BLE radio transmission

[Ric]

Hello,

I am using a custom PCB with ISP130301 BLE module based on nRF51822. The PCB layout for the module is designed based on the recommended PCB land pattern and solder mask layout. But, when I program the module using s110_nrf51822_7.0.0 - softdevice, I find that the module does not send the advertisement packets on the frequency channels 2402, 2426 and 2480 MHz instead I am seeing two Peaks at some random frequency 2438 and 2490 MHz of strength around -50dBm.

Due to this reason my BLE module is not visible to any of the receviers. Has anyone come across a similar situation? Is there anyway I can debug this issue either in Hardware or Software?

To mention, the BLE module is also used to control some peripehral components of the custom board like ADC, Analog Switch etc using I2C and SPI communications. And these communications are successful with any issue.

I would be glad to receive any suggestions. Thank you

[Ric]

Hi,

Thank you for your quick replies.

This is the layout for the BLE module. As I mentioned, I still believe the RF matching is internally done in the SoC as mentioned in the block diagram and datasheet

[Øyvind Karlsen]

You are right, I thought the antenna was external, but with an internal antenna you should be fine on that part, so the problem has to be somewhere else. Have you tried this with multiple cards, or tried changing the crystal?