BLE radio frequency calibration

[xianke]

I want to to ensure the stability of BLE connection for BLE frequence calibration,but i don't know how to get the nordic into the test mode and broadcast the empty packet.who can help me to deal with it?

[cbd]

For this type of work, including certification, I would suggest that you use Direct Test Mode. This allows you to set the channel frequency and trigger continuous transmission of the carrier wave without any data modulation. Incidentally, it does have a mode that will broadcast a known packet sequence as it's a requirement for certification.

You can place your device into Direct Test Mode and control the sequence yourself, but normally it's best to have a jumper on your circuit that allows a UART to be connected to an external control device and have your code set to respond to external commands.

[xianke]

OK，are these external commands defined by myself? If not where can I get these commands?another questions:if finally i get the frequence  in the scope of 2.399990GHz~2.410010GHz,when i get out the Direct Test Mode,how can I hold it?

[Martin Lesund]

Hi xianke,

Have you read the documentation for DTM?

[xianke]

OK,let me see.

[cbd]

In answer to your questions:

As Direct Test Mode is required by the Bluetooth SIG you don't have to specify the commands. Have a look in ble_dtm.h.

There's an example project in the SDK for Direct Test Mode.

You can use sections of the DTM functionality yourself, so for example, if you wish to output the carrier signal at a specific frequency then you can, although from what I can remember you have to select a channel as opposed to a frequency and you set the configuration for CARRIER_TEST. Once set it should continue to transmit until you tell it otherwise or you turn it off.

[xianke]

OK,thanks you very much,this is a good help for me.But I will come back if I have a new question.

[xianke]

HI! I have seen the SDK about Direct Test Mode,but it's not what I want.What I want to do is that I want the device get into a certain state that broadcast continue,and I can get the BLE frequence offset and TX Power through the spectrometer,then I want to change one or more parameters about BLE to get the frequence offset in the range of -10KHz~10KHz in broadcase channel 0,and the distance in device and spectrometer is about 50cm.