Many thanks in advance for any ideas
Just a thought: Try disconnecting your antenna from the RSP's antenna connector, if the interference bars go away then the interference is being received by your antenna.
If its being received by your antenna then you should read all you can on the subject of eliminating common mode noise.
Here is a very simplistic overview:
The interference generated by the nasty devices in your house and your neighbour's houses appears as an RF signal impressed across a mains "feedline" consisting of mains neutral/ground (which are bonded together but certainly do not present a short circuit to RF) and mains active. Those wires with all that crappy RF on them are connected directly to your house using nice big fat mains wire conductors.
The RF on those wires goes a long way. Compare it with ADSL for example which is an HF signal up to 2MHz and works very nicely even beyond 4 kilometres using an underground twisted pair and a much lower signal level.
The key thing to note about this interference is that it's an RF voltage potential generated against GROUND/NEUTRAL.
If you use a balanced antenna, say a centre fed dipole or a quad loop for example, the RF is NOT a voltage potential against ground, it's the potential difference between the two poles of your dipole. Hence it is "quieter" than an end fed antenna which sees signals as an RF potential between their feed point and ground and the signal you are trying to receive is just another RF voltage mixed in with the crappy interfering RF signals.
Unfortunately even with a balanced antenna, if you use coax as a feed line it forms part of a chain that includes the ground of your RSP, your USB cable, your computer and your power supply and therefore is *directly connected* to MAINS/NEUTRAL/EARTH and thus to all those interfering devices.
So... all the crappy RF - because it exists as a potential difference variously against ground and neutral and mains active - uses your coax braid as an ANTENNA and your braid radiates crappy RF all the way up your mast to your feed point where it is received by your actual antenna.
A well designed common mode choke (or two or three) on your coax braid and/or at your feed point, presents a high impedance to RF on the braid that is at a potential against ground and thus eliminates or at least heavily reduces the interference.
The choke does not affect the "good" RF because the good RF exists as a potential difference between the inner conductor and the braid and therefore does not create an electromagnetic field and thus presents no impedance to your chokes.
Hope that's not too garbled or simplistic, it's meant to do no more than stimulate and stoke a desire to get the real info by searching for quality articles on the subject of common mode RF interference. It's fascinating.
Armed with the right information I was able to reduce my noise by well over 20dB using home made simple inexpensive chokes along with better grounding and feed line practices. I also now mostly use and prefer balanced feed lines, as does every rock and roll band with their audio systems, for exactly the same reason.