User's Manual

Document Number/Ref.-No. Issue
00-6383A01 1.0
(113491 2)
Page 12 of 26
Copyright  2000 by Harris Corporation, RF Communications Division
All rights reserved. No part of this publication may be reproduced or transmitted in
any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in
writing by
Harris Corporation, RF Communications Division,
Rochester, New York, USA
The calibration consists of accurately measuring the simulated GPS signal period and determining the error (in
microseconds) from one second. The CountsPerSecond entry of the configuration file should then be changed by that
number. The default value of CountsPerSecond is 16960, which will provide a nominal 1 PPS simulated GPS signal
given an ideal crystal oscillator.
For example, if the simulated GPS period is measured and determined to be 0.999977 seconds (23 microseconds
less than one second), and the CountsPerSecond parameter is currently set to 16960, the new value for
CountsPerSecond would be 16983, to increase the period by 23 microseconds. The entry in the configuration file
would be:
CountsPerSecond=16983
The simulated GPS signal may be measured between pins 4 and 5 of the connector labeled J2(TX) on the Interface
Box. The LAAS Host Simulator program must be running, the Counter I/O ISA Card cable must be connected, and the
Interface Box must be powered to make this measurement.
4.5 Explanation of Collecting Block Failure Rate Statistics to a File Command
The
bfr
command allows a second command line argument which is used to log the test results to a file.
When used, the following statistics are written to the file (in the order displayed):
a. Received Counter
b. Missed Burst
c. Total Missed Bursts
d. CRC Status (0 – CRC is valid, 1 – CRC is invalid)
e. Total Messages with CRC error
f. FEC Status (0 – FEC was not used, 1 – FEC was used)
g. Signal Strength (dBm)
To access this option enter the following command:
bfr value filename
where
value is the size of the message (ex. 222)
filename is the name of the file to which the statistics are written (ex. test)
filename
has the following constraints:
a. the file is written to the directory where the LAAS Host Simulator is executing
b. the file extension of bfr is added to the entered filename
c. the file name is limited to 8 characters, if more than 8 characters are entered, the entered file name is
truncated to 8 characters
d. if file name entered is identical to a file already in the directory, then the existing file is overwritten.
To close this file (this also stops the BFR test) enter the following command: