Motorola pro7100 Manuel de service télécharger pdf (Page 26)

2-12 Theory of Operation

2.3.4.2 High Speed Data

High speed data refers to the 3600 baud data waveforms, known as inbound signalling words (ISWs)

used in a trunking system for high speed communication between the central controller and the

radio. To generate an ISW, the µP first programs the ASFIC CMP (U0221) to the proper filter and

gain settings. It then begins strobing U0221-19 (HSIO) with a pulse when the data is supposed to

change states. U0221’s 5-3-2 state encoder, which is in a 2-state mode, is then fed to the post-limiter

summer block and then the splatter filter. From that point, it is routed through the modulation

attenuators and then out of the ASFIC CMP to the RF board. MPT 1327 and MDC are generated in

much the same way as trunking ISW. However, in some cases these signals may also pass through

a data pre-emphasis block in the ASFIC CMP. Also these signalling schemes are based on sending

a combination of 1200 Hz and 1800 Hz tones only. Microphone audio is muted during high speed

data signalling.

2.3.4.3 Dual Tone Multiple Frequency (DTMF) Data

DTMF data is a dual tone waveform used during phone interconnect operation. It is the same type of

tones which are heard when using a "Touch Tone" telephone.

There are seven frequencies, with four in the low group (697, 770, 852, 941Hz) and three in the high

group (1209, 1336, 1477Hz).

The high-group tone is generated by the µP (U0101-44) strobing U0221-19 at six times the tone

frequency for tones less than 1440Hz or twice the frequency for tones greater than 1440Hz. The low

group tone is generated by the ASFIC CMP, controlled by the µP via SPI bus. Inside U0221 the low-

group and high-group tones are summed (with the amplitude of the high group tone being

approximately 2 dB greater than that of the low group tone) and then pre-emphasized before being

routed to the summer and splatter filter. The DTMF waveform then follows the same path as

described for high-speed data

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Motorola pro7100 Manuel de service Page 26