GPS and LTE frontend testing and improvements

[dzenbo]

Hi,

We are the company which widely use your products in our devices. Currently we have the nRF9160 based device which have permanent trouble with radios. I want to ask you to help improve our design answering on the next questions:

1) nRF9160 has built-in features to test signal and communication quality. Do you have some references and/or manuals to make these parameters useful for us? Maybe you have some scripts or software to check the RF performance? Most of them is from the communication field of knowledge which is slightly out of my specialty and today I will prefer to save my time for development and rid of digging in this way.

2) Our product have a small factor 50x40mm. Based on your experience what topology for the radios you can advice as one which offers better performance, reliable communication stability in hand-held solution and without titanic efforts in development (especially antenna matching): with multiplexor and one antenna LTE+GPS (as Thingy:91 has) or splitting antenna practice without multiplexing (as your larger dev board has or NOTM.2 do for instance https://www.phytec.fr/fileadmin/user_upload/IoT_ew20_e_DS_web.pdf). I'm sure you know similar products which already implements successful solutions and I hope you can share some ideas to made a robust design. If you have some antennas, amplifiers, filters which you prefer to use in the design I will be happy to get your suggestions in the parts selection section. I saw the "nRF9160 Antenna and RF Interface Guidelines" document but it does not contain practice experience based notes and compares.

Thanks in advance!

. 

[Andreas]

Hi,

 

1) See the Hardware Verification Guidelines Whitepaper: https://infocenter.nordicsemi.com/topic/nwp_034/WP/nwp_034/nwp_034_intro.html Generally you are limited to either using a call-box tester or the AT%XRFTEST command with a spectrum analyzer.

 

2) Generally you should replicate the nRF9160 reference design and reference designs or layout guidelines for the antenna you plan on using. If you do not do this you can not expect it to perform according to the specifications. Antennas might also have requirements or specifications that relate to the size of the PCB or ground plane, so you need to make sure that the antenna you use can support the form factor. Smaller size is generally not a good thing though, especially when smaller than a quarter wavelength, this might reduce performance overall and require a tuning circuit like in our Thingy91 to support multiple bands. In addition to the Antenna and RF interface guidelines document, see the Hardware Design Guidelines whitepaper: https://infocenter.nordicsemi.com/topic/nwp_037/WP/nwp_037/nwp_037_intro.html?cp=16_1 At the end, when you have received your samples, you need to make sure your antenna is correctly tuned and matched using a network analyzer.

 

I also recommend that you submit your design for a review here on Devzone before you order samples, or if you experience issues with performance.

 

Best regards,
Andreas