Situation Review: SDR Transceivers

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This presentation is a great overview about the capabilities and shortfalls of current SDR Transceivers. The presentation was created and presented by Claudio, I4LEC in September 2012 at the …

This presentation is a great overview about the capabilities and shortfalls of current SDR Transceivers. The presentation was created and presented by Claudio, I4LEC in September 2012 at the HamRadioWeb Convention in Bologna, Italy.

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  • 1. HRW PresentThink Different II To SDR or To Not SDR? I4LEC - Claudio September 22nd 2012 Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 2. Todays question mark Should I still continue to use a “classic” radio.... Or move to the latest Software Defined ones.... Seconda Convention HamradiowebOrganizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 3. Fundamentals: The three radio components1. RF Part2. Signal Processing3. User Interfce Courtesy of DH1TW The RF component transforms high frequency signals into baseband signals or vice versa. Parts of the RF component are filters, mixers, amplifiers, oscillators, etc. The baseband signal is processed / generated in the Signal Processing component. In this component we will find functionality taking charge of modulation, demodulation, filtering, noise reduction, etc. The User Interface (UI) is the command and control unit of the radio. It’s the frontend to the (human) operator. The user interface might consist of buttons, knobs, LEDs or just a PC screen. Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 4. Main differences between the two Classic Radio, all three components are within the same black box. With the advent of digital technologies, phisical dependecy increased even more Courtesy of DH1TW SDR Radio, all three components are independent and can be combined based on specific needs/architectures. No phisical or logical independecy Seconda Convention HamradiowebOrganizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 5. SDRs modular design The “radio” consists of two physical components, the Quadrature Sampling Detector (QSD) or Digital Down Converter (DDC) and a desktop PC. The only connection between the QSD and the PC is a stereo audio signal. There is no physical dependency. The QSD could be exchanged (e.g. a softrock receiver against a Genesis) without affecting the signal processing or the user interface at all.Courtesy of DH1TW The user connects through the web browser to the WEB server. The Web browser is WebSDR the User Interface. The user selects the desired signal on the band with a single mouse click. A few milliseconds later he can hear the signal through his loudspeakers. The user can be located everywhere in the world. Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 6. In spite of the enhanced flexibility why SDRs radios do not take off, specially among contesters ?1. Lack of performances ? 22. Lack of features ? 33. Lack of reliability ? 114. Lack of stations devices integration ? 15. Lack of proper user interface (UI) ? 106. Pc dependence ? 107. More critical under heavy RF field ? 88. Others ? 5 Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 7. Lack of performances ? I dont think so IP3 2kHz (dBm) 28,5 12,5/21,5 21 17,5 -14/4 -6Overall dynamic receiver’s range IP3= (IMD x 1,5) + MDS Courtesy of Sherwood lab. sorted by close-in dynamic range (DR) IP3 2kHz (dBm) 12 -10 -9 -7,5 -13 -27,5/-18,5 Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 8. The 3rd order intercept point (IP3): A Measure of Merit• The ratio of the smallest usable signal to the largest tolerable signal.• The amplitude range over which a mixer can operate without degradation of performance.• Noise should determine the lower limit of a receiver’s dynamic range.• However, the lower limit can be set by the MDS—a some what more qualitative measure.• The upper limit is normally set by either noise or distortion. The graph illustrates that the 3rd order intercept point is defined by the intersection of two hypothetical lines. Each line is an extension of a linear gain figure: first of the signal of interest; and second, of the 3rd order intermodulation distortion product—from which IP3 gets its name. Courtesy of W4UOAThe larger the value of IP3, the less likely the receiver will be adversely affected by 3 rd orderintermodulation products Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 9. LO noise (Rec. Mix) & IMD figures The LO noise is the upper limit, the aim is to fulfil the gap in the way that the IMD product values at the given spacing get as close as possible to the LO noise values.Flex’s figures based on claims data Courtesy of I4SBX Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 10. Real life performances based on the table• Lower sensitivity! Ran two years a side by side IC775 (-135dBm) and Flex 1500 (-115dBm), even with 20 dB delta, on 10m never felt the lack of sensitivity, both radios operating with their pre-amps ON. Very weak signals were barely readeble on boths radios, the 8 bands equalizer helped readibility on the Flex. (CompareCW) (CompareSSB) (YJ0VK_UN)• Slightly worst blocking! Less than 10dB difference on average among the other radios, practically to saturate the Flex it takes a signal of 0 dBm (S9+73dB), while the Elecraft can handle up to +10dBm (S9+83dB). The little Flex 1500 blocks at -8dBm (S9+65dB), happened only once while beaming at IR4X. Not really meaningful since IMD3 takes place much earlier.• Noiser local oscillator! Closer to the carrier dynamic range is highly desirable here. A low noise oscillator can mean clean audio reproduction where a noisier carrier will mean more distortion inherent in the recovered signal audio. Basically the radio limit, ideally IMD figures should tend to this limit.• Better Dynamic Range! Close spaced Dynamic Range: 75-80 dB or so is acceptable for most users, as per my IC 775, higher here is better especially during contest/dx/serious cw work. Only the Yaesu is better, Elecraft picks up with the ultra narrow 200Hz 5 poles roofing in. The Flex keeps the same figures at any spacing. Did I ever feel the need of more dynamic, no on both radios, however on the 775 I thought to place a narrower roofing, in the right place of the chain, for improving the DR. Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 11. Lack of features ? I dont think soBinaural audio features make use of the human mind & ears ability to gainintelligibility by the way of the head-related transfer function, animprovement in reception available at this time only in the hamshackother than through SDR. Being able to listen to the RX in a true binauralmode by listening to the I and Q channels in separate ears.Having built in diversity reception is otherwise presently only in few very highend single transceivers (Flex 5000 plus opz. RX2).Using multiple receivers connected to separate antennas for improving theintelligibility of received signals by improving the signal to noise ratio andmitigating signal fading and drop outs.The transmitted voice processing, equalizer, compender, compression andother tweaks is available in the hamshack in stand alone gear, though threepieces of specialist kit would be needed.Recording either the entire bandwidth (up to 192kHZ) or just the receivingchannel. Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 12. Lack of features ? I dont think soAccurate meter, with dBm & S unit reading, not altered by the pre-amps.Pre-amps increase sensitivity, noise floor lowers accordingly .Very sharp & narrow customized CWfilters, as narrow as 12Hz. My cascaded250hz filters (IC 775) compared with12HzDSP filters, makes a theoretical differenceof 10log 250/12 =13.2 dBm.Memory banks with related parameters. Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 13. Lack of features ? I dont think soEven the little Flex 1500 has all PowerSDR’s features, these are building up at everynew release, as per the latest one, with the Tracking Notch Filter(s) TNF add on
  • 14. Lack of reliability ? Essentially SW relatedStart up and shut down procedure to follow preciselyin order to avoid the need of data base reset, I had to do itthree or four times in two years time Power SDR, not settled yet, new releases still on going, even if at lower pace, not just to implement new features but also to correct bugs. Occasionally some audio pops, often related to the load introduced by other applications, as Skype, Mozilla, etc. Had to send the Flex 1500 to the European service once for 40 m power alignment, exceeding 5W. Power Master Watt meter deemed necessary. Documentation still on draft version Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 15. Lack of stations devices integration ? The main strengthBy means of virtual audio cable (VAC) and virtual serial cable (VSC)PowerSDR integrates very well with third party SW, mostly freeware No hardware device interfaces required Station components like rotor control, antenna switching, audio recording, Watt/SWR Metering, Digital Mode, Amplifier, Logging Programs, DX Spots, and audio processing under control, the SDR opportunity allows a single shack interface through the computer, no matter whether Hardware or Software Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 16. Lack of proper user interface (UI) ? I think soHuman interface by means of a mouse drag, click, wheel turn onPowerSDR application. It does very well but you ought to onPowerSDR active window.During quick running or contest environment, focus must be mainly onLogging program, while you should still be able to operate the radio astuning both VFOs, filtering, band changing, etcI do consider this the main flaw, recently Flex introduced an accessorycalled flexcontrol, which some how met the target but at the expense ofa single knob and three programmable push buttons Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 17. Lack of proper user interface (UI) ? I think soHere is what Tobias, DH1TW, has developed to fulfil the gap, a USB microcontroller device fullyprogrammable to your taste, the SW bridge is called PowerSDR-UI available in beta version…..cons. you ought to wait for Tobias new releases Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 18. The 3rd way (my way)Hybrid solution.....classic plus SDR Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 19. The 3rd way (my way) How to combine the two Seconda Convention HamradiowebOrganizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 20. The 3rd way (my way)In the contest with Win TestAll logging and Power SDR’s windows within the same screen, radio’s operation by meansof the DJ console, focus on the entry logging window
  • 21. Operation experiencesVery easy and effective split operations…thanks to separate VFOs audio sources divertedinto right & left ear as well as the visual aid which allows an instant tune…… D64K
  • 22. Personal experiences and testsOn the Flex 1500, single tone image down around 100dB, dual tone just a little over 70dB, during a CWcrowed contest, some images were detected/decoded below the lower band edge by the in-houseskimmer Courtesy of I4SBX Inserire immagini
  • 23. Personal experiences and testsWide band white noise test (NPR) resulted in poorer Dynamic Range on QSDSDR’s radio than the classic radios....……this due to the image rejection issue Sorted by noise Power Ratio (NPR)The NPR method emulates many signal by loading the receveirs with whitenoise. In this way, all combinations of carrier frequency spacing are taken intoaccount, and a true worst-case measurement is made. Courtesy of I4SBX, I2VGA Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 24. Personal experiences and testsNoise Power Ratio test for an overal RX measurements, including inputfilters, not just the Mixer. Courtesy of I4SBX
  • 25. An educational instrumentAn S9+20dB signal perfectly within the filter bandwidth
  • 26. An educational instrumentSame signal strengh, what a difference, 8kHz wide bandwidth, poorTX IMD….?
  • 27. An educational instrument Yes….indeed Courtesy of I4SBXAs per the here above case…..3rd order only down 25dB, we worry so much on RX IMD and almostnone on TX IMD. The DR3 number is important on CW. It is less important on SSB since the IMDproducts of all transmitters, except very few cases, is worse than most radios. Thus the limit in howclose you can work a weak station next to a strong one is almost always the generated IMD productsof the strong undesired near by signal, not the dynamic range of the receiver. Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi
  • 28. An educational instrumentAm I out of band? YesWhere should I tune in order not to bother ? Right on the tuned Freq.
  • 29. Best buy/performances (under test) TS 590 IP3 = -14/4dBmFlex 3000 IP3 = 12dBmK3 IP3 = 12,5/21,5dBmIP3 = Overall dynamic receiver’s range Courtesy of Sherwood lab. and I4SBX lab.
  • 30. Then, SDR, Classic or………both ?It seems like the old question beetwen Quad and Yagi, the Quad claimsbetter gain, lower take off angle, less subject to noise, better F/B.How many of these Quads are used among the serious contesters?……..subject for another session? Thank you Seconda Convention Hamradioweb Organizzata da Hamradioweb e dalla Sezione A.R.I. di Bologna con il patrocinio del Comune di Sasso Marconi