Autoland and motor stop of Multiwii quadcopter, altitude hold, GPS hold and return to home. Laser Tape Measure Hacking. APM 3G Telemetry. An Introduction to GNSS | Chapter 4 - Real-Time Kinematic | NovAtel. The positioning technique we described in Chapter 2 is referred to as code-based positioning, because the receiver correlates with and uses the pseudorandom codes transmitted by four or more satellites to determine the ranges to the satellites. From these ranges and knowing where the satellites are, the receiver can establish its position to within a few metres. For applications such as surveying, higher accuracies are required. Real-Time Kinematic (RTK), a technique that uses carrier-based ranging, provides ranges (and therefore positions) that are orders of magnitude more precise than those available through code-based positioning. Real-time kinematic techniques are complicated. The basic concept is to reduce and remove errors common to a base station and rover pair, as illustrated in Figure 38.
These error sources were discussed in Chapter 2. Figure 38 Real-Time Kinematic A complicated process called “ambiguity resolution” is needed to determine the number of whole cycles. Piksi : The RTK GPS Receiver by Swift Navigation Inc. We’ve had a lot of interest in the Piksi RTK system from professionals in the GIS and mapping fields, but our RTK Kit alone was not enough to fulfill this need. To use Piksi in these settings, you need a durable, integrated solution - one that can be turned on with the flick of a switch, and is accompanied by an easy, intuitive user interface.
So, we have added a new reward, a ruggedized version of our RTK Kit containing two Piksi receivers each fully assembled with an enclosure, a Bluetooth module, an SD card slot, an integrated radio link, and 10 hours of rechargeable Lithium Polymer batteries. We’ll also be releasing data collection apps for Android and iOS that interface with Piksi over Bluetooth; you’ll be able to take measurements, plot points on your smartphone’s map, and for professionals, export to common formats to integrate into your standard mapping workflow - all with the 4 centimeter accuracy of the Piksi RTK system.
Some possible applications: Piksi Technical Specs: Centimeter-level precision GPS for $900. RTKLIB on the Raspberry Pi. I've got a workmate. He wants to build an autonomous, electric, rotary hoe. Anyway, he needs to locate the hoe to within a few centimetres. I'd been contemplating DGPS for a while as I've found GPS tracks are a bit wandery when logging tracks for OpenStreetMap. I thought it'd be a good capability to have, so I've stepped up to the task of tracking Robohoe.
Background Information This is basically a link dump of what I've found so far: RTKLIB : DGPS software This is the bees knees for cheap arse DGPS. It's also got a number of other super handy programs, that do things like convert RTKLIB output into a Google Earth KML file, serve serial input out to multiple processes via Unix sockets etc. The RTKLIB manual is here. LEA-4T : GPS hardware The U-Blox 'T' series of modules (the LEA-4T, LEA-5T, and NEO-6T) produce data suitable for input to RTKLIB.
The pinout for this module is (from here):antenna - SMB male connector 2 4 6 8 1 3 5 7 bottom EBay : USB serial unit Generic FTDI USB serial dongle. Regular GPS not accurate enough? Try RTK-GPS! Detect airplane/UAV using Passive Radar technology.