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1. Chris Lorek G4HCL PO Box 400 Eastleigh S053 4ZF E mail g4hcl rsgb org uk WiNRADIO WR G3131 PC controlled receiver There is currently a growing number of software based radios around with black box receivers and transceivers using a PC for a virtual front panel control Chris Lorek reviews the latest offering from the Australian firm of Rosetta Labs the WiNRADiO WR G313i T WiNRADiO WR G313i is a PC plug in multimode receiver on a PCI card covering 9kHz to 30MHz with an option of frequency extension to 180MHz It s described as a high performance HF receiver intended for government military security surveillance broadcast mon itoring industrial and demanding consumer applications Unlike its cousin the G303 the G313i has its own on board Digital Signal Processor which fully per forms the final stage IF filtering and audio demodulation and doesn t rely on the PC sound card for processing This of course means that you can use the sound card with appropriate software for other applications like data and SSTV decoding further DSP processing such as noise reduction and so on Also if you really want you can of course use multiple G313i receivers in a single PC enclosure The receiver card simply plugs into any available PCI slot inside your PC and on the rear is a small SMA antenna socket together with a 3 5mm audio output socket to feed either amplified speakers or of course your sound car
2. Fig 1 J Front End First IF stage Second IF stage Switchable attenuator e Crystal filters e Amplifier Switchable filters e Variable gain amplifier e AGC block e Preamplifier e RSSI block 9kHz to 30MHz 45MHz 16kHz optionally to 180MHz variable 12 22kHz DDS amp PLL lt peso bate gt DDS amp PLL 45 009 to 75MHz 32 768MHz 45 016MHz optionally to 225MHz audio lt lt D A converter DSP A D converter ag output PC 36 in 1Hz increments As well as this there s a variable bandwidth IF notch filter and a switchable noise blanker with a fully variable threshold set ting There s a real time 20kHz spectrum display with a 16Hz reso lution and a calibrated analogue style S meter display shows the received signal level in S units dBm level or uV down to the noise floor of around 140dBm As well as a built in audio recorder you can also record the 20kHz wide IF spectrum which lets you then experiment with various playback receive modes and filter widths etc Together with the real time analyser the receiver can also display a wide band spectrum analysis by fast sweeping the receiv er across the required range This also provides peak finding averag ing display storage and retrieval as well as a display of minimum and maximum sweeps as well as a differ ential display ie one sweep min
3. GC attack time But even so overall the receiver gave a very good account of itself with certainly at least as good on air performance of a simi larly priced hardware offering but with the G313i having vastly more operating features LAB TESTS My measured results are given in the accompanying table Of note is the very good IF DSP filtering down to several tens of dB below this synthesiser phase noise came into effect to widen it Above The main receiver panel display showing the selected signal frequency and IF bandwidth somewhat Likewise close in blocking and intermodulation was affected by phase noise but this was arguably no worse than many other receivers Within the 15 20kHz first IF band width filtering the lack of narrower up front IF crystal filtering was evident At greater frequency separations the blocking performance was excellent in fact pushing the limits of the cavity tuned signal generators I use There were only a couple of spurious receive responses at 11 25MHz and 15MHz which appeared no matter what fre quency the receiver was tuned to CONCLUSIONS After using and testing the receiver my overall thoughts were I m impressed The WR G313i has a technical perform ance matching that of conventional receivers in its price class but with the operational versatility of professional receivers costing 5000 or more I m sure it will have many happy and very well satisfied o
4. Rejection Increase over 12dB SINAD level of two interfering signals giving identical 12dB SINAD on channel third order intermodulation product SENSITIVITY BLOCKING AND IMAGE REJECTION MHz Signal Level MHz 100kHz 1MHz 10MHz 1st Image 90MHz 1 8 0 44yV 1 8 90 5dB 91 0dB 100 1dB 81 6dB 35 0 38pV 3 5 93 7dB 94 90B 102 1dB 80 8dB 7 0 0 35pV 7 0 97 8dB 101 7dB 103 9dB 79 4dB 10 1 0 35pV 10 1 99 2dB 103 8dB 102 0dB 64 4dB 14 0 0 35pV 14 0 98 1dB 102 0dB 103 9dB 64 5dB 18 9 0 35pV 18 9 95 7dB 102 4dB 101 4dB 66 0dB 21 0 0 35pV 21 0 94 8dB 102 2dB 101 6dB 66 2dB 24 5 0 35uV 24 5 93 2dB 101 8dB 102 2dB 66 5dB 28 0 0 394V 28 0 92 3dB 102 4dB 101 0dB 65 9dBa SELECTIVITY INTERMODULATION REJECTION CW 600Hz SSB 2 4kHz AM 6kHz 5kHz spaced signals 68 8dB 3dB 0 61kHz 2 43kHz 6 02kHz 10kHz spaced signals 73 50B 6dB 0 62kHz 2 43kHz 6 03kHz 20kHz spaced signals blocking limited 10dB 0 64kHz 2 45kHz 6 04kHz 40kHz spaced signals 82 10B 20dB 0 66kHz 2 47kHz 6 06kHz 40dB 2 19kHz 4 02kHz 7 56kHz SPURIOUS REJECTION 60dB 5 73kHz 7 47kHz 10 63kHz Measured with receiver tuned to above 7 3MHz 11 25MHz 61 5dB 15 0MHz 82 1dB the filter and notch slopes to be very steep indeed a classic brick wall response I did however often find strong adjacent signals induced some raspiness to the on channel received signals and often there was also audi ble clicking on fast rising signals such as strong SSB or CW probably due to a delay in A
5. d input The package includes the receiver card Windows based software a start up antenna consisting of a terminated coax lead connected to a length of insulated wire and a user s manual CIRCUITRY Up to the demodulator stage the radio uses a normal dual conversion The G313i is a plug in PCI card with an SMA antenna socket and audio output socket provided Fig 1 Block diagram of the WiNRADiO WR G313i superheterodyne approach with an analogue front end stage followed by a mixer down to a first IF of 45MHz with a synthesiser derived mixer injection signal See Fig 1 At the first IF two four pole 15kHz wide crystal filters are used together with a vari able gain amplifier followed by an analogue mixer down to the second IF of 16kHz nominal 12 22kHz vari able Here the signal is further amplified and AGC Automatic Gain Control and S meter signal levels are derived before the signal is passed to a 16 bit A D Analogue to Digital converter sampling at 64kHz From henceforth the DSP Digital Signal Processor circuitry steps in to per form the final signal filtering and demodulation before being passed to a D A converter to provide the final analogue audio output MODES amp BANDWIDTHS The receiver offers modes of CW LSB USB AM Synchronous AM Double Sideband DSB Independent Sideband ISB and narrowband FM each with a continuously variable IF bandwidth of between 1Hz and 15kHz
6. s I found unlike most amateur transceivers these did not also store the receive mode and band width etc but for this there are plen ty of memory channels available up to 1000 in each memory file in fact Plenty of pre set IF filter band widths were available and I could also manually enter any bandwidth I wanted and vary this as with most functions by using the appropriate small on screen up down buttons or more rapidly by a tiny slider between the buttons Likewise with the IF shift but here I could also tune the receiver to another frequency by simply dragging the entire filter passband over a peak of a visible sig nal on the spectrum display and drag the filter edge to vary it as needed to reduce adjacent interfer ence The notch filter I found very useful especially when a heterodyne appeared right in the middle of the signals I was tuned to Overall I found www rsgb org RadCom March 2005 LABORATORY RESULTS Measurement methods Sensitivity Input signal level in pV pd to give 12dB SINAD measured on SSB 2 4kHz bandwidth Blocking Increase in level of interfering unmodulated signal above 12dB SINAD ref level to cause 6dB degradation in 12dB on channel signal Image Rejection and Spurious Rejection Difference in level between unwanted and wanted IF image spurious signal levels each giving 12dB SINAD on channel signals Selectivity Single signal bandwidth measured in kHz Intermodulation
7. tch shift and speed control Again after you ve installed the suite the various modes are accessible from the top bar menu Finally if you d like to control your WiNRADiO from another location your office for example the optional WR G313 CSO client server lets you do this across all types of computer networks supporting the TCP IP pro tocol including the Internet With this in use you can listen to your receiver literally anywhere in the world ON THE AIR As soon as the card is fitted and you power up the PC it s automatically recognised by Windows and you sim ply load the driver software which comes on the supplied CD Then it s just a case of attaching an antenna I used an SMA to BNC adapter plus a further BNC to SO 239 adapter here and an amplified audio source I used a pair of amplified PC speakers and tuning in At first sight the very comprehen sive virtual front panel did look rather intimidating I believe the controls and operating facilities are well in excess of even the most comprehen sive top flight amateur class and even professional class receivers but I very soon got the hang of using it with the PC mouse The main tuning dial is controlled by the left right PC mouse buttons or I could use the small up down buttons below the main frequency display I could enter a frequency directly by using the PC keyboard and four switchable VFOs can be used to store your last used frequencie
8. us another which is useful to see if any new signals have appeared Another feature is a test and measurement facility performing measurements on the received signal including frequency accuracy ampli tude modulation depth frequency deviation THD total harmonic dis tortion and SINAD A real time audio spectrum analyzer with a 5Hz resolution can also be displayed You can also explore block diagrams of the demodulator for each mode and look at the real time signals at vari ous stages using two spectrum analysers and a vector voltmeter OPTIONAL PLUG INS DRM Digital Radio Mondiale is a non proprietary digital system for HF plus medium and long wave broad casts which has the potential of pro viding almost FM quality audio This can be added as a further purchase to the G313i as an XRS Extensible Radio Specification plug in which after you ve installed it is accessible very simply as another mode from the top bar menu Another optional plug in is the Advanced Digital Suite which adds a number of digital processing facili ties including a fax module for WEFAX and HF fax with a sched uler a NAVTEX decoder again with a scheduler Packet radio decoder ACARS decoder with a code data base CTCSS and DTMF decoders March 2005 RadCom www rsgb org with alarms a signal classifier an audio scope with waterfall display a signal conditioner with user defined filters and an advanced audio recorder with pi
9. wners Of note is that the operating software is constantly being updated and is freely available from the WiNRADiO website giving a considerable degree of future proofing to a purchased receiver in fact I downloaded an update to improve the operation even more during the review period Our thanks go to Radixon Ltd in Evesham for the loan of the review equipment 37

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