Honeywell KLN 90B Installation Manual page 139

BENDIX/KING
Definition
GPS Message
RAIM not avail- This means there are
able not enough satellites
Cross check posi- available to compute in-
tion tegrity (RAIM).
1. The satellites are
blocked from view by
obstructions.
2. They are too low on
the horizon for use, or
too high for adequate
geometry.
3. There is a loss of sen-
sitivity in the antenna,
the coax, or the Receiv-
er Module.
No RS-232 Data There is no RS-232 data
at the RS-232 input
port.
RCVR hardware These are error codes
error:__ that are detected in the
GPS receiver.
RAIM not avail- This is a calculated pre-
able diction of RAIM avail-
Approach mode ability. The message
inhibited appears when integrity
Predict RAIM on monitoring (RAIM) is
OTH 3 or STA 5 predicted to not be
available at either the
FAF or MAP. The GPS
will not allow the unit to
go into APR ACTV
mode until conditions
improve.
Rev 5, April/2003
GPS Page/Laptop Messages
Suggested Action
The aircraft should be in an open area with good
visibility, and the SNR (Signal to Noise Ratio) on
the STA 1 or OTH 2 should be as noted below:
KLN 89s will usually have 6-8 satellites shown,
and the majority of their SNRs will be 7 to 9. SNRs
of 3 and below are unusable, 4 is marginal, and 5
through 9 are considered good.
KLN 90/900s will usually have 6-8 satellites
shown, and the majority of their SNRs will be 40s.
SNRs of 30 and below are unusable, 30-35 are
marginal and 35-48 are considered good.
If the SNRs are low, it could be one of the follow-
ing, in the order of probability:
1. Check the antenna coax and connection for
problems.
2. Verify that 5 volts is present at the antenna end
of the coax.
3. Substitute the receiver to check for sensitivity.
4. Substitute the antenna to check for sensitivity.
The Air Data/Fuel Flow source is not providing RS
232 data to the GPS.
If no source of RS-232 is interfaced, the receiver
input must be jumpered back to the RS-232 out-
put on KLN 89/89Bs and KLN 90/90A/90Bs.
If no source of RS-232 is interfaced to a KLN 900,
the configuration may be set up wrong.
Refer to the GPS Fault/Error Code table.
This is a feature, not a system failure.
Turn to the OTH 3 or STA 5 page to perform a
RAIM prediction. It will give you an indication of
how long it will be until RAIM is available.
This prediction can also be performed prior to de-
parture to insure RAIM at your arrival.
10521I05.TDC
KLN 90B
Page C-7