ATS 1225 User manual

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MODEL 1225 TRANSCEIVER
TECHNICAL MANUAL
produced by:
APPLIED TECHNOLOGY SOLUTIONS, INC.
4200-F Technology Court
Chantilly, VA 20151
This manual contains information proprietary to Applied Technology Solutions, Inc. and may not be re-produced
without expressed permission.

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Document: FCC1225manual.wpd issued: jan99 revised: July 27, 1999 page: ii
MODEL 1225 TRANSCEIVER
TECHNICAL MANUAL
produced by:
APPLIED TECHNOLOGY SOLUTIONS, INC.
4200-F Technology Court
Chantilly, VA 20151

APPLIED TECHNOLOGY SOLUTIONS, INC.
Document: FCC1225manual.wpd issued: jan99 revised: July 27, 1999 page: iii
TABLE OF CONTENTS
SECTION TITLE PAGE
ONE INTRODUCTION...................................................................................................................................1
1.0 GENERAL...............................................................................................................................................1
1.1 SPECIFICATIONS..................................................................................................................................1
1.2 CONTROLS, INDICATORS, USER I/O...............................................................................................3
TWO OPERATION...........................................................................................................................................4
2.0 GENERAL...............................................................................................................................................4
2.1 ATS 1200 SYSTEM COMPONENTS...................................................................................................4
2.2 MODEL 1225 OPERATION..................................................................................................................4
2.2.1 Safety Considerations................................................................................................................4
2.3 EARPIECE/MICROPHONE ASSEMBLY............................................................................................5
2.4 BATTERY...............................................................................................................................................5
2.5 ANTENNA..............................................................................................................................................5
2.6 PRIVACY CODES..................................................................................................................................5
THREE THEORY OF OPERATION...................................................................................................................6
3.0 GENERAL...............................................................................................................................................6
3.1 FUNCTIONAL DESCRIPTION.............................................................................................................6
3.1.1 Audio/Digital Section................................................................................................................6
3.1.2 RF/IF Section ............................................................................................................................7
3.2 RF CHARACTERISTICS.......................................................................................................................8
FOUR MAINTENANCE....................................................................................................................................9

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4.0 TROUBLESHOOTING ..........................................................................................................................9
4.1 MAINTENANCE....................................................................................................................................9
4.2 REPAIRS .................................................................................................................................................9

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SECTION ONE
INTRODUCTION
1.0 GENERAL
This document is the Operating Manual for the Model 1225 Hand Held Transceiver produced by Applied
Technology Solutions, Inc. The Model 1225 is one component of the Voice Privacy Low Probability of Detection (VPLPD)
System 1200. Other System 1200 components include the Model 1245 Monitor System and the Series 1250 Transmitters.
The System 1200 uses spread spectrum modulation to provide secure, low probability of detection and
interception communications to the user. The transmitted voice data is scrambled with a user selected key, to provide voice
privacy and an additional level of security. The System 1200 employs an ATS proprietary self-synchronizing design. This
design provides nearly instantaneous receiver synchronization and provides improved performance over other spread
spectrum designs in a rapid fade, multi-path environment.
The Model 1225 Hand Held Transceivers can be used for direct communications with other System 1200
devices.
1.1 SPECIFICATIONS
The specifications for the Model 1225 Transceiver follow. Unless otherwise noted all specifications are
at 25oC with full capacity batteries.

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RF CHARACTERISTICS
RF Channels: 2, Crystal Controlled
Normal Mode: Transmit/Receive Channel A
or B
Repeater Mode: Transmit Channel A, Receive
on Channel B
Transmit
Power Output: 900 mW
Emissions
Spurious: -55 dBc
Out Of Band: -20 dBc
Freq. Stability: +100 ppm -25oC to +68oC
Receive
Sensitivity: -95 dBm
Selectivity
Adjacent Channel: -65 dB
Spurious & Image: -85 dB
Antenna System
Antenna: ½ Wavelength, flexible
RF Output
Compatibility: 50 Ω
AUDIO CHARACTERISTICS
Frequency Response: +6 dB, 300 - 5800 Hz
Microphone: Internal or external
Mic Audio Processing: Dual Time Constant AGC
Dynamic Range: 55 dB, Minimum
Speaker: Internal or Remote
Rated Audio Output: 400mW into 16 Ω(less than
5% distortion)
Remote Speaker/Mic: Model 1230-04
VOICE DATA SCRAMBLING
Type: Synchronous Key Stream
Key Generation: External, Hand Held, Model
1260 Key Loader
Key Storage: Internal, non-volatile memory
Number of Keys: Two sets, Private and
Common
USER CONTROLS
On-Off/Volume
Channel (Mode) Select
Code Select
PTT
INDICATORS
Power/Battery Low
Transmit
POWER REQUIREMENTS
Battery Pack: 1200 mAh, Nickel Cadmium,
rechargeable (1800 mAh
available)
TEMPERATURE
Operating: -25oC to +68oC
Storage: -40oC to +85oC
PHYSICAL DIMENSIONS
Less Battery: 6.25" x 2.75" x 1.50"
(HxWxD), 1lbs.
With 1200 mAh
battery: 8.625" x 2.75" x 1.5"
(HxWxD), 1lbs.

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1.2 CONTROLS, INDICATORS, USER I/O
This section describes the user interfaces and indicators provided by the Model 1225 Hand Held
Transceiver.
USER CONTROLS
VOLUME Dual function rotary switch. It is the power on/off switch plus volume control
CHAN The channels are A, B and R where R refers to repeater operation.
CODE A two position switch allowing selection of either the common (C) or private (P) code.
PTT A momentary push button switch that places the Model 1225 in the transmit mode.
STATUS INDICATORS
PWR Green, multi-function LED. Steady illumination indicates that power is on and battery condition
is normal. Blinking LED indicates that the battery voltage is low and approximately 180
minutes of receive or 15 minutes of transmit operation remain from the time the light starts
blinking.
TX Red LED, when illuminated, indicates that unit is in transmit mode.
USER CONNECTIONS
Key Loader A rear panel connector accessed by sliding the door. Connecting the Model 1260 Key Loader
to this port, privacy codes can be downloaded from the loading device to the Model 1225 where
they are stored in non-volatile memory. Operating power for the Model 1260 is supplied from
this connector.
Mic Side panel, 4 pin microphone connector. Accepts the standard Model 1230-04 Surveillance
Micphone/Earpiece Assembly.
CONNECTOR SPECIFICATIONS
Microphone: Hirose HR10A-7P-4P
Antenna: SMA Female to mate with special panel mount connector
NOTE: only the ATS provided antenna should be used with the Model 1225
Key Loader: ATS Model 1230-03 Adapter Cable

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SECTION TWO
OPERATION
2.0 GENERAL
The ATS Model 1225 Hand Held Transceiver is one of the System 1200 devices. The System 1200
devices were designed to provide secure communications to law enforcement agencies. This section describes the operation
of the Model 1225 with the other units in the System 1200 family.
2.1 ATS 1200 SYSTEM COMPONENTS
The ATS System 1200 includes the Model 1245 monitor Station and the Series 1250 Transmitters.
2.2 MODEL 1225 OPERATION
Before operating the Model 1225, the user should read Section 1.2 of this manual, where the user controls
and interfaces are described.
The ATS System 1200 was designed to support two primary operating scenarios. The first scenario is
direct transceiver-to-transceiver communications. In this scenario, communications occur between individual transceivers,
using either Channel A or Channel B. The second scenario requires the use of a repeater to extend the operating range. In
the Repeater Mode, system components transmit on Channel A (or Channel C) and receive on Channel B. The Model 1240
Portable Repeater was designed primarily to support the second scenario but it also provides for direct communications
capability.
To communicate with other units in the direct transceiver-to-transceiver mode, all units must be set to the
same channel, either Channel A or B, set to the same code, either C or P and have the same keys loaded. In the repeater (R)
mode, the Model 1240 Portable Repeater receives transmissions on Channel A and re-transmits them on Channel B. To
use the repeater, the Model 1225 CHAN select must be set to R.
A fully charged battery pack should be installed onto the Model 1225 Hand Held Transceiver prior to
each deployment. To operate the Model 1225, place the CHAN switch to the desired position, A, B, or R (repeater), select
either the common (C) or private (P) code with the CODE switch and turn the unit on by rotating the VOLUME control from
the OFF position.
NOTE
For non-repeater applications, all system transceivers MUST be set to the same
channel and code. Cross channel or cross code operation is not possible.
During idle periods, the Model 1225 will power down most of the receive circuits.
The Model 1225 Hand Held unit only transmits when the PTT switch is depressed. The integral, side
panel mounted PTT is a momentary switch and must be held down for the duration of the transmit interval. The Model 1225
also includes an integral microphone and speaker. The microphone is sensitive and should be held several inches away from
the mouth when transmitting.
2.2.1 Safety Considerations
The Model 1225, as with all electronic devices, radiates electronic energy and could pose a safety hazard
if used improperly. To minimize any potential radiation hazards, the user should:

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1. Hold the radio so that the antenna is away from the face and body, minimally 2-3", when
transmitting and,
2. Minimize transmit time to approximately 1 ½ minute duration over a 15 minute interval.
2.3 EARPIECE/MICROPHONE ASSEMBLY
Optionally, the Model 1230-04 Surveillance Microphone/Earpiece Assembly can be used with the Model
1225 Hand Held Transceiver. This assembly includes a covert PTT microphone and a covert earpiece that can be hooked
over the ear. The assembly connects to a top panel Hirose connector. The integral microphone and speaker are disabled
with the Surveillance Microphone/Earpiece Assembly connected.
2.4 BATTERY
The Model 1225 Hand Held transceiver operates from a 1200 mAh or an 1800 mAh Nickel Cadmium,
rechargeable battery. The battery slides onto the Model 1225 battery clip assembly located on the bottom of the unit. To
remove the battery, push the retaining clip upwards towards the top of the unit and slide the battery in the direction opposite
the clip. When installing a battery, insure the grooves on the top of the battery are properly aligned with the baseplate. The
battery should slide on easily.
A blinking PWR LED on the Model 1225 indicates low battery conditions. The battery should be
replaced immediately with a fully charged battery. The Model 1225 Hand-Held transceiver will operate for approximately
180 minutes in receive mode or 15 minutes in transmit mode after a battery low condition is indicated. Only critical
transmissions should be made after the battery low condition is indicated.
2.5 ANTENNA
The Model 1225 is provided with a flexible antenna. The antenna is screwed into the top panel mounted
connector and fits within the cup. No other antenna should be used with the Model 1225.
2.6 PRIVACY CODES
Privacy keys are stored in non-volatile memory. The keys are loaded into memory using the Model 1260
Key Loader. If a keyed unit is lost or stolen, the keys in the remaining units can be changed quickly to maintain the overall
security. Code selection is made using the top panel switch. Two codes selections are available, common (C) and private
(P). The C code is factory set on all units and provides a common scrambler code for use during inter-agency operations.
The P code is intended to be agency or group specific. The P code can be changed by the user. In operation, the Model
1225 uses different codes for Channel A and Channel B operation.
To load a P code into the Model 1225, use the Model 1230-03 Adapter Cable to connect the Model 1260
Key Loader to the key loader connector located on the bottom of the Model 1225. The POWER indicator on the Model 1260
should light (providing the Model 1225 is powered on). Select a code by rotating the KEY NUMBER thumb wheel switches
on the Model 1260. (Selecting a code number above 300 will result in an error indication on the Model 1260.) Depress
the LOAD KEY button on the Model 1260 to download the selected key. The KEY LOADED indicator on the Model 1260
should light, indicating that the new keys were successfully loaded into the Model 1225. If the LOAD FAIL indicator lights,
the key load sequence did not succeed.

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SECTION THREE
THEORY OF OPERATION
3.0 GENERAL
The Model 1225 Hand Held Transceiver is a push-to-talk, spread spectrum transceiver. It uses digitized
audio. The digital data stream is scrambled before modulation for security. The combination of spread spectrum modulation
and scrambled, digitized audio give the Model 1225 its low probability of detection and interception characteristics.
3.1 FUNCTIONAL DESCRIPTION
The Model 1225 block diagram can be divided into two sections. The upper half contains the digital and
audio signal processing functions. The lower half contains the IF and RF signal processing functions.
3.1.1 Audio/Digital Section
In the transmit direction, audio can come either from the internal microphone in the Model 1225, or from
an external speaker/microphone. Microphone audio is amplified by the microphone pre-amplifier stage. This stage also
has an audio AGC (Automatic Gain Control) function that produces a constant audio signal level for the CVSD
(Continuously Variable Slope Delta-modulation) encoder. The AGC has an attack time of less than 1ms and a decay time
of 150 ms. A lowpass filter between the pre-amplifier and the encoder limits the audio signal bandwidth to prevent aliasing.
CVSD encoding converts the analog audio into a serial data stream. The bit rate of this data stream is
equal to the CVSD clock signal frequency. Processing of the serial data stream is performed by the FPGA (Field
Programmable Gate Array).
Serial data from the encoder is processed by the scrambler/ de-scrambler in the FPGA. The
scrambler/de-scrambler is a dual purpose block that is switched between transmit and receive modes. In transmit mode, the
encoder data stream is combined with a pseudo-random key stream. The key stream is generated from the scrambler key
that is stored in the key memory. The scrambler key manager monitors the status of the CODE signal. It then reads the
appropriate key from the key memory, and sends it to the scrambler/de-scrambler. The same key is used for both
transmitting and receiving.
Key memory programming access for the Model 1260 Key loader is provided through the key loader input
jack.
Once the data stream from the CVSD encoder is scrambled, it is ready to be spread spectrum modulated.
The PN (Pseudo-Noise) sequence generator produces a long digital sequence, at a clock rate that is much greater than the
signal from the data scrambler. The PN sequence is combined with data scrambler signal by the spread spectrum modulator.
This produces the spread data signal, which, along with the PN sequence, is bi-phase modulated by the clock signal from
the modulator clock generator. Further processing of these signals occurs outside the FPGA.
Two clock generator circuits are included in the FPGA, both being driven from the same crystal oscillator
stage. The data clock generator has three outputs: the PN clock, the scrambler clock and the CVSD clock. The modulator
clock generator has two outputs, one being twice the frequency of the other, driving the bi-phase modulators.
In the receive direction, the FPGA demodulates the BPSK (binary phase shift keyed) signal from the 2nd
IF to recover the scrambled digital data. At the same time, the lock detector determines when a valid system signal is
present, and controls the lock functions. .
The demodulator produces the baseband data signal, which is a scrambled CVSD data stream. The

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descrambler removes the scrambler key stream from the baseband data signal to recover the CVSD RX data signal. This
signal is output from the FPGA to the CVSD decoder. The decoder converts this data stream to an analog audio signal.
The audio output from the CVSD decoder is lowpass filtered to remove high frequency switching
components. The Model 1225 has two audio amplifiers. One drives the internal speaker, while the other is used with the
external speaker/microphone. A common volume control sets the gain of both amplifiers. The power on/off switch is
integrated with the volume control.
All other controls, PTT, CODE, and CHANNEL, interface directly with the FPGA. The voltage monitor
and activity detector also provide inputs to the FPGA. The FPGA generates the channel, code and T/R control signals based
on the status of the front panel controls, and it drives the PWR LED.
The voltage monitor checks the battery voltage and sends a signal to the FPGA if the voltage gets too low.
The FPGA contains logic that will blink the PWR LED indicating low battery voltage.
The activity detector measures the amplitude of the 2nd IF signal. Once a minimum threshold is passed,
it sends a signal to the FPGA. The FPGA responds by taking the data demodulator out of power-down mode. The
demodulator is powered-down during idle periods to conserve battery capacity.
Drive for the TX LED is taken from the switched DC power output from the power control. The power
control switches based on the status of the T/R signal from the FPGA.
3.1.2 RF/IF Section
During transmit, the two biphase modulated signals from the FPGA are individually bandpass filtered,
and then added together, to produce the baseband composite spread spectrum signal. This signal is up-converted at the first
TX mixer. The output from the first TX mixer is bandpass filtered by the IF band split filters. The outputs from these filters
are summed together by the IF combiner to produce the composite IF signal. The IF bandpass filter section is used for both
transmitting and receiving. The signal source for the filters is switched by the IF T/R switch.
The composite IF signal is up-converted to the final transmit frequency by the TX up-converter mixer.
The output of the TX up-converter mixer is bandpass filtered and amplified to drive the RF power amplifier. For economy,
the bandpass filter used here is shared between the transmit and receive signal paths using RF switches controlled by the
T/R signal. The RF switches isolate the transmit and receive signal paths to prevent interference.
The power amplifier is connected to the antenna through the antenna T/R switch. The status of this switch
is controlled by the T/R signal from the FPGA.
Received signals from the antenna go through the antenna T/R switch to the LNA (Low Noise Amplifier).
The output of the LNA is bandpass filtered by the shared channel filter. An RF amplifier stage follows the filter and drives
the RX down-converter mixer. The down-converter mixer output signal frequency is the same as transmit signal frequency.
Additional signal gain is provided by the IF amplifier.
In receive mode, the IF T/R switch connects the output of the IF amp to the IF band split section. Here,
the received spread spectrum signal is separated into its composite parts, the spread data and PN signals. These signals drive
the despreader mixer which produces a BPSK at the 2nd IF frequency. This signal is further amplified and filtered, prior to
going to the FPGA for demodulation.
Receive AGC control for the RF and first IF amplifiers is generated from the composite IF signal by the
AGC generator. The AGC loop maintains a fixed signal level at the despreader output.
Channel switching is accomplished by changing the frequency of the local oscillator that drives the TX
up-converter mixer and the RX down-converter mixer. The output from the local oscillator is shared between the two

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mixers. The state of the CHANNEL logic signal from the FPGA causes the local oscillator to output the appropriate
frequency for either Channel A or Channel B operation.
3.2 RF CHARACTERISTICS
In rural areas, the Model 1225 provides line-of-site communication range with a practical limit of
approximately 3 miles over normal terrain. Suburban communication range is affected by reflections and fading with a 0.5
mile radius being typical. In metropolitan areas, communication ranges are dependent on the site characteristics such as
building density and RF environment. Operating ranges of approximately 1 block radius are practical.

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SECTION FOUR
MAINTENANCE
4.0 TROUBLESHOOTING
When supplied with power, the top panel PWR LED should light. If the PWR LED blinks, the battery
is low and must be replaced or recharged. If the PWR LED does not illuminate at all, verify LED operation by keying the
transmitter and verifying the TX indicator lights. If the TX LED does not illuminate, attach different battery pack and retry.
If the LED still does not illuminate return the unit for repair.
If the unit will not descramble the signal from another unit :
a. Insure that both units are set to the same channel operation.
b. Insure that both units are set to the same code setting.
NOTE:
Both units must be operating with the same code to achieve communications. Field personnel will
not be able to verify the actual codes associated with common or private operation. If necessary,
the issuing office should re-load the codes or return the units to ATS.
c. Verify that the antenna is properly connected to the antenna jack.
d. Return the unit to the factory for repair.
4.1 MAINTENANCE
The Model 1225 is designed for simple installation and use. There are no user maintenance requirements.
4.2 KEY LOADER
If the LOAD FAIL indicator lights, the key load sequence did not succeed. If the this occurs
a. Check the setting of the KEY NUMBER switches to ensure that it is not set above 300,
2. Verify that the interface plug on the Model 1260 cable is fully seated into the KEY LOADER
connector on the Model 1225,
3. Continuing LOAD FAIL indications mean that either the Model 1260 or the Model 1225 is
defective and should be returned for repair. If a Model 1260 is suspected of failure, it should
be tried with another Model 1225. If failures still occur, the Model 1260 is defective.
4.2 REPAIRS
Repairs to the Model 1225 should be performed by an authorized factory representative.

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