Discussion:
[TECH] Looking for small RF Audio TX RX Unit
Jim Ruxton
2018-06-26 18:02:39 UTC
Permalink
Hi,

I was wondering if anyone could recommend a reliable audio
transmitter/receiver pair. This is for a performance setting. A dancer
would wear the receiver end so the receiver should be small. I would
prefer not to use Bluetooth as I would like more range  (100 feet) and
not have to deal with pairing. The unit should carry a stereo signal or
2 channels.  Sony and Sennheiser make these systems but they are quite
expensive and have more features than I need. I am looking more for a
board level module I can integrate into my system. If anyone has any
recommendations I would be happy to hear them.

Thanks,

Jim

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Van Horn, David
2018-06-26 18:48:31 UTC
Permalink
I have seen these on Wish at relatively low prices.


-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of Jim Ruxton
Sent: Tuesday, June 26, 2018 12:03 PM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: [TECH] Looking for small RF Audio TX RX Unit

Hi,

I was wondering if anyone could recommend a reliable audio transmitter/receiver pair. This is for a performance setting. A dancer would wear the receiver end so the receiver should be small. I would prefer not to use Bluetooth as I would like more range  (100 feet) and not have to deal with pairing. The unit should carry a stereo signal or
2 channels.  Sony and Sennheiser make these systems but they are quite expensive and have more features than I need. I am looking more for a board level module I can integrate into my system. If anyone has any recommendations I would be happy to hear them.

Thanks,

Jim

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Dwayne Reid
2018-06-26 20:00:28 UTC
Permalink
Hi there, Jim.

Although I work with the higher-end systems that you mention (Shure,
Sennheiser, Lectrosonics), there are lots of inexpensive alternatives
available.

I just now went to eBay and pounded the string "in ear monitor" into
the search field. First page of results has complete systems ranging
in cost from less than US $50 to US $250.

I have exactly zero experience with any of these low-cost systems but
this might be a suitable starting place.

dwayne


At 12:02 PM 6/26/2018, Jim Ruxton wrote:
>Content-Transfer-Encoding: base64Hi,
>
>I was wondering if anyone could recommend a reliable audio
>transmitter/receiver pair. This is for a performance setting. A dancer
>would wear the receiver end so the receiver should be small. I would
>prefer not to use Bluetooth as I would like more range (100 feet) and
>not have to deal with pairing. The unit should carry a stereo signal or
>2 channels. Sony and Sennheiser make these systems but they are quite
>expensive and have more features than I need. I am looking more for a
>board level module I can integrate into my system. If anyone has any
>recommendations I would be happy to hear them.
>
>Thanks,
>
>Jim


--
Dwayne Reid <***@planet.eon.net>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

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Jim Ruxton
2018-06-26 21:09:57 UTC
Permalink
Thanks Dwayne and David. Yes there seems to be plenty of options. I was
hoping someone had experience with a specific model. I may end up just
picking something that looks reasonable however.

Jim


On 2018-06-26 04:00 PM, Dwayne Reid wrote:
> Hi there, Jim.
>
> Although I work with the higher-end systems that you mention (Shure,
> Sennheiser, Lectrosonics), there are lots of inexpensive alternatives
> available.
>
> I just now went to eBay and pounded the string "in ear monitor" into
> the search field. First page of results has complete systems ranging
> in cost from less than US $50 to US $250.
>
> I have exactly zero experience with any of these low-cost systems but
> this might be a suitable starting place.
>
> dwayne
>
>
> At 12:02 PM 6/26/2018, Jim Ruxton wrote:
>> Content-Transfer-Encoding: base64Hi,
>>
>> I was wondering if anyone could recommend a reliable audio
>> transmitter/receiver pair. This is for a performance setting. A dancer
>> would wear the receiver end so the receiver should be small. I would
>> prefer not to use Bluetooth as I would like more range (100 feet) and
>> not have to deal with pairing. The unit should carry a stereo signal or
>> 2 channels. Sony and Sennheiser make these systems but they are quite
>> expensive and have more features than I need. I am looking more for a
>> board level module I can integrate into my system. If anyone has any
>> recommendations I would be happy to hear them.
>>
>> Thanks,
>>
>> Jim
>

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Harrison Cooper
2018-06-27 14:42:28 UTC
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I used to work for a company that builds these.....too bad I didn’t keep a couple when I left, we had lots of "B" stock, I would have just sent them to you! Just looking at the website, they now have rx that are small....3.75"x2"x0.64", 2.4oz in weight. Runs on 72Mhz, 216Mhz

-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of Jim Ruxton
Sent: Tuesday, June 26, 2018 12:03 PM
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: [TECH] Looking for small RF Audio TX RX Unit

Hi,

I was wondering if anyone could recommend a reliable audio transmitter/receiver pair. This is for a performance setting. A dancer would wear the receiver end so the receiver should be small. I would prefer not to use Bluetooth as I would like more range  (100 feet) and not have to deal with pairing. The unit should carry a stereo signal or
2 channels.  Sony and Sennheiser make these systems but they are quite expensive and have more features than I need. I am looking more for a board level module I can integrate into my system. If anyone has any recommendations I would be happy to hear them.

Thanks,

Jim

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Jim Ruxton
2018-06-27 15:15:45 UTC
Permalink
Thanks Harrison,

Can you tell me the name of the company and I'll take a look. One of the
tricky parts of this project is that the performance happens in both the
UK and Canada and these countries have different frequency allocations.
I may need to use two separate units. I was thinking of using 2.4 GHz
which is open in both but because this is worn by a dancer I am
concerned about signal dropouts. UHF and VHF frequencies would be much
less affected by the body.

Jim




On 2018-06-27 10:42 AM, Harrison Cooper wrote:
> I used to work for a company that builds these.....too bad I didn’t keep a couple when I left, we had lots of "B" stock, I would have just sent them to you! Just looking at the website, they now have rx that are small....3.75"x2"x0.64", 2.4oz in weight. Runs on 72Mhz, 216Mhz
>
> -----Original Message-----
> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of Jim Ruxton
> Sent: Tuesday, June 26, 2018 12:03 PM
> To: Microcontroller discussion list - Public. <***@mit.edu>
> Subject: [TECH] Looking for small RF Audio TX RX Unit
>
> Hi,
>
> I was wondering if anyone could recommend a reliable audio transmitter/receiver pair. This is for a performance setting. A dancer would wear the receiver end so the receiver should be small. I would prefer not to use Bluetooth as I would like more range  (100 feet) and not have to deal with pairing. The unit should carry a stereo signal or
> 2 channels.  Sony and Sennheiser make these systems but they are quite expensive and have more features than I need. I am looking more for a board level module I can integrate into my system. If anyone has any recommendations I would be happy to hear them.
>
> Thanks,
>
> Jim
>

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Neil
2018-06-27 15:29:17 UTC
Permalink
I've just started looking for something similar (for a telepresence
robot) but don't want to be on 2.4Ghz since there's too much else on
there nowadays.
Found some decent-looking stuff (wireless PA microphones) by Pyle,
Hisonic and others, but I'm also looking at baby monitors which I
understand are available in "encrypted" versions nowadays.

Cheers,
-Neil.


On 6/27/2018 11:15 AM, Jim Ruxton wrote:
> Thanks Harrison,
>
> Can you tell me the name of the company and I'll take a look. One of the
> tricky parts of this project is that the performance happens in both the
> UK and Canada and these countries have different frequency allocations.
> I may need to use two separate units. I was thinking of using 2.4 GHz
> which is open in both but because this is worn by a dancer I am
> concerned about signal dropouts. UHF and VHF frequencies would be much
> less affected by the body.
>
> Jim
>
>
>
>
> On 2018-06-27 10:42 AM, Harrison Cooper wrote:
>> I used to work for a company that builds these.....too bad I didn’t keep a couple when I left, we had lots of "B" stock, I would have just sent them to you! Just looking at the website, they now have rx that are small....3.75"x2"x0.64", 2.4oz in weight. Runs on 72Mhz, 216Mhz
>>
>> -----Original Message-----
>> From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of Jim Ruxton
>> Sent: Tuesday, June 26, 2018 12:03 PM
>> To: Microcontroller discussion list - Public. <***@mit.edu>
>> Subject: [TECH] Looking for small RF Audio TX RX Unit
>>
>> Hi,
>>
>> I was wondering if anyone could recommend a reliable audio transmitter/receiver pair. This is for a performance setting. A dancer would wear the receiver end so the receiver should be small. I would prefer not to use Bluetooth as I would like more range (100 feet) and not have to deal with pairing. The unit should carry a stereo signal or
>> 2 channels. Sony and Sennheiser make these systems but they are quite expensive and have more features than I need. I am looking more for a board level module I can integrate into my system. If anyone has any recommendations I would be happy to hear them.
>>
>> Thanks,
>>
>> Jim
>>

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RussellMc
2018-06-28 07:53:04 UTC
Permalink
On 28 June 2018 at 03:29, Neil <***@narwani.org> wrote:

> I've just started looking for something similar (for a telepresence
> robot) but don't want to be on 2.4Ghz since there's too much else on
> there nowadays.


I've been (idly) wondering for some while how practical it would beto use
LORA based equipment for voice communications. ​
Using existing IP voice software it should essentially be a matter of plug
in and go - how hard can it be [tm] :-).

LORA TXRX modules are available for under $US20

______________________________

ADAFRUIT transceiver. Digikey $US19.95/1 / Uses RF solutions modules.
Adafruit RFM69HCW and RFM9X LoRa Packet Radio Breakouts
https://cdn-learn.adafruit.com/downloads/pdf/adafruit-rfm69hcw-and-rfm96-rfm95-rfm98-lora-packet-padio-breakouts.pdf
​ RFM69HCW in either 433 MHz or 868/915MHz

The RFM69 radios have a range of approx. 500 meters line of sight with
tuned uni-directional antennas. Depending on obstructions, frequency,
antenna and power output, you will get lower ranges - especially if you are
not line of sight.

​ The RFM69 radios have a range of approx. 500 meters line of sight with
tuned uni-directional antennas. Depending on obstructions, frequency,
antenna and power output, you will get lower ranges - especially if you are
not line of sight. What ranges can I expect for RFM9X LoRa radios? The
RFM9x radios have a range of up to 2 km line of sight with tuned
uni-directional antennas. Depending on obstructions, frequency, antenna and
power output, you will get lower ranges - especially if you are not line of
sight ​

​ All other things being equal (antenna, power output, location) you will
get better range with LoRa than with RFM69 modules. We've found 50% to 100%
range improvement is common.

___________________

*Microchip RN2483 *
$13.18
$
https://www.digikey.com/product-detail/en/microchip-technology/RN2483A-I-RM104/RN2

2 page summary / glossy -
http://ww1.microchip.com/downloads/en/DeviceDoc/70005219A.pdf

RN2483 data sheet -
http://ww1.microchip.com/downloads/en/DeviceDoc/50002346C.pdf

Circuit diagram -

Click thumbnails on:
https://www.digikey.com/reference-designs/en/wireless-communication/transceivers-txrx/24


https://media.digikey.com/Photos/RDL/DV164140-1%20-%20Schematic%201%20-%20Full.png

________________________


Murata
$US17.82/1
https://wireless.murata.com/RFM/data/type_abz.pdf ​
https://wireless.murata.com/RFM/data/typeabz_brief.pdf

12.5 x 11.6 x 1.76 mm metal shielded package •
Comprises a *Semtech SX1276 *ultra long range spread spectrum wireless
transceiver and an *STMicro STM32L0 series ARM Cortex M0+ 32 bit
microcontroller *(MCU) • Communication with the module can be achieved via
UART, SPI, or I2C peripheral interfaces • Includes 192kB flash and 20kB
RAM, and an optional STSAFE secure element can be incorporated into the MCU
to enhance the network security capabilities

​___________________________​

​RF Solutions​
16mm x 16mm
​$17.11/1​
​http://www.hoperf.com/upload/rf/RFM95_96_97_98W.pdf​

D
​igikey "catalog" page -
https://www.digikey.com/catalog/en/partgroup/rfm95w-868s2/50906?mpart=RFM95W-915S2&vendor=357

The RFM95/96/97/98(W) transceivers feature the LoRa™ long-range modem that
provides ultra-long range spread spectrum communication and high
interference immunity while minimizing current consumption. Using Hope RF’s
patented LoRa™ modulation technique RFM95/96/97/98(W) can achieve a
sensitivity of over 148dBm using a low cost crystal and bill of materials.
The high sensitivity combined with the integrated +20dBm power amplifier
yields industry leading link budget making it optimal for any application
requiring range or robustness. LoRa™ also provides significant advantages
in both blocking and selectivity over conventional modulation techniques,
solving the traditional design compromise between range, interference
immunity and energy consumption. These devices also support high
performance (G)FSK modes for systems including WMBus, IEEE802.15.4g. The
RFM95/96/97/98(W) deliver exceptional phase noise, selectivity, receiver
linearity and IIP3 for significantly lower current consumption than
competing devices. ​

____________________________

LORA transceiver modules

https://www.digikey.com/products/en/rf-if-and-rfid/rf-transceiver-modules/872?FV=ffe00368&quantity=&ColumnSort=7&page=1&k=lora&pageSize=25

SEEED
RM95 $7.09/1
RM 95 96 97 98
https://github.com/SeeedDocument/RFM95-98_LoRa_Module/blob/master/RFM95_96_97_98_DataSheet.pdf
https://www.digikey.com/products/en?mpart=109990165&v=1597
$ -
https://www.digikey.com/product-detail/en/seeed-technology-co-ltd/109990166/1597-1488-ND/7033232

_____________________________

​DF Robot Firebeetle TX only
​$18.34​
​https://media.digikey.com/pdf/Data%20Sheets/DFRobot%20PDFs/TEL0121_Web.pdf

__________________________

LORA PCBAs. Legion
$19.95 - $1000 !
https://www.digikey.com/products/en/rf-if-and-rfid/rf-evaluation-and-development-kits-boards/859?FV=ffe0035b&quantity=&ColumnSort=1000011&page=1&k=lora&pageSize=100

____________________

"Daughter cards"
https://www.digikey.com/products/en/development-boards-kits-programmers/evaluation-boards-expansion-boards-daughter-cards/797?FV=ffe0031d&quantity=&ColumnSort=1000011&page=1&k=lora&pageSize=100
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Brent Brown
2018-06-28 11:16:54 UTC
Permalink
On 28 Jun 2018 at 19:53, RussellMc wrote:
<snip>
> I've been (idly) wondering for some while how practical it would beto use
> LORA based equipment for voice communications.
> Using existing IP voice software it should essentially be a matter of plug
> in and go - how hard can it be [tm] :-).

<snip>
> *Microchip RN2483 *
> $13.18
> $
> https://www.digikey.com/product-detail/en/microchip-technology/RN2483A-I-RM104/RN2

Yeah, pretty cool modules. For a look look inside:

https://www.scoop.it/t/the-french-wireless-connection/p/4047963860/2015/07/20/mic
rochip-rn2483-teardown

- PIC18LF46K22 micro
- Semtech SX1276 transceiver
- Support for 433MHz & 868MHz (two antenna connections, only 1 active at a time)
- 24AA02E64 EEPROM with gobally unique EUI-64 node address
- 32MHz crystal
- 32kHz crystal

The uC ICSP pins are brought out on module pins, so you can re-flash it with your
own code (yes, modifying it will void the approvals). The Semtech chip is really quite
powerful, can do OOK and FM as well as LoRA. It's nearly as cheap to buy a
module as it is all the indivdual parts, reducing the bother of assembling and RF
design work.

The RN2903 module is mostly the same, but single antenna & 915MHz.


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