The MX375 is a CMOS LSI microcircuit which combines CTCSS Encode/Decode operation with voice band frequency
inversion. Frequency inversion is achieved by modulating the input audio with a 3333 Hz carrier frequency. Higher voice
band frequencies are translated downward, and lower frequencies upward, resulting in a 鈥渕irror image鈥?voice
transmission.
PvtSQUELCH鈩?/div>
combines CTCSS with inverted speech to prevent users from understanding each other鈥檚
communications unless the transmissions are accompanied by the group鈥檚 assigned tone. Its net effect is to eliminate
casual eavesdropping and give mobile radio users a certain degree of privacy at a minimal price. Up to 38
PvtSQUELCH
user groups (one per CTCSS tone) can share a single radio channel. With
PvtSQUELCH,
competing businesses can
share a radio channel without compromising communications security.
Device features: 1) serial or parallel tone programming capability (serial or parallel offered on MX375J, P & LH8), 2) the
ability to operate under NOTONE conditions, 3) on-chip Tx and Rx audio filtering, 4) pin-selectable Private/Clear
operation, and 5) pre/deemphasis filters in the Tx path, for optimal recovered audio quality.
A low-cost 4 MHz crystal/clock and a single 5V supply are required for operation. The MX375 is available in the following
package styles: 28-pin PDIP (MX375P), 28-pin CDIP (MX375J) 28-pin PLCC (MX375LH8), and
24-pin PLCC (MX375LH).
漏 1997 MX鈥OM Inc.
www.mxcom.com Tele: 800 638-5577 910 744-5050
Fax: 910 744-5054
Doc. # 20480026.007
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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