on LSB Only needs computer + 80m antenna Software is free (Digipan, HamRadio Deluxe, etc) Great for late night QSO’s Cost for the transceiver as a kit is $49 USD


21October 15-17, 2004

Software

Many software packages available on the INTERNET mostly “freeware” or “shareware”

Single Mode programs i.e. RTTY Multi Mode Programs Soundblaster compatible


22October 15-17, 2004

SOFTWARE

Single Mode MMTTY (RTTY) WinPSKse (PSK31) W1SQLPSK (PSK31) RckRTTY (RTTY) FELDHELL (Hell) IZ8BLY (MT63) STREAM (MFSK16) MMSSTV (SSTV)


23October 15-17, 2004

SOFTWARE

Multi-Mode WinWarbler (PSK31, RTTY) Digipan (PSK31, PACTOR I) Hamscope (CW, PR, RTTY PSK31, MFSK16) MultiPSK (BPSK31, QPSK31, PSK63, PSKFEC31, PSKAM,

PSKAM10, CW, CCW, RTTY, SITOR-AMTOR-NAVTEX, FELD HELL, PSK HELL, HF FAX, FILTERS)

MixW (SSB, AM, FM, CW, BPSK31, QPSK31, FSK31, RTTY, Packet (HF/VHF), Pactor (RX only), AMTOR (FEC), MFSK, Hellschreiber, Throb, Fax (RX only), SSTV, MT63)

INTERCOM (CW, RTTY Feldhell, PSK (RX & TX),TOR-FEC (RX)

Many others!!


24October 15-17, 2004

GETTING STARTED

Any modern solid state HF rig (low power ok for most digital modes)

PC (Pentium + preferred but some modes will work ok on 486) with Soundblaster compatible sound card

Interface Software (download from Internet)


25October 15-17, 2004

GETTING STARTED

Where to find digital modes?? 6 Meter Band: 50.290 - 50.292 Mhz 10 Meter Band: 28.110 - 28.125 Mhz 12 Meter Band: 24.920 - 24.930 Mhz 15 Meter Band: 21.060 - 21.090 Mhz 17 Meter Band: 18.100 - 18.110 Mhz 20 Meter Band: 14.065 - 14.090 Mhz 30 Meter Band: 10.130 - 10.145 Mhz 40 Meter Band: 7.060 - 7.080 Mhz 80 Meter Band: 3.620 - 3.640 & 3.575 - 3.585 Mhz


26October 15-17, 2004

GETTING STARTED

PSK 31 Frequencies 1838

35807035 for region 1 and region 3, and 7080 for region 2 * 10142

1407018100 21070

24920 28120


27October 15-17, 2004

GETTING STARTED


28October 15-17, 2004

GETTING STARTED


29October 15-17, 2004

What’s In the Future

Present options are excellent! Can it get much better? Software Defined Modes on Software Defined Radios? Speed? Continuous path testing. Automatic compensation for

fading and interference?


30October 15-17, 2004

INTERNET RESOURCES

http://home.teleport.com/~nb6z/frame.htm Great source of technical information

http://www.aintel.bi.ehu.es/psk31.html The “Official PSK31 Homepage”

http://www.qsl.net/wm2u/psk31.html Interface designs, links etc.

http://psk31.com/ Lots of information

http://mmhamsoft.ham-radio.ch/ Slow scan TV

http://www.arrl.org/tis/info/HTML/psk31/index.html PSK31 information

http://winlink.org/ WinLINK information

Do a Google search PSK31!!


31October 15-17, 2004

HW Suppliers – there are many

Interfaces http://www.radioworld.ca/ http://www.packetradio.com/psk31.html http://www.mfjenterprises.com/ http://www.westmountainradio.com/RIGblaster.htm

Radio on a card http://www.smallwonderlabs.com


32October 15-17, 2004

ACKNOWLEDGEMENTS

Thanks to NB6Z for providing some materials for this presentation: http://home.teleport.com/~nb6z/frame.htm

1 october 15-17, 2004 quarter century wireless association what's that racket?- hf digital...

Documents

common digital modes

demo slide

hf digital modes ken

tor modes amtor

hf bands

generosity of radio

hardware software

programming knowledge