Our baby monitor has one base unit and two little handheld remote units. We bought it about 3 months ago and have used it steadily without any problems.
In the past few days though we have noticed that there is a lot of interference noise coming from one of the handhelds. We have it in our bedroom, and if someone gets up to go to the washroom, or if someone is in the hallway, it starts making that buzzing / humming sound, and doesn’t stop until we move it and position it “just so”. Then if we’re lucky that interference noise goes away or at least gets quieter.
Any ideas what is going on? Nothing electronically in our house has changed and the handhelds are usually in the same places every day.
Could be your neighbor got a new cordless phone/wireless internet/blender/vacuum cleaner and you’re getting interference from that. The range on some baby monitors is several lots (well over 100 feet). Our monitor used to pick up and broadcast entire conversations from our across-the-street neighbors. (Which was a little awkward, as most of the conversations were the Mrs. planning her divorce from her clueless husband with her paramour!)
It only has two channels, and both do the exact same thing. It’s just so damn weird that it will be totally fine and then someone moving around 20-30 feet away will cause it to start acting up.
Oh, and we don’t use the batteries - the handhelds came with AC adaptors so they can be plugged in.
I guess we need a louder baby so we don’t need the damn monitors anymore!
What I meant was, have you tried moving the remote units around, to find out if they both have the same problem if placed at the same location? If they behave the same way, it’s external interference and there’s not much you can do. If they behave differently, one of the units is faulty.
Do you have a wireless internet access point? That often runs on the same frequency as baby monitors, and since it is digital data it sounds like noise. Try changing the channel or position of the antenna on that instead of the baby monitors and see if it helps.
That section of the frequency spectrum used by baby monitors is one of the most troublesome.
It’s used by a whole bunch of devices (baby monitors, cheap walkie-talkies (FRS, Family Radio Service), wireless intercoms, door answering systems, etc. It’s pretty much freely available, with little FCC paperwork needed to build something that uses those frequencies.
So it is very heavily used, often by cheaply-made devices that aren’t especially resistant to interference. Plus the frequency range itself is a lower one, so it’s more sesceptable to random interference from random electrical devices, like the motor in a blender or electric mixer, a misbehaving transformer on an electrical pole, etc.
Basically, you have to spend a lot more on higher quality equipment, or just live with it. You can take measures like switching the frequency (‘channel’) used, repositioning the receivers slightly, etc. You can generally find a way to make it work well enough for your purposes.
I once was running a horse show using the cheap walkie-talkies that use these frequencies, when we started getting interference from local police planning a drug raid. Then both of us were blasted off by a wailing baby!
I was surprised that police would use this, but a policeman friend told me later that is was probably a one-time thing, because the regular police frequencies might be monitored by drug dealers, but they wouldn’t bother with these frequencies.
I’ve found that low-energy fluorescent light bulbs emit enough interference to be picked up on an FM radio. I have to turn the hallway light off if I’m making recordings.
It means the aliens are coming. See the movie ‘Signs’. (We actually had the same model of baby monitor as in the movie at that time and we would always get some sort of interference. We always joked that the aliens were coming.)
Seriously though, in that frequency range, someone walking around the room could change the rf environment enough to cause that, i.e. the radio waves are bouncing off the other person and interfering with the ‘clean’ radio waves that the monitor had been receiving up to that point.
It also seemed like (at least on the previously mentioned baby monitor that we had) there was some sort of feedback. Maybe the monitor squealed loud enough that the mic in the baby’s room picked it up and setup the feedback loop, or cheap circuitry allowed some current leakage that would overdrive the amp or something.
