Leica MX400 Operating Instructions Manual page 133

Operator's Manual
Apply DGPS corrections to the receiver immediately? The
default setting is Yes. Each DGPS correction message actually
contains DGPS corrections for multiple satellites. Selecting Yes
causes the receiver to apply the correction of each satellite as
soon as it is decoded from the correction message. Selecting No
causes the receiver to apply the correction only after decoding
the entire DGPS correction message.
Max Age:
Sets the maximum time limit that the last received DGPS
correction will be applied to the satellite range measurement in
the receiver. The default setting is 60 seconds. The receiver will
accept values from 10 to 999 seconds. While the receiver will
accept a longer period of correction aging than 60 seconds, we
highly recommend that 60 seconds be the highest value you use,
regardless of your application. Remember that DGPS's purpose
is to provide you with a very accurate position fix in the
presence of US DoD imposed Selective Availability (S/A). S/A
is implemented by injecting errors in the satellites clock and
navigation message. These errors are injected in something of a
random fashion. Since these errors are constantly changing,
presumably at a rate of once per second, DGPS corrections
begin creating more errors in your position fix the longer they
age. The receiver expects to receive DGPS corrections every
few seconds. Although the beacon system is rated for 5 meter
accuracy, there is no guarantee that your receiver will always
maintain the 5 meter level of accuracy. Chances of maintaining
this level of accuracy are far less if you choose to use an age
limit longer than 60 seconds.
If you are attempting to use the receiver in an application where
accuracy is important, set the age limit to 30 seconds.
Message 16 Alarm:
Sets the alarm to on or off if a reference station text message is
received. The default setting is Yes. Operators of the reference
station can send text messages up to 90 characters in length to
provide system outage or advisory information to all users of the
system. These messages are known as RTCM SC-104 Type 16
messages and are displayed on the DGPS3 screen, regardless of
the alarm setting.
120
Configuration
Version 3.3