Download SiRFstarIIeLP Evaluation Kit User's Guide

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Table 3-52 Detailed Description of Test Mode 1 Data
Name
Message ID
SV ID
Period
Bit Sync Time
Bit Count
Description
Message I.D. number.
The number of the satellite being tracked.
The total duration of time (in seconds) that the satellite is tracked.
The time it takes for channel 0 to achieve the status of 37.
The total number of data bits that the receiver is able to demodulate during
the test period. As an example, for a 20 second test period, the total number
of bits that can be demodulated by the receiver is 12000 (50BPS x 20sec x 12
channels).
Poor Status
This value is derived from phase accumulation time. Phase accumulation is
the amount of time a receiver maintains phase lock. Every 100msec of loss of
phase lock equates to 1 poor status count. As an example, the total number of
status counts for a 60 second period is 7200 (12 channels x 60 sec x 10 / sec).
Good Status
This value is derived from phase accumulation time. Phase accumulation is
the amount of time a receiver maintains phase lock. Every 100msec of phase
lock equates to 1 good status count.
Parity Error Count The number of word parity errors. This occurs when the parity of the
transmitted word does not match the receiver’s computed parity.
Lost VCO Count The number of 1 msec VCO lost lock was detected. This occurs when the
PLL in the RFIC loses lock. A significant jump in crystal frequency and/or
phase causes a VCO lost lock.
Differential Corrections - Message ID 17
Message ID 17 provides the RTCM data received from a DGPS source. The data is
sent as a SiRF Binary message and is based on the RTCM SC-104 format. To interpret
the data, see RTCM Recommended Standards for Differential GNSS by the Radio
Technical Commission for Maritime Services. Data length and message output rate
will vary based on received data.
Table 3-53 RTCM message
Name
Bytes
Message ID
1
Data length
2
1
Data
variable
Payload length: variable
Example (Hex)
11
002D
Example (Decimal)
17
45
1. Data length and message output rate will vary based on received data.
OkToSend - Message ID 18
Output Rate: Two messages per power-saving cycle
Example:
A0A20002—Start Sequence and Payload Length
1200—Payload
Output Messages
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