First tests of the LimeSDR with GQRX

The LimeSDR is a new SDR $299 USD currently seeking crowdfunding over on CrowdSupply. At the time of this post the LimeSDR is currently 60% funded, with 29 days left to go. The LimeSDR is a RX/TX capable device, with a 100 kHz – 3.8 GHz frequency range, 12-bit ADC and 61.44 MHz bandwidth. From the price and specs, we consider it to be a potential next generation HackRF type device which will have vastly improved RX performance.

Over on the MyriadRF blog, Alexandru Csete has received a demonstration unit, and has written about his first thoughts on the LimeSDR. Alexandru was able to easily set the device up by using SoapySDR and GQRX on Linux. He first did the “hello world” of SDR and was able to successfully receive broadcast FM signals. Next he tried to receive Amateur Satellite signals and was successful in receiving the FO-29 satellite. Finally he was also successful in receiving NOAA weather satellite images.

From a quick judge of the waterfall images it looks as though the LimeSDR has a very clean spectrum with a low noise floor, which looks good for RX. In future posts Alexandru hopes to test out the transmit capabilties of the LimeSDR, as well as its shortwave RX performance.

LimeSDR receiving the FO-29 satellite on GQRX.
LimeSDR receiving the FO-29 satellite on GQRX.
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hackrfissish

Then it should have had some protection built in for that money,when a $10 RTL doesn’t get fried it says something, especially when the git who made it ignores those with this problem…suffice to say he does harm to others as I will not buy any more kickstarters now.

marty

It is a bit like buying a car and driving it off a cliff and complaining that it should have inbuilt protection. “Look at the money I spent. I can roll this $10 plastic beach ball off a cliff and it still works”.

You look for the maximum specifications of the device, above which physical damage occurs and do not exceed that limit. And if the limits are not obvious you contact the seller and ask them. Like the maximum RX power into a LimeSDR is +12dBm (0.90V or 16 mW), if this is exceeded you would damage the equipment. Is it possible to add protection circuitry to block signals above this level – yes, is it cheap to do so – no, will it reduce sensitivity – yes, for 99.999% of users would it be needed – no.

Watt

i’m trying to cut through the marketing behind this crowd funding campaign. i don’t see this this thing as innovative or as disruptive as the $20 RTLSDR. It is a cheaper B200, but with worse performance than the B200.

Also does anyone know is this chip available? Is this chip similar to the parallella kickstarter? If so why are they hiding that fact, if not why can’t I find any other device that uses this chip? All of this is very suspicious, and very deceptive of the company if true.

Marty

If a $299 board gives higher RF performance than a B200 ($686), that would be impressive. But so too would be a B210 ($1,119) giving higher performance than a $10,258 https://www.pervices.com/crimson-tng/ you are not exactly comparing like with like.

LimeSDR pro: LMS7002M ($110), 2 TX channels, 2 RX channels, con 40K LE FPGA
B200 pro: AD9364 ($167.34) , 75K LE FPGA, con: 1 TX channel, 1 RX channel

Parallella-RF – LMS6002D ( https://wiki.myriadrf.org/Parallella-RF )
Novena-RF – LMS6002D ( https://wiki.myriadrf.org/Novena-RF )
BladeRF – LMS6002D ( https://nuand.com/ )

I can’t find any non evaluation boards that uses the LMS7002 chip. Which is a bit odd since the chip has been in production since October 2014.

Although if I was looking at the chip alone, I would hold off until they release their LMS8001 chip, that looks much more interesting. 100kHz to 12GHz ( http://www.limemicro.com/products/ ).

ben

Hi Watt,

In what area(s) is the B200 better than the LimeSDR?

Thanks,
Ben

hatehackrf

Yeah but is this one going to turn into toast the second a 1mw signal is transmitted with 100 miles of it then the maker ignore those asking for help to repair? Sadly being plastic it doesn’t even make a good paperweight. Funny my £10 RTL doesn’t have this problem

Marty

I tried to understand what you are saying, but I still have no idea.
What plastic ?
1mW ?

Have you looked at the Gerber files for the LimeSDR is has 12 layers of copper, the BladeRF has 8, the HackRF has 4 and a RTL-SDR has 2 layers of copper. There are 7 ground layers between the clock layer and the surface on the analog side of the PCB. It is well designed. And there are very few traces that go to that side of the board. For the price it is a very good board, at least on paper, from reading through their files:
https://github.com/myriadrf/LimeSDR-USB/tree/master/hardware/socket/1v2/Project%20Outputs%20for%20LimeSDR_1v2s/Gerber

hatehackrf

I was referring to the Hackrf

Marty

So someone was keying near your HackRF ?

https://github.com/mossmann/hackrf/wiki/HackRF-One#receive-power
-5dBm (0.32 mW) [+10dBm (10 mW)]

If I assume a 5W (+37dBm) hand-held and 145MHz TX frequency and I go with -5dBm instead of the more sensible +10dBm (it would be a bad idea to leave the DC-6GHz amplifier on all time)
https://en.wikipedia.org/wiki/Free-space_path_loss#Free-space_path_loss_in_decibels
Then the minimum distance for damage would about 0.01 meters.

I do not think that about 10cm (~4″) is not all that unreasonable. But I am just picking random numbers, I have no idea what the common RF environment is like around you.