Recently, I've been looking at a couple of M-LINK compatible devices, one from Multiplex and the other from SM Modellbau.
Multiplex GPS sensor
The Multiplex sensor (#85417) provides basic height and distance data, as well as derived quantities such as speed, track, and bearing. My full review of the Multiplex GPS sensor was printed in RCMW, Feb 2012 issue. Suffice to say that I had a lot of fun with one in an Easy Glider, using a Royal Pro M-LINK transmitter and RX-7-DR receiver. Data is displayed directly on the screen of the transmitter.
Multiplex's offering works well enough, but it does have a couple of limitations. The unit doesn't show rate of climb - for that you need to purchase an additional barometric vario sensor (#85416). Also, there's no built-in data logger - in order to record the GPS data (e.g. for display in Google Earth), it's necessary to purchase the Multiplex Flight Recorder module (part no. #85420).
The sensor can be configured either using the free "Launcher" software, or via the MPX Multimate programmer (#82904). The Launcher software requires a Windows PC and is a little rough at the edges - for day to day configuration the Multimate is the better option. However the Launcher software will be required if you need to update the firmware.
SM Modellbau GPS-Logger
The other sensor is by German company SM Modellbau, and is called 'GPS Logger'. It will interface with telemetry systems from Multiplex, Jeti and Graupner, with slight differences in capability depending on the system used.
The rest of this discussion will focus on operation in an M-LINK environment.
|The GPS Logger is the little gizmo at the lower end of the cable. Also shown is the UniDisplay.|
GPS-Logger incorporates three key components: a GPS sensor, a barometric sensor (for a vario function), and a data logger. The logger records not only the GPS and vario data, but also all M-LINK telemetry data appearing on the MSB bus. Data is written to a removable Micro SD card. Data files are in .nmea format.
The units supports Multiplex's MSB protocol. This means that telemetry of GPS and vario data is available through any telemetry-capable M-LINK receiver - no additional boxes are required.
Accompanying the GPS-Logger was a UniDisplay. This is a miniature hand held terminal which connects to the GPS-Logger via a ribbon cable. You can use it to (a) configure the GPS-Logger, and (b) read the GPS-Logger's sensor data directly.
The GPS-Logger looks to be a cool piece of kit. However, a lot will depend on how easy it is to use in the field, and the tools available for post-flight analysis. I should also mention here that the documentation is all in German, although my club mate Dick Whitehead has done a pretty good job of translating most of the key stuff.
In the above intro I've only scratched the surface with the GPS-Logger, it's a sophisticated unit with several facets to its operation. The first flight test has already been accomplished, and I will be writing a full review in a future issue of AMI (Aviation Modeller International). [update: sadly, AMI was closed down before the review could be published.]