Raveon RV-M3-M User manual

Model: RV-M3-M
MURS Radio Modem Module
Version D4
November, 2006
Raveon Technologies Corporation
2780 La Mirada Dr. Suite C
Vista, CA 92081
www.raveontech.com

1 Overview
This RF modem is a low-cost, high-speed, 1/2 watt VHF data modem. It has
outstanding communication range, often e ceeding a mile and in some cases,
will operate 5-10 miles. It outperforms all other radio modules on the market that
utilized unlicensed radio channels. It has such outstanding communication range
for a number of reasons:
1. V F Radio Frequencies 150MHz has 3-10X the transmission efficiency of
other 915 or 2.4GHz frequency radios.
2. ½ watt RF Power ½ watt is +27dBm, 5X the power of most other low-cost
radio modules.
3. Outstanding Receiver The RV-M3 module can reliable receive signals
down to -118dBm. 2-10X more sensitive than other OEM modules.
This all adds up to a radio module that will work reliably over thousands of feet,
and miles of open space. It is perfect for low-power hand-held remotes, remotely
controlled devices, and embedded telemetry applications.
The RV-M3 contains a receiver, a transmitter, base-band circuits, and a
microprocessor. The user interface to it is ASYNC data in and out. Modem
operation is transparent to the user, although the configuration of the modem is
via the user serial port.
This Radio Modem is very easy to use. One byte in the transmitting modem will
cause the same byte to come out of the receiving modem. The sophisticated
over-the-air protocol hides the idiosyncrasies of RF communications from the
user application. Raveon’s MURS radio modem’s 32-bit microprocessor handles
all of the typical radio communication issues such as PLL loading, TX-RX timing,
PA ramping, packetizing data, sending pre-ambles, synchronizing to receive
data, and CRC checking. It can be configured to run at many different baud
rates, both over-the-air, and its user serial port.
A 4-digit 16-bit ID code is set in every modem, along with an address mask. This
allows modems to co-e ist on the same channel, and not interfere with each
other.
2 FCC Issues:
This module is designed to meet FCC parts 15 and 95J (MURS operation). It is
provided as an OEM module, and it is the responsibility of the OEM to obtain
FCC approval of the finished product that incorporates this module.

3 Features
• Built-in radio transceiver with integrated modem
• Small size module Perfect for hand-held OEM devices
• Lowest cost narrow-band radio modem
• 16 bit ID and 16 bit address mask in each modem
• Built-in CRC checking of the data No bad data and no dribble bytes will come out
• 1/2 watts of RF output May be programmed to 100mW for lower-power applications
• Full spec –30 to +60 degrees C
• Easily configured using “AT” commands
• User interface is asynchronous serial data for TX, RX, and configuration
• 3 3V CMOS level inputs and outputs
• Wide DC operating voltage 5-8V DC
• Very low receive and standby current consumption

4 Specifications
4.1 General
All measurements made per TIA-603-B
Size (inches) ....................................................................................................2.11 X 3.40 X 0.6
Vpwr input Voltage .........................................................................................................5-8V DC
Average current draw, unit off......................................................................................... <250uA
Average current draw, normal operation, receiving ......................................................... <60mA
SLEEP mode (SLEEP pin grounded) current draw ......................................................... <25mA
Current draw when transmitting data ....................................................................<0.6A at 1/2W
Power supply ripple and noise limit......................................................................... <50mV RMS
Frequency Stability........................................................................................ better than ±5ppm
Serial Port Baud Rates.......................................... 300, 1200, 2400, 4800, 9600, 19200, 57600
Over-the-air baud rates (programmable) ........................................................ 2400, 4800, 9600
Operating temperature range.............................................................................. -30ºC to +60ºC
Storage temperature range................................................................................. -30ºC to +70ºC
TX-RX and RX-TX turn-around time ................................................................................ <50mS
Power on time to operational ......................................................................................... <500mS
Sleep to ON time.............................................................................................................. <60mS
4.2 Transmitter
RF Power output, 5V DC in.......................................................................... 0.5 watts (+27dBm)
RF Power output, 8V DC in......................................................................... 1.0 watts (+30 dBm)
Ma imum Duty Cycle 5V DC in............................................... 50% over full temperature range
............................................................................................................. 100% below 35ºC (95ºF)
Ma imum Duty Cycle 8V DC in............................................................................................ 50%
Ma imum Transmit frequency deviation ..................................................................... ± 2.25kHz
Occupied bandwidth......................................................................................................... 11 kHz
TX Spurious outputs...................................................................................................... < -70dBc
4.3 Receiver
RX sensitivity (1% BER)
4800bps ........................................................................................................................-113dBm
2400bps ........................................................................................................................-118dBm
RX selectivity...................................................................................................................... -60dB
RX intermodulation rejection........................................................................... -65dB at 2400bps
4.4 User Input and Output Signals
Voltage Levels........................................................................3.3V CMOS, 5-volt tolerant inputs
Modem handshake signals ..................................................................................RTS, CTS, CD
RF I/O......................................................................................................................50 ohm SMA
Power ......................................................................................................... B+ input and Ground

5 User I/O Connector
The User I/O is via a female 16-pin .100” header connector.
The following pins are defined.
Front-view of 16-pin header connector on modem module
in # Name Dir Function 5.1.1.1.1 Level / Specification
1, 2 Power In/out DC power
User may supply the main DC power to the
modem on this pin. 5.0 – 8.0V DC in.
3 /Sleep In Puts modem into SLEEP
mode.
Leave open if unused. Pull low to enter sleep
mode. Internally pulled up to 3.3V.
4 R D In Receive serial data
Data in. 3.3V logic levels.
5 T D Out Transmit serial data
Data out. 3.3V logic levels.
6 RTS In Request to send
Used to stop/start the flow of data coming out
of the modem T D pin. 0 = OK to send, 1 =
don’t send. Connect to GND, pin 9&10 if
unused.
7 CTS Out Clear to send
Used to stop the flow of data coming into the
RXD pin. 0 = OK to send, 1 = don’t send.
Open Drain output, with 10K pull-up to 3.3V.
8 CD Out Carrier detect
If enabled, indicates presence of carrier. 0
means carrier is present. If disabled, it is
asserted (0) whenever the modem is
operational, and not in the configuration
mode. It will be a 1 when the modem is in the
configuration mode.
11 Audio Out Audio output.
For test purposed. Leave open circuit.
9, 10 GND Ground connection
Signal and power ground
12 /config In Puts modem into the
configuration mode.
Leave open circuit if unused. Pull low to put
modem into the configuration mode.
13 ENABLE In On/Off control line.
Leave open or pull > 2V to enable the
modem. Pull low to turn modem power off.
15 IO3 In/Out Special function digital I/O
Do not connect. Digital I/O for OEM
applications. In standard version, this signal
is the same one the drives the TX LED on the
module.
16 IO4 In/Out Special function digital I/O
Do not connect. Digital I/O for OEM
applications. In standard version, this signal
is the same one the drives the RX LED on the
module.
14 Reset In Reset input
Do no connect.
At a minimum, the user must apply DC power to pins 1&2, ground pins 6, 9, 10,
and connect data in and data out to pins 4&5. All other pins may be left
disconnected.

6 Serial Port Data and andshaking
In computer terminology, the RF modem is considered a “Data Communications
Equipment” device, or DCE. The user’s hardware that the modem is connected
to is considered “Data Terminal Equipment”, or DTE.
Following is a description of how data and control is communicated over the
various serial port signals between the modem (DCE) and another device (DTE)
that the modem’s I/O port is connected to.
Note: The MURS modem serial port utilizes CMOS level thresholds. A
CMOS to RS-232 adapter is required for communication between the
modem and a PC.
6.1.1.1 RxD (INPUT)
This line is used to transmit data from the DTE to the DCE. It is maintained at a
logical 1 state when nothing is transmitted. If Hardware Flow Control is enabled
in the modem, the terminal will start to transmit data to the modem when a logical
1 is present on all of the following lines:
• Clear To Send (output from modem)
• Request to Send (output from the DTE)
6.1.1.2 TxD (OUTPUT)
This circuit is used to transmit data from the DCE to the DTE. The modem will
start to transmit data to the DTE when a logical 1 is present on all of the following
lines:
• Data Terminal Ready (reply that it is OK to send)
• Data Set Ready (asserted by the modem)
6.1.1.3 RTS
On this line, the DTE will send a signal when it wants to receive data from the
modem (DCE). The modem will not output data unless this pin is low, or “Flow
Control” has been disabled in the modem set-up. When a DTE (such as a PC or
microcontroller) wants to stop the flow into it, it negates RTS. Negated "Request
To Send" (digital 1) means "request NOT to send to me" (stop sending). When
the DTE is ready for more bytes it asserts RTS (digital 0) and the flow of bytes to
it resumes. DCE equipment works the same way but sends the stop signal out
the CTS pin. Thus it's RTS/CTS flow control using 2 lines.
6.1.1.4 CD
On this line the modem indicates to the DTE that it has received a carrier from a
remote device. It will assert this signal any time there is a carrier detected. The
modem may be configured to assert this when an RF carrier is detected (any on-
channel RF, voice or data), assert it only when another RF modem signal is
detected, or always assert it.

7 User Serial Port Commands
7.1 Overview
The asynchronous serial portion the MURS RF modem is used to send and
receive data over the air, as well as to configure the RF modem. In normal
operation, the user sends data into the T D pin of the user port, and this data
will be sent over the air. Receive data from another RF modem is output to
the user via the R D pin of the user port. One byte in one modem, gives the
same byte out the other modem. No noise, no errors, no dribble bytes. This
is the normal operating condition of the RF modem.
There also is a configuration mode, where in the RF modem accepts certain
commands via the T D pin. The commands can be used to change certain
internal parameters of the radio modem.
7.2 Configuration Mode
The RF modem may be put into a “config mode”, by entering a sequence of
characters (+++) or by pulling the hardware /CONFIG pin low.
To Enter the Config mode when using AT Commands -
Using serial communications software, send the 3-character command
sequence “+++” while observing times of silence before [BT (Silence Before
Sequence) Command] and after [AT (Silence After Sequence) Command] the
command character.
The default sequence for entering into AT Command Mode:
The default sequence for entering into AT Command Mode: The default sequence for entering into AT Command Mode:
The default sequence for entering into AT Command Mode:
1. No characters sent for 1 second.
2. Input three (3 plus characters (“+++” within one (1 second.
3. No characters sent for one (1 second.
7.3 Reading a Parameter
To read the value of a particular setting, issue the command, with no
parameter. The modem will return the value followed by an “OK”. The
modem response is:
The value in ASCII decimal format.
<CR> <LF> sequence (ASCII 0D, ASCII 0A).
An “O”, “K”, <CR>, and <LF> sequence.
For e ample, to read the ID of the modem that previously had its ID set to 1234,
issue at ATDT command, with no parameter. The modem will return the current
ID, in this case, 1234.
User Modem
ATDT<CR> 1234<CR><LF> OK <CR><LF>

Company Confidential 8 Raveon Technologies Corp.
7.4 Configuration Mode Commands
AT
Command Command Description arameters Factory Default
AK
Enable/Disable ARQ – When ARQ is enabled, this modem will
automatically send an ACK packet back to a modem that sends
it data. 0=off, =on.
Range: 0 – 0 (no AKCs
sent)
AS
Auto Status Report Interval– Sets the time between auto
status reports. Time is in minutes. 0 means disabled.
Range: 0 –56000
(minutes) 0 (Off)
AT
Silence AFTER Sequence - Sets period of silence after the
command sequence characters in mS.
Range:0 – 000
(mS) 500
BD
Baud Rate – Sets serial com port baud rate (bps). Over-the-air
(throughput) baud rate is factory-set only.
If a PC’s serial baud rate is set higher than the fi ed over-the-air
baud rate of the module, may need to be implemented.
Range: 0 – 6
0 = 1200 bps
1 = 2400
2 = 4800
3 = 9600
4 = 19200
5 = 38400
6 = 57600
3
BC
Busy Channel ock Out – Enable/disable the BCL. If enabled,
the modem will not transmit on a radio channel that is busy (has
RF on if). 0-OFF, =ON.
Range: 0-
BT
Silence BEFORE Sequence – Sets period of silence before
the command sequence character in mS.
Range: 0- 000
mS 500
CH
Configure Hardware Flow Control – Enable ( ) or disable (0)
flow control. When enabled, the modem will monitor the RTS
line, and if it is negated, stop sending data out the serial port. If
disabled, the modem will ignore the state of RTS, and always
send out characters.
= Enable
0 = Disable 0
CN or O
Exit AT Command Mode – Exits module from AT Command
Mode and returns it to Idle Mode. Parameters are not saved in
EEPROM.
none none
CT
Time Out from AT Command Mode – If no valid commands
have been received within this time period (in milliseconds),
modem returns to normal operation mode from Command
mode. If the CONFIG button inside the modem is pressed, this
parameter will be automatically set to 60000.
Range: 00-
60000mS 60000
DT
Destination Address to call– Sets address of the modem to
send data to. Note, this parameter is entered in HEX format.
Each digit may be a 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,or an F.
Range: 0-FFFF 1234
E0 , E1
Echo – Character echo set on (E1) or off (E0). This applies to
the Command Mode only. Range: 0 , 1 0 (no echo)
F
Display frequencies – Display all of the frequencies
programmed into all of the channel memories. N/A
FT
Transmit Frequency – Program the transmit frequency for this
channel. Enter in Hz or in MHz. The frequency will
automatically be saved in non-volatile memory (flash) for this
current channel number.
Range: See product
data sheet. For MURS
products, frequency
cannot be changed.
See product
data sheet.
FR
Receive Frequency – Program the receive frequency for this
channel. Enter in Hz or MHz. The frequency will automatically
be saved in non-volatile memory (flash) for this current channel
Range: See product
data sheet. For MURS
products, frequency
cannot be changed.
See product
data sheet.

Company Confidential 9 Raveon Technologies Corp.
number.
FX
TX and RX Frequency – Program the receive and transmit
frequency for this channel. Enter in Hz or MHz. Same as
issuing an ATFR and an ATFT command. The frequency will
automatically be saved in non-volatile memory (flash) for this
current channel number.
Range: See product
data sheet. N/A
HP
Channel Number – Select separate channels to minimize
interference between multiple sets of modules operating in the
same vicinity.
Range: 1 - 6 1
Enable/Disable the LEDs – 0 = LEDs always off. This reduces
some power consumption. 1 = LED operate normally. 0 or 1 1
MA
Monitor Address – – Configures the address that status
transmissions are sent to. Only used if Auto Status is enabled.
Each digit may be a 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,or F. Note:
FF is interpreted as a group. See addressing section.
Range: 0000 - FFFF FFFF
MK
Address Mask – Configures local and global address space.
Each digit may be a 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,or F. In most
applications, this is kept at FFFF.
Range: 0000 -
FFFF FFFF
MT
rotocol Select – The over-the-air communication protocol.
0=Packetized mode, 2=Streaming data. Range: 0-2 0
MY
Unit Address – Configures the individual; address for this unit.
Each digit may be a 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,or F. Note: FF
is interpreted as a group. See addressing section.
Range: 0000 -
FFFF 1234
NB
arity – Selects parity format. Settings 0-4 transfer 8-bits over
antenna port and generate the parity bit on the RF receiving side.
Range: 0 – 5
0 = none
1 = Odd
2 = Even
3 = Mark (1)
4 = Space (0)
0
NS
Stop Bits – Selects the number of stop bits. Range: 1-2 1
PE
Packet Error Display – Shows statistics to compute packet-
error rate. Displays Packets Per Minute (PPM) and a running
total.
None (display
PER)
1 = reset counters
2 = Stop PER
display
None
R0
Symbol Peak Deviation – Set the peak FM deviation of the
transmit symbols. Note: This can be a negative number to invert
the modulation.
Range: - 000 –
000 - 85**
R1
Select CD pin output signal – CD may be RF carrier detect, or
modem data detect.
Range : 0 - 2
2 = Always assert
CD
= Data CD
0 = RF CD
R2
Over-the-air bit rate - This is the data rate the radio uses to
send data over the air. All RF modems in the network must
use the same over-the-air baud rate.
Range:
3 = 4800
3
R3
Serial Port time out – Number of mS of no activity before
transmitting. Range: - 5000 20 (mS)
R5
Preamble length – The number of bytes to send over-the-air in
the pre-amble. Range: 3 - 255 8**
R8
Frequency Offset. Used to set the radio on the center of the radio
channel.
Range: -500 to
+500 2**
R9
Modulation Balance. Range: 0- 00 88**
RA
Select RF CD output threshold – This value is the RSSI
threshold where the carrier detect is asserted. Note: To force
Range : 0-999
300**

Company Confidential 10 Raveon Technologies Corp.
CD always on, set this to 0, and R to RF Carrier Detect.
RB
Number of retries. If this modem does not get an ACK back
when it sends data, this is the number of times it will re-transmit
the packet and wait for an ACK. 0=disabled feature.
Range: 0-99 0
(ACKs are not used)
RF
RF Carrier Required – When enabled, there must be RF
energy on the channel for the modem to output data.
Streaming data mode only. -RF required. 0=ignore rf energy
when receiving.
Range: 0, 0 (no RF
required)
RG
Transmit Time-Out-Timer – Sets the transmitter time-out-timer
in seconds. This is a fail-safe timer for improper configuration
or operation of the modem. In normal operation, the TOT
setting is not changed.
Range: 0-999
(seconds) 60
RQ
Receiver Signal evel – Reads the Receiver Signal Strength
this instant, and returns the level in dBm.
Range: -40 to –
40 (dBm) varies
by model
-
RS
RSSI (Receive Signal Strength Indicator) – Returns the signal
level of last received packet. The reading is in dBm.
No parameters.
Returns a number :
-40 to – 40 (dBm)
varies by model.
none
S
Serial Number – Reads and returns a unique serial number for
thjs unit.
Read Only
1 - 999999999
unique
SH
Show – Display the configuration of the modem. This will return
a page of ASCII characters, showing the main configuration
parameters.
none None
SV
Save – Save all the parameters to EEPROM. This command
must be used if changed parameters are to be stored in non-
volatile memory, and used ne t time the modem is powered up.
Modem e its configuration mode after this command is e ecuted.
It saves all parameters e cept the frequency (The frequency is
automatically saved when an ATFT, ATFR, or ATFX command is
e ecuted)
none None
TD
Transmit Random Data – When issued, the modem will begin
sending random data. Entering a <CR> will terminate the
transmission.
0 = Go back to normal
1 = Random
2 = Hop up/dn one channel
3 = Force PLL to fast
4 = TX all 0s
5 = TX all 1s
6 = Test Points ON
7 = Transmit CW
8 = Transmit 1010101…
TT
Max acket Size – Set the ma imum number of bytes in an
over-the-air packet. 1 - 512 240
VR
Firmware Version – Returns firmware version currently loaded
on the module. Read Only, 3 characters none
&F
Restore Factory – Restore the factory default values. This
command will not erase the calibration values. After this
command e ecutes, the modem will still be in the CONFIG mode.
None
VB
Read DC input Voltage– Returns the DC input voltage reading,
in mV (12500 = 12.5VDC input). None None
RV
Enable Remote Access – When enabled (set to a 0), the
modem will respond to over-the-air RPR requests and over-the-
air commands. Default is ON (0). See FireLine System
Protocol Manual for remote diagnostics information.
0= Remote Access on
=Remote Access off 1

Company Confidential 11 Raveon Technologies Corp.
** indicates values that are calibrated in the factory and are unit-
specific.
7.5 Default Frequencies
The MURS modem has five user selectable channels. The channel is selected
with the ATHP command.
1 151.820 MHz
2 151.880 MHz
3 151.940 MHz
4 154.570 MHz
5 154.600 MHz
8 Factory-Only Debug and Test Facilities
Debug Related Commands
8.1 Testing
(Must be in command mode to test. Enter +++ at the keyboard to put unit into config/test mode.)
ATTD x Various test routines.
0 = Go back to normal mode. Stops the test.
1 = Random data transmit.
2 = Hop up/down one channel
3 = Force PLL to fast lock mode
4 = Transmit all 0s
5 = Transmit all 1s
6 = Enable the test points on the PCB.
7 = Transmit CW on center of channel
8 = Transmit alternating 1s and 0s
SHOW Display an overview of the configuration.
STAT Display statistics of how the modem is working.
AT$5 Display RSSI. It will scroll the reading until another character
comes in the serial port.
8.2 Packet Counter
AT E 0 Reset the packet counters back to zero
AT E 1 Begin counting and displaying the packet counters every minute
AT E 2 Stop counting and displaying packet counters
9 Using the Radio Modem – Packet Mode
This section describes the MURS modem operation in the Packet Mode of
operation. Packet Mode is the factory-default operating mode. It is the easiest
and most reliable mode of operation for a modem. Note: The configuration of
the Radio Modem is done when it is in the “Command Mode”. Refer to Section

Company Confidential 12 Raveon Technologies Corp.
7.4 on page 8 for details on all of the available commands and programmable
features.
In Packet Mode, all transmissions are sent in bursts or packets, and contain
address, error detection, and error correction information. Date enters the
Radio Modem’s serial I/O port, and is stored in a buffer within the modem until
it is ready to be transmitted. Packetized operation has these advantages over
non-packet modems:
Packet Mode Advantages
1. Error Detection The modem uses a 16-bit CRC at the end of every
packet of data. The CRC is used to check the data for errors, and if there
are any errors, the data will not be passed onto the user.
2. Error Correction Automatic error correction may be used. The Radio
Modem incorporate an optional ARQ method to re-transmit packets with
error, to ensure the user’s data is delivered error-free.
3. Addressing Packetized operation allows for a more versatile network
architecture, with source, destination, and network addresses. The Radio
Modem uses a 16-bit address to identify data packets.
4. No Dribble Data Even in the presence of noise, the modem will not
output e tra data or have random bit errors. Modems without packet
operation generally do not work well with weak noisy signals.
5. Transparent Operation Because of the high-reliability and error-free
operation the Packet Mode offers the user, most user applications will
seamlessly work using the Radio Modem in its Packet Mode.
6. Repeatable and Routable. Radio Modem packets are structured so that
they may be repeated using a store-and-forward repeater, and/or routed
using specialized hardware.
Streaming Mode Advantages
1. Low Latency The transmitter will key-up immediately upon the user’s first
byte of data entering the modem. Packetized operation waits until a
packet has been loaded before keying. (Although high serial-port data
rates can minimize this packet latency to a negligible level).
2. Data with Errors The Radio Modem will continue to receive data, down
into the noise-floor of the radio. If the channel is noisy or the signal is
weak, there may be bit-errors in the data, or the modem may output
additional noise data. User applications must (and often do), take this into
account, and thus can operate with weaker signals and have longer
communication range.

Company Confidential 13 Raveon Technologies Corp.
Figure 1 (Packet Mode of Operation)
For operation of the modem in the streaming data, non-packetized mode, see the
section Streaming Mode on page 21 The Packet or Streaming operation is
configured using the ATMT command, with Packet Mode being the factory
default.
9.1 Setup
1. Apply DC power to pins 1&2, ground pins 6, 9, 10, and connect data in
and data out to pins 4&5 of the modem.
2. Connect a good quality antenna, cut to the operating frequency, to the
SMA connector on the modem. Use a good antenna, and place is at high-
above obstructions as possible.
3. Connect a computer terminal, or PC computer running HyperTerminal,
through a CMOS-to-serial adapter, to the modem connector. The factory
default serial ports settings are 9600 bps, 8 data bits, 1 stop, no parity.
4. Program the modem’s operating frequency to your desired operating
frequency. This is done with the ATFX xxx.xxxxx command. See the
section “Serial ort Commands” for information describing the various
parameters that may be modified in the modem. In most applications, the
default settings from the factory will work fine.
5. Using the AT commands, change any of the default operating parameters
that must be modified. From the factory, the modems are configured and
shipped ready-to-use. Out of the bo , they will communicate on the
default radio channel using the factory defaults. In general, the
parameters you may want to modify will be:

Company Confidential 14 Raveon Technologies Corp.
ATFX Frequency for this channel. Set to your frequency.
ATMT 0 0 for normal Packetized operation. Default mode.
ATAK 0 for no ARQ, 1 if this unit sends ACKs. Default is no ARQ.
ATRB Set the number of retries if ARQ is used ( ). 0 if no ARQ used.
Factory default is no ARQ.
ATBD Serial port baud rate
ATMY The ID of this unit. Default is 1234.
ATMK The network address mask. Default is FFFF.
ATDT The address of the unit this modem will talk to. Default is 1234.
ATBC Enable/disable busy channel lock-out. Default is off, 0.
6. Connect your serial data device to the modem via the CMOS-to-serial
adapter.
The radio is now ready to use. Any serial data going into the modem will be
transmitted over the air, and any data received over the air will be sent out the
serial port.
Remember, that from the factory, all modems are configured to simply work.
Plug in power and connect to the serial port at 9600 baud, and the modems will
communicate on the default channel. Change the channel frequency to your
specific frequency, and they will be ready to work on your channel.
9.2 Programming Channels and Frequencies
The modem has memory for up to 6 channels. A channel is a pair of
frequencies, one for transmit and one for receive. They may be different or they
may be the same. You may program any valid frequency into any channel
number. To program a channel, perform the following steps.
1. Change to the channel you wish to program, using the ATH x command,
where is the channel number.
2. Program the frequency for this channel , using the ATFT, ATFR, or
ATFX command. Note that the frequency may be entered in MHz as long
as you use a decimal point. For E ample, enter ATFX 151.82 to set the
channel frequency to 151.820MHz. Alternately, you may enter the
frequency in hertz by entering ATFX 151820000. You must enter all of
the zeros if you enter the frequency in hertz.
3. Review the frequency setting with the ATFT, ATFR, or ATFX command.
To see a list of all of the channels, enter ATF.
4. To change the radio channel, use the ATH x command while the modem
is in the command mode.
If the channel number is changed using the ATHP command, and power is later
lost, the channel number will be retained in non-volatile memory as long as was
saved using the ATSV (Save to non-volatile memory) command.
Due to the nature of the synthesizer used in the radio, the frequency
programmed into the unit must be an even multiple of its internal reference

Company Confidential 15 Raveon Technologies Corp.
frequency. For narrow-band radios (12.5kHz channels), the user’s frequency
must be a multiple of either 6.25khz or 5.00kHz. For wide-band models, the
frequency must be an even multiple of 10kHz or 12.5kHz.
9.3 Data Transmission
To transmit data, simply send one or more bytes of data into the serial port of the
modem. When a full packet of data has been collected into the internal buffer of
the modem, or when there is a pause in the data, the modem will automatically
key its transmitter, and send the data over the air.
9.4 Serial Port Baud Rate
While the modem is transmitting, the user may continue to send more data into
the Radio Modem Because the buffers in the Radio Modem are full-duple , the
serial port data rate and the over-the-air data rates are independent. The serial
port baud-rates may be set slow to accommodate legacy equipment, or set at
high-speed to minimize latency. The over-the-air data rate is usually 4800 baud
for narrow-band channels, and 9600 baud for wide-band, although faster or
slower rates may be used.
In acket Mode, selection of the serial port baud-rate is important. As shown in
Figure 1 (Packet Mode of Operation) above, if the serial port baud-rate is the
same as the over-the-air baud rate and the packets are short, the channel
utilization is only about 50%. But, if the serial port baud rate is set much higher,
say 2-8X the over-the air rate, the channel utilization becomes near 100%.
Because the modem can handle serial-port data rate far in e cess of the over-
the-air rate, the efficiency of the modem in Packet Mode is appro imately the
same as other brand modems that cannot operate in a Packet Mode — with the
added benefit or ARQ, error-free data, and addressing.
Note that many Windows applications which use the serial port, such as
HyperTerminal, put large gaps between the bytes of data they send out the serial
port. If an application is not getting the desired throughput, verify that it is not an
artifact of the Operating System or the computer.
9.5 Flow Control
If large amounts of data will be sent with the Radio Modem, it may be possible to
overflow the internal data buffer. To ensure the transmit buffer does not
overflow, enable and use hardware flow control. Hardware flow control is
enabled with the ATCH 1 command. Note that the modem will always indicate
the status of its internal buffer using the CTS signal on the DB-9 serial connector.
When CTS is negated, the internal buffers are more than 80% full. When it is
asserted and it is “Clear to Send”, the buffers are less than 80% full.
9.6 Packet Size
The over-the-air packet size may be set with the ATTT xx command. Once the
modem receives one full packet of data via the serial port, it will automatically key
the transmitter and send the data. Factory default is 80 bytes.

Company Confidential 16 Raveon Technologies Corp.
9.7 Key-On_Data
When serial data is entering the Radio Modem’s RS-232 port, the Radio Modem
looks for pauses in the data as indication that it is time to send a packet of data
over the air. The factory default duration of the pause it looks for is 20mS, but
the user may change this to other values using the ATR3 xxx command, where
is in milliseconds.
9.8 Busy-Channel Lock Out
If your system operation requires the modem to monitor-before-transmit, or if you
do not want the Radio Modem to transmit on a channel that is busy, you can
enable “Busy-Channel-Lockout”, using the ATBC 1 command. ATBC 0 disables
BCL, and thus the modem will transmit whenever it has data to send out. The
factory-default is BCL disabled. Use caution when enabling it, as a CW
interferer, PC with poor shielding, or some other source of RF can stop the
modem from transmitting. The threshold where the Radio Modem senses RF
carrier, and determines that the channel is busy is set by the ATRA command.
This is factory calibrated to an equivalent RF level of appro imately -110dBm.
9.9 Data Reception
When the modem receives data over the radio, it checks it for errors, and if it is
error-free, it will send it out the serial port. Again, the serial port may be set to
any baud rate the user wishes, and the radio receiver and transmitter will
continue to operate independently of the baud rate.
When the modem receives a signal, it will assert the CD hardware signal on the
RS-232 serial port if it was configured to do so.
9.10 Addressing (Packetized Mode only)
9.10.1 Addressing Basics
One of the more powerful aspects of the modem is its addressing scheme.
Incorporating addressing in the modem allows multiple radio systems on the
same frequency to co-e ist, and not interfere with each other. Also, some user
application cannot tolerate receiving data that was not intended for it, and by
setting the addresses in the modems properly, the system can be configured to
allow reception of only data intended for the recipient.
If addressing is not needed or desired, it can be turned off so that all modems
receive data from all other modems, and all modems can talk to all other
modems.
Each Radio Modem contains a 16 bit address, called its Unit Address, and is
represented as a 4 digit he adecimal number. Modem address may be any
number between 0000 and FFFF, which is effectively 65,535 different addresses.
Every modem has a Unit Address programmed into it, as well as the ID of the
unit it will send data to. The Unit Address is programmed with the ATMY xxxx
command, and the Unit Address of the destination modem (the Destination
Address) is configured with the ATDT xxxx command.

Company Confidential 17 Raveon Technologies Corp.
The default UNIT ID in all Radio Modems is 1234, and 1234 is the default for the
destination ID. An Address Mask is used to select which digits of the address will
be used to determine if a particular reception was intended for the modem. The
default Address Mask is FFFF, which means all digits will be used.
9.10.2 exadecimal Numbers
For those not familiar with he adecimal numbers, a he adecimal digit represents
a 4-bit binary pattern. There are 16 possible values
(0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,and F). These 16 values represent 4 bits of
information, thus 4 he adecimal digits can represent 16 bits of information. The
he adecimal numbers represent 4 bit data in the following way:
exadecimal Table
ex # Binary ex # Binary ex # Binary ex # Binary
0 0000 5 0100 8 1000 C 1100
1 0001 6 0101 9 1001 D 1101
2 0010 7 0110 A 1010 E 1110
3 0011 8 0111 B 1011 F 1111
When communicating over the air, the radio modems transmit their Unit Address
and the Destination Address along with the data. Receiving modems check the
received Destination Address, and see if it matches their Unit Address. If it does
match, the receiving modem outputs the data it received via its serial port. If it
does not match, the receiving modem discards the data, and does not send it out
the serial port.
9.10.3 Setting A System-Wide Address
If individual addressing is not needed in your system, there are two ways to
ensure it is not used. One way is to set all modems in the system with the same
Unit Address and destination address. From the factory, these are both set to
1234, and thus, all modems can communicate with all other modems, using the
address 1234. The advantage of using this system-wide address, is that if there
are other modems on the channel, but in some other system, they probably will
not have the same Unit Address, and thus will not interfere with your system. To
reduce the possibility of data cross-talk, the system implementer may wish to use
a different system-wide address for the Unit Address instead of 1234. There are
over 65,000 addresses available.
An alternate way to disable addressing altogether, is set the Address Mask to
0000 (ATMK 0000 command). This tells the Radio Modem to ignore the
address, and receive every transmission. The disadvantage to this method is the
adjacent-system problem. If there is another Radio Modem system on the same
channel, all modems with the 0000 mask will receive them also.
Most users who do not use individual modem addressing, choose to set a global
system address, and have all modems in their system use the same Unit ID and
same destination address.

Company Confidential 18 Raveon Technologies Corp.
9.10.4 Broadcast Transmissions
The double FF is used to identify a broadcast packet. A transmission with a two
digit FF in the first two positions of the destination ID, or in the last two positions
of the destination ID, will be interpreted as a broadcast, and any modem with an
ID that matches the two non-FF digits will receive the data. For e ample,
sending data with a destination ID of 12FF will be received by any modem with a
unit ID 1200 through 12FF. Sending data with a destination ID of FF34 will be
received by any modem with a unit ID of 0034 through FF34.
9.10.5 The Address Mask
The reason to use he adecimal digits to represent the unit address, is that along
with the Unit Address programmed into the Radio Modem, there is an “Address
Mask” programmed into it. The default mask is FFFF. The address mask is also
used to determine if a particular data transmission should be received by the
modem. For most applications, where one modem talks to one modem, or where
all modems in the system communicate with all other modems in the system, the
Address Mask should stay set to FFFF.
Only in systems where some modems should only talk to certain other modems,
might you want to change the address mask. Whenever data is received over
the air, the Destination Address of the transmission is logically “ANDed” with the
Address Mask in the receiving modem. This is the Effective Destination Address.
The receiving Radio Modem also ANDs its own Unit Address with its Address
Mask. The result is the Effective Unit Address. The Effective Unit Address is
compared to the Effective Destination Address, and if the two are identical, the
data will be received.
Note: Logically 1 AND 1 = 1, 0 AND 0 = 0, 1 AND 0 = 0, 0 AND 1 = 0

Company Confidential 19 Raveon Technologies Corp.
` Figure 2 (Address Filtering)
One effect of this is that an address mask of 0000 will cause the Radio Modem to
received any data from any unit that transmits. The Destination Address will
effectively be ignored if the mask is set to 0000.
9.10.6 Addressing Examples:
E ample 1 (default configuration)
Sending Destination Address = 1234
Receiving Unit Address = 1234
Receiving Unit’s Address Mask = FFFF
Result: Unit will receive the data, because the addresses identically match. When the
addresses are identical, the value of the mask is not important.
Notes: This is the default configuration. All units have address 1234, and all modems will
talk to all other modems with address 1234.
E ample 2 (a configuration that won’t work)
Sending to Destination Address = 1236
Receiving Unit Address = 1234
Receiving Unit’s Address Mask = FFFF
Result: No data will be received, because the address do not match, and the address
mask of FFFF requires that all digits in the address match. .
E ample 3 (able to receive a data from a group, 1230 – 123F)
Sending to Destination Address = 1236
Receiving modem Unit Address = 1234
Receiving modem Address Mask = FFF0
Radio Modem receives
data over-the-air to
Destination Address
Radio Modem has
Unit Address yyyy
Radio Modem has
Address Mask
zzzz
“
AND
” them
together
Compare the two results
from these two ANDs
“AND”
them
together
Output the data via
serial port if the two
results were identical

Company Confidential 20 Raveon Technologies Corp.
Result: Data will be received. 1236 ANDed with FFF0 is 1230. 1234 ANDed with FFF0
is 1230. The results of the ANDing match, and thus the data will be received.
E ample 4 (able to receive from a group, 34 where is any two digits)
Sending Destination Address = 2234
Receivin modem’s Unit Address = 1234
Receiving modem’s Address Mask = 00FF
Result: Data will be received. 2234 AND 00FF equals 0034. 1234 AND 00FF equals
0034, therefore they match. The results of the ANDing match, and thus the data will be
received.
9.11 Error Correction
The Radio Modem has a built-in error correction mode, commonly referred to as
Automatic Repeat request (ARQ). It works by checking each reception for errors,
and if the data is OK, it sends a short “ACK” packet back over the air telling the
sending station the data was OK.
The Radio Modem uses a traditional Carrier Sense Multiple-Access (CSMA)
algorithm with randomized re-try time slots to determine when to re-transmit
packets that must be re-sent. The duration between re-tries increases as the
number of attempts increases.
If received data has an error in it or if the receiving modem does not get the
data due to interference, the receiving modem does not send the ACK back,
and the sending station will automatically re-send the data. There are two
aspects to configuring ARQ:
1) Enable the ARQ mode in the modem to allow it to transmit ACKs
(ATAK 1 command). This command enables the modem to
transmit ACK packets.
2) Configure the number of retries the modem should attempt if an
ACK packet is not received back when it sends data (ATRB xx
command). For e ample, if you set ATRB to 5 with the ATRB 5
command, the modem will wait for an ACK whenever it sends data.
If it receives and ACK back from the modem that it sent data to, it
will do nothing more. But if it does not receive an ACK, it will
resend the same data, trying up to 5 more times.
The factory default condition is not to send or require ACK packets, so if you wish
to use this mode, program the Radio Modem to transmit ACKs with the ATAK 1
command. This will cause the modem to send an ACK anytime it receives data
from another modem. Note: If the destination address was a broadcast (FFFF,
FF , or FF), it will not wait for an ACK.
The number of times it retries to send data that does not get through (does not
get an ACK) is up to the user, but a number of 5 is usually a good compromise.
If after 5 times, the data does not get through, then there probably is something
seriously wrong with the channel or system.