Blaze ALT-7 Operating Manual
Page 6
Cal Factor:
This is the pressure sensor offset in 0.1mB increments. Adjust your static pressure to be close to sea level pressure. The
exact altitude is not important and can be up to several hundred feet. Adjust the calibration factor so the altitude readout
in the top right hand corner of the display agrees with your pitot static test set.
Cal Gain:
Once you are satisfied that the low level altitude “CAL FACTOR” is correct, apply a static pressure that will result in an
altitude between 20000 and 30000 ft. Adjust the “CAL GAIN” until the altitude readout in the top right hand corner of the
display agrees with your pitot static test set
NOTE:
Adjusting the “CAL GAIN” also changes the low level altitude calibration achieved when adjusting the “CAL
FACTOR”. Please recheck your low level altitude calibration and adjust if necessary. Recheck your altitude readout at the
higher altitude, and if needed slightly adjust the “CAL GAIN” again. Repeat the process until you are satisfied with both
the “CAL FACTOR” altitude and the “CAL GAIN” altitude.
Serial Out:
Select
“ON”
to enable the RS232 serial altitude output. This formatted serial RS232 message can be directly interfaced to
various RS232 serial input transponders.
Prot:
Select the protocol of the serial RS232 output message. The protocol can be selected between GARMIN AT, Magellan,
Northstar / Garmin, Trimble / Garmin, MGL Avionics and Microair UAV. Please note that the baud rate is automatically
adjusted according to which protocol is selected. The output format is as follows. The message contains the current
pressure altitude with a fixed reference to 1013.25mB (29.92 inches mercury). All protocols use 8 databits, no parity, and
1 stop bit. The message is outputted once a second.
Protocol
Baud
Rate
Message format
Example
Garmin AT
1200
#AL, space, +/-, five altitude digits right
justified zero padded, T+25, checksum,
carriage return
The checksum is a simple modulo 256 sum
of the binary values of the individual
characters. The checksum is sent as two
characters in hexadecimal format
#AL +25DF[CR]
Magellan
1200
#MGL, +/-, five altitude digits right justified
zero padded, T+25, checksum, carriage
return
The checksum is a simple modulo 256 sum
of the binary values of the individual
characters. The checksum is sent as two
characters in hexadecimal format
$MGL+2513[CR]
Northstar,
Garmin
4800
ALT, space, five altitude digits right justified
zero padded, carriage return
ALT 02372[CR]
Trimble,
9600
ALT, space, five altitude digits right justified
ALT 02372[CR]
