Hi Motus Community,
I’m Wesley, an undergraduate research assistant that’s new to the motus ecosystem and the general RF field. I’m trying to obtain tag detections with SG software with a couple Lotek test tags, with the ultimate goal of correlating the received signal strength to the distance between a tag and receiver.
I can currently read out that pulses are being received by the sensorgnome, but these pulses do not correlate to a tag detection as seen below:
Preliminary testing of signal strength (copy and pasted from the local UI) against distance also show noisy/inconclusive results, which leads me to believe the pulses received at the SG are external noise and not the Lotek tags I’m looking for.
Attached is a picture of the current SG setup, powered by USB connection to a laptop,
,
and the SG receiver info is as follows:
Project ID: #975
Receiver ID: SG-035ERPZ28B0B
I tried narrowing down the root cause by breaking the setup into four components:
- Antenna
- RTL-SDR Dongle
- Sensorgnome
- Lotek Tags
The antenna used is this 169MHz whip antenna. From Internet research, I got the gist that this should suffice for obtaining a roug correlation given they’re approximately centered around the frequency range of the Lotek tags.
The RTL-SDR V4 Dongle was purchased directly as well.
I tested the Antenna+RTL dongle combo by using SDR# to tune into local radio stations. Since this was successful, I’d think that both pieces of equipment are functional and shouldn’t be the root cause to my issue, but would appreciate any feedback/advice on whether that’s enough evidence to say so.
Moving on to the sensorgnome, I utilized the default configuration using a rpi zero 2W, and I’m not too sure how to test that this is working as expected. Attached are some logs from sessions where I record a lot of pulses with no tag detection. SG-035ERPZ28B0B-2025-07-23T20_14_26.930Z-logs.zip (1.9 MB)
Lastly, to check that the tags have been activated and working as expected, I saw from this forum that SDRangel can be used to check the pulses of the tags, attached are screenshots of the output when the tags are
Right next to the antenna:
Placed in a metal cabinet to prevent the signal from being read:
Attached is also a video of the output when tags are placed next to the antenna, I didn’t see any distinct blips/pulses to show the tags are outputting a signal, which I’m taking to mean that I’m not getting tag detections because my tags aren’t activated.
Since I’m really new to RF and Motus, I’d like to ask:
- Have I correctly setup the SDRangel project to detect the lotek tags, and I’m not detecting pulses on the waterfall plot because of the tags and not my incompetence? Would this be the correct way to check my tags are working?
- I’m still not sure whether there’s anything wrong with my SG software setup. Is there anything I can do on the SG software side to understand what’s happening under the hood of why all these pulses aren’t being linked to a tag detection, or any general recommendations to better troubleshoot?
Please let me know if my post needs to be edited, and thank you so much in advance!