SparkFun Forums

[aml25]

Hello all,

I am currently working on my Architecture/Media Study thesis at the State University at Buffalo. I have been trying to figure out how to solve this issue I am having with not much luck. I am hoping someone here may have some insight as to how to address this issue.

My application requires I have ~10 different piezo elements (contact mics) spread around a room - about 50ft x 15ft and wirelessly transmit the audio from each to either 1 central receiver or separate receivers plugged into a mixing board. I am open to various ways of arranging this set up, but this is how I have been imagining it.

As of right now I have a Tao Tronics audio bluetooth transmitter and receiver and this works perfectly, the problem arises when I need multiples since the names of each unit is the same and confuses the transmission/reception, as well as only being able to connect 1 transmitter to a receiver. I have tried FM transmission but this is not so reliable and receives a lot of static.

Does anyone have any experience with this or know where I may begin to address my situation? This will be an installation and requires a very clean aesthetic as well as little to none physical contact with the space thus requiring a wireless solution.

- Thank you, Adam

[brennen]

The nRF24Z1 by Nordic provides a one-to-one wireless audio solution (up to 16 bits, 48 kHz, stereo). You will need an external ADC on the microphone side and an external DAC on the mixer side, though, as the Z1 doesn't do any analog conversion.

[aml25]

Thank you for your response. Would this allow me to use 10 (for example) at the same time? I suppose I am confused by your specification of "one-to-one." Would I need a receiver for each module or 1 receiver for all of them?

Thank you.

[brennen]

You would need one receiver and one transmitter for each audio stream. So for 10 microphones, you would need 10 transmitting nRF24Z1 units and 10 more receiving nRF24Z1 units. If you were able to connect two microphones into one nRF24Z1, you could reduce it to 5 TX modules and 5 RX modules, as the Z1 allows for stereo operation.

[aml25]

Thank you for your quick responses, I really appreciate it. Basically I would need 2 of these (http://store.diyembedded.com/index.php? ... ucts_id=19) --- which looks like it is from your store, and I can get an audio stream going (with an ADC and DAC) by giving each power and an audio input/output? As well I can keep adding pairs to my installation in order to add more streaming sources?

Thanks again, your help is much appreciated.

[aml25]

Sorry, but I have one more question: Will this module/breakout board work as well? http://store.diyembedded.com/index.php? ... ducts_id=7 or will this not work with audio?

Thanks again.

[leon_heller]

The nRF24L01+ is suitable for audio. You can get nRF24L01+ modules much cheaper on Ebay:

http://www.ebay.co.uk/itm/NRF24L01-2-4G ... 43adb2b3a5

They require an MCU, which is included on those other Nordic Semi chips. I designed this prototyping PCB for them which could be used for development:

http://www.leonheller.com/Wireless%20Sensor/WS.jpg

It uses a PIC18F24J11, which includes a 10-bit ADC; it is a very low power XLP device. A DAC could be added to the prototyping area, as well as a higher quality ADC, and microphone amplifier.

For higher quality, I'd probably use a 16-bit PIC24 or dsPIC instead of the 18F24J11. dsPICs are available with an audio-quality DAC.

[brennen]

Sorry, but I have one more question: Will this module/breakout board work as well? http://store.diyembedded.com/index.php? ... ducts_id=7 or will this not work with audio?

I will agree that the nRF24L01+ will work for audio. It just depends on how much code you want to write yourself to handle timing the audio correctly. The nRF24Z1 handles that for you.

Basically I would need 2 of these (http://store.diyembedded.com/index.php? ... ucts_id=19) --- which looks like it is from your store, and I can get an audio stream going (with an ADC and DAC) by giving each power and an audio input/output? As well I can keep adding pairs to my installation in order to add more streaming sources?

The nRF24Z1 can be brought up without a microcontroller by programming a I2C or SPI EEPROM with the proper register values and connecting it to the nRF24Z1. It can also be interfaced by an external microcontroller over an I2C or SPI interface to set up the registers that way.

You could definitely start with one pair of the nRF24Z1 boards and work your way up from there. I have audio ADCs on the site already (WM8737) and I will be putting up a new audio DAC (WM8711BL) within the next week or so on my site. The ADC and DAC I mentioned must have a microcontroller to set up their registers, though. One other thing to keep in mind with the nRF24Z1 is that it does require the ADC or DAC that is connected to it to have an audio interface (I2S is the typical one).

The nRF24L01+ is suitable for audio. You can get nRF24L01+ modules much cheaper on Ebay:

http://www.ebay.co.uk/itm/NRF24L01-2-4G ... 43adb2b3a5

I did notice that these boards apparently can't be shipped to North America, so if you're in the USA, you're out of luck with those guys.

[leon_heller]

Those modules are available from several suppliers that do ship to the US. Here is one of them:

http://www.ebay.co.uk/itm/NRF24L01-Wire ... 4aaa921cec

[aml25]

Thank you so much for the help. There are a lot of terms here that I am unfamiliar with so I have some reading up to do. But thanks for helping me out. This is all to be done within the next 4 weeks so I will be working quick. @Brennen - will you be getting more of the nRF24Z1+breakout boards in stock anytime soon? I would love to order some.
Thanks

[brennen]

@Brennen - will you be getting more of the nRF24Z1+breakout boards in stock anytime soon? I would love to order some.

I am planning on having more in stock within a week or so.