MX COM Inc MX014P, MX014J Datasheet
DATA BULLETIN
MX014
Voice Band inverter
Features Applications
•
CTCSS Compatible
•
Fixed Frequency Inversion
•
Low Power CMOS
TX Audio Feedback
TX Audio In
BIAS
RX Audio In
RX Audio Feedback
Rx Path
RX Path
6dB/Octave
Pre-emphasis
10dB Gain
Bandpass
Filter
300-3033 Hz
Filsav1
Filter
BALMOD
Carrier
•
Land Mobile Radio Systems
•
Community Repeaters
PathInv ert
Bandpass
Filter
300-3033 Hz
BPF Out
6dB/Octave
De-emphasis
Filsav1
Filsav2
DEEMP Out
TX
TX BufferIn
RX BufferIn
BIAS
RX Path
TX Audio Out
TX
RX Audio Out
Clock
Clock
PTT
PTT
RX Audio Enable
RX Audio Enable
PTL
PTL
Privacy Enable
3333 Hz
LOGIC
Carrier
Filsav1
Filsav2
RX Path
EMPSAV
TX
PathInv ert
CLK
3333 Hz
CLK Generator
V
DD
V
SS
BIAS
The MX014 Voice Band Inverter gives the security of private voice communications to land mobile radio users, as well as
to the users of other shared radio channel systems. Designed for use in half-duplex systems, the MX014 exchanges high
and low frequencies in the voiceband and renders transmitted messages unintelligible. This privacy function is achieved
by a single frequency inversion. When used with CTCSS,
SQUELCH
Pvt
TM
privacy adapter operation is achieved.
Sharp cut-off in the internal voiceband filters permits operation with CTCSS and similar sub-audio signaling schemes. This
results in high quality recovered audio.
The core of the MX014 consists of two audio band pass filters and a balanced modulator. The device uses a
programmable clock divider which controls the carrier and filter cut-off frequencies. Control of the RX/TX, PTL and
privacy function is by pin selection.
The MX014 operates from a single 5V supply and uses a 4 MHz crystal oscillator to ensure the correct pitch in recovered
speech. Signal coupling and decoupling are the only external components needed. The device is available in 24-pin
PLCC (MX014LH), 24-pin PDIP (MX014P) and 24-pin CDIP (MX014J) packages.
1997 MX•COM, INC. www.mxcom.com Tele: 800 638 5577 910 744 5050 Fax: 910 744 5054 Doc. # 20480013.006
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by there respective companies.
Voice Band Inverter 2 MX014
CONTENTS
Section Page
1. Block Diagram.................................................................................................................................. 3
2. Signal List......................................................................................................................................... 4
3. External Components...................................................................................................................... 5
4. Application ....................................................................................................................................... 6
5. Performance Specification.............................................................................................................. 8
5.1 Electrical Performance.............................................................................................................................. 8
5.1.1 Absolute Maximum Ratings...............................................................................................................................8
5.1.2 Operating Limits.................................................................................................................................................8
5.1.3 Operating Characteristics ..................................................................................................................................8
5.2 Packaging ................................................................................................................................................ 10
MX•COM, Inc. reserves the right to change specifications at any time and without notice.
1997 MX•COM, INC. www.mxcom.com Tele: 800 638 5577 910 744 5050 Fax: 910 744 5054 Doc. # 20480013.006
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by there respective companies.
Voice Band Inverter 3 MX014
1. Block Diagram
TX Audio Feedback
TX Audio In
BIAS
RX Audio In
RX Audio Feedback
RX Audio Enable
RX Audio Enable
Privacy Enable
Rx Path
PTT
PTT
PTL
PTL
RX Path
3333 Hz
6dB/Octave
Pre-emphasis
10dB Gain
LOGIC
Bandpass
Filter
300-3033 Hz
Filsav 1
Carrier
Filsav 1
Filsav 2
RX Path
EMPSAV
TX
Path Invert
Filter
BALMOD
Carrier
Path Invert
Bandpass
Filter
300-3033 Hz
Filsav 2
CLK
3333 Hz
BPF Out
6dB/Octave
De-emphasis
Filsav 1
CLK Generator
TX
DEEMP Out
TX Buffer In
RX Buffer In
BIAS
RX Path
TX
V
DD
V
SS
BIAS
TX Audio Out
RX Audio Out
Clock
Clock
Figure 1: Device Block Diagram
1997 MX•COM, INC. www.mxcom.com Tele: 800 638 5577 910 744 5050 Fax: 910 744 5054 Doc. # 20480013.006
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by there respective companies.
Voice Band Inverter 4 MX014
2. Signal List
Pin No. Name Description
1 XTAL An external 4MHz clock can be applied to this input. The clock circuit on chip has a resistor
and capacitors so that only one external crystal is required.
2
XTAL
3PTT
4
PTT
5PTL
6
PTL
7 RXAUDEN
8
RXAUDEN
9 PRIVEN Privacy Enable controls the input action of the balanced modulator by switching the carrier
10 RXOUT This is the receive audio output pin. It is biased at VDD/2 when in the TX mode.
11 TXOUT This is the “send” voice output pin. It is biased at VDD/2 when in RX mode.
12 V
SS
13 BPFOUT For a gain of one in the RX Output stage, these two pins are wire linked together. However,
14 RXBIN
15 DEMPOUT The pre-emphasis circuit has a 10dB gain at 1 kHz. Additional gain, or attenuation can
16 TXBIN
17 BIAS This is the internally generated VDD/2 decoupling pin.
18 FILTR This filter is the output of the Input Audio BPF and must be a.c. coupled into the Balanced
19 BALMOD This is the input to the balanced modulator. It must be a.c. coupled to the Filter Output.
20 RXIN This is a negative input of an op-amp at the input of the RX path. It can be used, along with
21 RXFB RX Audio Feedback is the output of an op-amp at the input of the RX path. See RXIN.
22 TXIN The negative input of an op-amp at the input of the TX path. It can be used, along with TX
23 TXFB TX Audio Feedback is the output of an op-amp at the input of the TX path. See TXIN.
24 V
DD
This is the inverted 4MHz clock output for use when a crystal oscillator is used, or as a buffer
for driving other clocked devices.
Push To Talk is an input with a 3MΩ pull-down resistor.
This is the inverted PTT output. It has a 100kΩ output impedance.
Push To Listen is an input with a 3MΩ pull-down resistor.
Push To Listen
is the inverted output of PTL; it has a 100kΩ output impedance.
RX Audio Enable is an input with a 3MΩ pull-down resistor.
RX Audio Enable
is the inverted output of RX Audio Enable; it has a 100kΩ output impedance.
clock. When audio signals are inverted, the signal path gain is adjusted automatically to
compensate for the upper sideband loss. It contains a 3MΩ pull-down resistor.
The negative supply pin (ground).
if gain is introduced at the RX input, attenuation may be introduced at the RX Output using
these pins and two resistors.
be introduced as in the RX path.
Modulator Input through a 0.1µF capacitor.
RX Audio Feedback and two external resistors, to increase the signal to its optimum level prior
to frequency inversion/filtering. This may improve the S/N.
Audio Feedback and two external resistors, to increase the signal to its optimum level prior to
frequency inversion/filtering. This may improve S/N.
The positive supply pin.
Table 1: Signal List
1997 MX•COM, INC. www.mxcom.com Tele: 800 638 5577 910 744 5050 Fax: 910 744 5054 Doc. # 20480013.006
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by there respective companies.
Loading...