Motorola M12 Oncore User's Guide download pdf (Page 41)

Chapter 3 – Receiver Description

Motorola GPS Products - Oncore User’s Guide

Motorola Binary

Format Input/Output

Processing time

INPUT/OUTPUT PROCESSING TIME

The Oncore receiver always operates in position fix mode and the input buffer data is

serviced once a second. When powered on and available satellites are tracked, the

current receiver position is available. If no satellite signals are received, the last

known position is output.

The message response time will be the time from the transmission of the first byte of

input data to the transmission of the last byte of output data. The command

processing time will be skewed since the time will be dependent on when the input

message buffer is processed. For best case processing, the input command would

have to arrive just before the input buffer data is processed, and the output response

would have to be the first (or only) receiver output. For worst case processing, the

input command would have to arrive just after the input buffer data had been

processed, and the output response would have to be the last receiver output.

Assuming 1 ms per transmission of a data byte, assuming 50 ms command

processing, and assuming a uniform distribution for time of input command data

entry, the best case, typical case, and worst case scenarios are shown below.

Best case GMT Offset command:

BC time = shortest command input + command processing +

shortest command output

= 10 ms +50 ms +10 ms

= 70 ms

Typical case:

TC time = input anywhere across one second period + command

processing + output anywhere across one second

period following command processing

= 0.5s+0.05s+0.475s

= 1.025 s

Worst case:

WC time = input beginning of one second period + output end of

one second period

= 1 s+1 s =

= 2 s

Note: The receiver Self-Test command takes 5-10 seconds to complete.

Revision 5.0 08/30/02

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Motorola M12 Oncore User's Guide Page 41