I gather this is kind of like those old radio you could build and listen to with a headphone without the radio having any power source other than radio waves?
I imagine the power these things can gather is very small.
It's interesting to think about. I wonder if it will have genuinely practical applications. I doubt one will be able to charge their cell phones this way.
Yeah you're talking about the old crystal radio, I actually had one. I think there were about 3 components on it and it would sometimes actually pick up a radio station (usually late at night).
Given that they're testing fairly close to TV transmitters and that they have antennas that are much closer to resonance than is practical with AM radio, they should be able to extract more power from the signal than a crystal radio, but still not much. What's a little mysterious is the reflection vs absorption of an ambient signal as a means of communication. Anyone have any insight as to how that might work? I don't know a lot about antennas, but if you put a matched load at the feedpoint of the dipole, then short it out, that would make it absorb when the load is there and reflect when the load is replaced by a short, right? I'm thinking with a short it would be just a resonant wire like the reflector on a Yagi. But how does the receiver detect it? Relative signal strength, or ???
I've been trying to build wireless mesh circuits for some time and there are lots of modules around but they all take quite a bit of power when just listening eg 20ma at 5V or 100mw. Batteries run down too quick and solar panels need quite a large battery for worst case of a week of no sun.
Flea power radio is intriguing. This paper looks at the energy you can extract http://www.oldradioworld.de/gollum/analysis.htm which is microwatts to nanowatts. But if that energy can be stored in a low leakage capacitor, then data can be transferred intermittently.
One would need a super low power chip, or maybe some sort of wakeup circuit, which could be analog or a microprocessor. A low power wakeup circuit could boostrap a higher powered one, listen for a data packet, process it and then go back to sleep.
It would be interesting to audit where the RF energy is in different bands. In our house, lots of 2.4Ghz energy from the always on wifi, but it is only 10mw. Mobile phones are a different frequency and more intermittent but higher power. There will be 900Mhz from a cordless phone. There is 50mhz to 500Mhz from TV stations. And there is all the energy in the AM radio bands around a few megahertz. Each of these needs a different sized antenna to extract energy and if you need lots of different antennas it would be better to focus on where most of the energy is.
A good ground seems to help a lot.
Interesting to ponder how it might fit with a propeller chip that spends most of its time in sleep mode.
If it's using the crystal radio set-up...That's one bad *** signal diode!
'
It seems feasible, If you consider the really high gain/super clean pre-amp's on the input side of a WiFi device for communication.
'
Another signal diode pulling power from a really strong near by radio tower to power the device.
'
Back in my radio hay days, I had a 24" florescent lamp placed in an orange tree in the back yard. No wire's, just a lamp. I could lite the florescent lamp when I keyed my radio! (about 185watts on a dead carrier), Around (2500watts with some modulation "whistle")
I've been trying to build wireless mesh circuits for some time and there are lots of modules around but they all take quite a bit of power when just listening eg 20ma at 5V or 100mw.
I've been thinking about wireless sensor networks a lot over the last few years. The Nordic nRF24L01+ modules I keep mentioning are close to the 20mA range is current consumption. I think the cheap ebay modules (see post #1 of my index for a link) use about 17mA while listening.
One thought I've entertained is to have a check-in period at set times of the day. Rather than have Propeller and transceiver listen for incoming communication all of the time, you could keep communication limited to certain predetermined times and wake the Prop and transceiver up at these times to listen for incoming messages. The Nordic transceivers can even be powered from a Prop I/O pin so you could cut the power to the transceiver completely when it's not in use.
Having your node only listen part of the time does greatly reduce the applications where they could be used but I have wondered if it could be worth limiting functionality of the network in order to get by on less power. The Prop could shut down all but one cog and the single cog could use RCSLOW and use a loop of maximum waitcnt calls as an approximate timer. When it was close to the specified communication time it could check with a RTC to make sure it was ready listen when required. It would be interesting to see how little power a network like this could be by on.
I think energy harvesting of RF noise would be a huge task. I'd be surprised if the energy one could harvest would be worth the effort unless the device were near a powerful transmitter (just and uneducated guess on my part). I think solar would still be a better option than RF harvesting as a way to supplement battery power.
The Nordic nRF24L01+ modules I keep mentioning are close to the 20mA range is current consumption. I think the cheap ebay modules (see post #1 of my index for a link) use about 17mA while listening.
I've posted a couple of projects using these modules. The mood enhancing LEDs used SparkFun's Nordic fob as an input device.
I also used some Nordic fobs in my panic button project. I was able to keep six modules from talking over each other and bounce messages from one Prop to the next until all six Propeller board has received the message.
I've used them as remote control units in several projects. The Roomba (you made me buy) used a module to receive commands from a PlayStation 2 controller (the PS2 was interfaced with a Propeller). I used an earlier version of these modules to control the Roboni-I robot (another erco induced purchase).
My super duper robot remote has a Nordic nRF24L01+ in it to communicate with my robot army. I haven't posted info about this remote yet.
My Mecanum wheeled robot has occasionally been controlled with one of these modules.
These things are so darn cheap I can afford to include them in lots of my projects. I also like how you can receive telemetry back from the robot with these two way transceivers.
The main downside to using these is they're not nearly as simple to use as XBees. There are a zillion registers to configure and they require a bunch of I/O lines to communicate via SPI. The code examples I have links to in post #1 of my index make using these a lot easier than coming up with your own driver.
I just added a link to a datasheet to post #1 of my index.
If you plan to use your modules with a Prop, let me know. I have an improved driver I've been meaning to upload and if you'll use it, I'll make sure and get it posted soon.
I never made a video of my Roboni-I robot. My niece and her family are coming to visit next week so I'll try to get it up and running again in time to show them. I'll make a video when I have it running again. It runs a lot smoother than the original version.
$10 a pair? They are not as inexpensive as the Nordic modules but the UART interface makes much easier to use.
I think they've got the Wixels beat in price but I'm not sure how useful they would be for wireless programming. I don't see a way of sending flow control information to reset a uC prior to programming?
Just got my Inhaos modules yesterday. TINY! Those headers ain't 0.100". Should be fun to play with once I find the time. But first I gotta wrap up my Jameco Coasterbot before the Sept deadline. A Labor Day of love...
Franklin
Posts: 4,747
Comments
I imagine the power these things can gather is very small.
It's interesting to think about. I wonder if it will have genuinely practical applications. I doubt one will be able to charge their cell phones this way.
I've been trying to build wireless mesh circuits for some time and there are lots of modules around but they all take quite a bit of power when just listening eg 20ma at 5V or 100mw. Batteries run down too quick and solar panels need quite a large battery for worst case of a week of no sun.
Flea power radio is intriguing. This paper looks at the energy you can extract http://www.oldradioworld.de/gollum/analysis.htm which is microwatts to nanowatts. But if that energy can be stored in a low leakage capacitor, then data can be transferred intermittently.
One would need a super low power chip, or maybe some sort of wakeup circuit, which could be analog or a microprocessor. A low power wakeup circuit could boostrap a higher powered one, listen for a data packet, process it and then go back to sleep.
It would be interesting to audit where the RF energy is in different bands. In our house, lots of 2.4Ghz energy from the always on wifi, but it is only 10mw. Mobile phones are a different frequency and more intermittent but higher power. There will be 900Mhz from a cordless phone. There is 50mhz to 500Mhz from TV stations. And there is all the energy in the AM radio bands around a few megahertz. Each of these needs a different sized antenna to extract energy and if you need lots of different antennas it would be better to focus on where most of the energy is.
A good ground seems to help a lot.
Interesting to ponder how it might fit with a propeller chip that spends most of its time in sleep mode.
'
It seems feasible, If you consider the really high gain/super clean pre-amp's on the input side of a WiFi device for communication.
'
Another signal diode pulling power from a really strong near by radio tower to power the device.
'
Back in my radio hay days, I had a 24" florescent lamp placed in an orange tree in the back yard. No wire's, just a lamp. I could lite the florescent lamp when I keyed my radio! (about 185watts on a dead carrier), Around (2500watts with some modulation "whistle")
I've been thinking about wireless sensor networks a lot over the last few years. The Nordic nRF24L01+ modules I keep mentioning are close to the 20mA range is current consumption. I think the cheap ebay modules (see post #1 of my index for a link) use about 17mA while listening.
One thought I've entertained is to have a check-in period at set times of the day. Rather than have Propeller and transceiver listen for incoming communication all of the time, you could keep communication limited to certain predetermined times and wake the Prop and transceiver up at these times to listen for incoming messages. The Nordic transceivers can even be powered from a Prop I/O pin so you could cut the power to the transceiver completely when it's not in use.
Having your node only listen part of the time does greatly reduce the applications where they could be used but I have wondered if it could be worth limiting functionality of the network in order to get by on less power. The Prop could shut down all but one cog and the single cog could use RCSLOW and use a loop of maximum waitcnt calls as an approximate timer. When it was close to the specified communication time it could check with a RTC to make sure it was ready listen when required. It would be interesting to see how little power a network like this could be by on.
I think energy harvesting of RF noise would be a huge task. I'd be surprised if the energy one could harvest would be worth the effort unless the device were near a powerful transmitter (just and uneducated guess on my part). I think solar would still be a better option than RF harvesting as a way to supplement battery power.
What a coincidence, I just got two. Any good? BTW, Polida's price on a ten-pack has dropped to $13 w/shipping:
http://www.ebay.com/itm/10PCS-Arduino-NRF24L01-Wireless-Transceiver-Module-/251062580786
What amazing things have you achieved with these? Got a data sheet, Boss?
Thanks for the info. I just updated my index with the new price.
I've posted a couple of projects using these modules. The mood enhancing LEDs used SparkFun's Nordic fob as an input device.
I also used some Nordic fobs in my panic button project. I was able to keep six modules from talking over each other and bounce messages from one Prop to the next until all six Propeller board has received the message.
I've used them as remote control units in several projects. The Roomba (you made me buy) used a module to receive commands from a PlayStation 2 controller (the PS2 was interfaced with a Propeller). I used an earlier version of these modules to control the Roboni-I robot (another erco induced purchase).
My super duper robot remote has a Nordic nRF24L01+ in it to communicate with my robot army. I haven't posted info about this remote yet.
My Mecanum wheeled robot has occasionally been controlled with one of these modules.
These things are so darn cheap I can afford to include them in lots of my projects. I also like how you can receive telemetry back from the robot with these two way transceivers.
The main downside to using these is they're not nearly as simple to use as XBees. There are a zillion registers to configure and they require a bunch of I/O lines to communicate via SPI. The code examples I have links to in post #1 of my index make using these a lot easier than coming up with your own driver.
I just added a link to a datasheet to post #1 of my index.
If you plan to use your modules with a Prop, let me know. I have an improved driver I've been meaning to upload and if you'll use it, I'll make sure and get it posted soon.
I never made a video of my Roboni-I robot. My niece and her family are coming to visit next week so I'll try to get it up and running again in time to show them. I'll make a video when I have it running again. It runs a lot smoother than the original version.
Mine are coming. I'm planning some wireless programming experiments using these modules. Specs at http://www.inhaos.com/uploadfile/otherpic/UM-LC-1000-V10-EN.pdf
Wow, those look like a good deal.
$10 a pair? They are not as inexpensive as the Nordic modules but the UART interface makes much easier to use.
I think they've got the Wixels beat in price but I'm not sure how useful they would be for wireless programming. I don't see a way of sending flow control information to reset a uC prior to programming?