I was wondering if anyone has recommendations on how to test for interference before doing an install. We’re hoping to do some site visits in the coming months out on the Channel Islands and we want to determine if some potential areas are no-go’s because of high interference (due to military activity/existing communications installations).
There are some general ideas on how to test on the Motus website, but they describe them as not being well tested, so thought I’d check to see if anyone has landed on a protocol that worked well for them.
Thanks,
Laney
USGS Western Ecological Research Center lmwhite@usgs.gov
Matt Webb and Kylie Lamoree at Bird Conservancy of the Rockies have done some work on this. Some advice may have been recorded from a Western Motus Coordinators meeting or on Western Motus slack.
If we expect interference (for instance with antenna’s nearby or solarpanels nearby) we do a check with an SDR receiver (like the funcube) in combination with software like SDRconsole or SDRSharp, but of course that is only a check for the situation at that moment.
I think you have to consider two types of interference;
masquerading / saturating interference (which will mask your tags with noise so the receiver can not find tags in the noise) the noise might be permanent.
And damaging interference which might even damage your equipment.
But that will not damage our equipment (it was far away) and will be only a problem for a short period a week.
And we had a location where there where solar panels installed close by (<100meter) which cause enormous interference only during daytime (I have a long period graph somewhere showing day/night exactly)
Also we had a 4G/3G/5G tower close at a location causing trouble and even false detections, and shielding the box with funcubes helped a bit over there.
I don’t like to install antenna’s close to marine radio sites, I am afraid it will damage the receivers.
Military communications is probably only short messages during training activities, and the rest of the days nothing.
If we expect interference (for instance with antenna’s nearby or solarpanels nearby) we do a check with an SDR receiver (like the funcube) in combination with software like SDRconsole or SDRSharp, but of course that is only a check for the situation at that moment.
I think you have to consider two types of interference;
masquerading / saturating interference (which will mask your tags with noise so the receiver can not find tags in the noise) the noise might be permanent.
And damaging interference which might even damage your equipment.
But that will not damage our equipment (it was far away) and will be only a problem for a short period a week.
And we had a location where there where solar panels installed close by (<100meter) which cause enormous interference only during daytime (I have a long period graph somewhere showing day/night exactly)
Also we had a 4G/3G/5G tower close at a location causing trouble and even false detections, and shielding the box with funcubes helped a bit over there.
I don’t like to install antenna’s close to marine radio sites, I am afraid it will damage the receivers.
Military communications is probably only short messages during training activities, and the rest of the days nothing.
Glad to see that you are taking the ‘bull by the horns’, so to speak, and that you are interested in determining interference issues at potential Motus sites. As you already mentioned, there’s no single protocol now, but to add on to the great information Bart and Pat already provided, I would add that:
If you happen to own a handheld receiver (preferably a Lotek handheld SRX800 type), it is a great idea to spend some time “listening” for radio interference with it, at the spot you plan to potentially install Motus antennas. The Lotek 166MHz frequency is more prone to detecting “false positives” than 434MHz. If you bring a Lotek handheld during your site visits, you are able to listen for radio noise/static in all directions to avoid pointing your future Motus antennas in the direction where the interference is the worst. You might also start picking-up false positive tag IDs (they will show up on the LCD display screen), which would indicate mis-interpretation of interference to a specific tag ID.
Once you select a site, I would also encourage you (and anyone) to plug-in a Sensorstation or Sensorgnome at the potential install location, preferably with an antenna loosely connected to the top of the mast, so that you can spin it in all directioons, and connect your laptop to the Motus computer SG Interface. While you slowly turn the antenna in different directions over the course of a few minutes. If there’s any interference, youo should start seeing hits that will appear in the SG Interface display box.
I think along with solar panels and communication towers, a huge issue for interference is electric power lines in the vicinity of a Motus station. I try to install at sites away from power lines.
A few other points, if you’re still reading:
As Bart already mentioned, any test you conduct will only represent a small instance of time during which you are at the potential site, so you will not be able to gauge whether interference varies over time, but better than not testing at all.
At this time, Motus stations with an antenna suffering lots of false positive detections cannot be trusted and unfortunately most researchers will filter these Motus stations out of their analyses. So thanks for trying to minimize interference
Also, in cases where people pay for modem connectivity and suffer from large amounts of false detections at an antenna, it can increase your modem data fees, up to several hundreds of dollars per month.
Thanks to everyone for the great information! This is super helpful, especially as many of our sites will be difficult to access so we want to try to work through as many potential issues as possible ahead of time.
And thanks for typing all of that out, William! The more information, the better!
Hello Laney,
Keep us posted on install plans. Some of us may be close enough by to help with early installs and have equipment like Lotek receivers and signal strength meters.
