CMX631A データシートの表示（PDF） - MX-COM Inc

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CMX631A

Low Voltage SPM Detector

MX-COM Inc  

Low Voltage SPM Detector

6

CMX631A PRELIMINARY INFORMATION

4 General Description

4.1 Tone Follower Mode

The Tone Follower Output Mode will respond and/or de-respond when a signal is detected or a NOTONE, by

providing a Logic level output. When a signal has been detected, a Logic 0 is provided at the output for the

duration of the valid signal. When a NOTONE or invalid decode is detected a Logic 1 is provided at the

output until a valid signal is available. See Figure 3.

4.2 Packet Mode

The Packet (Cumulative Tone) Mode Output will respond and/or de-respond after a cumulative 40ms of good

tone (or NOTONE) in any 48ms period by providing a Logic level output. See Figure 3.

This process does ignore the small fluctuations or fades of a valid frequency input. During a 40ms toneburst,

no tone interruption (small fluctuation or fade) is allowed during this period for the signal to be considered

valid. If a 45ms toneburst occurs, then a 2ms interruption is allowed, and the signal is still considered valid.

For NOTONE, there must be 40ms of continuous no tone or for a 45ms period, there may be 2ms of tone and

the NOTONE still be valid. For a valid detect of tone the output provides a Logic 0. For the valid detect of

NOTONE, the output provides a Logic 1.

This output is available for µProcessor ‘Wake-Up’, Minimum Tone detection, NOTONE indication, or transient

avoidance.

SIGNAL INPUT

TONE FOLLOWER OUTPUT

PACKET MODE OUTPUT

Response

RESPONSE DELAY

RESPONSE DELAY

SIGNAL INPUT

TONE FOLLOWER OUTPUT

PACKET MODE OUTPUT

De-response

DERESPONSE DELAY

DERESPONSE DELAY

Figure 3: Tone Follower and Packet Mode Outputs

4.3 Sensitivity Setting

The CMX631A input sensitivity can be accurately adjusted and set to support many national 12kHz and

16kHz SPM specifications.

4.3.1 Input Gain Calculation

The input amplifier, with external circuitry, is used to set the sensitivity of the CMX631A to conform to the

user's national level specification with regard to ‘Must’ and ‘Must-Not’ decode signal levels.

With reference to the graphs in Figure 4 and Figure 5, the following steps will assist in the determination of the

required gain/attenuation.

1. Draw two horizontal lines from the Y-axis [Signal Level (dB)] in Figure 4 and Figure 5. The upper line

represents the required ‘Must’ decode level. The lower line represents the required ‘Must-Not’ decode

level

© 1999 MX•COM Inc.

www.mxcom.com Tele: 800 638-5577 336 744-5050 Fax: 336 744-5054

Doc. # 20480177.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

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