SP-7

Description

The SP-7 contains a MEMS based three axis gyroscopic device (strapdown
gyroscope) and a three axis accelerometer. Using advanced software algorithms it
uses the measurement data from these sensors together with other information as
may be available via the interfaces to provide a best estimate AHRS solution.
The SP-7 typically provides bank and pitch angle, rate of turn as well as gravitational
forces or acceleration to the host system.
Using a newly developed dynamic aiding algorithm the SP-7 is able to provide
outstanding resilience to performance degrading effects caused by vibration and
airframe shocks while avoiding negative affects of traditional aided systems.
The SP-7 AHRS provides measurement of angular rates up to 250 degrees per
second on any axis and measures G-forces up to 6 G.
The SP-7 forms an ideal companion product to MGL’s EFIS systems but can also be
used stand-alone using a AV-1 or AV-2 instrument.
The SP-7 provides several interfacing options: The reliable CAN bus is used with
iEFIS exclusively. On older Odyssey and Voyager systems you can use either CAN
bus or the older MGL Airtalk link (CAN bus is recommended due to higher
performance). Finally, the SP-7 provides a traditional RS232 serial interface at
57600 Baud intended for simple third party use as well as for Firmware updates.
SP-7 devices manufactured after September 2013 can also receive firmware
upgrades through the CAN interface via iEFIS systems.
Overview
The SP-7 AHRS is MGL Avionics’s seventh generation AHRS system. The core
building blocks of the system includes a three axis ST MEMS rate gyroscope, a
three axis ST MEMS accelerometer and an ARM Cortex 32-bit microprocessor system.
While the SP-7 is much cheaper than a traditional AHRS system as installed in
military aircraft or airliners, the very same principles of operation are used and the
same restrictions and limitations are present. More than with any other system in
your aircraft, the performance of the AHRS is dependent on the correct installation
of the system.
The SP-7 is a “strapdown AHRS”, a term used for a system that is not
based on the traditional spinning body gyroscope (vacuum or electric gyro) but
rather uses three separate gyroscopic devices to measure rotation
rates around each of the three major axis. This is combined with three accelerometers
that measure specific force in the same three axis.
Specifications
 Weight:
Excluding cables: 126 grams
Including cables: 175 grams (RCA signal and DB9 power cable included)
 Electrical and Temperature Characteristics:
Input voltage range: 8V to 20V DC regulated preferred for maximum performance.
11-14V is suggested as operating voltage.
Current consumption: 50 mA (heater off) at 13.8VDC input voltage
120 mA (heater on) at 13.8VDC input voltage
Temperature Regulation: 35ºC (internally maintained temperature)
 Accelerometer Specifications
Accelerometers: MEMS
Sensor Limits: /- 8G
Maximum G-force loading: 30G (any axis)
 Rate Gyroscope Specifications:
Rate Gyroscopes: MEMS
Maximum rate : 250º/second
Non-linearity: 0.2% FS, best straight line fit
 Attitude calculations:
Quaternion system, IEEE Single floating point, normalized.
No attitude angle restrictions in any axis.
Quaternion update rate: 40Hz
Euler angle output rate: 10Hz
 Output Messages
Interface: MGL Avionics Airtalk compatible
Normal output message: 50 ms (average) latency
Raw output message: 12 ms (average) latency