# How to start signal receiving simultaneously on a large number of LimeSDR-USB boards

**URL:** <https://discourse.myriadrf.org/t/how-to-start-signal-receiving-simultaneously-on-a-large-number-of-limesdr-usb-boards/8738>\
**Category:** LimeSDR\
**Created:** [1 April 2025 12:44 UTC](https://discourse.myriadrf.org/t/how-to-start-signal-receiving-simultaneously-on-a-large-number-of-limesdr-usb-boards/8738 "2025-04-01T12:44:53Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![andrin](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@andrin](https://discourse.myriadrf.org/u/andrin)\
**Post date:** [8 April 2025 20:41 UTC](https://discourse.myriadrf.org/t/how-to-start-signal-receiving-simultaneously-on-a-large-number-of-limesdr-usb-boards/8738/4 "2025-04-08T20:41:14Z")

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This became possible very recently to sample accuracy thanks to a firmware modification. Check this post on the limesdr mini:

> [@Question regarding how 2 SDRs running simultaneously are timed](https://discourse.myriadrf.org/t/question-regarding-how-2-sdrs-running-simultaneously-are-timed/8551):
>
> I have 2 LimeSDR Minis (v 2.4) that are connected to the same clock. I am running them simultaneously and am not surprised that their output is not synchronized in time. What does puzzle me is the following: there is a time offset between the two that is constant over multiple loops of LMS\_SendStream - this is what is sending out the TX stream and even though the offset between the transmit streams (from the two different SDRs) varies from one initialization to the next (brought on by restarting…

On the limesdrUSB, the same firmware mod can be implemented. It’s few lines in the vhdl code, but you need to sacrifice one of the fpga gpio’s for that, whereas limesdr mini uses egpios. As we now have limesdrUSBs back on the track, that very nice sync feature might be implemented in firmware? (@VytautasB )

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