Technical description of -300 Symbol Generator

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Technical description of -300 Symbol Generator

Postby mxmxmx » 08 Nov 2007, 22:12

I had a discussion about the functioning of the Symbol Generator (SG) for the EFIS (EADI and EHSI) of the 737-300, so I'm looking for a technical description of it. What's written in the flight manual is not detailed enough.

Anyone willing to share his information with me? The more detailed the better.

Thanks in advance,
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Joined: 08 Nov 2007, 22:07

Re: Technical description of -300 Symbol Generator

Postby Boeing 737-Fan » 06 Jun 2008, 14:14

Hello Chris,
i have some informations from my Training Letters. I hope thät helps you :wink:

Have a nice day

The EFIS symbol generator receives data from the EFIS control panel and the
airplane’s navigation and guidance systems. The symbol generator then processes
the data and provides video signals for display on the EADI and EHSI.
The input data is received on ARINC 429 low speed and high speed data
buses, as well as ARINC 453 weather radar high speed buses, and discrete
A symbol generator can supply all display units. However, in this case captain’s
displayed data and FO’s displayed data are the same.

Most of the parameters displayed on the EADI and EHSI utilize signals that
originate from various systems on the airplane. However, the display of a number
of parameters requires computations based on inputs from several systems.
The computations for these parameters are performed by the symbol
The symbol generator computed displays are as follows:
 Airspeed trend vector
 DH alert
 Altitude alert
 Curved trend vector
 NAV/IRU position difference
 Range disagreemement message
 Course deviation and TO/FROM indication
Boeing 737-Fan
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Joined: 05 Dec 2007, 12:26

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