CC2642R: Frequency deviation

Hey Shrikant,

Can you clarify the use case? What are you trying to accomplish? Without any context it is very difficult to answer this question as this is 100% application dependent.

Which example project are you using? From the Bluetooth LE perspective, this is not a modifiable field, it is fixed and set by the BLE5-stack team based on the Bluetooth LE specification.

Hi Ammar N,

As per the attached snapshot. frequency range is preset.

whenever i am trying to send packet from simple central device that time i am getting 3 peak into the spectrum analyzer.

That 3 peak range is 2400 - 2483Mhz.

So that's why i asked you which frequency should i consider.

please find attached image for your reference.

Regards,

Shrikant 

Hey Shrikant,

The peaks shown here look like transmissions on BLE channels.

I apologize, I'm still unable to follow the question you are asking about. I am not sure what your end goal is and it's difficult to advise what frequency to consider with no context on your application goals. Are you developing a product using Bluetooth LE? If so, I would recommend reviewing our SimpleLink Academy training: https://dev.ti.com/tirex/explore/node?node=A__AJfAa5knnYceGpWKAKQqcg__com.ti.SIMPLELINK_ACADEMY_CC13XX_CC26XX_SDK__AfkT0vQ__LATEST to start.

Hello Ammar,

yes i am using Bluetooth LE.

As per attached image my concern is whenever i am sending the packets,

that time I am getting 3 to 5 peak.

we want to calculate the power in dBm.

our query is 

• why we are getting multiple peaks.
• which peak we should consider to calculate the power.

Your reply is highly appreciable. 

Regards,

Shrikant 

Hey Shrikant,

I understand you are using simple_central to send packets to a device. Is this device a mobile phone, another LaunchPad (perhaps running simple_peripheral)? If you are using simple_central, have you entered a connection with the peripheral device?

Shrikant Koli said:

why we are getting multiple peaks.

There are multiple packet exchanges that occur upon connection establishment, for more information refer to Section 4.5 "Connection State" of the Bluetooth v5.2 specification. When a connection is formed, simple_central will send a connection indication packet on an advertising channel. The peripheral will then respond and both devices will switch away from the advertising channels to communicate during the connection. This could explain why you see multiple peaks on different channels.

As a follow up, we really need to know what "packets" you are sending. Is the device in an active connection state? Is it a notification packet?

Shrikant Koli said:

which peak we should consider to calculate the power.

I would recommend taking a look at this App note to calculate power: https://www.ti.com/lit/swra478d.

Depending on what those peaks are, you may need to consider all of them. When using the spectrum analyzer, are you taking conducted measurements? This is important to isolate this test from any outside interference.

If you have a DC power analyzer, this will give you more information about the power consumption.