Software Defined Radios A Contesters Perspective by Bob
Software Defined Radios A Contester’s Perspective by Bob Wilson, N 6 TV n 6 tv@arrl. net With thanks to Jeffrey Pawlan, WA 6 KBL Ilberto di Bene, I 2 PHD Visalia DX Convention Contest Forum April 26 th, 2008
This is not a technical talk § I will not try to explain how SDRs work § I will try to show they could be used by contesters
What you will see § Brief overview of some available SDR hardware § Demo of Win. Rad software, by I 2 PHD § The “Waterfall display” § Demo of CW Skimmer by VE 3 NEA § An SDR on the Web § Implications and Discussion
Softrock-40
Softrock 6. 1
RFSpace SDR-IQ
Microtelecom Perseus (used to make demo recordings)
Flex. Radio Flex-5000 A
Flex. Radio Flex-5000 C
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
Win. Rad demo § Playback of a 10 min. recording made with a Perseus SDR § Captured low end of 20 m (~ 122 k. Hz wide) § Antenna: 5 ele 20 m yagi, 42’ boom § Instructions at http: //www. kkn. net/~n 6 tv – Win. Rad 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 k. Hz mode” § With a compatible SDR, you could watch up to 96 k. Hz 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. N 4 ZR)
An SDR on the Web § § § 40 and 80 m remote SDR in the Netherlands http: //websdr. ewi. utwente. nl: 8901/ Note: contest rules generally prohibit the use of remote receiving sites, even for M/M – They are not within the property limits / 500 m 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 K 3 EST 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 Win. Rad and the “Waterfall display” § Demo of CW Skimmer by VE 3 NEA § 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? – “Z 80 OP” – developed by N 6 TR, 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
- Slides: 21