Extremely weak reception of strong signals, defective LimeSDR?

Projects LimeSDR
1

I reinstalled everything on Ubuntu (as this is supported by packages).

Everything looks OK, I can make the self test, I can update the firmware of the LimeSDR, etc.
But I am a newbie to Lime.
I have not done the easy HF fix (yet), as I wanted to explore the behaviour of the LimeSDR before altering it.
I have connected a small antenna to LNAL.
I have looked at 900 and 100 MHz.
I have done the same with a cheap 20 USD rtl-sdr dongle.

Here are the results:

The same is true for FM broadcast radios.
Very, very strong ones can be barely decoded by the LimeSDR.
The RTLSDR works perfectly, and I get extremely good SNR.
With Lime even the strong ones barely rise above the noise floor.
Did I receive a defective unit?
Do I need to make some adjustments in LimeSuite in order to make it work??
At the moment it is completely DEAF!!

Please help me … I have no clue if I am doing something wrong, or if my HW is defective.

2

Antenna RX1 antenna setting LNAH

3

What do you mean exactly?
I have set the antenna to LNAH in gqrx, and also connected it to RX1H.
No improvement:

If I misunderstood you, please be a bit more verbose what I should try and in which program.

4

Increase PGA gain

5

I have set all gain settings in gqrx to the maximum setting.
No real change:

Extremely strong broadcast FM radio stations arounf 100 MHz are still bearly hearable!

6

Whats system you running it linux or win if win try reinstall driver then software if still same try it on different computer.

7

I first tried it with KaliLinux and self compiled drivers.
Today I installed Ubuntu 16.04 and have used the provided packages by Lime.

BTW. the self compiled drivers showed the same results, I just thought that I did something wrong!

Drivers are OK.
LimeUtil and SoapySDRUtil find the board without problems.
Only that it is deaf :(((

Anybody else has any helpful hints?

8

I have the same situation, if you look down on forum.
It seems some Lime’s have problems, but it seems no chance for exchange with a good one from Crowd Supply
Money on the river water… :frowning:

9

Here is the FM band:

10

Count the scale …

Your FM signal is around 35db from noise floor … the ADC is only good for 70db. Ajust analog LNA gains for the minimum noise floor (this does not mean no noise but what you can barely detect)

11

Stil not satisfied?

You should update gqrx

12

I started with lower gain settings. But after the signal popped out of the noise, it did not really change. Ie the situation is not better with lower gain settings either.
Sombeody in this thread advised to even increase the gain more.

Regarding gqrx.
Is there a known bug with it??
I used the package supplied by Myriad/LimeMicro together with the recommended distribution.

I have this version:
gqrx -version
linux; GNU C++ version 5.4.0 20160609; Boost_105800; UHD_003.010.001.001-release

Controlport disabled
Gqrx software defined radio receiver 2.6.1

13

Alex,

please get with @andrewback regarding the issue you’re having with your LimeSDR - He can work with you and Crowdsuppy to get this resolved.

@andrewback: Can you work with Alex (from Romania) to help him resolve the issue he’s having with his LimeSDR?

73 de Marty, KN0CK

1 Like
14

What i see from his screen shot is a version of gqrx that has only one gain control. The built from git version i have/use has 3.

What kind of signal level does ricsi exspect above the noise floor of a FM broadcast signal … 120db?

15

Mike,

All good on GQRX, but I think Alex is using SDRConsole for his tests.

@yo2ldk: Can you confirm this Alex…?

73 de Marty, KN0CK

1 Like
16

Hi martywittrock

Thanx for your answer!
Much appreciated!
How can I contact andrewback??

73 de OE1RIC

17

Hi Kc8noa

I have tested with LimeSDR and RTL-SDR

The first has 3 gain settings (LNA, TIA and PGA)
I assume you refer to a screenshot of the RTL-SDR that I have posted for comparison.

18

@ricsi,

I can do that here…

Paging @andrewback …Looks like @ricsi has a suspect LimeSDR…Please respond.

73 de Marty, KN0CK

19

Hi Marty,

Pinged @Zack to see if he has any suggestions and, in both cases, once we’ve exhausted things to try we can look at a return/exchange.

2 Likes
20

Hi Andrew

Thanx!

I have talked 2 colleagues into buying LimeSDRs.
At least one of them has already received it.
I will try to compare theirs to mine … can take some time

One of them also has a HackRF, I can try to compare it to that as well.

In the meantime … if there is something I should try just tell me what to do.