# VCOM/VCOH autoselect - GNUradio

**URL:** <https://discourse.myriadrf.org/t/vcom-vcoh-autoselect-gnuradio/6628>\
**Category:** Uncategorized\
**Created:** [19 October 2020 14:02 UTC](https://discourse.myriadrf.org/t/vcom-vcoh-autoselect-gnuradio/6628 "2020-10-19T14:02:49Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Vanimiaou](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/vanimiaou/32/3369_2.png) [@Vanimiaou](https://discourse.myriadrf.org/u/Vanimiaou)\
**Post date:** [19 October 2020 14:02 UTC](https://discourse.myriadrf.org/t/vcom-vcoh-autoselect-gnuradio/6628/1 "2020-10-19T14:02:49Z")

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Hello,

I have noticed when we generate a frequency under 60MHz the VCOH option is automatically selected, but for our signal at 52.5MHz, the shape of VCOH temporal signal is closer to a triangular signal than a sinus signal and VCOM gives a better temporal shape but at a lower frequency

We wonder if is possible to change this option and try to use VCOM at 52.5 MHz?

We also want to ask as well that later we want to use GNUradio to generate multiple frequencies in the range of 35-70MHz, what VCO option would be use after sinking onto the SDR and how can we change it?

Thank you

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**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [20 October 2020 09:05 UTC](https://discourse.myriadrf.org/t/vcom-vcoh-autoselect-gnuradio/6628/2 "2020-10-20T09:05:39Z")

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Could you provide some more information, please. E.g. what SDR? Is it a LimeSDR and if so, which model?

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**Author:** ![Vanimiaou](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/vanimiaou/32/3369_2.png) [@Vanimiaou](https://discourse.myriadrf.org/u/Vanimiaou)\
**Post date:** [20 October 2020 11:11 UTC](https://discourse.myriadrf.org/t/vcom-vcoh-autoselect-gnuradio/6628/3 "2020-10-20T11:11:12Z")

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Hello,

We’re using the LimeSDR USB with Aluminium Kit

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**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [20 October 2020 15:59 UTC](https://discourse.myriadrf.org/t/vcom-vcoh-autoselect-gnuradio/6628/4 "2020-10-20T15:59:37Z")

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Thanks for the clarification.

@Garmus @Zack perhaps you could advise.