I built an Android SDR app for wildlife tracking and I'd love feedback.
Not sure if these posts are allowed, but I'll try anyway! I've been doing wildlife monitoring in the Kalahari (https://workingwithwildlife.org/) for the past 7 years tracking animals with VHF telemetry. The cost of dedicated receivers pushed me to look for an SDR solution, but every app I tried was simply not practical for field conditions, and could not meet my range needs. Even though I built it with wildlife tracking in mind, there was obviously no point to confine it to CW and typical wildlife frequency ranges. So it should be useful for other fields.
RTL-SDR.com featured it today: https://www.rtl-sdr.com/tracking-wildlife-in-south-africa-with-rtl-sdr-and-an-android-app/
The app supports CW, AM, NFM, WFM (mono and stereo), LSB, and USB and has a high resolution waterfall. Please let me know if the waterfall causes audio stuttering for anyone, it was a nightmare to get the high resolution waterfall and high sample rate to work smoothly on low-end devices. I only have a handful of devices that I can personally test on, but my J4 Core and Galaxy Tab 6 are both smooth now.
To get the most out of it for wildlife tracking, I tried to make it as user friendly as possible and to work well one-handed in the field.
- I tied the volume buttons to the Gain setting to mimic a conventional receiver.
- A toggle switch to easily enable/disable BiasT.
- Added a portrait-lock mode to prevent rotating in the field, and a dark mode for night work.
- Only four IQ filter bandwidth settings per demodulation mode. Wildlife beacons are typically ~20-50ms pulses, so the tightest filter (Extreme) eliminates most of the noise.
- Built-in mapping with bearing logging, triangulation, KML import/export. For me, I can import a KMZ of the reserve that I work on, and I can likewise import/export my bearings, POIs, and tracks to transfer between multiple devices or to open in Google Earth, QGIS, Excel, R, etc.
I also added a pulse-coherent detection mode that calibrates against the CW beacon (wildlife collar in my case) and coherently integrates periodic signals over time, pulling these weak CW signals out of the noise. This has helped me immensely to locate animals even when I can no longer hear the beacon.
The end result is that my ~$50 combo of a RTL-SDR V3/LNA combo is outperforming my $1 200 Comm Spec R-5000 receiver for my needs (which is a great device). I'm fortunate to have minimal RF noise given how remote I am, but I suppose some might require a bandpass filter depending on their situation.
I'd genuinely appreciate feedback from people who use their RTL-SDR regularly. I've been developing this mostly in isolation out in the bush and I know there's a lot I could improve upon. Here are some promo codes so some of you can try it out and let me know what you think:
C09TH1NFMZH84VJQLHWRWPV
2DYFMAMPFQ6W5QTUMQAHW9T
YL64DZS2Q62YJLNSAC4KEDM
JM3D0RJSQ5VA15N0MQ906C7
7SAH2HG8T0UZXZET3MB433A
I'll make the same post on r/amateurradio with different codes, but if they're all claimed and you still want to try it, send me a message.
Google Play: https://play.google.com/store/apps/details?id=com.wildlifetracker.vhf
Happy to answer any questions about the app or the wildlife tracking side of things. I'll be heading out now for some pangolin work now through the evening, but I'll try get back to questions (should there be any) later this evening. If my work takes longer than expected, I'll be on the road tomorrow for my first time away from the bush in forever, but I will respond as soon as I can!
Thanks for any feedback!