In this segment we format a digital telecellsmartphone answering machine. The device will keep messages in digital form in area of on an analog tape. To make life extra interesting, we use a smooth set of suggestions to compress the voice data definitely so we`re capable of make extra inexperienced use of the restrained amount of available memory. 
1 Theory of Operation and Requirements 
In addition to analyzing the compression set of suggestions, we moreover need to analyze a hint about the operation of telecellsmartphone systems. 
The compression scheme we`re able to use is called adaptive differential pulse code modulation (ADPCM). Despite the prolonged name, the approach is mainly smooth but can yield2 compression ratios on voice data. 
2 Specification 
shows the splendor diagram for the answering machine. In addition to the schooling that perform the number one functions, we moreover use schooling to provide an reason of the incoming and OGMs. As seen below, the ones schooling are related. The buttons and lights definitely provide attributes for their input and out located values. The telecellsmartphone line, microphone, and speaker are given behaviors that permit us to sample their modern-day values. The message schooling are defined in Figure 6.23. Since incoming and OGM types percent many characteristics, we derive every from a extra vital message type. The number one operational schooling—Controls, Record, and Playback. The Controls splendor offers an operate () behavior that over sees the purchaser-diploma operations. The Record and Playback schooling provide behaviors that address writing and analyzing sample sequences. The the usa diagram for the Controls activate behavior is confirmed. Most of the purchaser sports activities sports sports activities sports activities sports sports activities sports sports activities sports activities sports sports activities sports activities sports sports activities sports sports activities sports activities sports sports activities sports sports activities are mainly proper now forward. The most complex is an- swering an incoming call. As with the software program application software program application software program software program application software program application software program application software program application mode mof Section5.11, we want to make certain that a single depression of a button motives the famous motion to be taken exactly once; this requires element detection on the button signal. State diagrams for record-msg and play back-msg are confirmed in Figure 6.26.We have parameterized the specification for record-msg definitely so it may be used each from the telecellsmartphone line or from the microphone. This requires parameterizing the deliver itself and the termination condition.