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Using the SDR-IQ for EME

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  1. Using the SDR-IQ for EME

  2. Using the SDR-IQ for EMEApplication to random QSO’s with JT65by Edward Cole – KL7UW Recent years have seen increasing use of computers in the EME station: • Antenna Control / Tracking Software • Radio Control • Design and Engineering Analysis Tools • DSP • Waterfall & Spectrum Displays • Digital Modes • Migration to Internet scheduling: e-mail & loggers • Software Defined Radios

  3. Software Defined Radios Amateur Radio is beginning to experiment with SDR’s (software defined radios): • Recent Examples: SDR-14, SDR-1000, DSP-10, USRP, FLEX-5000 • Fall 2006 RFSpace introduced the SDR-IQ; a software defined receiver that covers 500-Hz to 30-MHz • Single 3.75 inch square pcb • Interfaced and powered thru computer’s USB-2.0 port • 200 Demo Boards offered at end of 2006 for $375 • I had to have one!

  4. The SDR-IQ • Minimal RF hardware; Direct convertion to base-band which is converted to digital data and transferred to the USB port • Entire LF-HF band is sampled at 66.66 MHz by AD6620 at 23 bits • 16 bits of I/Q data is transferred • Processed by software to recover virtually any modulation type. • DSP filtering & NB detection

  5. Covers 500-Hz to 30-MHz in 1-Hz steps Clipping level > -4 dBm Image Rejection 80-dB IP3 (typ) +15-dB 5 Vdc at 425 mA Ext. Radio control via DB-9 Open source Active-X Drivers: Win/Linux/Mac Network server for remote operation of SDR-IQ Spurious -80 dBfs, -100 typ 28-MHz noise floor -134 dBm 28-MHz MDS-133 dBm/Hz No freq drift measured Shielding Test at 20-MHz: -111 dBM (5w @ 25-feet) -100 dBm (50w @ 25-feet) 190-KHz displayed real-time Minimum RBW: 0.75 Hz for BW=190 KHz 0.031 Hz for BW=5 KHz Spectravue software provided SDR-IQ Specs

  6. Software • RFSpace provides Spectravue for immediate use of the SDR-IQ. • Modes: CW, CWr, SSB,DSB, WBFM, NBFM, AM • Displays: raw signal, 2D and 3D spectrum, waterfall, combo 2D+waterfall, total power, and IQ phase • SW controls: sample size, smoothing, amplitude scale, RF & Demod freq, mode, filter bw, NB and AGC • Alberto, I2PHD offers a SDR-IQ driver for Winrad (windows version of Linrad) which is written for weak-signal/EME. • Winrad modes: CW and SSB, only, but with more settings for improved audio reception of weak-signals. • Displays for both are both shown, later • Refer to their websites for more details

  7. Using the SDR-IQ for 144-MHz EME • To use the SDR-IQ for EME I bought a DEMI 144/28 transverter (only receive side used). • I added a 18-dB mmic WBIF amp in between them. • Simulations using a signal generator input to my 2nd 2m preamp I get: -18 on JT65 with -141 dBm -26 on JT65 with -150 dBm -28 on JT65 with -152 dBm • The JT65 readings were obtained with my FT-847 plus soundcard with JT65B/Spectra-JT running. • This provided comparison of the SDR-IQ to JT65

  8. Using the SDR-IQ for 144-MHz EME Figures 1-6 are made with the signal generator input: • Fig-1 shows typical JT65 screen • Fig-2 Winrad, no IF amp, BW=50 KHz, RBW=3.4 Hz, display is 3-KHz wide, signal= -150 dBm • Fig-3 Winrad plus IF amp, BW=50, RBW=3.4, display 3-KHz, signal= -166 dBm • Fig-4 Winrad BW=50, RBW=54.3, -150 dBm input • Fig-5 Not shown • Fig-6 Winrad BW=100, RBW=1.7, -150 dBm input

  9. Using the SDR-IQ for 144-MHz EME Figures 7-12 are actual EME signals: • Fig-7 K6MYC on JT65, -21 signal • Fig-8 K6MYC on Winrad, BW=5 KHz, RBW=2, -17 signal • Fig-9 K6MYC on Winrad, BW=50, RBW=3.5, -24 signal • Fig-10 WE9Y & WQ5S on JT65, -22 and -20 signals • Fig-11 WE9Y on Winrad, BW=26, RBW=9.2, -20 signal • Fig-12 The 144.100-144.150 MHz EME band at KL7UW

  10. SUMMARYClearly the SDR-IQ will display most JT65 signals over a wide enough band to cover EME activity and randomly detect digital stations! • Economical viewing of EME sub-band • Up to 100-KHz displayed on moderately fast computers • Full 190-KHz with CPU > 2-GHz. • Enables random digital EME contacts • K1JT working on blend of JT65 and Linrad to decode all stations in 100-KHz band. • Cost $499 with enclosure plus $170 for 144-to-28 MHz conv. • Limitations are what software designers can think of! • http://www.kl7uw.com/SDR.htm