# Simultaneous transmission on two different TX ports at different frequencies using LimeSDR

**URL:** <https://discourse.myriadrf.org/t/simultaneous-transmission-on-two-different-tx-ports-at-different-frequencies-using-limesdr/13242>\
**Category:** General Discussion\
**Created:** [11 June 2026 05:58 UTC](https://discourse.myriadrf.org/t/simultaneous-transmission-on-two-different-tx-ports-at-different-frequencies-using-limesdr/13242 "2026-06-11T05:58:13Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Praveen](https://avatars.discourse-cdn.com/v4/letter/p/3ec8ea/32.png) [@Praveen](https://discourse.myriadrf.org/u/Praveen)\
**Post date:** [11 June 2026 05:58 UTC](https://discourse.myriadrf.org/t/simultaneous-transmission-on-two-different-tx-ports-at-different-frequencies-using-limesdr/13242/1 "2026-06-11T05:58:13Z")

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Has anyone successfully transmitted different modulation schemes (e.g., AM on TX1 and FM on TX2) simultaneously using LimeSDR?

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**Author:** ![KarlL](https://avatars.discourse-cdn.com/v4/letter/k/dfb087/32.png) [@KarlL](https://discourse.myriadrf.org/u/KarlL)\
**Post date:** [11 June 2026 10:09 UTC](https://discourse.myriadrf.org/t/simultaneous-transmission-on-two-different-tx-ports-at-different-frequencies-using-limesdr/13242/2 "2026-06-11T10:09:54Z")

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The LimeSDR has 2 Local Oscillators: 1 for receiving, 1 for transmitting.

As a result, you can easily receive at one frequency and transmit at a completely different frequency. But you cannot receive on channel 0 at one frequency and receive on channel 1 at a completely different frequency, same limitation for transmitting.

You can receive or transmit on 2 different frequencies if they are close enough, thanks to the NCO, but it seems the maximum difference is 80MHz, and it can depend on the sampling rate. Check [Max NCO, relation to sampling rate, and NCO effect](https://discourse.myriadrf.org/t/max-nco-relation-to-sampling-rate-and-nco-effect/4304)