NSAM265SF datasheet(9/58 Pages) NSC

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10 Theory of Operation (Continued)

Other Detectors

Detection of busy and dial tones and no-energy is con-

trolled by tunable parameters You should tune the thresh-

olds of these parameters to fit your hardware For more

information see the TUNE command in Section 32

Dial and busy tone detectors work with a band pass filter

that limits the frequency range in which tones can be detect-

ed to 0 Hz – 1100 Hz Its frequency response is illustrated in

Figure 1-1 and the busy tone cadences in Figure 1-2

Tone Generation

The CompactSPEECH can generate DTMF tones and sin-

gle-frequency tones from 300 Hz to 2000 Hz in increments

of 100 Hz CompactSPEECH tone generation conforms with

EIA-470-RS standard Note however that you may have to

change the value of some tunable parameters in order to

meet the standard specifications since the energy level of

generated tones depends on the analogue circuits being

used

Tune the DTMF TWIST LEVEL parameter to control

the twist level of the generated DTMF tones

Use the VC command and tune the TONE GENERA-

TION

LEVEL parameter to control the energy level at

which these tones are generated

Use the GT command to specify the DTMF tones and the

frequency at which single tones are generated

19 SPEECH SYNTHESIS

Speech synthesis enables you to announce prerecorded

voice prompts or form a sentence by combining individual

words A built-in is supplied with the CompactSPEECH for

announcing the number of messages and the time and day

The main speech synthesis features are

On-chip English vocabulary for announcing the number

of messages and the time and day

Additional

vocabularies

ROM

FLASH

(NSAM265SF only)

International Vocabulary Support (IVS) without changing

the microcontroller code

Up to 220 words in each vocabulary Each word can be

announced separately

Sentences announced from a predefined table of sen-

tences

On-the-fly sentence announcement

191 Explanation of Terms

The following terms are used throughout this document

Vocabulary

A complete set of

words and sen-

tences Words are arranged in a word

table Sentences are arranged in a

sentence table

Word Table

A set of

words arranged in a table

as part of a

vocabulary

Sentence Table

A set of

sentences arranged in a ta-

ble as part of a

vocabulary

The

structure of a

sentence table is de-

scribed in detail in the

International

Vocabulary Support User’s Manual

The Internal Vocabulary includes a

built-in table with two entries

Word

An entry in a

word table which repre-

sents a spoken word or phrase A

word is played with the SW (Say

Words) or SO (Say One word) com-

mands

Sentence

A series of

words synthesized from a

vocabulary A sentence is defined as

an entry in the

sentence table and is

synthesized with the SS (Say Sen-

tence) or SAS (Say Argumented Sen-

tence) command or is synthesized

‘‘on-the-fly’’ with the SW command

Internal Vocabulary

The

vocabulary in English which re-

sides on the CompactSPEECH’s in-

ternal ROM

External Vocabulary

An optional

vocabulary which resides

on external ROM or (NSAM265SF

only) FLASH

International

A method that enables the same

CompactSPEECH command to syn-

Vocabulary

thesize

sentences with the same

Support (IVS)

meaning but in different languages

from separate

external vocabularies

TLEE12378 – 3

FIGURE 1-1 Busy and Dial Tone Band Pass Filter Frequency Response

TLEE12378 – 47

E1 b E3 k 90 ms

S1 b S3 k 90 ms

100 k Ei k 1700 ms

50 k Si k 1300 ms

FIGURE 1-2 Busy Tone DetectorCadence Specification

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