Increasing Coverage of nRF51822 BLE module

[Vaio]

For some sort of geofencing application, we want to include the BLE module nRF51822 into a Base Station (BS), and a small mobile device (MS). The MS should detect the presence of a signal from the BS. If it is/is not present, certain actions are being triggered.

1.) While the maximum TxPower seems to be +4dBm, I heard that using an amplifier one can send up to the regulated limit of +20dBm.

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2.) Alternatively, I heard on the nRF51822 a custom protocol can be implemented. The design goal would be to reach maximum coverage (ideally, beyond walls inside a house).

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For both cases, the same questions arise:

Does anybody have experience / more infos on this? Mainly:

• what is the maximum coverage (in theory and practice)?
• what are the implications on power consumption (as this will be done in the BS, it shouldn't really matter)?

Thanks!

[Håkon Alseth]

forgot to mention; does not matter if it's a devkit or an evkit. Both will do the trick, however the devkit requires that you have nRFgo motherboards. If you do not have/need nRFgo motherboards for nRF24L-series development, I would go for the EVkits.

-H

[Vaio]

Thanks Håkon,

At this moment, it has it's restrictions

Can you elaborate on them?

Let me summarize what we wanna implement again: Base Station: send out a beacon regularly (via custom 2,4 GHz protocol, 250 kbps) Mobile Station:

1. check for presence of this beacon periodically, e.g. 10 times per minute (via custom 2,4 GHz protocol)
2. act as BLE peripheral, by advertising periodically (every few seconds), and wait for connection requests from a Master (eg smartphone)

It seems periodic BLE advertising is contradicting to scanning for BS beacons (ESB || GZLL) at the same time from the MS?

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We don't have nRFgo motherboards yet; nRF24L-series is 2.4 GHz only (no BLE), correct? We don't need that, so EVkit(s) will be fine.

For a pure coverage test, wouldn't a single EVkit do the trick? (as it includes Tx board + Rx dongle). Why would I need two? If we go on and develop both the BS and MS side (as per the requirements above), I would of course need two EVkits.

[Håkon Alseth]

The restriction is that you have to disable the SoftDevice before using the radio for other purposes, ie: break your BLE connection. It is not concurrent dual RF protocol. This could create issues for some multi-protocol applications. It usually takes in the range of 5-10 ms to switch protocol, depending on your configuration, but you will also have the re-connection time in BLE mode, which depends on the masters scanning period.

The nRF24L-series is proprietary RF only, no BLE. However, it is compatible with nRF51 over-the-air using for instance Gazell. You do not need two 51-kits for checking range, you could do with either the nRF51-dongle included or a nRF24LE1 (Note: LE1 has slightly reduced sensitivity compared to nRF51).

Since you have the motherboard already, it does not matter if you go for ev-kit or dev-kit. They're priced the same as well. It depends on what you prefer, I guess.

BR Håkon

[NK]

Hi @Vaio,

if you have managed to make any progress on this question [with regards to increasing coverage/range of NRF51822] - whether by means of reducing the data-rate in the Gazelle proprietary protocol as discussed in one of the answers below, or some other manner, could you kindly share your experience? Thanks.