From 08e6c40cd01cd8af059fe27474e655a75732776e Mon Sep 17 00:00:00 2001 From: Jet Hughes Date: Thu, 23 Mar 2023 10:24:03 +1300 Subject: [PATCH] vault backup: 2023-03-23 10:24:03 --- content/notes/08-proximity sensors.md | 210 ++++++++++++++++++++++++++ content/notes/info-305.md | 3 +- 2 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 content/notes/08-proximity sensors.md diff --git a/content/notes/08-proximity sensors.md b/content/notes/08-proximity sensors.md new file mode 100644 index 000000000..14fb14cca --- /dev/null +++ b/content/notes/08-proximity sensors.md @@ -0,0 +1,210 @@ +--- +title: "08-proximity sensors" +tags: +- lecture +- info305 +--- + +Lecture 8: Location Sensors 2 Tobias Langlotz INFO 305: Advanced Human-Computer Interaction and Interactive Systems 2 + +Proximity Sensors & Near Field Communication +- Different technologies for sensing proximity or exchanging data (often dual purpose) +- Stand-alone infrastructure approaches +- Not widely accepted due to special hardware requirements infrastructure costs (for tracking) +- Conceptually often similar to cell-based approaches but require extra infrastructure NFC (Example: PayWave) Bluetooth RFID IrDa 3 + +Proximity Sensors & Near Field Communication +- Different protocols on top of Bluetooth LE +- iBeacon (Apple) +- Broadcasts a UUID +- ID is used with database integrated in the app +- Further information on request (e.g. range information) Different iBeacon capable beacons Range Information from iBeacons 4 + +Proximity Sensors & Near Field Communication +- Different protocols on top of Bluetooth LE +- iBeacon (Apple) +- Broadcasts a UUID +- ID is used with database integrated in the app +- Further information on request (e.g. range information) Different iBeacon capable beacons +- Eddystone (Google) +- Beacons broacasts information about the beacon (telemetry frame e.g. battery or sensor information) +- Beacons broadcasts and redirects to an URL (physical web) Eddystone lighthouse, role model for Eddystone functionality 5 + +Proximity Sensors & Near Field Communication +- Different technologies for sensing proximity or exchanging data (often dual purpose) +- Stand-alone infrastructure approaches +- Not widely accepted due to special hardware requirements infrastructure costs (for tracking) +- Conceptually often similar to cell-based approaches but require extra infrastructure NFC (Example: PayWave) Bluetooth RFID IrDa 6 + +Proximity Sensors & Near Field Communication +- RFID: Radio-frequency identification +- Uses radio-frequency waves to transfer data between a reader and a movable item +- Identify, +- Categorize, +- Track, +- Tag objects of interests +- No physical sight or contact needed RFID Tag + +Proximity Sensors & Near Field Communication 7 +- RFID: Radio-frequency identification +- Basic Types: +- Active +- Tag transmits radio signal +- Battery powered memory, radio & circuitry +- High Read Range (300 feet) +- Passive +- Tag reflects radio signal from reader +- Reader powered +- Shorter Read Range (4 inches - 15 feet) +- Tags can be read-only or read-write RFID Tag Active RFID Tags + +Proximity Sensors & Near Field Communication 8 RFID Tag +- Host Manages Reader(s) and Issues Commands +- Reader and tag communicate via RF signal + - Carrier signal generated by the reader + - Carrier signal sent out through the antennas + - Carrier signal hits tag(s) + - Tag receives and modifies carrier signal + - Antennas receive the modulated signal and send signal to the Reader + - Reader decodes the data Different RFID Tags Hitachi "powder" type RFID chip measuring 0.05 x 0.05 mm + +> [!INFO] can get implants of RFID +> usually connected to a database which identifies stuff. e.g., this tag is this cow +> small rfids you need to be very close as the signal is not very strong + +Proximity Sensors & Near Field Communication 9 Hitachi "powder" type RFID chip measuring 0.05 x 0.05 mm Other RFID form factors + +Proximity Sensors & Near Field Communication 10 +- Different substandards (frequencies) RFID Tag +![table of freqs](https://i.imgur.com/IuJ0mnq.png) + +Proximity Sensors & Near Field Communication 11 +- Near Field Communication (NFC) + - Subgroup of RFID techniques (13.56 MHz) + - Operating distance typical up to 10 cm (but up to 1m) + - Data exchange rate today up to 424 kilobits/s + - Usually used for Smartcards, digital payment, or device to device communication/ authentification NFC smartcards + +Proximity Sensors & Near Field Communication 12 NFC-based communication / authentification + +Proximity Sensors & Near Field Communication 13 +- Each full NFC device can work in three modes: +- NFC card emulation +- NFC-enabled devices act like smart cards, allowing users to perform transactions such as payment or ticketing. +- NFC reader/writer +- NFC-enabled devices to read information stored on inexpensive NFC tags embedded in labels or smart posters. +- NFC peer-to-peer +- Enables two NFC-enabled devices to communicate with each other to exchange information in an adhoc fashion. 14 + +Proximity Sensors & Near Field Communication +- Different technologies for sensing proximity or exchanging data (often dual purpose) +- Stand-alone infrastructure approaches +- Not widely accepted due to special hardware requirements infrastructure costs (for tracking) +- Conceptually often similar to cell-based approaches but require extra infrastructure NFC (Example: PayWave) Bluetooth RFID IrDa Location Sensors - GPS + +GPS - Overview +- (Navstar-) GPS is a satellite-based navigation system that provides users with Positioning (and Timing services +- Provides information anywhere on Earth with unobstructed Line Of Sight +- Operates in any weather conditions (but with accuracy constraints) +- Available to military, commercial and civil users +- Similar systems: +- Glonass (Russia, Operational) +- Beidou/Compass/Beidu 2 (China, operational since 2020) +- Galileo (Europe, expected operational since 2020) +- Local coverage (DORIS, IRNSS, ..) + +GPS - Applications +- Numerous GPS applications & GPS Receivers: +- Military +- Car navigation +- Marine +- Flight control +- Agriculture +- Recreation +- For mobile devices +- Car an personal navigation +- Location-based services +- Augmented Reality + +GPS - History +- GPS project was developed in 1973 by U.S. Department of Defence (successor of Transit/NAVSAT +- Originally comprised of 24 satellites, now 30 (including redundant satellites), 65 launched +- Originally intended for military applications +- U.S government to open GPS to civilian use in 1983 (after a Soviet jet accidentally shot a civil Korean airplane, due to navigation errors) +- Civil based GPS was limited through Selective Availability (SA) +- Accuracy errors of 100m +- SA was removed for civilian users in 2003. +- GPS achieved initial operational capability (24 Satellites) in 1993 GPS – Satellites +- Constellation of 24 + X satellites transmitting radio signals to users +- Altitude of 20,000km (approx.) +- Each satellite orbits Earth twice/day +- Arranged in 6 orbital planes +- Each plane has four slots +- At least four satellites from virtually anywhere on earth (we come back to this..) +- Satellites use high precision atomic clock + +GPS - Signal +- GPS satellite constantly transmits radio signals (L1 signal for privat, L2 military +- The navigation message is made up of three major components: +- GPS date and time, plus the satellite's status and an indication of its health +- Orbital information called ephemeris data and allows the receiver to calculate the position of the satellite (valid ~4h) +- Almanac, contains information and status concerning all the satellites; their locations and PRN numbers needed to find satellites (valid ~180days) +- Each satellite has a unique ID called “Gold codes” or PRNs (pseudo-random noise sequences) to differentiate each satellite + +GPS - Receiver +- Uses messages received from satellites (n≥4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location + +GPS - Receiver +- Uses messages received from satellites (n≥4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location Triangulation = working with angles Trilateration = working with distances + +GPS - Receiver +- Uses messages received from satellites (n"4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location In 2D (3 Circles) Dunedin + +GPS - Receiver +- Uses messages received from satellites (n"4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location In 2D (3 Circles) Dunedin + +GPS - Receiver +- Uses messages received from satellites (n"4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location In 2D (3 Circles) Dunedin + +GPS - Receiver +- Uses messages received from satellites (n"4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location In 3D (4 Spheres) Dunedin + +GPS - Receiver +- Uses messages received from satellites (n"4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location In 3D (4 Spheres) Dunedin + +GPS - Receiver +- Uses messages received from satellites (n"4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location In 3D (4 Spheres) Dunedin But our receiver does not have an atomic clock!! + +GPS - Receiver +- Uses messages received from satellites (n≥4) to determine the satellite positions and time sent +- Gives roughly distance to satellite +- Applies Trilateration for computing location +- The receiver has four unknowns, the three components of GPS receiver position and the clock bias [x, y, z, b] +- Using four (or more) satellites, we can set up 4 linear equations to solve for x, y, z, b +- In some cases we know z or b we need less satellites! Urban Canyon +- Urban environment similar to a natural canyon +- Can impact radio reception of GPS receivers +- Buildings reflect and occlude satellite signals +- Reducing precision of positioning in urban environments +- Makes positioning impossible Urban Canyon +- Urban environment similar to a natural canyon +- Can impact radio reception of GPS receivers +- Buildings reflect and occlude satellite signals +- Reducing precision of positioning in urban environments +- Makes positioning impossible www.hci.otago.ac.nz The end! \ No newline at end of file diff --git a/content/notes/info-305.md b/content/notes/info-305.md index af4dd4bfe..221d6135f 100644 --- a/content/notes/info-305.md +++ b/content/notes/info-305.md @@ -22,5 +22,6 @@ tags: - [x] [[05-pervasive-ubiquitious-2]] - [x] [[06-challenges-for-ubicomp-and-intro-to-sensors]] - [x] [[07-location-sensors]] - +- [[08-proximity sensors]] +- # Info \ No newline at end of file