What is the actual operational frequency range?


#1

I’ve been researching the LimeSDR-mini and the “FPRF” chip that it is based on, the LMS7002M. After reading much of the documentation, I notice that there is some variation in the reported frequency coverage. For example wiki for the latest revision reads 3.5 Ghz. Since I plan to operate at 3.4 GHz, I’m worried that the performance would degrade near the edge of the advertised spec.

Has anyone tested out the LimeSDR-mini in the higher frequency ranges? I see the question has basically already been asked?
… but never replied to.


#2

Do you have a spectrum analyzer? It should be straight forward to sweep a tone from 3.0 to 3.5GHz and look at the output to see what sort of roll off to expect (if any).

–Chuck


#3

Yes, I do, what I don’t have is the LimeSDR. I’m actually a bit hesitant to order because of the disorganized feel of the website and support network. Lime enthusiast, please change my mind!


#4

Uh yeah, about that. I’m not sure I’m the guy to change your mind :slight_smile:

There are several threads about transmit power in the forum (just search for them) and you will see that for TX2 its ok for TX1 it drops off fairly quickly as you approach 3.5Ghz. Of course you can compensate for that in your PA.

In my opinion you don’t gain all that much by going “cheap” with the Mini and you gain a lot by sticking with the LimeSDR-USB (like all the various channels of the chip brought out for use). So for $140 “extra” you get a much better system (and it supports MIMO unlike the mini).

If you don’t care about MIMO or better frontend selectors then the ADALM-PLUTO ([https://www.mouser.com/new/Analog-Devices/adi-adalm-pluto/]) is pretty solid up to 3.8Ghz, single channel of course and cheaper than the LimeSDR-mini.

But the bottom line is that you can screw up by starting too cheaply, you will end up buying three or four radios when you really only needed to buy one. Currently the most flexible at the best price is still the original LimeSDR-USB at $299.

–Chuck


#5

Thanks for the info Chuck! That was exactly my line of thinking… going cheap doesn’t pay off. I’ve been shopping around quite a bit and was leaning toward the PLUTO. The main thing is when size really matters. Only a few SDRs are less than 10 cm long.

I won’t write off the Lime offerings yet, but so far I’m not convinced.


#6

@evilmrmahler
What do you like to see?
From my experience, Lime works OK on all declared freq above 1 MHz

Sure PLUTO support is “much better”
see here -> https://www.plutosdr.com/ site down, and before lot’s of spam trash…


#7

In all fairness the wiki for Pluto SDR is also a bit disorganized, it’s true (although the link you provided isn’t it…)

What I’m really scared from is reading forum threads about lime mini, probably the USB version works but the mini is definitely an SDR I will stay away from.