How about XTRX – A Fairwaves tiny SDR with LMS7002M on board?

Following them since mid 2016. development going quite slow.

Wondering how they handle cooling issue knowing how hot LimeSDR can go.
Any (insider) info appreciated…

I did a similar design as an undergrad utilizing the AD9361. That chip ran hotter than the LMS7002M and had a bigger FPGA attached to it (Zynq-7000). Comparatively, cooling a mini-PCIe board isn’t too difficult, the problem is the form-factor and standard inherently limits you for power consumption even more than USB3. You’re allowed to draw a maximum of 3.3W + 0.7 W on two power rails nominally.

the guys from fairwaves held a talk on the xtrx at 33c3 in germany last december
the main issue is the bandwidth at the moment. apparently they only have one prototype

Some news after long time…

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Problem with heat / dissipation … no surprise for me… GL with heat :smiley:

Some bad luck with rev3

Crowd campaign live now…

Wow, you’ve been following our developments! Thank you :slight_smile:
Let me know if you have any questions/feedback.

Alexander Chemeris / Fairwaves CTO


Question: The campaign page says Max RF Bandwidth 120 MHz. Do you have any more details to share? How are you getting that much bandwidth with the same LMS7002M as the LimeSDR?

It is based on Mini PCIe instead USB 3.0

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I would be interested in hearing the answer to that also. Are you using analog interface to reach over 80MHz worth of bandwidth?
@ipse Can you comment on that?

@elemeno @leoha As @ccsh has mentioned above, we can get a much higher bandwidth because of the PCIe bus. LimeSDR throughput is limited by the USB3.0 interface which then limits the available RF bandwidth. With XTRX we’re currently getting 80 MSPS (equals 80 MHz of bandwidth) working stable right now, and we’re confident we can go to about 120 MSPS after further tuning.

PS Sorry for the delayed recponse - I didn’t get a notification to my e-mail and only now have noticed your questions. I’ve now changed the preferences and I hope I’ll get e-mail notifications now.

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I understand that the PCIe bus has greater throughput than the USB 3.0 interface. That explains how you can get greater digital throughput from XTRX to host. That doesn’t explain how you can sample a larger RF bandwidth than the advertised capability of the LMS7002M. Granted, the advertised specs are a bit of a moving target:

From the LimeMicro LMS7002M product page: 120 MHz (through analog ports), 60 MHz (through digital interface)

From the LMS7002M datasheet: 48 MHz (through digital interface MIMO), 96 MHz (through digital interface SISO), 160 MHz (through analog interface)

BTW, I’m already a backer. Looks like an excellent product. Just looking for clarification.

Yes, a moving target is a right word. We’re very closely working with the Lime team to get the maximum out of the chip. We’re currently doing 80 MSPS MIMO very stable and we expect to achieve 120 MSPS with further optimizations. The bus is DDR, so we’re operating at the edge of what’s possible but that’s fun!

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Fantastic! Thanks for your response. Very much looking forward to getting my hands on one.

Is there a forum for the XTRX?

Not right now, no. If you write in this forum - please don’t forget to mention me so I could draw attention of our team.

@ipse Alex are you finally delivering the boards with USB add on?

I haven’t checked with the team but my understanding is that we’ll get the USB3 carrier components from the fabs in about 2 weeks, then we’ll assemble and test them and start shipping.

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