A Sample of HF Digital Modes JANUARY 12, 2017

Selected HF Digital modes

• CW, Contestia, DominoX, Hell Schrieber

• MFSK, MT63, Olivia, QPSK, PSKR

• RTTY, THOR, THROB, TRUMP

• Lookup: http://www.sigidwiki.com/wiki/Signal_Identification_Guide

Other popular HF Digital modes

• JT-65 HF

• PSK-31

Similarities

• Text based communications.

• Simple, common hardware set-ups.

• Uses free or “donationware” software.

• Quiet, low power, useable in poor band conditions.

• Modest computing requirement.

This is a Practical Presentation

Lots of mathematics going on:

• Forward Error Correction• Compression• Frequency Division Multiplexing• Time Division Multiplexing• Other non-Trumptonian science-y stuff

Let’s have some fun instead.

Common Hardware Set-up

1. Software specific to the digital mode.

2. Windows-based desktop or laptop (Win XP thru Windows 10).

3. External sound card.

4. Cabling from PC to external sound card.

5. An HF Transceiver.

6. Cabling from external sound card to transceiver.

7. Setup can go directly from PC to Transceiver as well.

Basic communication required

• Receiving

1. Audio from radio to computer input (Mic or line in)

2. Decoding to readable text (software)

• Transmitting

1. Text to Audio (software)

2. Audio from computer (line out or speaker) to transmitter.

3. Trigger PTT or equivalent on transmitter

External Sound Card – Tigertronics Signalink USB

• Built-in Low-noise Sound Card• Complete Radio Isolation• USB Port Powered• Works with most radios• Uses Mic, Data, or Accessory

Port

External Sound Card – Rigblaster Advantage

• Built-in Low-noise Sound Card• Complete Radio Isolation• USB Port Powered• Works with most radios• Uses Mic, Data, or Accessory

Port

Why use an External Sound Card?

• Takes sound processing (analogue to digital) away from the PC.

• Allows better performance of the PC and the software.

• Separates computer sounds from the reception / transmission

• Makes audio level adjustments easier and quicker for send/receive

A Typical Hardware Setup

Our first mode - JT- 65 HF

• Weak-signal radio communication (below noise level).

• Developed and released in late 2003 by Joe Taylor, K1JT.

• American astrophysicist and Nobel Prize in Physics laureate for his discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation.

• JT-65 allows amateurs to exchange contact information without signals even being audible to the operator.

JT- 65 HF• Messages are transmitted after being compressed and encoded

with a process known as Forward Error Correction (FEC).

• Demo software used http://jt65-hf.com/downloads/ is open source and free.

• Software adds redundancy to the data, so all of a message may be successfully recovered even if some bits are not received by the receiver.

• Uses 65 tones. 200 Hz wide.

JT- 65 HF• Each transmission begins at t = 1s after the start of a UTC minute

and finishes at t = 47.8 s.

• Computer time is critical. Set PC using WWV, CHU Canada or internet time

• 100% duty cycle on transmit – Can your transmitter handle it?

• 5 milliwatts to 50 watts maximum on HF. More is not better, just deafening to others.

JT- 65 HF

• No rag chewing here, strictly making and acknowledging contact.

• Message types: CQ, Acknowledge, Report and 73. All messages are generally software generated – short and sweet.

• Receive on odd/even minute and transmit on the opposite.

• Wait and hurry-up. (8-10 secs. to respond after 47+ secs. to receive)

• Requires a pretty good PC for fast decoding. Not a lot of time before receiving and sending. (13 seconds if you’re lucky)

• Act quick - receiving, selecting contact and pick the right standard message to send back.

JT-65 HF – a Typical “Short” QSO

• CQ VE3HOR EN93 - takes 47.7 seconds to send (odd minute)

• VE3HOR W1AW FN31 – 47+ secs to receive and decode (even min.)

• W1AW VE3HOR R-09 – sent on the odd min with signal report.

• VE3HOR W1AW RR-12 – even minute – roger roger & my sig. rpt.

• W1AW VE3HOR 73 – odd minute – confirming receipt – buh-bye

• Total 5 minutes + wait for next odd minute to CQ again.

JT-65 HF – a “Short” QSO – Brazil 5 watts - vertical

JT-65 HF – a Typical “Short” Standard QSO

JT-65 HF – Waterfall or a Trickle

JT-65 HF – Settings

JT-65 HF

• Fun?

• Not for everyone, but it does work even in poor band conitions.

• Not a contesting mode.

• The shack is quiet! Unless something goes wrong.

2nd mode: PSK-31

• Uses Phase Shift Keying, 31 Baud (roughly 30 characters per second).

• Other variants/speeds but this one is the most popular.

• The information is transmitted by patterns of polarity-reversals (sometimes called 180-degree phase shifts).

• 5 -35 watts (50 max) on HF. Usually USB.

• Don’t ever use 50 watts on Field Day. You’ll never live it down.

• 100% duty cycle on transmit. Watch it on long raw-chewing QSOs.

• Is it a contesting mode? Yes. Definitely. But not at the start.

PSK-31

• Some available software: Digipan 2.0, FLDigi, AirLink Express.

• Some are freeware, some are “donationware”.

• Lookup: http://www.airlinkexpress.org/

• Macro-based transmissions generally.

• Rag-chewing is definitely used.

• Not time dependant, so no waiting to send/receive.

• Is not “noise floor or below” workable.

• Just above is OK though.

PSK-31 – Sample Field Day Macros

• M1 | CQ Field Day: <tr>cq fd cq fd VE3LON VE3LON VE3LON cq fd k<rec>

• M2 | Answer: <tr><callsign> de VE3LON VE3LON k<rec>

• M3 | Send rpt: <tr><callsign> <rpt> 7A ONS 7A ONS 7A ONS <callsign> <rec>

• M4 | 73 and write to log: <tr><callsign> QSL 73 sk<add-log><rec>

• M5 | QRZ: <tr>QRZ? AGN? AGN?<rec>

PSK-31

• Fun? Yes.

• Great for folks who are mic shy or who love to type their QSOs.

• Macros save typing, thinking.

• And again, the shack is quiet! Spouses love that I hear.

• Because PSK31 has a bandwidth of only 31Hz, many signals can fit into the same bandwidth that would be occupied by an SSB signal (2.4kHz approx.). It is quite common to see 15 or more signals on a 2.5kHz waterfall display.

PSK-31 – One strong and 14 weak contacts Waterfall

PSK-31 Full Screen – 8 x 10 Glossy edition

PSK-31 Decoding – it ain’t perfect at times

PSK Reporter

PSK Reporter

• Web-based tool showing identified contacts my mode.

• In real time.

• Where is my signal being heard?

• Where are stations active?

• World-wide.

A Sample of HF Digital ModesQuestions and JT-65 Demo