I have a couple of RB751U-2HnDs that work ok but I haven’t been greatly impressed with the wireless performance on this model. I ran a spectrum scan on these and see a huge amount of noise just above the 2.4 band that can peak out up at about -20 db. This noise has the be generated by the radio card itself and I am wondering whether this is what is impacting my wireless performance. It’s not on the frequency I am trying to use but is populating the 80 MHz just on the upper side of the US 2.4 band.
Any one have any information on this and is there a way to get rid of it?
I thought that too at first however I have two different 751s in two far different locations and both are showing the exact same noise. Any ideas on that?
The problem I have is that this noise creeps into the US 2.4 band right at 2472 which is the upper side of channel 11 on 20 MHz. This is a problem on using channel 11 since there is no guard band between the noise and my channel 11 data. Since this unit is designed to be a SOHO router, you can’t change many factors from the default settings and still get laptops and other devices to connect.
Interference doesn’t usually show up the exact same in every location. I find that solution a little hard to believe since moving the device doesn’t show a difference in the readings at all. The noise has to be coming from inside the device. It may not be the radio card but I think it’s something inside the device.
Where are you both located? Is the unit indoors? We have tested this extensively, the board does not emit anything. It has also passed CE and FCC, which would be not possible if it would radiate something.
It could be some analog link too. I have seen analog wireless security cameras using 2.4 GHz in some sites. This blocks all wlan communication in channels affected.
Attachment shows analog security camera in about ch1 blocking about half of 2.4 GHz wlan channels. Then it was turned off.
Bluetooth and microwaves both work in the 2.4 band but as Raf noted microwaves operate around 2450. Bluetooth also uses very small chunks of the regular 2.4 band and not the huge piece that is being seen on my scan above the 2.4 band.
I’ll try and get that test done as soon as I can but things have been busy.
If you mean microwave oven, it has to be turned on to cause interference, no? There’s no restaurant in our neighbourhood which would use microwaves 24/7. And I don’t use mine more than once a day for 1min. I’ll turn off the cable modem which is next to the router to see if it makes a difference though.
So I did the test you requested and found unfortunately that the noise got over 10 db higher. This actually proves the noise is coming from inside the 751 somewhere and I have 2 different units doing it.
I am getting the same results with RB751U-2HnD, RB751G-2HnD and RB711UA-2HnD with swivel antennas … all three devices are very far away (100km+) so it is impossible for them to share the same signal source … unless there is a satelite gone bezerk somwhere above central europe. Routeros 5.19 on all three, dude 3.6.
