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Audio "Broadcast" & receive solution?

Hello, if I want to broadcast low def music at a range of up to 200 meters, what would be the optimum solution?

This is the brief idea: broadcasting device with boosted signal + receiving ends with no need to talk back.

There is one tricky (nothing excruciatingly difficult) part though: ideally, you don't have to do anything to "tune in", you just turn on your receiving device, and it will pick up all the packets being send over the air automatically with no concern for when it will start, when it will end, how to interpret the packet (because we will make sure they work by the same protocol), which means if the broadcaster is running a different version of protocol, the receiver will still try to interpret the packet it received erroneously, as long as the CRC etc. low level properties were correct.

My concern is more on the receiving side, and this is my preliminary scheme:

GAP profile + advertising packet, if one packet isn't enough to stuff the payload (which is odd because I recall the payload is 24bit, that should be good enough for 16 bit audio music)

I think the latest nrf52840, with the impressive 5 mbps transfer rate should be more than enough to do the trick.

So, a quick recap, in case you are not clear about what I just said:

A tuned/modified broadcaster continuously and aimlessly sends out gap advertising packet with music data payload in side

Receivers pick them up, sequentially, and queue them into a FIFO buffer, and then play them using for example, DAC. Receivers will not attempt to talk back, nor will it attempt to establish any bond of any sort, because it is completely unnecessary.

Question: what are the flaws in my scheme?

  • Well if you code redundancy as one-way (which is definitely not as efficient as two-way connection based thing) then it could work.

  • Bluetooth 5 has some features that are specifically made for doing large data transfer over advertising, like for example audio, see here. As the site says, both nRF52832 and nRF52840 have features that are compatible with bluetooth 5, except for that the nRF52832 don't have the long range option (125kbps). The SoftDevices does not support advertising extensions yet, but it will come in the future.

    That said, having 200 meter range and sending audio will be hard as both Jan and Wojtek says. If you want that range you should go for 125kbps on-air datarate. Based on the receiver sensitivity this has about twice the range compared to 1Mbps mode and about four times the range compared to 2Mpbs mode (6dBm is about double the range). But if you go for long range you get low throughput and for audio you need high throughput. You can't have both at the same time.

    ESB (without ack) is a better option when it comes to throughput for connection less links, but here the receiver sensitivity is lower than for BLE operations.

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