Comments on: Harry Potter Marauders map realized

By: shicks

shicks — Wed, 09 Sep 2009 05:27:24 +0000

@Jack Ironic that I could listen to analog cellular communications with my UHF television receiver (without modification) in the 80s.

By: Leigh

Leigh — Wed, 09 Sep 2009 04:30:18 +0000

I did this project for the 2009 Maker Faire for the National Association for Amateur Radio (“ARRL”) booth.

Thanks for all the comments, especially the first one comparing the project to APRS.

My idea was to show how to combine parts and techniques from the MAKE/DIY world with the ham radio world. There’s a significant overlap, both in interests and in individuals, and I felt that a project bringing something from each together would help cross the bridge in both directions.

I didn’t see it mentioned in the write-up, but there are some Youtube videos of both the MM project and some APRS projects at the Maker Faire:

For Part 1 (the Marauders) see
http://www.youtube.com/watch?v=S_Q69eQ_OK0
For Part 2 (the Map) see

If you’re interested in doing something like this, but with more range, consider getting a ham radio license and trying out APRS.

By: FriedPope

FriedPope — Tue, 08 Sep 2009 02:32:04 +0000

Everybody remembers http://www.openbeacon.org/ .
Not to downplay the current project, but open-beacon seems a bit more like a marauders map to me.

By: Jack

Jack — Mon, 07 Sep 2009 06:31:00 +0000

Usually cellphones don’t constantly broadcast gps data. Unless they have been stolen, or the owner just loves to drain their battery. Lol.

By: xrazorwirex

xrazorwirex — Sun, 06 Sep 2009 23:52:23 +0000

I looked into it more and to actually go through and monitor cellphone information (it’s encrypted) is a pain in the ass anyways – but alot of cellphones use standard gps I think, and I know you won’t have jackboots on your doorstep if you’re just trying to interface with gps satellites, so… figure it out – mabye use the cellphone’s internet connection to transmit its gps data to a server somewhere…

way too much thought is going into this….

By: xrazorwirex

xrazorwirex — Sun, 06 Sep 2009 23:46:31 +0000

Ok; I read up on the ‘laws’ (aka: whatever the FCC decides it wants to enforce) and apparently it’s also “Illegal to monitor remote radio-TV broadcast signals”… so.. your television is illegal… or maybe it’s illegal to make a television that doesn’t have an FCC stamp on it.. I’m not sure, probably whatever’s more convenient for them..

So ok, you may be violating an FCC law, but are you ‘really’ committing a crime that’s going to be enforced? And if you aren’t broadcasting on a registered spectrum or anything then it’s pretty tough to get caught since you aren’t interfering with anybodies stuff.

By: Jack

Jack — Sun, 06 Sep 2009 19:54:02 +0000

@xrazorwirex took a quick picture off the back of my radio scanner… heres a link http://tinypic.com/r/2mo36ys/3

By: Jeff

Jeff — Sun, 06 Sep 2009 13:31:20 +0000

@s0crates82 There are “intelligent” traffic systems that are being experimented with by the NY State DOT that do exactly what you suggested.

By: Roee

Roee — Sun, 06 Sep 2009 05:46:06 +0000

Can you add the initiation words of the Harry Potter version to it?

By: xrazorwirex

xrazorwirex — Sun, 06 Sep 2009 05:41:46 +0000

You can’t interfere with the signals and jam them or anything, but the air is still free and the electromagnetic waves traveling through you or your property can be freely absorbed and any information disseminated is public domain. It’s no different than if I was shouting out my window to my neighbor, just over the electromagnetic spectrum.

Now if you broadcast on an ‘unauthorized’ bandwidth or subsequently jam any ‘legal’ signals then they get pissed and ‘fine’ you ‘a million dollarz’ or something, but I’m pretty sure that his exact frequency, although in the block allocated for digital transmission, most likely resides in one of the many white space gaps inbetween channels, being as how it’s quite a specific frequency.

Just speculation however…

By: Jack

Jack — Sun, 06 Sep 2009 01:05:11 +0000

It would be illegal however to do this, im pretty sure. I think cellular radio communications are protected by the FCC, I know they are at least with scanners and voice traffic…. I don’t know about data over a cellular transmission.

By: s0crates82

s0crates82 — Sat, 05 Sep 2009 23:56:26 +0000

imagine if you could tap into stuff that’s already constantly pinging gps in a network.

gm’s onstar cars? instantly know traffic conditions without having access to dot radar stations. blackberrys? easily find concentrations of business travelers. iphones? now you know where to advertise the farmer’s market. etc.

By: Jack

Jack — Sat, 05 Sep 2009 23:18:04 +0000

Or doing it the swarm way where they all have synchronized internal clocks and directional antennas and can calculate relative locations.

By: Gonzalo

Gonzalo — Sat, 05 Sep 2009 23:03:16 +0000

What about doing it the other way?

Setting up three receivers and radio power meters in some three points and then triangulating the signals?

By: Joel Haasnoot

Joel Haasnoot — Sat, 05 Sep 2009 22:27:27 +0000

Isn’t this what we call a “wireless sensor network”, it just has some high power requirements due to the GPS…