special tuning for underwater application

RE: special tuning for underwater application

Fabien Comte — Mon, 21 Sep 2015 07:21:05 GMT

Ok thank you

RE: special tuning for underwater application

MartinBL — Wed, 16 Sep 2015 12:33:42 GMT

You can set the register RADIO->FREQUENCY = 100. Have a look at Chapter 17.1 and 17.2 in the Reference Manual v3.0.

There is no way to change the PLL settings or use frequencies below 2.4GHz.

RE: special tuning for underwater application

Fabien Comte — Wed, 16 Sep 2015 12:07:49 GMT

Thank you for your response.

How to change to 2.5 GHz ?

No way to do a test at 868 MHz with an internal PLL setting ? If i change quartz ?

RE: special tuning for underwater application

MartinBL — Wed, 16 Sep 2015 09:15:06 GMT

Hi. No this is not possible. You can only change the carrier frequency to 2.5 GHz on the nRF51. You will need to go much lower than that to get any range at all under water.

Using a power amplifier to boost signals in air is possible though. Here is a relevant application note: Range Extension for Nordic nRF51 Series with RFaxis RFX2411N RFeIC™.

RE: special tuning for underwater application

Dave_couling — Tue, 15 Sep 2015 22:37:22 GMT

This is possible, but I'm not sure if its possible with the nRF51 chip. I've done some work in these applications and used Zigbee instead.