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Does someone have an idea about these birdies ?
Hi,
The Kiwi is in a house where there is no computer, only a tablet.
The 3 power supplies are linear regulated ones : Kiwi, antenna, WiFi interface (Linksys)
I have birdies from 10 to 30MHz : http://f1jeksdr1.ddns.net:8073/?f=27950.40usbz6
This seems to be computer noise. But which computer ? The Kiwi (which is under the roof) ?
Help ? Any idea ?
J-Luc F1JEK
The Kiwi is in a house where there is no computer, only a tablet.
The 3 power supplies are linear regulated ones : Kiwi, antenna, WiFi interface (Linksys)
I have birdies from 10 to 30MHz : http://f1jeksdr1.ddns.net:8073/?f=27950.40usbz6
This seems to be computer noise. But which computer ? The Kiwi (which is under the roof) ?
Help ? Any idea ?
J-Luc F1JEK
Comments
These 'birdies' are apparently from the same source as those I have commented on, my measurements are concentrated on 23125-23127KHz.
They sound very similar!
The ones I measure around have two major peaks about 32dB above noise and two maybe three minor peaks about 15dB above the noise level. These birdies do seem to drift around just a little, I first found them centred on 23127.
So far I have tried ferrite rod common mode filters on PSU line, network connections and antenna cables, then I went to Ferrite rings FT240-31 on the same cables and then got a greater reduction, but it is still 30dB above noise. Now i'm looking for more FT240-31 rings.
The antenna used is a ukrainian active Miniwhip about 4m distant and with 13m of feeder. There are two common mode filters on this line.
The sounds of the birdies I hear do change when I select several more windows as separate users up the max of 4.
What is frightening is that the birdies are still visible and audible when I remove the antenna connection leaving only the 5V power, from a linear PSU, and the netwrok cable. And they radiate into another set-up using a FCDpro+ alongside. This was fed from a 11m longwire.
I surmise that the birdies are, maybe partially, internally coupled into the receiver. Or through a hitherto unlocated common earth impedance.
And they can be found on a selection of the sites coupled through the SDR-hu website, although at varying degrees!
I didn't check all of the connected receivers but I suppose someone should.
I must add that the PSU to the network switch is a linear one, my main PC has been turned OFF for some of the tests, and the connection into the house is via optical fibre.
Those birdies sound pretty much like an Ethernet noise I have fought on my Kiwi with ferrite cores.
I strung about one meter of them onto the coax near the receiver and about 80 cm at antenna end.
That helped a lot, but didn't killed them completely. Also I found that making Ethernet cable as short
as possible helps too.
My active antenna is at equipment vicinity (3 or 4 meters away) that's why it catches all that noise.
I made some experiments at my summer house with longer cable and larger distance from the equipment
to the antenna (about 20 meters) and the stray noise picking was much less.