Dual antenna with nrf51822 to detect exact position of BLE device

RE: Dual antenna with nrf51822 to detect exact position of BLE device

Chris Fog — Tue, 19 Apr 2016 11:38:44 GMT

@endnode: Thanks! We met with Philip Dumas from Unikey last week, and are considering using them as a supplier :)

RE: Dual antenna with nrf51822 to detect exact position of BLE device

endnode — Tue, 19 Apr 2016 08:09:30 GMT

Hi Chris, patent search is discipline on its own (which gives business to various lawyers and other free-loaders) and I cannot advice on that as I'm luckily not in charge of it in our group. However just by simple look it should be evident that trying to patent this in 2016 is coming like 2-10 years after the party. Here is one example from locksmith/access control business, it should lead to many older applications not by this company only: www.freshpatents.com/-dt20130711ptan20130176107.php

Cheers Jan

RE: Dual antenna with nrf51822 to detect exact position of BLE device

Chris Fog — Tue, 19 Apr 2016 07:56:20 GMT

@endnode, how would I search for those patents? We are also looking at a similar solution! I googled without success.

RE: Dual antenna with nrf51822 to detect exact position of BLE device

FormerMember — Thu, 31 Mar 2016 05:52:58 GMT

From what I can see, this question consists of two parts:

How to control the RF switching.
How to use BLE in this scenario.

RF switching: You will want to switch between the two antennas before a RX event.

nRF51: Radio notifications can be used to konw whether the radio is being used or not, using a software interrupt; it will send an ACTIVE signal prior to a radio event, and a nACTIVE signal after a radio event. The ACTIVE signal will tell you if a radio event is coming up, however, you cannot know whether it is a TX or RX event. To distinguish between TX and RX events, you will have to use the VDD_PA pin. VDD_PA will go to 1.8 V 130 us before a TX operation starts. Note that a radio event can consist of multiple RX and TX.

nRF52: With the softdevice S132 it is possible to use the LNA configuration to control the RF switching; it will toggle a GPIO to know when to turn on/off a LNA. In your case, you can use this information to switch between the two antennas.

The LNA configuration is enabled using sd_ble_opt_set(..) with the option BLE_COMMON_OPT_PA_LNA and configuration parameters of the type ble_opt_t -> common_opt --> pa_lna (ble_common_opt_pa_lna_t)

BLE: If the nRF5 device is in a connection with a smart phone, it can alternate between the two antennas between connection each events, each connection interval. In BLE, the central/master has to transmit a packet each connection interval.

RE: Dual antenna with nrf51822 to detect exact position of BLE device

endnode — Tue, 29 Mar 2016 21:17:57 GMT

Yes, it will work (= it works). Just be careful, there are already bunch of patents around such solution. Unless you don't care...