Agilent Technologies 8935 series e6380a AMPS-TACS, NAMPS-NTACS Decoder, Interpreting Decoded Data

Signaling Encoder and Decoder - Screens and Control Fields

AMPS-TACS, NAMPS-NTACS Encoder and Decoder

AMPS-TACS, NAMPS-NTACS Decoder

The AMPS-TACS, NAMPS-NTACS decoder acts like a base station receiver by analyzing Reverse Control Channel (RECC) and Reverse Voice Channel (RVC) message streams for various cellular telephone formats.

The decoder can also be used to analyze Forward Control Channel (FOCC) and Forward Voice Channel (FVC) data from the base station.

Decoder Mode Differences

The AMPS-TACS and NAMPS-NTACS decoder modes are essentially the same for analyzing reverse control channel (RECC) information. However, the voice channel (RVC) information for NAMPS-NTACS is displayed differently than AMPS-TACS information. Fields and decoder measurements that are only used for either mode are noted in their descriptions.

Interpreting Decoded Data

RECC and AMPS-TACS RVC Measurements

See “NAMPS-NTACS Reverse Voice Channel Measurements” on page 256 for information about NAMPS-NTACS RVC measurements.

After being armed, the measurement begins when the last bit of Word Sync has been received. The Gate Time field specifies the measurement period for all RECC measurements and the AMPS-TACS RVC measurement.

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.

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