Https://myriadrf.org/news/limesdr-made-simple-part-4-pothos-beyond/

#1

I’m trying to follow the above link to create a simple fm reciever using limesdr mini and pothosware tool.

image

in the image above it says select LNAL in channels for antenna Type. But i dont find LNAL option in the dropdown. the options available are DEFAULT, NONE, LNAH, LNAL_NC, LNAW, Auto.

I tried all of them but i can just get some noise as output.
I have a tp link TL-ANT2408CL which is a 2.4GHz 8dBi antenna.

Can someone tell what might be wrong?

#2

I’m going to guess that the connector on the TL-ANT2408CL antenna is a Male RP-SMA and when connected to a Female SMA connector there is no path for the signal to travel through. For Bluetooth/WiFi RP-SMA connectors are the default, for general RF SMA connectors are the default and the two are incompatible by design.

#3

This blog post series was written for the LimeSDR USB, at a time before the LimeSDR Mini existed. Hence steps would be slightly different and you could not run examples which use the waveform player, since the Mini doesn’t have DDR memory and so this is not supported on it.

#4

Thanks for the comment.

I tried the below connector as well:

Which is a SMA type conncetor.
Still no luck.

#5

@andrewback thanks for the comment.

I tried different values in the same example for gain and decimation but its just noise until now. I removed the waveform generator as well. I’m just hoping to get some audio output.

Could you tell me what values i can change or maybe is there something missing in the example.

I’m just getting started with limesdr mini and i have tried many examples from the internet but nothing seems to work.

#6

A well designed antenna optimised for reception (and transmission) of signals around 2.4GHz (a wavelength of ~0.12491 meters or ~0.40982 feet) should strongly attenuate signals at 90.9 MHz (a wavelength of ~3.298 meters or ~10.82 feet). For a quick test, if it is for RX only* then a basic quarter wavelength monopole (or dipole) antenna would work fine.

*The reason I say RX only is because a bad impedance mismatch, is never going to cause any damage (just a lower signal level). But for TX a bad impedance mismatch could reflect some, or all, of the energy back into the device and in the best case cause much lower transmission power levels and in the worst case cause permanent damage to the device.

#7

@mzs
Thanks again for that detailed explanation.
So it’s time get a new antenna.
Will keep you posted.