skspurling
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How about a new game?

Tue Dec 22, 2015 3:07 pm

I was over at ModMyPi, reading the tutorial on powering the zero with a battery pack, when I got the notion of the throwies stuck in my head for some reason. I have also always thought that unconnected WIFI data caches offered an interesting idea for non-internet based local community information sources. A small forum in a coffee shop where users could chat and leave posts and such. Kind of like a virtual builtin board. A source for advertising and placing orders and finding resources and coupons.

For those who don't know what a throwie is, you take a LED, CR2032 battery, a rare earth magnet, and some tape. You wrap it all together, and throw this little LED light up on a metal structure.

Here's the fun part. Remember the Pi-rate radio project for making FM radio signals come out of a GPIO pin? What if you combine the zero, GeoCaching, Pirate radio, and throwies all together. Maybe even hack a small Wifi AP, wiring in a cheap dongle, into the mix for fun? I know it would probably only last for a day or two. Maybe figure out some way to integrate a small solar charging system into it?

Make it a learning opportunity. Have the kids build and hide them. Then they could go out to find them. What does every one think?

Thanks

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Re: How about a new game?

Tue Dec 22, 2015 3:13 pm

I think I get the idea but struggling to see where the Pirate FM fits in.

(The RPi FM transmit part won't be popular on here as they are illegal in some countries)

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Re: How about a new game?

Tue Dec 22, 2015 4:11 pm

There is already an internationally recognised orienteering-type sport using (licensed) radio beacons on amateur bands that have to be found using a Direction Finding receiver. I don't see why hunting hidden WiFi Access Points wouldn't work as well. The aim is to see who can find all of five or six APs first -- and leave a Timestamped message to prove it. The trick (so it isn't too easy) is that each AP is only enabled for about one minute in five or ten, on a schedule so that no two are on together. You would need a set of APs to be hidden, each with scheduling software and probably an RTC for accuracy. Each competitor needs a portable Pi (or just a laptop). The competition would need to be in an area accessible on foot where trying to use a vehicle gives no advantage (bicycles could be allowed in suitable areas).

But don't bring unlicensed/illegal radio into it. That brings the activity, and the kit behind it, into disrepute and damages the Foundation's educational aims.
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Re: How about a new game?

Tue Dec 22, 2015 4:15 pm

Hmmm....Pirate FM....I'm all ears.
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Re: How about a new game?

Tue Dec 22, 2015 4:21 pm

Heater wrote:Hmmm....Pirate FM....I'm all ears.
turn a gpio into an FM radio - bleeds em radiation all over the place and is not good
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Re: How about a new game?

Tue Dec 22, 2015 4:28 pm

Greetings.

Good idea.

There is a not on foot idea, I'm reading a book named Getting Started with HAM RADIO. It told me there are competition on amateur radio frequency that aim to "communicate with other station as much as possible".
It works like this: The host define a time period, saying 1 week or so, and give a record method, which maybe a piece of software. During the time, the competitor try to speak to other people on air to earn point. Such as an American competitor could earn 2 points if he got a record speaking to an Asian people on air, or earn 1 point for speaking to an Canadian people, because of the distance. The software, or whatever the record method is, is a proof at last.

So I think it would also work in a small area: different AP would on air in different time period, the guy connected the most wins the game.

Edit: By "different AP", you could just using a single Pi and write a software to switch its SSID automatically, then it looks like different APs.

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Re: How about a new game?

Tue Dec 22, 2015 4:33 pm

RaTTuS,

Quite so. A Pi will be a terrible FM transmitter. And very power hungry and short range for the suggested game.

A more up to the minute idea might be a "hunt the LoRa" transmitter game. It's legal, it's cheap, it's long range 5 or 10Km, it's low power.

Long range so people have a chance to find it, but I'm betting locating a LoRa transmitter is a bit of a challenge!
Last edited by Heater on Tue Dec 22, 2015 4:41 pm, edited 1 time in total.
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Re: How about a new game?

Tue Dec 22, 2015 4:40 pm

RaTTuS wrote:
Heater wrote:Hmmm....Pirate FM....I'm all ears.
turn a gpio into an FM radio - bleeds em radiation all over the place and is not good
Agreed, we should maybe stick to 2.4GHz WiFi.

It just comes to my head that in fact, Nintendo 3DS, which is a hand held game console, did the idea. It would broadcast WiFi signal during it's sleeping, and if during the time, two 3DS pass each other, they would exchange some gift information. I don't know what they call this in English version 3DS, Japanese is すれちがい通信 .

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Re: How about a new game?

Tue Dec 22, 2015 4:42 pm

Ah yes, すれちがい通信. Totally with that idea.
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Re: How about a new game?

Tue Dec 22, 2015 4:58 pm

It looks like English version is StreetPass Communication: https://en.wikipedia.org/wiki/SpotPass_and_StreetPass

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Re: How about a new game?

Tue Dec 22, 2015 9:48 pm

Not to be illegal, but low power non-invasive (like under a few meters or something like that) FM radio is legal in the states. We use it to transmit audio to car radios and in kids toys. The RPi thing only transmits within a few feet, and could be used to identify that you are in the right place to pick up the clue to the next spot, or something like that. You just can't interfere with a commercial station on a licensed band. Either that, or have a small wifi hotspot with a page you could register with and pick up a clue to find the next hotspot. The GPIO radio thing has been done and is out there.

As an art project, you could build hidden isolated hot spots that have a builtin board and some content. people can sign them or see something hidden. Just an idea....

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Re: How about a new game?

Tue Dec 22, 2015 10:16 pm

skspurling wrote:Not to be illegal, but low power non-invasive (like under a few meters or something like that) FM radio is legal in the states. We use it to transmit audio to car radios and in kids toys. The RPi thing only transmits within a few feet,
Illegal in many other countries. Also you will find posts here from someone who tried PiRate, and found it had a range measured (IIRC) in miles rather than feet. It is just not easy to predict radio propagation, particularly of ill-formed signals from Pi-style "transmitters". I'm not sure that even the American authorities would accept that.

The rest of the idea is good. The FM radio element destroys an otherwise good idea, and as others have said is completely unnecessary to the idea.
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Re: How about a new game?

Wed Dec 23, 2015 6:00 pm

davidcoton wrote:Illegal in many other countries. Also you will find posts here from someone who tried PiRate, and found it had a range measured (IIRC) in miles rather than feet. It is just not easy to predict radio propagation, particularly of ill-formed signals from Pi-style "transmitters". I'm not sure that even the American authorities would accept that.
Miles? I seriously doubt that.
http://www.icrobotics.co.uk/wiki/index. ... ransmitter
When they say ridiculously powerful, they mean less that 500m in open air. Pretty good for just modulating a GPIO pin.
Since the site is in the UK, I am thinking this isn't as frowned upon as people keep making out to be. You are just making one of these: https://en.wikipedia.org/wiki/FM_transm ... al_device)
The maximum pin current for a GPIO pin is 16mA. That's at 3.3v. I doubt you will exceed the legal limit just playing around with copper wires off your GPIO pins. If there's no antenna on it, I bet you will absolutely be within legal specs.
So, if all this bothers you, and you want to do the FM part more above board in a more legal manner, use this... viewtopic.php?t=40599&p=378991

Either way, the core of what I am talking about is not invalidated because I said the magic words "FM radio". That's a logical fallacy. I am American, I know a fallacy when I see one. Have you seen our politicians? :-)

What I am trying to say is that, regardless of what form of radiation/signal (LED, LCD, WIFI, FM, stick on servo poking your eye or tossing a jam sandwich at you), they would make a really cool orienteering/Geo Cache target for some kind of multi stage scavenger hunt.
Any one want to talk about that part?

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Re: How about a new game?

Wed Dec 23, 2015 6:07 pm

Yes, what about the LoRa idea?
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Re: How about a new game?

Wed Dec 23, 2015 7:32 pm

Heater wrote:Yes, what about the LoRa idea?
I shall ask this earlier.

Could you tell me what is hunt the LoRa game? I googled and it looks not on the first page.

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Re: How about a new game?

Wed Dec 23, 2015 9:31 pm

skspurling wrote:
davidcoton wrote:Illegal in many other countries. Also you will find posts here from someone who tried PiRate, and found it had a range measured (IIRC) in miles rather than feet. It is just not easy to predict radio propagation, particularly of ill-formed signals from Pi-style "transmitters". I'm not sure that even the American authorities would accept that.
Miles? I seriously doubt that.
http://www.icrobotics.co.uk/wiki/index. ... ransmitter
When they say ridiculously powerful, they mean less that 500m in open air. Pretty good for just modulating a GPIO pin.
Since the site is in the UK, I am thinking this isn't as frowned upon as people keep making out to be. You are just making one of these: https://en.wikipedia.org/wiki/FM_transm ... al_device)
The maximum pin current for a GPIO pin is 16mA. That's at 3.3v. I doubt you will exceed the legal limit just playing around with copper wires off your GPIO pins. If there's no antenna on it, I bet you will absolutely be within legal specs.
So, if all this bothers you, and you want to do the FM part more above board in a more legal manner, use this... viewtopic.php?t=40599&p=378991

Either way, the core of what I am talking about is not invalidated because I said the magic words "FM radio". That's a logical fallacy. I am American, I know a fallacy when I see one. Have you seen our politicians? :-)

What I am trying to say is that, regardless of what form of radiation/signal (LED, LCD, WIFI, FM, stick on servo poking your eye or tossing a jam sandwich at you), they would make a really cool orienteering/Geo Cache target for some kind of multi stage scavenger hunt.
Any one want to talk about that part?
Sorry I can't find the original post. Enough to say the OP was shocked. I did find a post here quoting FCC rules which impose a distance limit of 200 feet. From the reference you mention,
The antenna is optional, but range is reduced from ~100 meters to ~10cm without the antenna.
With an antenna, you could easily exceed 200 feet. Without it, the system is unworkable.

I am not rubbishing the rest of your idea. As I said think it is good, and worth developing. Just that you discredit a good idea by joining it to a bad one. Abandon FM, and any other unlicensed system. It's not necessary to the big idea. I look forward to trying a competition sometime. I might even set one up -- but I probably need to wait until retirement to find time!
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Re: How about a new game?

Thu Dec 24, 2015 12:18 am

allfox,
...what is hunt the LoRa game
I just invented it to reply to this thread :)

The idea here seems to be some kind of "hunt the transmitter" game. Perhaps FM radio, perhaps WIFI, I have not been following so closely.

FM and WiFi are old hat. LoRa is the new kid on the block.

The idea behind LoRa is to provide long range but low power communications for Internet of Things devices. That is low power consumption but unlike WIFI a much longer range, 5, 10, 15 or so kilometers. In order to get that kind of range it uses very low data rates, so no good as a regular IP connection like WIFI, but perfect for a little device that needs to announce it's sensor readings once a minute and such like.

Tiny little LoRa modules are already available.
http://www.microchip.com/pagehandler/en ... /lora.html
https://www.cooking-hacks.com/documenta ... el-galileo

I think LoRa will be huge soon. IoT is growing like crazy and people like Microchip are getting in on making the modules so they will be very cheap.

So there is the "Hunt the LoRa Game". Hide one or more LoRa modules around a city or forest and have people find them. Might be quite a challenge given the low power signals and modulation used.

But hey, it's perfectly legal.
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Re: How about a new game?

Thu Dec 24, 2015 4:29 pm

Heater wrote: The idea behind LoRa is to provide long range but low power communications for Internet of Things devices. That is low power consumption but unlike WIFI a much longer range, 5, 10, 15 or so kilometers. In order to get that kind of range it uses very low data rates, so no good as a regular IP connection like WIFI, but perfect for a little device that needs to announce it's sensor readings once a minute and such like.
This one sounds cool ! I've just read those about ESP8266 WiFi modules, and here is another cool thing.

At LoRA Key Features section of http://www.microchip.com/pagehandler/en ... /lora.html
It says "Interference immunity" and "Long battery life over 10 years", which sounds something from alien technology.
They work in a lower frequency than WiFi, guessing that is also a reason for its long range.

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Re: How about a new game?

Thu Dec 24, 2015 4:36 pm

Yep, low data rate gives long range.

As far as I can tell though you can push things up to 50 or 100 Kb/s in exchange for range.

I also found a supplier of 20 dollar LoRa modules that makes it dead easy to set up point to point or many to point connections. Sadly I can't remember their name or find a link just now.
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Re: How about a new game?

Thu Dec 24, 2015 4:37 pm

Note that all posts discussing PI :evil: FM will be deleted here, to keep the innocent safe! (that's why you cannot find any).
Its not a "FM" transmitter in any sense, more a shitty illegal broadband transmitter, worst idea -ever-!

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Re: How about a new game?

Thu Dec 24, 2015 8:34 pm

mahjongg wrote:Note that all posts discussing PI :evil: FM will be deleted here, to keep the innocent safe! (that's why you cannot find any). Its not a "FM" transmitter in any sense, more a [expletive-deleted - this is a family-and-education-friendly forum, you poor excuse for a moderator - _you_ need to be deleted] illegal broadband transmitter, worst idea -ever-!
Your overly-broad description of using a Pi to generate FM signals is not only ill-informed, it's just plain wrong. There are quite legal ways of doing this, the internationally-recognized method being to have an amateur radio license and broadcasting in appropriate amateur bands, which doesn't even require knowledge of Morse code any more. What you are apparently conflating is FM broadcasting technology vs. the reserved FM broadcast spectra of 87.5 to 108.0 MHz in Europe, Australia, and Africa (ITU region 1), 88.1 to 107.9 MHz in the Americas (ITU region 2), 76.0 to 90 MHz in Japan, and 65.8 to 74.0 MHz in the OIRT band in Eastern Europe (except that Russia now primarily uses the 87.5 to 108 MHz ITU region 1 band). You're also ignoring the difference between just slapping a wire onto a GPIO pin and using additional passive or active elements to filter out-of-band harmonics generated by pulse-width-modulated (PWM) signals that would be created on a bare GPIO pin.

Then, there's the whole subject of Software-Defined Radio technology:

viewtopic.php?f=63&t=46347#p365147


Amateur radio projects:

http://www.g0hwc.com/raspberry-pi-ham-radio.html


and other perfectly-legal uses of RF technology using a Pi:

http://cpc.farnell.com/wirelessthings/b ... dp/SC13019


Instead of the typical heavy-handed, police-state, government-knows-best approach exhibited here (and you keep wondering why the former colonies ran away as fast as they could, taking most of the great, world-improving ideas with them), you should adopt the educational tone that this forum is supposed to portray. You should point out the differences in laws between various locales (e.g., the 200-foot FCC Part 15 rule in the U.S. that allows micro-power transmitters in the 88.1 to 107.9 MHz band), the additional filtering components needed to eliminate out-of-band harmonics generated by a GPIO pin, the amateur bands where FM transmissions are perfectly legal with links to the requirements for earning an amateur license, etc.

Amateur license applications have fallen steadily over the years due to the very fact that there is no commercial interest in promoting the hobby. Any organization purporting to have an educational mission should consider what it can do to foster this very important segment of information science and electrical engineering. Most professional radio/video broadcast technicians start out studying for and earning amateur licenses, which requires knowledge of the very issues noted above, and we can't have enough people of every age educated in this area. Amateur radio is extremely critical in rural and remote areas outside the comfy climes of Merry Olde England, particularly in times of emergencies (and I certainly remember the deadly storms and floods in the UK and the rest of Europe not that long ago). 24+ tornados ripped across 150 miles of the U.S. South last night, that killed people and destroyed structures and vehicles, less than 100 miles from where I am.

Let's reserve the knee-jerking for when the doctor knocks your leg with the little rubber hammer. When someone uses a term such as "Pi-rate radio", hooking up a bare wire to a GPIO terminal just to see what happens, etc., steer the conversation to the legally and technically proper methods. If they insist on continuing discussions clearly meant to promote illegal activity, then remove their posts, or edit them with plain language as to why the Foundation can't support publici(z/s)ing the specific use they're discussing.

Again, watch your language here - it's at least as bad as the discussions you're complaining about.
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Re: How about a new game?

Thu Dec 24, 2015 9:04 pm

Jim,

PiFM in particular is an extremely bad offender because it causes such a complete mess of the radio spectrum well outside the commercial FM bands (where unlicenced micropower is allowed).

We have seen it intrude on VHF airband which sits just above the FM band and, among other things, has international marine and aeronautical distress channels on it. When you tune PiFM to any frequency in the FM band, you get harmonics and subharmonics all the way up to hundreds of MHz.

These are not simple interactions due to the way that FM modulation works. Look at the sample plots of the "wideband" FM spectra here:

https://ccrma.stanford.edu/software/snd/snd/fm.html

You'd need a filter with a far higher Q factor than your usual air coil and foil cap to stop that mess from propagating outwards. Even worse, it won't just radiate from the antenna segment. The GPIOs are not RF-isolated from the rest of the Pi so power cables, the screen on the HDMI cable and any other conductor plugged into the Pi is a viable antenna.

PiFM / PiRate considered harmful. Do not use.
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Re: How about a new game?

Thu Dec 24, 2015 9:21 pm

Jim,

You are always good for a laugh:
Instead of the typical heavy-handed, police-state, government-knows-best approach exhibited here (and you keep wondering why the former colonies ran away as fast as they could, taking most of the great, world-improving ideas with them),
Coming from a citizen of the USA, that has the highest per capita prison population in the world, that is a chuckle.

A country that increasing numbers of people from the civilized world think twice about visiting for fear of it's draconian regime.

Stop it already.

On the other hand, I agree with you. Why should the Pi not be involved in amateur radio activities, sounds like a match made in heaven.
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Re: How about a new game?

Thu Dec 24, 2015 9:27 pm

Heater wrote:FM and WiFi are old hat. LoRa is the new kid on the block.
Tiny little LoRa modules are already available.
http://www.microchip.com/pagehandler/en ... /lora.html
https://www.cooking-hacks.com/documenta ... el-galileo
I think LoRa will be huge soon. IoT is growing like crazy and people like Microchip are getting in on making the modules so they will be very cheap.
Well, at €85.00+ for the Pi version of the Cooking-Hacks products, I don't see how LoRa is going to be very huge any time in the future, let alone soon. Also, with a line-of-sight (LOS) range of 21 kms / 14 miles, and through-buildings (non-LOS - NLOS) range of 2 kms / 1.2miles, we're not talking IoT, especially since there doesn't appear to be any security associated with the technology (sure, it can be done at the application level, but no one is even talking about doing that). It also appears that the LoRaWAN products have to be used for anything beyond point-to-point links, they're even more expensive, and they seem to require some sort of "base station". The Microchip product seems to only be for European markets, and following the certification links for the FCC doesn't include that product, only those using WiFi.

The frequency bands used at 433/868/900 MHz are interesting, but that seems to be at a very high cost of extremely low data rates - I saw mention of rates as low as single-digit bits per second (no, that wasn't a typo, not Megabits per second, _bits_ per second). Perhaps that's at the extremes of the LOS or NLOS ranges, but I didn't see a description of what the best-case data rates are at more typical IoT distances (tens to hundreds of feet). They also cite that less infrastructure is needed due to the longer ranges, but that generally means a higher probability of interference by non-associated nodes over wider areas, resulting in even lower effective data rates.

I should note that I'm pretty suspicious of IoT being more of a marketing ploy for a solution in search of a problem, not to mention the universal lack of attention to security, and the only scenario I can imagine where my fridge needs to talk to my door locks would be to share computer porn! :o I also don't own a "3-D" TV, with or without a curved screen, or a "smart" phone with a display that wraps around the edge of most of the thickness of the phone, either :roll:.
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Re: How about a new game?

Thu Dec 24, 2015 10:03 pm

Jim Manley,

I agree, 85 Euro is crazy. However I have a bunch of tiny LoRa modules on order that are 20 Euro each. With Microchip and the like commencing production of these things we can expect it to get at lot cheaper.

As far as I can can understand so far a "base station" is not required. Not until you want to get out to the internet. But hey a LoRa module and a Pi can do that. Which is my next Pi project when I get these modules.

I'm not sure what you mean by 21 kms not being IoT. Currently most IoT ideas I see rely on WIFI which has much less range. With LoRa you can cover much of a city with only a hand full of "base stations".

People around here have done tests burying LoRa devices under ground and communicating through buildings. Worked well enough.

Low data rates for sure. That is the whole idea. For many applications only very low data rates are required. Think domestic meter reading or my weather station out in the forest. But it's a trade off between speed and range.

Consider this. A rubbish bin that can detect when it is full and report back to base means that the garbage truck only has to visit when required. 20 dollars of electronics saves thousands in unnecessary fuel and work. This is already operational around here.

I do agree, I'm very suspicious of a lot of the current IoT "gold rush". I imagine that like the "internet bubble" of 2000 or whenever a lot will be invested and lost. After the shake down it will be huge anyway, as the internet today is.

Security....oh yeah...let's see how that goes...
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