# Notcon 04

> Notcon 04 notes: Spotcodes, circular barcodes for mobile phone interaction; and Reverend Rat's 10-watt long-range Bluetooth receiver.

- Page: https://www.elasticspace.com/2004/06/notcon/
- Author: Timo Arnall (https://www.elasticspace.com/)
- Section: Notes (https://www.elasticspace.com/notes/)
- Published: 2004-06-07
- Updated: 2026-07-04
- Tags: Art, Barcodes, Conference, Media, Mobile, Technology
- Site map for agents: https://www.elasticspace.com/llms.txt

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A circular barcode printed on a sticker, small enough to fit on a poster edge. Point a Nokia Series 60 camera phone at it and the phone reads 42 bits of data, enough to trigger a URL, a Bluetooth handshake, a position fix. Spotcodes.

*Two things from [Notcon 04](http://www.notcon04.com/) in London worth writing up. A May 2004 not-con organised by Yoz Grahame and others, as a cheap and unstructured alternative to the more formal industry events. Notes below.*

### Barcodes for spatial markup and control

[Spotcodes](https://web.archive.org/web/20040630191807/http://www.highenergymagic.com:80/spotcode/index.html) use a very [simple circular barcode](https://web.archive.org/web/20040704223804/http://www.highenergymagic.com:80/spotcode/symbols.html) to mark objects for interaction with a camera-equipped phone.

- Requires a [small application](https://web.archive.org/web/20040630190321/http://www.highenergymagic.com:80/spotcode/download.html) running on a Series 60 phone to scan barcodes with the built-in camera
- Each barcode can currently store 42 bits of data using technology modified from iris tracking and wavelet technologies (as far as I understood)
- Potential for more data by increasing the number of rings, but the current setup is a compromise for low-quality cameraphone cameras
- The phone application can determine the phone’s position relative to the barcode by the elliptical distortion of the circle, potentially useful for accurate tracking with multiple spots
- The phone application communicates via Bluetooth or GPRS, using the barcodes as triggers for interactions
- Coded ‘close to the hardware’ to do barcode calculation on video input in realtime; Java/Symbian apps don’t have an API for realtime video input
- In commercial use via [Bango](http://www.bango.net)

### Bluetooth mapping

[Reverend Rat](https://web.archive.org/web/20040607014132/http://www.spy.org.uk:80/ratblog/) demoed his 10-watt Bluetooth receiver, ten times more powerful than a 35-mile 802.11b receiver, and a hundred times more powerful than a Bluetooth dongle.

Not particularly interesting in itself, but from a high vantage point it might be used to map usage patterns in urban areas or track the flow of people and devices.

### Some photos

![Public markup of Notcon 04 session schedule on a venue wall](https://www.elasticspace.com/images/notcon/notcon01.jpg)

*Nice impromptu public markup*

![Inside the Notcon 04 venue](https://www.elasticspace.com/images/notcon/notcon02.jpg)

*Inside*

![Outside the Notcon 04 venue](https://www.elasticspace.com/images/notcon/notcon03.jpg)

*Outside*

![Anil demonstrating test Spotcode barcodes on a camera phone](https://www.elasticspace.com/images/notcon/notcon04.jpg)

*Anil demonstrates test barcodes for Spotcode*

![Reverend Rat scanning for Bluetooth devices with a long-range receiver](https://www.elasticspace.com/images/notcon/notcon05.jpg)

*Reverend Rat discovers Bluetooth devices*

![Celia and Rod at Notcon 04](https://www.elasticspace.com/images/notcon/notcon06.jpg)

*Celia and Rod*

![Informal gathering of attendees at Notcon 04](https://www.elasticspace.com/images/notcon/notcon07.jpg)

*Geeks*