LimeSDR XTRX mPCIe SDR readies for launch!

I’m not affiliated with lime, but I’ve messed around a lot with the new gateware. After synthesis the it uses about 2200kb of block ram, but the xc7a35t only has 1800kb. I’m sure someone really dedicated could probably optimize and make it work, but that’s beyond what I can do.

Thanks a lot for the info. So it seems it won’t easily be compatible with rev 4 unfortunately.

Are you happy with the new gateware? We’ve basically never been able to use our XTRX, as it seemed we only received noise. We were never able to know for sure whether the gateware or hardware were at fault.

Yeah I’m in the same boat, I’ve been disappointed in it for 4 years. Good news though, the new driver stack is already in a better state than the fairwaves stack, and the performance seems quite good! There are a couple of caveats for now. The new limesuite isn’t quite finished, and the gain functions for xtrx haven’t been implemented. I added them myself, but the calibration routine isn’t working so the carrier is 10-13 db above my signal and I haven’t been able to get rid of it yet. As soon as I get that taken care of I can throw some 3gpp waveforms through it and see how well it does :grin:


Tagging @ricardas in this thread, as my understanding was that we have been using XTRX with 5G NR, so in which case I’m wondering if there is another branch or specific commit etc. to use.

Yes, we have used XTRX with 5G NR, right now everything is in litepcie-update branch. I haven’t yet fully checked the calibration, just ported it from MCU so it would be doable/debugable from PC. The gains and calibration values can be adjusted manually using GUI and saved as configuration file, so currently I’m focused on other areas.

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Hm… At this point in time I would be happy to use my rev4 with even half the speed (single PCIe lane), and I think I am not alone with it. I am not a VHDL developer so I have no idea, but if there is an “easy” way to fit into 1800kb with just loosing performance, that would be great. 5GT is still better than USB3 anyway :slight_smile:

I’ve been very excited about, and waiting for, the LimeSDR XTRX since the takeover and relaunch was first announced. I must say, I’m very disappointed that the price is $700, with no incentives for ordering multiple units or for early-bird buyers, especially since the Fairwaves version was priced at $200. $700 puts this SDR beyond the reach of many hobbyists.

Are there any plans to offer enclosures, like the Fairwaves USB enclosure?

That was the price at launch 6 years ago. Following which they updated the design and XTRX Pro as of 2019 was priced at $599. Another 4 years has passed since then, together with regular component price increases and more significant jumps following the semiconductor shortage, and the price has increased by $100. The design has also been updated again and incorporates new features.

Not at this point. The USB enclosure used a device which tunnelled PCIe over USB and that part is now end-of-life. I’m also not sure how well it ever performed in practice.

I understand that the market has changed significantly since the original XTRX launch, and I’m still disappointed at the price point for the LimeSDR version. One key aspect of the marketplace shift is inflation, of course. While that obviously impacts component and manufacturing costs, it also affects consumer discretionary spending. Prices go up, discretionary spending goes down, and sales volume for high-ticket discretionary items dries up.

There are many interesting potential use cases for the XTRX due to its wide instantaneous bandwidth. I have a project I’d love to build involving a custom bidirectional broadband comm protocol, which would require two units, and the XTRX is the only SDR that really fits the requirements. Unfortunately, I cannot justify spending $1400 at this time.

I want this product to be successful, since I believe it’s the most interesting SDR platform since the HackRF One (for very different reasons). I guess we’ll see over the coming weeks whether the market accepts the $700 price point. By my count, looking at the old campaign page, the original XTRX campaign sold 682 units during its run on CrowdSupply. While I’m disappointed that I’m priced out of this initial campaign, hopefully there will be enough other people interested who can justify the expenditure.

It costs $100 more than the last available Fairwaves version — which was a number of years ago and predates component price increases — and represents a ~17% price increase.

I don’t mean to sound rude, but I kind of agree about the price being too high. I was planning to back this project, but when I went to the crowdfunding website I was surprised to see the price at $700. WTH?? At first I thought it was a typo, but now I see it’s for real. I was expecting the price to end up in the $300 to $400 range, but $700? Ugh, that’s a bit out of my budget. Not to mention that we in EU still have to pay additional +22% VAT on top of that as well as import taxes and handling. That can quickly accumulate to nearly a grand.

Sorry guys, maybe next time. I wish you best of luck with your project.

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That would be a price reduction of between $199 and $299 based on what XTRX cost 4 years ago.

While the reality is that component costs have increased, I think people still generally expect that electronics prices decrease over time (or that capability increases for a particular price point). I hope the XTRX sells well enough that I might eventually be able to pick one up on the secondary market at a price that I can justify. If it does not sell as well as expected, I hope you will consider our feedback and reassess your pricing model. Many crowd-funding campaigns choose to offer several backing options, including volume discounts and early-bird pricing. If you have room in your margin on the XTRX, it may be worth considering adding such options to provide an incentive for early purchasers and those of us who would like to buy multiple boards.

I come from the telecoms world and not the hobby/amateur radio space, so from my perspective these things are unbelievably cheap. There’s only one other company right now producing something comparable and the price difference isn’t even funny. And having worked on similar hardware, I can say the margins on this aren’t as wide as you probably think they are. These things are almost half the price of a USRP B210 with more than double the bandwidth and an inbuilt GPSDO.

Edit: just a note, 600 USD in 2019 is 730 USD today. So a 21% inflation, but only a 17% price increase.

@andrewback What are production plans post-crowdfunding? Will there be continued availability, or will it just be available in batches?

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We always have to manufacture in batches and these be of some minimum size, otherwise the costs would start to increase steeply. The hope is for it to be generally available at any particular time, but this depends upon the size of orders placed by distributors — e.g. Crowd Supply and Mouser — vs. rate of sales.

I live in both the commercial telecom and hobbyist spaces, and I agree that the combination of features and price point could be very attractive for commercial projects (and the associated larger budgets), provided the software support arrives as expected.

For my personal/hobby projects, though, I just can’t justify the cost, considering I already own several other SDRs and the $700 price point is for a bare board, meaning I would still need to assemble a dev kit (particularly to make use of the mPCIe interface). I had also been anticipating the Fairwaves XCOM project (, which would have provided an integrated dev kit platform. One of the reasons I’m hoping the LimeSDR XTRX is successful is because I’d love to see the XCOM resurrected as well.

@andrewback @Zack

Just to keep the topic afloat: the rev.4 user base would really appreciate any support (even perf. limited) for the boards already out there. If it is really “just” a memory issue, maybe loosing one of the PCIe lanes or MIMO might make an “easy” solution to this problem in the gateware.

Now that I am thinking, I have my rev.4 board in a single PCIe lane config, if someone can tell me that I can safely flash the rev.5 gateware on my rev.4 board (or at least it is possible to recover in case it does not work), I am happy to be the guinea pig and try the new gateware.


+1 for rev 4 Fairwaves XTRX gateway support.

an update on the XTRX status would be much appreciated.

I should be able to find out next week and will report back.

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