HFU HF Underground
Technical Topics => SDR - Software Defined Radio => Topic started by: ChrisSmolinski on January 10, 2019, 1529 UTC
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I'm doing some comparisons this morning between SDRs on the 305 kHz DGPS band. Each test is two SDRs, both using the same antenna, a 500 ft beverage oriented NE, with a 500 kHz low pass filter and then a splitter, so each SDR sees the same signals. Each is recording for the same time period, and then the I/Q files are run through Amalgamated DGPS. I need to make a 4:1 splitter so I can test all at the same time, but this will do...
First up, the AFE822x vs the netSDR. The AFE822x is a 12 bit SDR, the netSDR is 16 bits and should be better, right? Well, hmm. no. It seems not. Now, the AFE822x has one major difference, there is a built in adjustable amplifier. I have the gain cranked all the way up, to use as many of the A/D bits as I can. Normally this would cause an overload, but with the low pass filter, that does not happen, since the MW and HF bands are blocked.
AFE822x:
Count ID ref1 ref2 kHz Baud City Country Lat Lon km Deg
3 828 246 247 301.0 100 Angleton, TX United States 29.301 -95.484 2,046 241
481 808 016 017 314.0 200 Card Sound, FL United States 25.442 -80.452 1,619 193
290 830 100 101 296.0 100 Wisconsin, Point WI United States 46.708 -92.025 1,444 308
245 827 244 245 312.0 200 Tampa, FL United States 27.85 -82.543 1,414 203
1292 831 102 103 298.0 100 Upper Keweenaw, MI United States 47.233 -88.628 1,257 316
355 926 318 319 300.0 200 Riviere du Loop, QC Canada 47.762 -69.606 1,073 31
5778 777 218 219 304.0 200 Mequon, WI United States 43.202 -88.066 1,002 296
3481 927 316 317 309.0 200 Lauzon, QC Canada 46.821 -71.165 920 29
5646 799 044 045 290.0 200 Penobscot, ME United States 44.453 -68.776 858 49
3364 778 192 193 292.0 100 Kensington, SC United States 33.491 -79.349 723 198
1580 929 312 313 296.0 200 St Jean Richelieu, QC Canada 45.324 -73.317 693 24
5958 838 116 117 319.0 200 Detroit, MI United States 42.306 -83.103 590 301
6117 772 198 199 306.0 200 Acushnet, MA United States 41.749 -70.889 561 64
6114 844 094 095 324.0 200 Hudson Falls, NY United States 43.272 -73.542 489 35
2414 839 118 119 322.0 100 Youngstown, NY United States 43.239 -78.972 427 338
3981 803 006 007 293.0 100 Moriches, NY United States 40.794 -72.756 378 70
3948 806 012 013 289.0 100 Driver, VA United States 36.963 -76.562 307 173
6162 804 008 009 286.0 200 Sandy Hook, NJ United States 40.475 -74.02 266 70
netSDR:
Count ID ref1 ref2 kHz Baud City Country Lat Lon km Deg
1205 777 218 219 304.0 200 Mequon, WI United States 43.202 -88.066 986 295
827 778 192 193 292.0 100 Kensington, SC United States 33.491 -79.349 753 197
651 838 116 117 319.0 200 Detroit, MI United States 42.306 -83.103 571 299
2954 772 198 199 306.0 200 Acushnet, MA United States 41.749 -70.889 549 67
3114 844 094 095 324.0 200 Hudson Falls, NY United States 43.272 -73.542 464 37
540 839 118 119 322.0 100 Youngstown, NY United States 43.239 -78.972 396 336
3426 803 006 007 293.0 100 Moriches, NY United States 40.794 -72.756 370 75
3225 806 012 013 289.0 100 Driver, VA United States 36.963 -76.562 340 173
5228 804 008 009 286.0 200 Sandy Hook, NJ United States 40.475 -74.02 258 77
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AFE822x vs SDR-14. Once again the AFE822x wins.
AFE822x:
Count ID ref1 ref2 kHz Baud City Country Lat Lon km Deg
14 828 246 247 301.0 100 Angleton, TX United States 29.301 -95.484 2,046 241
614 808 016 017 314.0 200 Card Sound, FL United States 25.442 -80.452 1,619 193
969 827 244 245 312.0 200 Tampa, FL United States 27.85 -82.543 1,414 203
1218 809 018 019 289.0 100 Cape Canaveral, FL United States 28.467 -80.554 1,292 196
1966 777 218 219 304.0 200 Mequon, WI United States 43.202 -88.066 1,002 296
546 799 044 045 290.0 200 Penobscot, ME United States 44.453 -68.776 858 49
1271 778 192 193 292.0 100 Kensington, SC United States 33.491 -79.349 723 198
32 929 312 313 296.0 200 St Jean Richelieu, QC Canada 45.324 -73.317 693 24
2075 838 116 117 319.0 200 Detroit, MI United States 42.306 -83.103 590 301
2069 772 198 199 306.0 200 Acushnet, MA United States 41.749 -70.889 561 64
1879 844 094 095 324.0 200 Hudson Falls, NY United States 43.272 -73.542 489 35
618 839 118 119 322.0 100 Youngstown, NY United States 43.239 -78.972 427 338
1249 803 006 007 293.0 100 Moriches, NY United States 40.794 -72.756 378 70
2077 804 008 009 286.0 200 Sandy Hook, NJ United States 40.475 -74.02 266 70
SDR-14:
Count ID ref1 ref2 kHz Baud City Country Lat Lon km Deg
8 828 246 247 301.0 100 Angleton, TX United States 29.301 -95.484 2,046 241
68 808 016 017 314.0 200 Card Sound, FL United States 25.442 -80.452 1,619 193
49 827 244 245 312.0 200 Tampa, FL United States 27.85 -82.543 1,414 203
1239 809 018 019 289.0 100 Cape Canaveral, FL United States 28.467 -80.554 1,292 196
1552 777 218 219 304.0 200 Mequon, WI United States 43.202 -88.066 1,002 296
336 799 044 045 290.0 200 Penobscot, ME United States 44.453 -68.776 858 49
1206 778 192 193 292.0 100 Kensington, SC United States 33.491 -79.349 723 198
4 929 312 313 296.0 200 St Jean Richelieu, QC Canada 45.324 -73.317 693 24
2065 838 116 117 319.0 200 Detroit, MI United States 42.306 -83.103 590 301
2095 772 198 199 306.0 200 Acushnet, MA United States 41.749 -70.889 561 64
1734 844 094 095 324.0 200 Hudson Falls, NY United States 43.272 -73.542 489 35
412 839 118 119 322.0 100 Youngstown, NY United States 43.239 -78.972 427 338
1320 803 006 007 293.0 100 Moriches, NY United States 40.794 -72.756 378 70
2087 804 008 009 286.0 200 Sandy Hook, NJ United States 40.475 -74.02 266 70
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I tried a comparison between the AFE822x and AirSpyHF+, but got very poor decodes from the AirSpyHF+, so bad I am not sure if they are even valid.
But even with testing only 3 SDRs, it is quite interesting how the AFE822x wins. I still suspect this is due to the amplifier, so more of the A/D range is used. Which leads to the next question... Could an additional external amp provide even more signal, and use more of the A/D range? I don't know how close to overloading I am right now, however. The good news is that amplifying a limited range of relatively low frequencies, say 250-350 kHz, is much easier than all of HF. A decent opamp might be all I need?
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Also see here for related;
http://www.sdrplay.com/community/viewtopic.php?f=7&t=4003