MX828DW 查看數據表（PDF） - MX-COM Inc
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MX828DW Datasheet PDF : 34 Pages
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CTCSS/DCS/SelCall Processor
5. Application
20
MX828 PRELIMINARY INFORMATION
5.1 General
The MX828 is intended for use in radio systems where signaling is required for functions such as trunking, control,
selective calling or group calling.
The CTCSS fast/predictive detector is useful for the detection of occupied channels indicating either the presence of any
sub-audio tone, or range of tones, depending if it is set in fast detect or predictive mode. This will increase the efficiency
of scanning and trunking systems, reducing the average time allocated to assessing each channel.
The facility to decode any of up to 15 programmed tones allows the use of tones for various signaling functions such as
masking a free channel or identifying sub groups within a user's groups.
Adjustable decoder bandwidths permit certainty and signal to noise performance to be traded when congestion or range
limits the system performance.
5.2 Transmitters
5.2.1 CTCSS
The CTCSS transmitter is enabled with Bit 7 in the SIGNALING CONTROL Register ($80) and bit 1 in the SIGNALING
SET UP Register ($82).
The Tx frequency is set using Bit 0 to Bit 12 in the CTCSS TX/FAST RX FREQUENCY Register ($83) using the formula
below:
A = fXTAL (Hz)
16 x fTONE (Hz)
where A is the binary number programmed into the 13 bits.
When Bit 7 (in the first 8 bits) is set to "1" the tone output is set at VBIAS or NOTONE without regard to the number "A"
programmed. When Bit 7 is "0" the programmed tone is set on the output. Programming the bits 0 to 12 to "0" puts the Tx
into powersave and the output goes to VBIAS. Powersave is also achieved by disabling the SUBAUDIO Tx and the CTCSS
FAST DETECT (Bits 7 and 5 in the SIGNALING CONTROL Register $80).
5.2.2 The SelCall transmitter
The SelCall transmitter is enabled with Bit 2 in the SIGNALING CONTROL Register ($80).
The Tx frequency is set using Bit 0 to Bit 12 in the SELCALL TX Register ($8D) using the formula below:
A = fXTAL (Hz)
4 x fTONE (Hz)
where A is the binary number programmed into the 13 bits.
When Bit 7 (in the first 8 bits) is set to "1" the tone output is set at VBIAS or NOTONE without regard to the number "A"
programmed. When Bit 7 is "0" the programmed tone is set on the output. Programming the bits 0 to 12 to "0" puts the
SelCall Tx into powersave and the output goes to VBIAS. Powersave is also achieved by disabling the SELCALL TX
ENABLE (Bit 2 in the SIGNALING CONTROL Register $80).
5.2.3 DCS Transmitter
The DCS transmitter is enabled with Bit 7 in the SIGNALING CONTROL Register ($80) and bit 1 in the SIGNALING SET
UP Register ($82).
The Tx data is set in the DCS BYTE 3, DCS BYTE 2 and DCS BYTE 1 Registers ($85, $86 and $87).
Note: The DCS transmitter produces an inverted output. When the signal is fed through the summing amp, in an inverted
configuration, the correct polarity of the DCS signal will be restored (The MOD1 and MOD2 amplifier blocks do not invert).
© 1997 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050 Fax: 336 744-5054
Doc. # 20480161.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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