# Transmit Power in Beacon Mode **URL:** \ **Category:** WiFi and Bluetooth Modules\ **Created:** [March 9, 2021, 4:21pm UTC](https://forum.sierrawireless.com/t/transmit-power-in-beacon-mode/23070 "2021-03-09T16:21:35Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![rolf](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@rolf](https://forum.sierrawireless.com/u/rolf)\ **Post date:** [March 9, 2021, 4:21pm UTC](https://forum.sierrawireless.com/t/transmit-power-in-beacon-mode/23070/1 "2021-03-09T16:21:35Z")
How is the transmit power for ble advertising in the Beacon mode set ? 1. Is it set with the Command TX\_POWER ? 2. Is it set in the BEACON\_DATA TX\_power Setting Thanks ---
**Author:** ![jerdung](https://avatars.discourse-cdn.com/v4/letter/j/82dd89/32.png) [@jerdung](https://forum.sierrawireless.com/u/jerdung)\ **Post date:** [March 10, 2021, 2:40am UTC](https://forum.sierrawireless.com/t/transmit-power-in-beacon-mode/23070/2 "2021-03-10T02:40:21Z")
Hi @rolf, Which device do you use? And what firmware is it running? Thanks, ---
**Author:** ![rolf](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@rolf](https://forum.sierrawireless.com/u/rolf)\ **Post date:** [March 10, 2021, 8:56am UTC](https://forum.sierrawireless.com/t/transmit-power-in-beacon-mode/23070/3 "2021-03-10T08:56:41Z")
Hi I use the BC 127. The Firmware is 7.3 Rolf ![~WRD0000.jpg](https://us1.discourse-cdn.com/flex025/uploads/sierrawireless/original/2X/5/52d5f1c08649212fe6768d2cacdcf8df711810d9.jpeg) ---
**Author:** ![jerdung](https://avatars.discourse-cdn.com/v4/letter/j/82dd89/32.png) [@jerdung](https://forum.sierrawireless.com/u/jerdung)\ **Post date:** [March 11, 2021, 9:44am UTC](https://forum.sierrawireless.com/t/transmit-power-in-beacon-mode/23070/4 "2021-03-11T09:44:27Z")
Hi @rolf According to Melody Audio 7.x User Guide ([https://source.sierrawireless.com/resources/airprime/hardware\_specs\_user\_guides/bc127-melody-audio-7-user-guide/](https://source.sierrawireless.com/resources/airprime/hardware_specs_user_guides/bc127-melody-audio-7-user-guide/)), the transmit power for BLE advertising in the Beacon mode will be set under BEACON\_DATA. You can refer to above document (Melody Audio 7.x User Guide, page 165) to set tx power for BECON mode. ![image](https://us1.discourse-cdn.com/flex025/uploads/sierrawireless/original/2X/4/4c38b940444a0d815b50b50e3c870014453818df.png) Thanks ---
**Author:** ![rolf](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@rolf](https://forum.sierrawireless.com/u/rolf)\ **Post date:** [March 11, 2021, 1:24pm UTC](https://forum.sierrawireless.com/t/transmit-power-in-beacon-mode/23070/5 "2021-03-11T13:24:07Z")
Hi jerdung Thanks for your help, but we cannot see a difference in the measured RSSI nearby. We measure the RSSI with a tablet and one ble scan app. Our module has an onchip antenna and is placed in the housing off a tetra radio set. We need the measurement “tetra and BT Transmitter on” for FCC acceptance test. Do you have another idea, to switch the transmitter continuesly with defined TX power on, on one channel. Thanks for your help Rolf ![~WRD0000.jpg](https://us1.discourse-cdn.com/flex025/uploads/sierrawireless/original/2X/5/52d5f1c08649212fe6768d2cacdcf8df711810d9.jpeg) ---
**Author:** ![jerdung](https://avatars.discourse-cdn.com/v4/letter/j/82dd89/32.png) [@jerdung](https://forum.sierrawireless.com/u/jerdung)\ **Post date:** [March 16, 2021, 10:04am UTC](https://forum.sierrawireless.com/t/transmit-power-in-beacon-mode/23070/6 "2021-03-16T10:04:41Z")
Hi @rolf, I used BEACON\_DATA command as above to set Tx Power for device in Beacon mode, then the Raw data which I captured is suitable with sent command. You can refer to below pictures: 1. Set tx power with -18dBm (EE) SET BEACON\_DATA=0 00 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF 04 D2 16 2E EE OKSET BLE\_CONFIG=1 OFF 80 OFF OKWRITE OKRESET 2. Set tx power with -2dBm(FE) SET BEACON\_DATA=0 00 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF 04 D2 16 2E FE OKSET BLE\_CONFIG=1 OFF 80 OFF OKWRITE OKRESET However, unfortunately that I don’t have the specific device which can measure the RSSI. So, I cannot go further on this. About your FCC acceptance test, I found that on document AirPrime - BC127 - Product Technical Specification - Rev4.0.pdf (link: [https://source.sierrawireless.com/-/media/support\_downloads/airprime/hardware\_specs\_user\_guides/airprime---bc127---product-technical-specification---rev4,-d-,0.ashx](https://source.sierrawireless.com/-/media/support_downloads/airprime/hardware_specs_user_guides/airprime---bc127---product-technical-specification---rev4,-d-,0.ashx) ) page 43, this BC127 device already get some FCC compliance. Hope it will be useful for you. If you are looking forward more detail information, you may need to contact to your distributor. Thanks,