Hi,
Where on the SDR board is this switch?
Hello MadMax,
And how about the high Input R. Loss from the Minicircuits transformer TC1-1-13MA?
Regards Ben
I believe RF loopback it’s adjustable via software e.g. https://wiki.myriadrf.org/LimeSDR-USB_Quick_Test#Enable_RF_loopback
But I’m pretty sure sure this is not enabled by default and you have to take explicit steps (above) to enable it.
Hello Ben,
here is the screenshot of that part you are asking for:
ben - according to wikipedia “A high return loss is desirable and results in a lower insertion loss.” What do you want to optimize here?
I just discovered that LMS_GetLoopback and LMS_SetLoopback are missing from LimeSuite.lib although present in LimeSuite.h so I can’t check this.
Thanks, my mistake.
Regards Ben
Hello Simon,
why not using the other antenna ports, the L or W ports. They have no RF switch just the transformer. This way you can see if this is a SW or HW problem. i do not have the LimeSDR unit hence can not pin point the RF switch device.
If you post some link to descent resolution photo of the LimeSDR I may indicate the part you asked for.
By the way, kudos for your SW, huge amount of job…
If you check schematic more carefully you will see RX_L and RX_W they using a coil 8.2nH or 10nH parrallel with input , this coil have impedance very low at HF ( at 10MHz it’s 0.628Ohm ) , in RX_H they using coupling capacitor only 2pF , this capacitor has impedance at 10MHz aprox. 8KOhm . With these values you can not using firmware to improve sensitive at HF , you need to modify these coil value
I’ve put Lime support on hold for now, there really is nothing more I can do. I have other projects I must dedicate my time to, please be aware I receive no remuneration for this work.
When we know exactly what the status is then I’ll give Lime support another go, but I’m not investing any more effort at the moment.
Hi @MadMax, @SimonG4ELI
There is no need to control the external RF loopback while it is set to working condition from FPGA by default. I mean external RF loopback is off by default.
I’m guessing there will be separate boards available with filter banks on them at some stage? In the meantime I’ll carry on building my own. Currently working on band 20 LTE … soldering the parts and then testing.
Why would there be?
This is a dev board, not a commercial product.
And Lime isn’t a filter company, they manufacture programmable RF chips.
If you want you need to roll your own.