HP 8920A - Interpreting Decoded Data

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S:\HP892XX\USRGUIDE\manual\decoscrn.fb
Chapter 8, Signaling Decoder Screen
Using the AMPS/TACS, NAMPS/NTACS Decoder
Interpreting Decoded Data
The following information refers to all Reverse Control Channel (RECC)
measurements, and the AMPS-TACS Reverse Voice Channel (RVC)
measurements. See the next section for information about NAMPS-NTACS RVC
measurements.
After being armed, the measurement begins when the last bit of Word Sync has
been received. All RECC measurements, and the AMPS-TACS RVC
measurement, last for the period specified in the
Gate Time field.
The received bits are displayed as hexadecimal (hex) characters. If the last bits
received do not complete the last hex character, the received bits are used as the
most significant bits in the character, and the remaining bit positions are filled
with zeros.
For example; if the last bits received are “01”, two zeros are added to the right to
produce the binary number 0100. The hexadecimal equivalent, 4, is displayed.
The first two hex characters of the RECC data displayed contain the 7-bit Digital
Color Code of the Seizure Precursor. The characters are right-justified so the
farthest bit to the left for the first hex character is always 0. The first word of the
RECC message begins in the third hex character of the displayed data.
All bits of the RECC and RVC data streams received after the initial Word Sync
are displayed, including Parity and additional Dotting and Word Sync sequences.
The decoder does not check for any errors in the received data stream.