Using the SDRIQ for EME Using the SDRIQ

Using the SDR-IQ for EME

Using the SDR-IQ for EME Application to random QSO’s with JT 65 by Edward Cole – KL 7 UW 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

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!

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 AD 6620 at 23 bits • 16 bits of I/Q data is transferred • Processed by software to recover virtually any modulation type. • DSP filtering & NB detection

SDR-IQ Specs • Covers 500 -Hz to 30 -MHz in 1 Hz steps • Clipping level > -4 d. Bm • Image Rejection 80 -d. B • IP 3 (typ) +15 -d. B • 5 Vdc at 425 m. A • Ext. Radio control via DB-9 • Open source Active-X • Drivers: Win/Linux/Mac • Network server for remote operation of SDR-IQ • Spurious -80 d. Bfs, -100 typ • • 28 -MHz noise floor -134 d. Bm 28 -MHz MDS-133 d. Bm/Hz No freq drift measured Shielding Test at 20 -MHz: -111 d. BM (5 w @ 25 -feet) -100 d. Bm (50 w @ 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

Software • RFSpace provides Spectravue for immediate use of the SDR-IQ. • Modes: CW, CWr, SSB, DSB, WBFM, NBFM, AM • Displays: raw signal, 2 D and 3 D spectrum, waterfall, combo 2 D+waterfall, total power, and IQ phase • SW controls: sample size, smoothing, amplitude scale, RF & Demod freq, mode, filter bw, NB and AGC • Alberto, I 2 PHD 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

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 -d. B mmic WBIF amp in between them. • Simulations using a signal generator input to my 2 nd 2 m preamp I get: -18 on JT 65 with -141 d. Bm -26 on JT 65 with -150 d. Bm -28 on JT 65 with -152 d. Bm • The JT 65 readings were obtained with my FT-847 plus soundcard with JT 65 B/Spectra-JT running. • This provided comparison of the SDR-IQ to JT 65

Using the SDR-IQ for 144 -MHz EME Figures 1 -6 are made with the signal generator input: • Fig-1 shows typical JT 65 screen • Fig-2 Winrad, no IF amp, BW=50 KHz, RBW=3. 4 Hz, display is 3 -KHz wide, signal= -150 d. Bm • Fig-3 Winrad plus IF amp, BW=50, RBW=3. 4, display 3 KHz, signal= -166 d. Bm • Fig-4 Winrad BW=50, RBW=54. 3, -150 d. Bm input • Fig-5 Not shown • Fig-6 Winrad BW=100, RBW=1. 7, -150 d. Bm input

Using the SDR-IQ for 144 -MHz EME Figures 7 -12 are actual EME signals: • • • Fig-7 K 6 MYC on JT 65, -21 signal Fig-8 K 6 MYC on Winrad, BW=5 KHz, RBW=2, -17 signal Fig-9 K 6 MYC on Winrad, BW=50, RBW=3. 5, -24 signal Fig-10 WE 9 Y & WQ 5 S on JT 65, -22 and -20 signals Fig-11 WE 9 Y on Winrad, BW=26, RBW=9. 2, -20 signal Fig-12 The 144. 100 -144. 150 MHz EME band at KL 7 UW

SUMMARY Clearly the SDR-IQ will display most JT 65 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 • K 1 JT working on blend of JT 65 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. kl 7 uw. com/SDR. htm