Best wireless technology to transmit an analog signal?
Posted by GaryJackson at
Hi Antone
It sounds to me like you are on the right track with Zigbee, but you also need to an ADC to sample the signal and a DAC to recreate the signal at the receiver.
The sample frequency of 300-400Hz will give a low resolution analog signal at the receiver, perhaps the resolution will be good enough for your application. I would suggest sampling an order of magnitude or 2 higher, but you know your application better than me.
In terms of a Zigbee solution to meet this requirement I would direct you to our very neat Zigbee modules, which can be found at: http://www.st.com/stonline/products/families/communication/wireless_modules/zigbee_modules/zigbee_modules.htm
Regards
Gary
Replies
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In terms of technology, Zigbee can transport the amount of data you hope to transport accross though I would recommend you to take in to account development time required for builiding a Zigbee solution.
Without turning this thread in to a marketting campaign what I would like to suggest to you is to have a look at,
http://uk.rs-online.com/web/6158802.html
This comes with an AT command style interface on USB/UART which will actually sheild you from nitty gritty of the Zigbee (you would still need to grasp few basic conecpts though) and allow you to quickly prototype and commission your application and will help you figure out a way forward.
The above product does have a 12bit A/D and the application, using AT commands, can be set to take periodic measurements to be sent over the air to the other node. The A/D resolution and sampling time mey not be enough to meet requirement but it will give you proof of concept and once you feel confident then you can either write your own application on ETRX or use a host processor with an appropriate ADC to meet your sampling rate requirements.
I am sure there are other products like ETRX around so feel free to have a look around and do keep us posted on your progress.
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Hi guys.
Thank you for your feedback. I will definitely look into your suggestions. I will keep you updated on my progress.
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Hi,
I can advise EnOcean wireless and lowpower communication.
The standard module has 8bit ADC onboard eg. the STM100 for transceiver and the RCM130 for receiver. The newer moduls from EnOcean even has a built in 10bit ADC as far as i rembember. It is called the STM300 or Dolphin platform. If you want to know more about EnOcena, you are welcome to write to me or check out their website.
Have a nice day.
Svend
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What is apparent from above comments is that you are unlikely to find an off the shelf product which will meet your requirements which inadvertantly means that you have to build your own system.
This brings in the question of development time, production cost, production quantities, etc which only you can judge better as you know the numbers.
My take on the subject would be if the numbers are production numbers a limited then
* Choose an RF module (Zigbee or non-Zigbee) which will support the data rate you want from point to point and which supports the wireless topology you want (from your description is STAR topology with only two end node).
* You should pay consideration to whether you want the data connection between the node to be unidirection or bidrectional
* Whether it is necessary to have the secure communication between the nodes.
* Another factor to take in to account is the resilience of the system to disruptions as unlike wires it is difficult to predict what impact the operating environment will have on the overall system.
Zigbee can provide all of the above like bidirectional data, star or mesh topology, wireless range extension, secure comms, reliable delivery of messages, data rate, universal 2.4GHz band.
On the other hand ISM band chipsets from TI (Chipcon) can also be used to meet your requirement and chips like CC2510 have a builtin processor and transceiver which is useful in reducing chip count and cost of the product.
I finish this comment by re-iterating that if you are after a quick solution and the production numbers are not great then use something like ETRX2 or ETRX3 (or anyother) which has simple command/data interface, which will save you from the hassle of going deeper in to world of messy airwaves, and put in place a seperate A/D and D/A with another processor and concentrate on your own application (strian guage measurements) instead of putting energy and effort in to the wireless (Zigbee or proprietary). If the production numbers are great then its worth considering the production cost, development costs and it may make sense to learn the nitty gritty of wireless comms (either Zigbee or proprietary) and make use of single chip processor and transciever to reduce BOM cost.
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Hi there , Microchip offer a 'cut down' version of Zigbee , it's called MiWi and runs on the same hardware we use for Zigbee , with your application being relatively straightforward Zigbee would be overkill and load any MCU with far too much code . Your application would need a low power MCU hooked on to our Zigbee / MiWi RF Module to handle the strain gauge output , Your reciver would use the same Zigbee / MiWi RF Module + MCU + DAC to obtain your DC output . Microchip offer a whole range of low power analog to enable long battery life.
RS stock a Zigbee / MiWi kit that has two identical boards allowing you to do most of what you require , part number is DM163027-5 .
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=dm163027-5&x=7&y=13
Of course the advantage of using a complete certified RF module is that it saves you all the grief of getting local type approval.
You could probably get away with a low pin count MCU since the MiWi code overhead on point to point is very small.
Yes , there will be lower cost solutions to your application but if you want to get something up and running fast you are 3/4 way there with this solution - hope all this makes sense ?
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Hi guys (and girls).
I would like to transmit an analog signal (from a strain gauge bridge amplifier circuit) wirelessly accross a short distance (1 - 2m). I would like to enquire which wireless technology/protocol would be most suited for this application.
The following specifications apply.
1. The sampling frequency is not critical - anything above 300-400 Hz will be suitable.
2. The system must have a low power consumption, since the transmitter will run from a battery.
3. I would like to transmit 2 signals from different positions to a single receiver.
4. The system must be analog-to-analog, i.e. the same signal sent in to the transmitter must come out of the receiver.
5. The signal will be more or less 0-10V.I have looked at the Zigbee technology and it seems that this technology will be ideal for my application. I am a electro-mechanical engineer, and my expereicne with electronics is limited, so your input will be apprecited. If you could suggest an altrenate technology to Zigbee, it would also be appreciated.
Also, if possible, I would like to buy one of those "development kits" from RS components, so that I can learn the technology and do not have to do to much PCB design.