Soundcard Digital Modes for Dxing Or Dxing on a Budget by Jim Sears WA3MEJ 10 August 2012

Typical Questions Newbies Ask Why use digital modes for Dxing? What hardware is necessary? What software is necessary? How much power is needed? Who is using digital modes? When and where should I look for stations? Copyright J.L.Sears WA3MEJ

Why Use Digital for Dxing? Don't need high power Lots of Dx stations use Digital You can gain 25 or more Db over SSB Some modes copy signals 20+ db below noise Great for hearing impared operators Copyright J.L.Sears WA3MEJ

What hardware is necessary? In addition to the normal station equipment a computer with a soundcard installed and an interface are all that are required. Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ Typical Interface Copyright J.L.Sears WA3MEJ

Where to get an Interface An interface can be homebuilt or can be purchased from one of the normal suppliers Tigertronics MFJ Rigblaster Buxcom Copyright J.L.Sears WA3MEJ

What software is necessary? Special software is necessary for soundcard digital modes. Some of the authors have written packages that support many modes. Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ Software JT65hf Mixw Digipan Fldigi Multipsk TrueTTY Winpsk Winwarbler And many more Copyright J.L.Sears WA3MEJ

How much power is needed? Typically less than 25 watts is used on all bands, many stations use 10 watts or less Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ The Digital Advantage Tests between WA3MEJ and W3JW in Deltaville, Va. Show 100% communications was possible with 1 watt on PSK31 when communications with 1500 watts on SSB was just barely possible on 160m in during the summer. 10 log (1500/1)= 10 log (1500)= 10 * 3.176= 31.76db Copyright J.L.Sears WA3MEJ

Compare Spectrum CW & PSK31 Copyright J.L.Sears WA3MEJ

Common Soundcard Digital Modes BPSK QPSK Olivia RTTY MT63 MFSK16 JT65hf WSJT Wolf Argo WSPR CW Copyright J.L.Sears WA3MEJ

Who is using digital modes? JY5FX 17m CO8LY 40M HB9ARI 40M ZS2ACP 40M ZL3NB 40M 5H3ME 20M SA6OA 80M UA9MA 20M TO3X 20M A61BK 40M SU9VB 30M TF3IG 20M J73WA 20M UU9JQ 40M VP2MFF 17M SV1EQA 17M 6D0LM 20M FG4NO 17M KG4SS 40M KF3AK 10M C31CK 20M J38RF 17M JQ1TIV 30M VK3LD 30M Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ What Goes Wrong Hardware Software Improper Adjustment Operator error Copyright J.L.Sears WA3MEJ

Example of Good Signals Copyright J.L.Sears WA3MEJ

Examples of Bad Signals Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ Bad BPSK Railroad tracks Transmitter probably drawing ALC and probably running too much power. Notice AGC action This is bad thing! It robs All the other stations because he hogs receiver gain Railroad Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ AGC Action Overdriven? Notice about half way Down. The change in color is due To AGC action This is bad thing! It robs All the other stations because he hogs receiver gain Copyright J.L.Sears WA3MEJ

How to Correctly Tune Transceiver Tune up as you do for CW/SSB Set mode to USB Leave Power set to Maximum output Adjust sound card "Out" to set power out & make sure xcvr does not draw ALC at all Adjust sound card "In" for just enough audio to get a good reliable trace on the waterfall Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ Weak Signals WORK You dont need a lot of power. This station is probably running Less than 30w and yet his signal is quite copyable Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ JT65 DX is Plentiful Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ Things NOT to DO Turn RF down after tuneup Run any ALC Run excessive power Copyright J.L.Sears WA3MEJ

Things You Will Want to Do Keep power low (25-30w or less) Listen before transmitting Adjust power out by adjusting audio from computer Have someone check your signal occasionally Don't be afraid to try operating above the listed MUF Check frequency do not interfere with others Have fun Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ 15M Contact Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ Real Time Map 8/31/12 Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ Paul N0NBH Predictions Paul N0NBH predicted 17.89 MHz for 3 Sept @ 0257Z Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ MUF Definition The MUF is the highest frequency for which an ionospheric communications path is predicted on 50% of the days of the month. On a given day, communications may or may not succeed at the MUF. Commonly, the optimal operating frequency for a given path is estimated at 80 to 90% of the MUF. Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ MUF Is a predicted number Varies acording to the takeoff angle Implies signal quality Highly path dependent Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ Calculating MUF Fcrit MUF = ------------- Cos θ <--- Incident Angle OR Sin θ <--- Take Off Angle Copyright J.L.Sears WA3MEJ

Critical Frequency (Fcrit) That frequency at which a signal will pass through the ionosphere and not be reflected back to earth Ref: http://www.its.bldrdoc.gov Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ VI Sounder Geometry Copyright J.L.Sears WA3MEJ

HF Signals - Angle of Arrival 20 Meters 17 Meters 15 Meters 12 Meters 10 Meters Europe 1-21 1-12 2-12 2-11 Far East 1-16 2-15 1-17 3-13 S. America 1-13 Oceana 2-10 S. Africa 3-12 S. Asia 2-14 3-14 4-11 Copyright J.L.Sears WA3MEJ

MUF based on Critical Angle Fcrit MUF-using cosine 1 6.5 6.50 10 6.60 15 6.73 20 6.92 25 7.17 30 7.51 35 7.94 40 8.49 45 9.19 50 10.11 55 11.33 60 13.00 65 15.38 70 19.00 75 25.11 80 37.43 85 74.58 Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ VI Sounder @ Boulder, CO Fcrit = 6 .0MHz Copyright J.L.Sears WA3MEJ

Copyright J.L.Sears WA3MEJ To Calculate MUF Must Know: Fcrit – critical frequency Take Off Angle or Incident Angle Minimum % time circuit must be present Implies: Circuit quality or signal to noise ratio Copyright J.L.Sears WA3MEJ