Put some ferrite on every lead that goes
out of the Pi. Any one of them can
radiate and create problems. Try using a longer cable
for the HF+ and placing it
further away from the Pi. You are in the near field
for at least the HF noise.
So doubling distance from the noise source will bring
as much as a 9 dB
improvement. It will help at much as 6 dB at VHF. A 5
meter cable would not be
out of line. But don't go beyond that without careful
testing with a powered USB
On 20180311 12:38, ea5ehs@...
> Hello David,
> I decided to go de Orange Pi UNO way for
different reasons; low cost, Gigabit
> ethernet outside the usb bus, only one usb 2.0
> My theory about the usb qrm from cables is that
there is a RPI USB design
> allowing for this. I have tested one Rpi2B and
two Rpi3B with identical results.
> QRM is only generated when an active data
connection is on, ie when a client
> connects to spyserver and start sdr#.
> When I connect the airspy HF+ to a usb port of my
Laptop and rin SDR#, no noise
> is generated with any of the six tested cables'
using the same antennas.
> I was considering the Tinkerboard SBC but as I'm
runing on solar power, every mW
> of power consumption counts. Tinkerboard seems
to draw more power than Rpi an
> Orange pi. Rpi3+airspy accounts for 630mA at 5V
during an active connection. I
> have also taken additional power saving measures
like turning off the on Board
> leds and the HDMI.
> Best Ni