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Join The Fun!. Digital HF: what are you waiting for? A presentation for the Gloucester County ARC, NJ by Jim Wright (N2GXJ) and Ken Newman (N2CQ). Why add digital modes?. Be honest Tired of your old radio? Too much static in the headset? Frustrated with band conditions?

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Join The Fun!

Digital HF: what are you waiting for?

A presentation for the Gloucester County ARC, NJby Jim Wright (N2GXJ) and Ken Newman (N2CQ)

why add digital modes
Why add digital modes?
  • Be honest
    • Tired of your old radio?
    • Too much static in the headset?
    • Frustrated with band conditions?
    • Tired of the same old operators?
    • Want to meet some new hams?
    • Want to enjoy more DX?

Then maybe the HF digital modes are for you!

hf digital modes
HF digital modes

To quote long time ham, NB6Z“The distinguishing features of live HF digital operation today are the use of lower power, compact or indoor antennas, and courteous operating technique. This reverses the trend of several years ago…”

Unexpected operating benefits

  • When operating radio in digital mode, there’s no microphone, no noisy speakers, no headset required!
  • Break free of the shack! With a laptop, can enjoy quiet time with your significant other, sitting together on the couch (pretending) to watch your (their) favorite (reality) TV show, while still chasing DX! (… Just saying… Not that anyone would do this... Would they?)
band conditions
Band conditions
  • “Conditions are terrible. The bands must be closed.”
    • Not so fast!
    • It used to be that you had to “hear ‘em to work ‘em”
    • Not so with some of the modern digital modes!To put it in perspective, a 2002 study found majority of CW ops could copy at an S/N ratio of 0db, but less than 4% could copy down to -7db*. Contrast that with digital mode ‘Olivia’ which can be decoded when it is 10-14 db below the noise floor (noise is 3x stronger than the signal!) And digital mode ‘JT65HF’, with QSOs possible to -20db! *ref: “The Weak-Signal Capability of the Human Ear”, Ray Soifer, W2RS, Proceedings of the Central States VHF Society Conference, 2002
    • Low sunspots, spectrum crowding, fading, impulse noise, static crashes, QRM, QRN, QSB, you name it:
      • Modern digital modes are popular because they can work well, even under less than ideal conditions!

Bands seem dead? Try HF digital modes instead!

enjoy more dx
Enjoy more DX!
  • “It’s hopeless. I’ll never get DXCC.”
    • Wrong! We’re lucky living on east coast USA!
    • You just need to try HF digital modes, they’re DX friendly! (See the 4 hour reception map on the title page of this presentation)
    • It’s not uncommon to log more than a dozen countries in a single hour with one mode (PSK31) on one frequency (14.070 Mhz).
    • Worked All States (WAS) and mixed mode DX Century Club (DXCC) awards in less than a year with under 50W and only a dipole antenna up in the attic? Yes, you can! (e.g. n2gxj)
    • If you’re an SSB and/or CW op, for fun, why not consider adding digital modes to your existing DX options?

Digital modes are DX friendly!

meet new hams
Meet new hams!

There’s a growing community of new digital users out thereall over the globe, on all bands, at all hours of the day!

Digital is the fastest growing area of our growing ham radio hobby! *ref2

*ref1: 4/21/2012 *ref2: “Ham Radio for Dummies”, W.Silver, Wiley&Sons pub

enjoy more dx1
Enjoy more DX!

East coast stations regularly catch digital DX

*ref: 4/17/2012

enjoy more dx2
Enjoy more DX!

Maybe add digital modes to your existing DX capabilities?

*ref: 4/17/2012

a typical saturday afternoon
A typical Saturday afternoon

How many digital QSO can you count in this 3khz of audio bandwidth?

panoramic simultaneous decode
Panoramic simultaneous decode!

That looks fun! … Ready to give it a try?

adding digital capabilities
Adding digital capabilities
  • Goals:
    • Upgrade, not replace, existing HF radio ($)
    • Preserve your existing CW/SSB capabilities!
    • Add a whole new world of HF digital possibilities!
  • How to? The options:
    • If your radio is an SDR, just add digital software 
    • Else, connect audio jacks/ptt on your radio via an adapter to ports on your PC, then add digital software to your PC
      • Via “build-it-yourself” interface, or
      • Via “buy-it-yourself” interface
build or buy interface
Build or Buy interface

Basic elements of either approach:

  • (RX) Audio from radio into the PC
  • (TX) Audio from PC to the radio
  • (TX KEY) PTT, or VOX, for transmit
build it yourself

For the $ saver, DIY enthusiast

  • For SWL, no circuit needed. Just let computer’s built-in mic listen to the radio
  • For clean RX/TX, use cables and the PC’s sound card for A/D, D/A conversion
  • Simple connection shown above, with VOX enabled on radio for TX, may be all you need
  • If ground loop issues, use audio transformers, as shown on right



If you are thinking of BIY, a recommended reference:

buy it yourself
Buy it Yourself
  • Easy install:
    • Vendor often can supply cables specific for your radio model
  • Interface simplicity:
    • USB between Box and your PC (most PC’s don’t have RS232 anymore)
  • Interface box contains its own soundcard
    • Soundcard in PC can still be used for PC sound

*Ref: Pictured units and trademarks are property of their owners: SignaLink (Tigertronics), RIGBlaster (West Mountain Radio), MFJ (MFJ)

digital mode software
Digital mode software
  • Hundreds of choices
    • Some that may have been good in 1999, or even 2007, just can’t compare to the most popular choices in use today
  • Some features to consider:
    • Continued support/upgrades
    • Compatibile with your PC’s OS
    • If it has the modes you want
    • Ease of integration with contesting/logging program(s)
    • Interfaces with online service(s)
      • Callsign lookup
      • Electronic QSL services
      • Spotting networks
      • Reverse beacon networks
    • Cost
multimode or specialty
Multimode or specialty?
  • Start with a multimode software package
    • Lets you operate many popular modes without switching programs
    • Learn once, use for many modes, higher enjoyment
    • Tend to be more modern, more features, more fun
    • Get familiar with one, then can compare with others,at your leisure
  • Later can look into specialty programs, e.g.
    • Weak signal beacons/reception reporting (e.g. WSPR),
    • Weak signal QSOs (e.g. JT65HF),
    • Digital slow scan TV (e.g. EasyPal),
    • Digital modes on smartphones (see cover story of May 2012 QST magazine)
top picks imo alphabetical
Top Picks (imo)(alphabetical)
  • Fldigi (
    • Available for Linux, OSX, and Windows. Popular for narrowband messaging, emergency comms use. Free.
  • HRD/DM780 (
    • Package includes integrated rig control, decoders, logger, and much more. Windows. Pay after June 2012.
  • MixW (
    • Windows. Favored by many digital contesters. Pay.
  • Multipsk (
    • Some consider this the “swiss army knife” of digital software packages. Register (pay) version more full featured.
  • older (Digipan, Hamscope) – try a few, see what works for you!

Ref with links to these, and more:

topics for future presentations
Topics for future presentations

Many digital software packages integrate with electronic logging systems (like LoTW, eQSL,, and online services (such as callsign lookup (e.g., DX clusters, and reverse beacon networks (above: qso’s logged in last hour,

Each of these are involved enough to be candidate topics for future discussion!

  • These are the ones to start with:
    • Radio Teletype (RTTY) Frequency Shift Keying
    • PSK31 Phase Shift Keying
  • After those, you might consider adding some of these modes to your digital DX repertoire
    • MFSK - if one or two tones are good, why not more?
    • JT65a - just for DX qso credit. No conversations at all.
    • Olivia - conversational, even for very faint signals
    • Hellschreiber – let your eyes do the fax processing
    • SSTV - sending regular and high def pictures over HF
  • How to recognize these modes, and where to look for them on the dial? (we’ll cover that next!)
when getting started
When getting started
  • Tip 1: Digital modes are typically 100% duty cycle, often with long duration transmissions. Care should be taken to avoid overheating and damaging your radio finals.
    • Keep power levels low
    • consider temperature monitoring, additional cooling, fans
  • Tip 2: Overdriven audio is most common cause of band splatter.Is easy to avoid being the guy with the ghosting shown above.
    • Turn off SSB compressor
    • Reduce audio drive levels to below AGC threshold
  • One of the oldest modes, in use since WW II
  • Popular for DX and world-wide radio contests
  • Continuous transmission using FSK (or AFSK) between two tones
  • Common: 28.080-28.100, 21.080-21.100, 14.080-14.099*, 7.080-7.100 Mhz
  • Typical setting: 45.45 baud, 170Hz shift between tones
  • Support for other bauds/shifts common, as is ‘reverse’ to allow use with USB or LSB radio setting (EU stations tend to use USB)
  • Limited character set (e.g. UPPER CASE ONLY)
rtty qso
  • RTTY QSOs tend to be brief, particularly for busy DX stations, and for contests where only calls and signal reports need to be exchanged (no names, serial numbers, nor locations
  • Simulated brief QSO example:
    • > CQ CQ CQ DE N2GXJ N2GXJ (n2gxj calling cq)
    • < W2MMD W2MMD (w2mmd answers)
    • > W2MMD 599 599 W2MMD (n2gxj acknowledges w2mmd, with sig report)
    • < N2GXJ 599 TU (w2mmd confirms report, and returns n2gxj’s)
    • > 73 DE N2GXJ QRZ? (n2gxj confirms report, and asks for next station)
  • Of course, RTTY is a keyboard typing mode, so you can ragchew for hours instead if you want
    • and some do!
operating rtty split
Operating RTTY Split
  • Rare DX and DXpeditions will often run RTTY “split”, where they TX on one frequency, and listen in range up/down 1-5 Khz
    • e.g. CQ CQ 7O6T UP 1-2
  • Tip: use “split” capability of your decoding software, instead of your radio’s split capability when ‘up’ is <3 Khz
    • See DX station’s TX and how he is ‘up’ answering on same waterfall
    • Easy drag/drop your TX freq to most likely place to be answered next!
psk 31 63 125
PSK (31,63,125)
  • Very popular!
  • 31Hz bandwidth advantages: QRP DX, less spectrum crowding
  • Seems like you can always find some PSK “tracks” on air!
    • Where’s the band open to? (Just check who’s on the psk frequencies!)
  • Common dial frequencies: 50.290, 28.120, 24.920, 21.070, 18.100, 14.070, 10.140, 7.040, 3.580, 1.838 Mhz.
  • PSK in different widths (31, 63, 125 Hz)PSK31 is better decode, but PSK63/125 faster for contests
  • “varicode”, so lower case letters send faster (cq cq cq)
psk qso
  • PSK QSOs tend to be push-button English language “macros”, with certain fields filled in by the software.Simulated example:
    • < N2GXJ DE W2MMD W2MMD
    • > W2MMD DE N2GXJHello OM, UR RST: 599 599QTH: Sewell, New Jersey LOC: FM29krName: Jim JimClubs: GCARC, EPC# 15956, PODXS070# 1424How Copy? BTU W2MMD de N2GXJ kn
    • (and on-and-on, often with ‘brag’ file about antenna, etc)
  • Even with prevalent macro use, once basics are out of the way, it’s still possible to end up in 30+ minute typing ragchews, especially on lower bands
other modes mfsk16
Other modes: MFSK16
  • MFSK16 frequency shifts between 16 tones to improve signal detection in presence of random distortions, including multipath
  • Look for signals near: 14.078, 3.584 Mhz (ref:
  • Not seen that often. Other digital modes based on frequency shifting between multiple tones are more common (including JT65a for HF, discussed next)
other modes jt65a
Other modes: JT65a
  • Developed for moon-bounce, then adapted for HF, is a popular weak signal mode for DX (many signals shown in the 1.5 Khz audio trace above)
  • 25 Watts is considered high power! Decodes to -20db S/N levels possible
  • Common dial frequencies: 28.076, 21.076, 18.102, 14.076, 7.076 Mhz
  • QSOs are SLOW. Stations alternate even/odd minutes with 46.8 second transmissions
  • Coordinated time synchronization of PCs needed for reliable decodes
jt65 qso
  • JT65A QSOs are very rigid – and just convey the bare essentials: callsigns, signal reports, and locations. (no “chat” mode)
  • Simulated example:
    • odd > CQ N2GXJ FM29 (n2gxj calling cq from Maidenhead grid square location FM29)
    • even< N2GXJ JE1LET PM95 (je1let answers, giving his location)
    • odd> JE1LET N2GXJ -13 (n2gxj acknowledges je1let, returning signal report of -13Dbm)
    • even< N2GXJ JE1LET R-12 (je1let confirms report, and returns n2gxj’s report of -12Dbm)
    • odd> JE1LET N2GXJ RRR (n2gxj confirms receipt of his signal report, so je1let wont resend)
    • even< N2GXJ JE1LET 73 (je1let says thanks, n2gxj can then do same, or call cq again)
  • That’s just one qso in 6 minutes
  • Often takes longer due to misses, and need to wait for next cycle to repeat
jt65a decode
JT65a Decode
  • Can be confusing. There is a 13 character “free form” available in place of final 73 message, but without callsign, need to look at Hz delta frequency to see who sent (e.g. @20:37, +0130 was KE0YI). Better to use the stock 73 message (push button “answer 4”).
olivia the magical mode
OliviaThe “Magical Mode”
  • Robust QRP-friendly keyboard conversational mode with excellent resiliency to fading and noise
    • QSOs possible even when can’t hear it, or see it on the waterfall!
  • Multiple bandwidth/tone format choices available
    • 500/16, 1000/32 most common, 250/8 shown in example above
  • Tuning: “Voluntary channelization” per band/format: e.g. DIAL=14074.65kHzUSB - AudioCenterMarker= 750Hz - Format= 500/16, (14075.4kHz(Center_Freq)) DIAL=14106.50kHzUSB - AudioCenterMarker=1000Hz - Format=1000/32, (14107.5kHz(Center_Freq)) DIAL=18102.65kHzUSB - AudioCenterMarker= 750Hz - Format= 500/16, (18103.4kHz(Center_Freq)) DIAL=21086.50kHzUSB - AudioCenterMarker= 750Hz – Format= 500/16, (21087.25kHz(Center_Freq)) DIAL=21152.50kHzUSB - AudioCenterMarker=1000Hz - Format=1000/32, (21153.5kHz(Center_Freq)) DIAL=28076.00kHzUSB - AudioCenterMarker= 750Hz - Format= 500/16 , (28076.75kHz(Center_Freq)) (see,
  • Expect a lag from signal on to decode start of 4-6 seconds
hellschreiber feld hell
Hellschreiber (Feld-Hell)
  • Fax-based teleprinter system, used by the Germans during WW II
  • Translated as “light writer”, result is a dot matrix print
  • Unique, in that it is visually-based decode mode
    • Turns out human brain is very good at reading text in noise
  • Look for signals below PSK range: 14.063-14.069 Mhz
  • Dedicated enthusiasts love the mode, maybe you too?(ref: )
sstv dsstv
  • Analog slow scan TV has been popular on HF for a long time. Send/receive GIF/JPG/BMP pictures via HF radio!
  • Now high def Digital SSTV is getting lots of buzz, thanks to DRM (digital radio mondiale), and new software packages like EasyPal (refs: , )
  • Want to listen in? These digital signals are found in “voice” part of bands. Try: SSTV near 21.340, 14.230, 7.171 ; DSSTV near 21.337, 14.233, 7.173 Mhz
recognizing signals by sight sound
Recognizing signals by sight/sound
  • Let’s try a round of “Decode that signal”
so what s holding you back
So what’s holding you back?
  • Join the thousands of hams using digital modes daily
  • Enjoy DX with low power and an attic antenna
  • Set aside all the static and shouting
  • Play on the radio without disturbing the rest of the family
  • Another way to help in emergency communication situations
  • Extend your own horizons with new opportunities:Digital contests, typing qsos, digi nets, awards
  • Push your hobby’s technology envelope
  • Experiment with new modes, meet new people

Come on in, Join the Fun!