Digital Ham Operations

An Overview - Mainly For Beginners

John MacFarlane VE7AXU / VA7PX 2013

Presented January 9, 2013 to the Surrey Amateur Radio Club, Surrey BC

with assistance from Brett Garrett VE7GM

Introduction• Getting on the air on HF can be intimidating for a

new ham. • I am assuming that you have a licence and have HF

privileges and you want to go beyond using VHF on the repeater

• Digital modes are a great way to get introduced to exciting on-air action with minimal investment.

• Its my hope that hams who are not currently operating on HF will become active through these exciting modes.

First Some Technical Background

• The basic element is the binary bit (0 or 1, on or off, plus or minus, yes or no, on or off)

• Morse for example is on and off

• (Sound of a morse (CW) transmission) (Sound recording courtesy of Brett Garrett (VE7GM) using Fldigi sofware – more on that later)

What Are Digital Modes?• Amateurs use an SSB Class-A transmitter to send and

receive (signals must be linear)• They use a personal computer sound card to code

and decode the signals (numerical values at a fixed rate) which create audio sounds. You can hear these signals on the air – but the computer decodes them.

• Letters, numbers etc. can be encoded using these techniques and transmitted over the air and decoded at the other end

• Characters are coded so that each letter and number etc. has a unique code, which often takes at least five data bits and a synchronizing bit per character.

• Each RTTY (radio teletype) character requires 7.5 bits – and at 45.45bps that sends 6 characters per second.

• RTTY is sent at 60 wpm• PSK31 is sent at 35 wpm• MFSK16 is sent at 40 wpm

Some modes use alphabets that have a variable number of bits per second. Morse or PSK modes frequently use characters with shorter sequences (eg. in morse “e” is one dit) – in other digital modes1 code for “space”11 code for “e”101 code for “t”111 code for “o”1011 code for “a”1111 code for “n”...... and so on ….1010101101 code for upper case “Z”

By increasing the number of bits used it is possible to send hundreds of different characters (eg. useful for sending Japanese characters)

Signals are synchronized so that the receiver can tell when one letter ends and the next begins so a special serious of bits marks the end.

Noise on air can confuse the decoder losing the data – causing errors at the receiving end – and cause what looks like garble – noise gets decoded too

• In digital signals there are built in methods to allow errors to be automatically fixed, either by ...

• the receiving station detecting the error and asking the sender to send again, (Automatic ReQuest repeat - ARQ)

• or sending extra information so that the character can be reconstructed and corrected without retransmitting (forward error correction - FEC)

Digital Modes• CW (morse code)• Pactor – used for sending email over the air.• RTTY (radio teletype) • PSK31 (phase shift keying at 31 baud)• Hellschreiber (sends a ‘picture’ of the character)• MFSK (sends lots of data to reduce errors)• Throb (very low speed – very accurate)• Olivia (requires precise tuning)• SSTV (slow scan television)• and others (each looks and sounds different)

What Equipment is Needed?

• Computer running Windows or Linux/Unix• Transceiver capable of SSB and monitoring of ALC at

about 20 watts or less (can be an older second hand rig)

• Interface between the computer and the transceiver (can be home made or purchased)

• HF antenna (I use a wire and vertical very successfully)

• Software to code and decode (good freeware is available)

Some Digital Hardware• Interface

– Usually a ‘box’ between the computer and transceiver connected by cables

– Can use the internal sound card in computer– Can be home-made– Can be purchased from suppliers (not hugely expensive)

• SignaLink• Rig Expert• Rig Blaster• US Interface Navigator (by KK7UQ)

What Equipment is Needed?

• Computer running Windows or Linux/Unix• Transceiver capable of SSB and monitoring of ALC at

about 20 watts or less (can be an older second hand rig)

• Interface between the computer and the transceiver (can be home made or purchased)

• HF antenna (I use a wire and vertical very successfully)

• Software to code and decode (good freeware is available)

My Setup

Some Popular Digital SoftwareSoftware Comment Source

MixW Many different digital modes. Logs QSOs and handles eQSL and LOTW. Costs about $50 – and if you buy it download it through their US internet site! Developers seem to have lost interest in supporting it.

www.mixw.net

Digipan Soundcard freeware. PSK31 & PSK63. Monitors multiple channels, logs QSOs. Can view multiple QSOs simultaneously – a great starter program

www.digipan.net

Fldigi Soundcard freeware. Many many digital modes – many hams consider this the best digital program on the air.

www.w1hkj.com

Hamradio Deluxe (PSK31 DeLuxe)

Soundcard freeware. PSK31. Part of a suite - links to logging program. Many many modes – the most popular program on the air but a very steep learning curve because it has so many great features.

hrd.ham-radio.ch

What Is PSK?• This digital mode introduced by Peter Martinez

G3PLX and uses phase modulation and special character coding

• Allows robust narrow bandwidth keyboard “chat” between two stations

• Bandwidth is equal to the baud rate (BPSK31 is 31Hz)

• Originally designed for a Windows soundcard using an SSB transceiver with PSK signal generated and received as an audio tone

• (PSK sound recording)

PSK mode• Similar in visual appearance to text messaging on a

computer using narrow bandwidth• Doesn’t require good hearing by users• Operates extremely well under low power – 30 watts

is generally the maximum for average use and will get you around the world. I use 20 watts.

• Users tend to be very friendly and very helpful• Equipment is very modest and software can be free

or at low cost• This is the mode to start in as a beginner

FLDigi Software• Its FREE (download it off the web from the

official site)• Mildly difficult to configure (ask for help if

needed – there is a great online help group)• Has on ‘on board’ log in the program• Can be “bridged” to N1MM or to DXKeeper

for logging with more robust features

Bridge to Logging Software• Google “bridging software”• www.n2amg.com/software/fldigi-dxlabs-

gateway/• Can go from Fldigi to many different logging

programs• Can ‘bridge’ from and to many other

programs too with freeware provided on this site

Assigning Com Ports• All digital software involves some configuring• You can see the port assignments on your

“system” in the control panel• You’ll need to know those allocations so you

can set up your software on your computer• They are all different so you need to see how

your computer is handling your allocations• Find out more on how to check this on the

internet – or ask an ‘elmer’

Interface set-up screen for a hardware computer interface

Some Other Digital ‘Flavours’MFSK16, DominoEx RTTY

QPSK and other flavours

WSJT65

Olivia: 2K, 1K, 500, 250,125 baud

Packet

Contestia: 2K, 1K, 500, 250,125 baud

Amtor/Pactor

RTTYM SSTV: many styles

Throb Hellschreiber: Feld Hell, FM Hell 245, FM Hell 105, PSK Hell

MT63: 2K, 1K, 500 CW

Clover (related to PSK) Stream

Some Suggested Operating Frequencies

• 160m – 1838 Mhz• 80m – 3580 Mhz• 40m - 7035 – 7045 and 7070 Mhz• 30m – 10142 Mhz• 20m - 14035 & 14070 Mhz• 15m – 21070 Mhz• (Also on 10m, 12m, 17m)

Example of a “good” signal

Example of a “bad” signal

Operating Screen Examples

Over-driven signal (too wide)

Empty carrier

Noise and weak signal

RTTY signal

• Popular contest mode• Fast action• Lots of users• Good for DX• Easy to use and set up

(Example of sound recording)

Example Hellschreiber signal

(Example of sound recording)

MFSK SignalGood for accuracy under difficult conditionsGood for message handlingIgnores lightning Tuning is critical

Signal seen horizontally

Signal seen vertically

(Example of sound recording)

Logging Software• Keep a log – its good operating practice• You need it to send and receive QSL cards• You need it if you ever apply for awards• Legally, a log of your transmissions would be invaluable in

proving your innocence in an interference complaint. A record of dates, times, frequencies and so on, will be evidence of your operating activity that can be compared to the dates and times of interference.

• Contact records can be an aid in determining which bands and times of day seem most useful for your station.

• There is the pleasure of looking back through the log at the contacts

DX Keeper• Software is free (part of a suite similar to

N1MM) and can be bridged to most popular digital software programs

• Active ‘reflectors’ for getting information and help

• Easy to use and set up• Regular updates provide (can be subscribed)

DX Keeper

Reflector Groups• Join the reflector groups for the software packages

you use – and pay attention to the postings• Don’t be shy about asking for help – no such thing as

a dumb question• But search the history in each one to see if someone

already asked it and got an answer – they all get saved in the archive

• Yahoo groups hosts some of the best• Also look on Eham.com – particularly in the “Elmer”

forum

QRZ.com• Look up your callsign on QRZ.com – its listed there

automatically • Sign up so you can edit your entry• Check your address and add your email address so

other hams can contact you• Give a brief bio on your ham activities and interests• Indicate whether you exchange QSL cards – and if you

do what methods do you use• Update the entry even if you don’t do much operating –

even your acquaintances may look you up

LOTW & eQSL• Seriously consider exchanging QSLs• Traditions method is a printed card to confirm contacts• eQSL is an electronic method• LOTW is the most serious approach (run by the ARRL)• You have to “join” both LOTW is free and eQSL

encourages donations

• DX Keeper handles both straight out of the logbook allowing both upload and download of confirmations