# Double SISO with different frequency

**URL:** <https://discourse.myriadrf.org/t/double-siso-with-different-frequency/2739>\
**Category:** LimeSDR\
**Created:** [30 April 2018 16:44 UTC](https://discourse.myriadrf.org/t/double-siso-with-different-frequency/2739 "2018-04-30T16:44:26Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Nawfal\_M](https://avatars.discourse-cdn.com/v4/letter/n/278dde/32.png) [@Nawfal\_M](https://discourse.myriadrf.org/u/Nawfal_M)\
**Post date:** [30 April 2018 16:44 UTC](https://discourse.myriadrf.org/t/double-siso-with-different-frequency/2739/1 "2018-04-30T16:44:26Z")

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Hi,

I am wondering if it is possible to set the LimeSDR to be transmitting (Receiving) simultaneously at different frequencies using 2 paths (BAND1 and BAND2) (LNAL/LNAW)?

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**Author:** ![martywittrock](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/martywittrock/32/66_2.png) [@martywittrock](https://discourse.myriadrf.org/u/martywittrock)\
**Post date:** [30 April 2018 17:53 UTC](https://discourse.myriadrf.org/t/double-siso-with-different-frequency/2739/2 "2018-04-30T17:53:10Z")

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@Nawfal_M,

They’re doing such a thing with the Vector Network Analyzer application that’s being developed and polished from this forum. It requires that a transmit and receive path are functioning simultaneously (or close to it)…If you review the code on that effort you’ll be able to mine quite a bit from it.

Hope this helps -

73 de Marty, KN0CK

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**Author:** ![Nawfal\_M](https://avatars.discourse-cdn.com/v4/letter/n/278dde/32.png) [@Nawfal\_M](https://discourse.myriadrf.org/u/Nawfal_M)\
**Post date:** [30 April 2018 18:00 UTC](https://discourse.myriadrf.org/t/double-siso-with-different-frequency/2739/3 "2018-04-30T18:00:33Z")

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@martywittrock

I am sorry, but it seems that my post was a bit confusing. I was asking about the possibility to set the LimeSDR to transmit at different frequecies using both BAND1 and BAND2

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**Author:** ![mleech](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@mleech](https://discourse.myriadrf.org/u/mleech)\
**Post date:** [30 April 2018 18:16 UTC](https://discourse.myriadrf.org/t/double-siso-with-different-frequency/2739/4 "2018-04-30T18:16:36Z")

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The two TX channels share an LO, as do the two RX channels. So the LO can only occupy a single frequency at a time. But if you can shift your baseband around within the sample rate, you can have two different “air” frequencies, but they can, at most, be separated by whatever your sample-rate is.

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**Author:** ![Nawfal\_M](https://avatars.discourse-cdn.com/v4/letter/n/278dde/32.png) [@Nawfal\_M](https://discourse.myriadrf.org/u/Nawfal_M)\
**Post date:** [30 April 2018 18:20 UTC](https://discourse.myriadrf.org/t/double-siso-with-different-frequency/2739/5 "2018-04-30T18:20:23Z")

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@mleech  
Thanks for your clarification…This was my first impression after looking quickly at the datasheet’s first page…But I was hoping that I was wrong