I ordered and received an rtl-sdr stick ... / 2013-07-26

I ordered and received an rtl-sdr stick with an HF convertor and active antenna, planning to do some HF with it.

For a simple test I tried to decode APRS messages, which has worked with the Noxon dab stick and rtl_fm/multimode. This new stick allows easy connection of external antennas through an SMA connector. Besides the cable to connect the HF convertor I also ordered an SMA - BNC cable which allowed me to connect other antennas, such as a 2 meter antenna.

There were not a lot of APRS messages to test with, but eventually I found the working settings. This stick works better with automatic gain.

koos@thompson:~/rtl-sdr$ ./src/rtl_fm -f 144800000 -s 22050 -o 4 -C - | multimon -t raw -a AFSK1200 /dev/stdin
multimod  (C) 1996/1997 by Tom Sailer HB9JNX/AE4WA
available demodulators: POCSAG512 POCSAG1200 POCSAG2400 EAS AFSK1200 AFSK2400 AFSK2400_2 HAPN4800 FSK9600 DTMF ZVEI SCOPE
Enabled demodulators: AFSK1200
Found 1 device(s):
  0:  Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle
Found Rafael Micro R820T tuner
Oversampling input by: 12x.
Oversampling output by: 4x.
Buffer size: 7.74ms
Tuned to 145064600 Hz.
Sampling at 1058400 Hz.
Output at 22050 Hz.
Exact sample rate is: 1058400.010094 Hz
Tuner gain set to automatic.
AFSK1200: fm PI1APU-0 to APND13-0 UIv pid=F0
>W3,NL7      PAradigm    operation!
AFSK1200: fm PD0PYL-0 to URPRW9-0 via PI1APU-0,WIDE2-1 UIv pid=F0
'z8%l .-/]
AFSK1200: fm PI1APU-0 to APND13-0 UIv pid=F0
>W3,NL7      PAradigm    operation!
AFSK1200: fm PI1APU-0 to APND13-0 via WIDE2-1 UIv pid=F0
!5205.28NS00506.75E#PHG3440/Utrecht http://pe1mew.nl/pi1apu mail:pi1apu@pe1mew.nl
AFSK1200: fm PD2WVH-0 to APU25N-0 via PI1APU-0,WIDE2-0 UIv pid=F0
>262031zDX: PI1FLD 52.21.08N 5.14.15E 49,3km 66. 22:27
AFSK1200: fm PI1APU-0 to APND13-0 UIv pid=F0
>W3,NL7      PAradigm    operation!
AFSK1200: fm PD2WVH-0 to APU25N-0 via PI1APU-0,WIDE2-0 UIv pid=F0
<IGATE,MSG_CNT=0,LOC_CNT=21
AFSK1200: fm PD2WVH-2 to APU25N-0 via PI1APU-0,WIDE2-0 UIv pid=F0
=5210.19N/00434.68E- {UIV32N}
AFSK1200: fm PD0PYL-0 to URPRW9-0 via PI1APU-0,WIDE2-1 UIv pid=F0
'z8%l .-/]

No timestamps, but there is not an awful lot of APRS traffic in this region.