# How to set appropriate value for a FM receiver \[LimeSDR-USB\]？

**URL:** <https://discourse.myriadrf.org/t/how-to-set-appropriate-value-for-a-fm-receiver-limesdr-usb/4356>\
**Category:** LimeSDR\
**Created:** [12 March 2019 14:49 UTC](https://discourse.myriadrf.org/t/how-to-set-appropriate-value-for-a-fm-receiver-limesdr-usb/4356 "2019-03-12T14:49:37Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ziyuanjun](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/ziyuanjun/32/2725_2.png) [@ziyuanjun](https://discourse.myriadrf.org/u/ziyuanjun)\
**Post date:** [12 March 2019 14:49 UTC](https://discourse.myriadrf.org/t/how-to-set-appropriate-value-for-a-fm-receiver-limesdr-usb/4356/1 "2019-03-12T14:49:37Z")

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I begin to construct a FM receiver using limesdr-usb.

 ![limesdr-prelaunch-1_jpg_project-body](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/4/4a33ae83cb34348498dedc80f9af6ab4f053366a.jpeg)  
Now, a .grc file can been run. But I found that I’m not quite sure how to set appropriate parameter values (RF gain, IF gain, BB gain, Transition Width and so on) for a FM receiver.  
 ![Screenshot%20from%202019-03-12%2007-08-51](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/f/f9163ff08256e8f1a698f08f18a9449dc9f4e4b9.png)

I’ve tested a lot of values. There are usually heavy noises in the output. It is strange that the output is not as good as the RTL-SDR’s output (with the same gain value, as show in the above fig).

By the way, there is an interesting phenomenon. Every time I touching the receiving antenna, the noise decreased.

**Without touching the receiving antenna:** (there is a FM music station at 97.4M, but i can’t hear the music)

 ![Screenshot%20from%202019-03-12%2007-14-25](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/b/b589208f94696f9f424e51cd8d94291e6ca1c0d9.png)

**Touching the receiving antenna:** (the station’s signal appears in the frequency spectrum, and I can hear music)

 ![Screenshot%20from%202019-03-12%2007-14-38](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/e/e3c5edf023cc437cc28035f0f82b1055f4a7045e.png)

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**Author:** ![ziyuanjun](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/ziyuanjun/32/2725_2.png) [@ziyuanjun](https://discourse.myriadrf.org/u/ziyuanjun)\
**Post date:** [16 March 2019 09:40 UTC](https://discourse.myriadrf.org/t/how-to-set-appropriate-value-for-a-fm-receiver-limesdr-usb/4356/2 "2019-03-16T09:40:55Z")

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Just replacing the original antenna by a thin wire, I can hear clear FM music.  
So, I think the original antenna gain is too low (at least for a FM signal).

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**Author:** ![cal70](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/cal70/32/2714_2.png) [@cal70](https://discourse.myriadrf.org/u/cal70)\
**Post date:** [17 March 2019 21:46 UTC](https://discourse.myriadrf.org/t/how-to-set-appropriate-value-for-a-fm-receiver-limesdr-usb/4356/3 "2019-03-17T21:46:54Z")

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A thin wire? what are you using, do you have a picture or description.

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**Author:** ![ziyuanjun](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/ziyuanjun/32/2725_2.png) [@ziyuanjun](https://discourse.myriadrf.org/u/ziyuanjun)\
**Post date:** [19 March 2019 15:06 UTC](https://discourse.myriadrf.org/t/how-to-set-appropriate-value-for-a-fm-receiver-limesdr-usb/4356/4 "2019-03-19T15:06:02Z")

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OK.  
Fig1: a straightened paper clip is used.

 ![IMG_20190319_224353](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/a/aeb1f6e8bce6c18a569543927ab39107668dba26.jpeg)

Fig2: A long wire is used. This one works better.

 ![IMG_20190319_224535](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/0/03a3a55bc787b3493269c8af16fa752be7dc697d.jpeg)

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**Author:** ![janezhang](https://avatars.discourse-cdn.com/v4/letter/j/48db29/32.png) [@janezhang](https://discourse.myriadrf.org/u/janezhang)\
**Post date:** [23 January 2020 04:22 UTC](https://discourse.myriadrf.org/t/how-to-set-appropriate-value-for-a-fm-receiver-limesdr-usb/4356/5 "2020-01-23T04:22:40Z")

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> [@cal70](#):
>
> ? what

hello Do you use gnu radio and limesdr to do that ?