MX465DS データシートの表示（PDF） - CML Microcircuits
部品番号
コンポーネント説明
メーカー
MX465DS Datasheet PDF : 17 Pages
| |||
Low Voltage CTCSS Encoder/Decoder
7
MX465
4 General Description
4.1 Description
Voice on shared radio channels are multiplexed with a subaudible CTCSS (Continuous Tone Controlled
Subaudible Squelch) tone as a means of directing messages among user groups sharing the same RF
frequencies. CTCSS modulates the transmitter with a discrete tone, from 39 standard CTCSS tones in the
range (67.0Hz to 250.0Hz) according to TIA/EIA-603. There are an additional eight CTCSS tones not
specified in TIA/EIA-603 that the MX465 will encode and decode. They are : 159.8Hz, 183.5Hz, 189.9Hz,
196.6Hz, 199.5Hz, 206.5Hz, 229.1Hz, and 254.1Hz, for a total of 47 CTCSS tones plus Notone.
The MX465 also incorporates TX/RX on chip speech filters. In early CTCSS designs, TX speech was not
filtered from the CTCSS tone, rather the filtering was dependent upon the host transmitter’s pre-emphasis
network. At only 6dB/octave, the attenuation of speech components at higher CTCSS tones was only a few
dB which resulted in talk-off (low frequency voice components unsquelching the receiver audio).
4.2 I/O Conditions
D0-D5
Input Pins Condition
RX / TX
PTL
Decode Comparator In
Output Pins Condition
RX TONE DETECT
RX TONE DECODE
Result / Function
Tone Transmitter Enabled
TX Audio Path Enabled
Tone Decode Enabled
RX Audio Path Enabled
Notes
Tone
0
0
X
0
1
Yes
Yes
No
No (Bias)
1
No Tone
0
X
X
0
1
No (Bias)
Yes
No
No (Bias)
2
Tone
1
0
0
0
1
No (Bias)
No
Yes
No (Bias)
3
Tone
1
1
0
0
1
No (Bias)
No
Yes
Yes
4
Tone
1
X
1
1
0
No (Bias)
No
Yes
Yes
5
No Tone
1
X
X
X
0
No (Bias)
No
Yes
Yes
6
Notes:
1. Normal tone transmit condition.
2. Notone programmed in TX mode, tone transmit output set to VDD/2. TX audio path enabled.
3. Normal decode standby.
4. Normal decode standby with PTL used to enable audio.
5. Normal decode of correct CTCSS tone condition, PTL has no effect.
6. Notone programmed in RX mode, tone transmit output (Bias). RX audio path enabled.
7. X = don’t care
Table 3: Combinations of Input / Output conditions
©1998 MX•COM, INC.
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. #20480143.008
4800 Bethania Station Road, winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
Share Link: 