Software Defined Radios A Contester’s Perspective by Bob Wilson, N6TV Visalia DX Convention Contest Forum April 26 th, 2008 With thanks to Jeffrey Pawlan, WA6KBL Ilberto di Bene, I2PHD

This is not a technical talk  I will not try to explain how SDRs work  I will try to show how they could be used by contesters

What you will see  Brief overview of some available SDR hardware  Demo of WinRad software, by I2PHD  The “Waterfall display”  Demo of CW Skimmer by VE3NEA  An SDR on the Web  Implications and Discussion

Softrock-40

Softrock 6.1

RFSpace SDR-IQ

Microtelecom Perseus (used to make demo recordings)

FlexRadio Flex-5000A

FlexRadio Flex-5000C

How to add an SDR “Band Scope” to your current transceiver  Feed IF out to an SDR tuned to IF freq. - or -  Share your transmit antenna with an SDR receiver 1.Connect “Rx Ant Out” to input of a 2-way Power Splitter  Output 1  SDR’s “Antenna” connector  Output 2  Rig’s “Rx Ant In” 2.Press “RX ANT” button  Rig’s T/R circuit protects SDR front end  QSK works fine

WinRad demo  Playback of a 10 min. recording made with a Perseus SDR  Captured low end of 20m (~ 122 kHz wide)  Antenna: 5 ele 20m yagi, 42’ boom  Instructions at – WinRad Software: 1.4 MB –Recording: 300 MB (zipped!)

Advantages of the “Waterfall” Display  Scan a band with your eyes instead of your ears  You can see faint signals and “new” signals  You can find “holes” where you can call CQ –Or call in a pileup  Clicking is faster than turning a knob  Significant improvement over legacy “band scopes”

CW Skimmer Demo  CW Skimmer running in “3 kHz mode”  With a compatible SDR, you could watch up to 96 kHz of a band with CW Skimmer

CW Skimmer  CW Skimmer = Code reader + bandscope  Simultaneous decoding of multiple channels  Another program can take CW Skimmer output and feed it into your contest software “bandmap” window –Or automatically post packet spots to a remote cluster (e.g. N4ZR)

An SDR on the Web  40 and 80m remote SDR in the Netherlands   Note: contest rules generally prohibit the use of remote receiving sites, even for M/M –They are not within the property limits / 500m circle –They are not spotting nets –They are not a “remote base”  But great for “testing propagation”

The CW Skimmer Controversy  Can single-ops legally use a local CW Skimmer in a contest? –Code readers are not prohibited –Band scopes are not prohibited –A local CW Skimmer is not a spotting net –Nothing in ARRL rules seems to prohibit it –CQ WW rules may prohibit it if K3EST says CW Skimmer counts as “other DX Alerting Assistance”

Editorial Opinion  CW Skimmer represents a major advance in the radio arts  It is far from perfect – banning them now seems premature  Let the radio arts advance  We never banned tape recorders, memory keyers, computer sent CW, computer logging, super check partial windows, pre-fill databases, code readers, band scopes, etc., so what’s the big deal?

Remember the Turbine-powered car?  Built by Andy Granatelli of STP  Entered in 1967 and 1968 Indy 500 –Driven by Parnelli Jones, Joe Leonard  Almost won both races  Never “banned” outright but … –So outclassed everything else that USAC reduced the allowable intake area sufficiently to strangle the engines and render them non-competitive.  Should we write rules that stifle innovation?

What you just saw  SDR hardware  Demo of WinRad and the “Waterfall display”  Demo of CW Skimmer by VE3NEA  An SDR on the Web  Still missing: integration of SDRs with contest software

What’s Next?  RTTY Skimmer? SSB Skimmer?  A “robot” – a totally automated op? –“Z80 OP” – developed by N6TR, in 1986!  Let’s sponsor an “X-Prize” –First totally automated op. to make Top Ten box in the CW NA Sprint  Competition encourage advancements in the radio arts –Don’t write rules that stifle innovation

Discussion