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LimeSDR

limemicro.com

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Re: LimeSDR

#71

Post by ohazi »

I wish them luck, but judging by the ~week I spent trying to get a LimeSDR mini to work, their product is so half baked that it's basically not fit for purpose, and if you're considering getting one, I'd recommend something with an Analog Devices front-end instead.

The PLL would fail to lock at random frequencies and temperatures. You'd try to scroll through e.g. the 2.4 GHz ISM band and would randomly get downconverted signal or baseband noise on every other click. Two minutes later, the set of bands you could capture would be entirely different. There was no consistency whatsoever.

When I went to their forums to see if other people had encountered the same issue, it turned out that basically none of the LimeSDRs even pass their own self tests [1]. I don't know how they're still selling these devices... they don't work.

I returned it, paid ~4x more for a USRP, and could not be happier. The hobby is playing with radio modulation schemes, not debugging a defective piece of silicon.

[1] https://discourse.myriadrf.org/t/new-limesdr-mini-loopback-t...

Re: LimeSDR

#72

Post by TaylorAlexander »

CSSer wrote: post #38
WrtCdEvrydy wrote: post #26

Earlier quoted context omitted.

The best one is the ADS-B Out from airplanes, you can map the planes around you with a $20 widget.

This sounds really cool. When you say 'around you', what kind of radius are we talking?

It’s very fun! I use it to monitor for low flying aircraft around a farm where I am doing some drone experiments. The legal drone limit in my area is 400 feet above ground level and near the hills some aircraft fly pretty low, so I’m going to ground the drone any time an aircraft is nearby that is not above 10kft.

Re: LimeSDR

#73

Post by scrps »

tzs wrote: post #17

The couple of times I've had something I wanted to do that needed an SDR more powerful than than an RTL-SDR and decided I wanted a LimeSDR or LimeSDR mini...the lead time on them has been such that it would not arrive in time for the project I wanted it for. Right now, both LimeSDR and LimeSDR mini orders place now don't ship until Feb 28 2022, except for the LimeSDR PCIe which ships Sep 29 2021. (You might be able t…

Not sure your exact use-case but if you are frequency-limited by the RTL and you feel like soldering, you can mod a SUP-2400[0] to be a 4.5GHz downconverter for the RTL[1].

[0]: https://www.solidsignal.com/zinwell-directv-b-band-converter...

[1]: https://www.kd0cq.com/2016/04/part-ii-the-mod-receive-up-to-...

Re: LimeSDR

#74

Post by ohazi »

cepher wrote: post #30

Does anyone know if this is more appropriate than the PlutoSDR for hobbyists? Seems like they have similar specs and are around the same price.

I haven't played with the Pluto, but I do have a USRP, which uses the Analog Devices front-end, and it's leagues more reliable than the LimeSDR.

I would absolutely go for the Pluto if it'll work for your application. I guess the main limitation is USB2 for getting the captured signal out, so you wouldn't be able to use it for crazy high bandwidth applications.

Re: LimeSDR

#75

Post by BuildTheRobots »

CSSer wrote: post #38
WrtCdEvrydy wrote: post #26

Earlier quoted context omitted.

The best one is the ADS-B Out from airplanes, you can map the planes around you with a $20 widget.

This sounds really cool. When you say 'around you', what kind of radius are we talking?

160 miles with a £6 rtlsdr and an antenna I bodged out of coax. Its painfully easy. Also have a nosy at POCSAG - there's still a little bit left in the UK.

Re: LimeSDR

#76

Post by toomuchtodo »

TaylorAlexander wrote: post #72
CSSer wrote: post #38

Earlier quoted context omitted.

This sounds really cool. When you say 'around you', what kind of radius are we talking?

It’s very fun! I use it to monitor for low flying aircraft around a farm where I am doing some drone experiments. The legal drone limit in my area is 400 feet above ground level and near the hills some aircraft fly pretty low, so I’m going to ground the drone any time an aircraft is nearby that is not above 10kft.

I highly recommend not relying on SDR ADS-B reception alone and also checking online data systems for ADS-B that also use multilateration to track aircraft using their transponder when they aren’t ADS-B capable. Otherwise you might be operating under the assumption there are no contacts in your working airspace when there is aircraft present but not announcing their location.

https://flightaware.com/adsb/mlat/

Re: LimeSDR

#77

Post by gorkish »

cschneid wrote: post #65
nlh wrote: post #14

I was super into the ham world many many moons ago (DE K2KD), and my curiosity is definitely piqued with the arrival of SDRs. Dumb question(s): Is it possible to do "traditional" HF/VHF ham stuff with these mini SDRs? Is there a good software package that emulates the old-school rigs (but with fancy new features)? Are these radios powerful enough to drive an amp to get to something like 100W (or 1500W) on HF?

Check out the Hermes Lite, it's an SDR with a transmit ability, and some other additional features. I think it's 10w by default, but a lot of people put that right into an amp to get up to 100+ watts.

I immediately hit reply to suggest the Hermes Lite also; despite the crazy supply chain situation, there is a current manufacturing run going right now. With N2ADR's filter board, you have a complete 10W HF direct sampling transceiver. Add a hardrock PA and you can take that easily to 50W or 500W at an insanely low price point.

I hand build a few of the early prototypes and have a couple of the production versions too. I cannot emphasize how underrepresented I think this radio is compared to a lot of the other SDR hardware out there. It compares favorably in performance and vastly exceeds the features of most amateur radio HF transceivers in the Because it speaks the OpenHPSDR protocol it can also run a digital predistortion algorithm called PureSignal that samples the PA output and distorts the input signal to correct for amplifier phase and power nonlinearity. Digital predistortion is relatively common in modern radios like cellular baseband, but to my knowledge PureSignal is the only open source implementation of such and the only implementation publicly available for an HF radio.

Re: LimeSDR

#78

Post by ericbarrett »

toomuchtodo wrote: post #76
TaylorAlexander wrote: post #72

Earlier quoted context omitted.

It’s very fun! I use it to monitor for low flying aircraft around a farm where I am doing some drone experiments. The legal drone limit in my area is 400 feet above ground level and near the hills some aircraft fly pretty low, so I’m going to ground the drone any time an aircraft is nearby that is not above 10kft.

I highly recommend not relying on SDR ADS-B reception alone and also checking online data systems for ADS-B that also use multilateration to track aircraft using their transponder when they aren’t ADS-B capable. Otherwise you might be operating under the assumption there are no contacts in your working airspace when there is aircraft present but not announcing their location. https://flightaware.com/adsb/mlat/

You need both data sources—a number of planes are “delisted” from the commercial trackers and won’t show up, but they still broadcast ADS-B. You can find partial lists of such registrations through a keen Google search.

Re: LimeSDR

#79

Post by lxe »

Blackthorn wrote: post #2

Does anyone know of a solution that can go down to the 5khz range? Older (...and even newer) gym equipment uses the gymlink protocol for heart rate monitors instead of low power Bluetooth and friends, and very few monitors support it anymore. I wanted to try to make a converter but couldn't find anything to output in that frequency.

Try an upconverter like this https://www.nooelec.com/store/ham-it-up.html or https://airspy.com/spyverter-r2/

Re: LimeSDR

#80

Post by jacquesm »

drmpeg wrote: post #70
jacquesm wrote: post #21

Earlier quoted context omitted.

Before you start pumping out that kind of power I'd invest in a spectrum analyzer (which are surprisingly affordable today) to ensure that the signal that goes out is clean. Those mini SDRs when used for transmission will output a ton of harmonics because they are almost by definition not going to have any filtering on their output because that would limit their usability. When used for reception that is not a proble…

That's for sure. Here's what an Ettus B210 (now $1472, not cheap) looks like with a fundamental at 145 MHz. 3rd harmonic is only 10 dB down. Power was 0 dBm (with a 20 dB pad on the analyzer input). https://www.w6rz.net/harmonic.png

That's even worse than I thought it would be. A cheap one will likely not do better. At least they picked the HAM bands smart so harmonics tend to end up in the next HAM allocated frequency range up. But SDRs being what they are there are no passive components on board to ensure the signal stays 'in its lane'.
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