Adcon A440 Product manual

ADCON
TELEMETRY
SMART WIRELESS SOLUTIONS
A440 Wireless Modem
Technical Reference Manual

ADCON
TELEMETRY
ADCON TELEMETRY AG
INKUSTRASSE 24
A-3400 KLOSTERNEUBURG
AUSTRIA
TEL: [phone]
FAX: [phone]
http://www.adcon.at
ADCON TELEMETRY INC
1001 YAMATO ROAD
SUITE #305, BOCA RATON
FL 33431 USA
TEL: [phone]
FAX: [phone]
http://www.adcon.com
ADCON TELEMETRY SRL
BD. ION IONESCU DELABRAD 8
R-71592 BUCHAREST
ROMANIA
TEL: [phone]
FAX: [phone]
http://www.adcon.ro
Proprietary Notice:
The Adcon logo, the A730 series, A720 series and addIT™, A440 and add-
WAVE, addVANTAGE® and AgroExpert™ are trademarks or registered trade-
marks of Adcon Telemetry AG. All other registered names used throughout
this publication are trademarks of their respective owners.
This publication contains confidential information, property of Adcon Teleme-
try AG. Disclosure to third parties of the information contained herein is pro-
hibited. Neither the whole nor any part of the information contained in this
publication may be reproduced in any material form except with the prior writ-
ten permission of Adcon Telemetry AG.
Release 1.0, February, 2001
Copyright © 2001 by Adcon Telemetry AG.
All rights reserved.

3
Table of Contents
Introduction ____________________________________________________7
About the A440 ______________________________________________________________ 7
Hardware _______________________________________________________9
Overview_____________________________________________________________________ 9
The Modem Interfaces ________________________________________________________________ 10
The Microcontroller and the Power Conditioning Sections _________________________________ 10
The Power Supply and Serial Interface___________________________________________________ 13
External Power Supply_________________________________________________________________ 13
Specifications________________________________________________________________13
PCB Parts Placement (A440) __________________________________________________15
Bills of Materials _____________________________________________________________15
A440MB _____________________________________________________________________________ 16
A440 Device’s Photographs___________________________________________________21
The A431 Radio Module _______________________________________ 27
About the A431 Radio Module________________________________________________27
Functional description________________________________________________________27
Receiver Section ______________________________________________________________________ 27
Transmitter Section____________________________________________________________________ 28
Manufacturing Issues _________________________________________________________30
Marking and labeling issues ____________________________________________________________ 30

4
Alignment Range and Switching Range __________________________________________________ 30
Tuning Procedure _____________________________________________________________________ 31
Setting Up the Default Parameters ______________________________________________________ 31
Commands valid for all bands ____________________________________________________ 32
Commands required for band 1 __________________________________________________ 32
Commands required for band 2 __________________________________________________ 32
Commands required for band 3 __________________________________________________ 32
Commands required for band 4 __________________________________________________ 32
Definitions ___________________________________________________________________________ 33
Test Equipment Settings _______________________________________________________________ 34
Network Analyzer (HP 8712 or equivalent)_____________________________________________ 34
Service Monitor (Rohde & Schwarz CMS50 or equivalent) _______________________________ 34
Trimming Elements ____________________________________________________________________ 35
Adjusting the Receiver Front End _______________________________________________________ 35
Adjusting the VCOs ___________________________________________________________________ 36
Adjusting the Crystal Reference _________________________________________________________ 37
Checking the Receiver Parameters ______________________________________________________ 37
Checking the Transmitter Parameters ____________________________________________________ 37
Data Transfer Check ___________________________________________________________________ 38
PCB Parts Placement_________________________________________________________ 39
Bill of Materials (A431) _______________________________________________________ 41
Frequency Reference Specifications ___________________________________________ 45
A431 Module’s Photographs _________________________________________________ 46
Software ______________________________________________________49
Short Description____________________________________________________________ 49
Tasks _______________________________________________________________________ 49
Controlling the Unit__________________________________________________________ 50
Serial Communication Protocol _________________________________________________________ 50
General Format of a Command _________________________________________________________ 50
General Format of an Answer___________________________________________________________ 51
Commands___________________________________________________________________________ 51
CMDS _____________________________________________________ 51
TIME _____________________________________________________ 51
SR ____________________________________________________________________________ 52
BL ____________________________________________________________________________ 52
FREQ _________________________________________________________________________ 53
DATA _________________________________________________________________________ 53
INFO _________________________________________________________________________ 54
RX ____________________________________________________________________________ 55

5
TX ___________________________________________________________________________ 55
B ____________________________________________________________________________ 56
Returned errors list____________________________________________________________________ 56
Command line interpreter _______________________________________________________ 56
Device descriptors and storage handler ___________________________________________ 57
Real time clock ________________________________________________________________ 57
Radio interface ________________________________________________________________ 57
Notifications __________________________________________________________________ 57
Adcon Packet Radio Protocol _________________________________________________57
Digital Squelch _______________________________________________________________________ 58
Modulation Technique Used (low speed modem) _________________________________________ 59
Generic Format of a Radio Frame _______________________________________________________ 59
Data Frames _________________________________________________________________________ 61

6

7
1. Introduction
1.1. About the A440
The A440 Wireless Modem is a portable low-power, medium-range serial interface
telemetry modem. The unit is based on a powerful 8-bit Flash RISC microcontroller,
which can also be programmed in the field (for software upgrades).
The units incorporates an A431 radio module operating in the 430 to 470 MHz
range, making it adaptable to most radio communication regulations in the world.
The output power is 0.5 W, while the modulation is narrow band FM (12.5, 20 or 25
kHz channel spacing).
Due to its construction, as well as to the software controlling it, the power consump-
tion is extremely low (average 1 mA). The unit operates from an extrenal 5.6 to 10
volt power supply. The power is fed via the common data/power connector/cable.
The A440 is a ruggedized unit, complying with the IP65 environmental protection
class (NEMA 4). It can be easily installed and is compatible with both the standard
Adcon low speed protocol and the upcoming high speed protocol.
This manual describes the technical details of the A440, both hardware and soft-
ware. It is organized in several parts, as follows:
• Hardware: includes the schematics as well as a description of the main board
of the A440 (the processor, modems and interfaces)
• The A431 radio module: includes the schematics and description of the radio
module
• Software: a short description of the software with the most important com-
mands that can be used to control the unit over the serial interface

8
Introduction
This manual is intended for the radio approval authorities and laboratories.

9
2. Hardware
2.1. Overview
Most of the electronics (including the A431 radio module) are situated on the main
board (for the A431 description, see “The A431 Radio Module” on page 27). The
main board (Figure 1) contains the radio unit, a low-speed and a high speed modem
interface, a microcontroller, RS-485 and RS-232 interfaces and a power conditioning
subsystem. The power and the serial lines are provided over a corresponding con-
nector (4-pin Binder for RS-485 or D-sub 9 pin for RS-232), while the antenna is fed
through a 50 Ω TNC connector.
Figure 1.
A440 Block Diagram.
A431 Radio
Antenna
µController
Modem
Interface Power
Conditioning
System Supply
Power
Module
Low Speed
Modem
Interface
High Speed
Level
Shifter
RS485/
RS232
Interfaces
Serial

10
Hardware
For further details, consult the schematic diagram in Figure 2.
2.1.1. The Modem Interfaces
The low speed modem operates with two tones: 1 kHz (representing the “1” bits)
and 2 kHz (representing the “0” bits). A bit cell is represented by a complete time
period ( 1/f ), thus the raw throughput varies between 1 and 2 kbps (average 1.5
kbps). The modem functions are essentially implemented in software by a separate
microprocessor. However, a signal pre-conditioning is performed on both receive
and transmit paths by means of two low-pass filters (U6 on receive and U19 on trans-
mit).
On receive, the buffered analog data signal from the radio unit is applied to a 3 kHz
low pass filter (U6). The filter output is further fed to the A/D input of a slave micro-
controller U5) performing the decoding operation for the low speed modulation
(see also “Modulation Technique Used (low speed modem)” on page 59). The slave
microcontroller (U5) communicates with the main microcontroller (U9) via a 4-wire in-
terface. In addition, the audio output from the radio unit is also applied to the GMSK
modem (U7) for decoding high speed data.
On transmit, the low speed data is generated again by the slave microcontroller (U5)
added by the R/2R network implementing a D/A converter. The slave microcontrol-
ler generates in effect the sinus waveforms required to encode the binary data. The
output signal is applied to the audio mixer U11, which adds the signal generated by
the high speed modem (U7). Obviously, only one modem will be activated at a time
by the master microcontroller (U9). The output signal of the mixer is applied to the
variable gain amplifier (U15) and then to the final low pass-filter (U19) that has a cut-
off frequency of around 7 kHz.
The high speed modem (U7) has two clocking options: either it can be clocked from
the main microcontroller’s clock via a buffer (U20), or it can be driven by its own
quartz crystal (X3). The low speed modem (U5) is always driven by the main micro-
controller’s clock.
2.1.2. The Microcontroller and the Power Conditioning Sections
The operation of the whole unit is under the control of U9, an Atmel ATMega 103
microcontroller. It is a powerful chip exhibiting a very low power consumption. Its
main functions are:
• Controls the radio unit
• Control the modems functionality
• Assembles the radio frames and waits for requests from a remote
• Implements Adcon radio and RS-485 protocol stack
• Manages the real-time clock

11
The Microcontroller and the Power Conditioning Sections
• Implements a serial Command Line Interface (CLI)
The chip operates at its maximum speed, in this case 4 MHz (the “L” version), and
uses a crystal (X2) for the on-board clock generator. The real time clock is imple-
mented by means of a 32.768 kHz crystal (X1) connected on the internal Timer/
Counter0.
The radio unit is controlled via the SPI bus (to set the PLL chip parameters) and via
several ports of the microcontroller for such operations as transmit and receive. In
addition, the high current 5 volt LDO voltage source (U4) is switched on before the
radio module’s PA is activated. The power output is adjusted by means of an elec-
tronic potentiometer (U2).
The A/D subsystem is used to sample the RSSI and Pout inputs. A stable 2.5 Volt
reference supplied by U3 is applied to the A
ref
pin. The reference is powered by the
microcontroller only when sampling the A/D input.
The serial interface is implemented by means of the built-in UART. Both the RS-232
and RS-485 interfaces are implemented using Maxim chips (U12 and U17 respective-
ly). The serial interface mode is selected by means of a pair of jumpers (J1).
An additional amount of 32Kbytes RAM is provided to the main microcontroller; the
RAM chip (U8) is attached to the multiplexed bus of the microcontroller with the aid
of a latch (U10).
A brown-out supervisor chip (U14) is used to assure a smooth start-up of the micro-
controller and avoid possible erratic behavior when the supply level descends below
the minimum operating value (2.7 volts).
A LDO voltage regulator (U16) is used to provide 3.3 Volt power to the main com-
ponents on the board.

13
The Power Supply and Serial Interface
2.1.3. The Power Supply and Serial Interface
The interface connector allows for:
• External supply (any DC source from 5.6 to 10
volts)
• Communication over serial lines, at 19200 baud
(RS-485).
For testing purposes, Adcon supplies a 220VAC power
adapter that provides also an RS-485 to RS-232 conversion. Thus, the unit can be
connected to a serial port of a PC and can be switched in various operating modes.
A list of commands is given in the sub chapter “Controlling the Unit” on page 50.
2.1.4. External Power Supply
In order to test the unit over the specified supply range, a special power cable is sup-
plied by Adcon Telemetry. This cable must be connected to the interface connector
of the unit before the serial cable (see Figure 3). The two wires with banana plugs
may then be connected to an external variable power supply: the red plug to plus
and the black plug to minus.
WARNING! Do not apply more than 10 Volts to the unit: permanent damage of the
device may result.
Figure 3.
Connection of an external power supply.
2.2. Specifications
The A440 fulfills the specifications of the EN 300 220-1, Class 12, and ETS 300 113,
as well as the FCC Part 90.214 (Subpart J) of the CFR 47.
1
2
34V+
BA
Gnd
INTERF
+
-
Black
Red
5.6 to 10 Volt
ANT To Interface Unit
A440

14
Hardware
Note: The parameters below were measured with the A440 + A431 combination.
Parameter Min. Typ. Max. Unit
Common
Supply 5.6 6.2 10.0 V
Operating Temperature -30 +70 °C
Relative Humidity 99 %
Class Protection IP65
RF Data Rate (Using the low-speed Modem) 1000 1500
a
a. Data rate is content dependent.
2000 bps
RF Data Rate (Using the high-speed Modem) 8000 bps
Operating Frequency (-44 version)
b
b. This parameter represents the alignment range; the switching range can
be limited in software to a narrower space (even to the extent of a single
channel).
430 450 MHz
Operating Frequency (-46 version)
b
450 470 MHz
Frequency Stability (-20 to +50°C) ±1.5 kHz
Frequency Stability (-30 to +60°C) ±2.5 kHz
Receive mode
Sensitivity (12 db S/S+N) -118 dBm
Image Frequency Attenuation (1st IF = 45 MHz) -70 dB
Local Oscillator Leakage 2 nW
Adjacent Channel Attenuation (12.5 kHz mode) -57 dB
RSSI dynamic 90 dB
Operating Current (incl. On-board Microcontroller) 32 mA
Transmit mode (all measurements made on a 50 Ω resistive load)
Output Power 27 dBm
Spurious Radiation 200 nW
Adjacent Channel Power (12.5 kHz mode) -34 dBm
Occupied Bandwidth (12.5 kHz mode) 7.0 kHz
Operating Current (incl. On-board Microcontroller) 600 mA

21
A440MB
2.5. A440 Device’s Photographs
Figure 6.
A440, Front view.
55 1 XTAL-MC306 32.76KH
zMC-306 X1 Seiko Epson
56 SMD Header 1 SLY8/SMD/055/4 S 2mm J1 Fischer Elektronik
57 Jumper 1 CAB10 2mm to J1 Fischer Elektronik
Pos Description Count Component Name Value Pattern Ref Des Manufacturer

22
Hardware
Figure 7.
A440, Back view.

23
A440MB
Figure 8.
A440, Top view.
Figure 9. A440, Bottom view.

24
Hardware
Figure 10.
A440, Left and Right views.

25
A440MB
Figure 11.
A440, Case opened.
Figure 12.
A440 Motherboard, top view.

26
Hardware
Figure 13.
A440 Motherboard, bottom view.

27
3. The A431 Radio Module
3.1. About the A431 Radio Module
The A431 was specially designed for narrow-band FM data communication. It exhib-
its a relatively flat response in the audio band from 10 Hz to 2.5 kHz, both on send
as well as on receive paths. Additionally, the receiver’s group delay is very low.
The module operates in the 430 to 470 MHz range, making it compatible with most
radio communication regulations in the world. The output power is 0.5 W, while the
modulation is narrow-band FM (12.5, 20 or 25 kHz channel spacing). The power con-
sumption in receive mode is remarkably low (under 32 mA), in spite of the good IP3
characteristics and high sensitivity. The switching from receive to transmit is fast, un-
der 20 mS.
3.2. Functional description
The following functional description refers to the schematic diagram in Figure 14.
3.2.1. Receiver Section
The antenna signal is fed through the common low-pass filter for both receive and
transmit and applied to the U3 antenna switch. From the J3 port of the switch, it is
then fed to the FL1 helical filter and amplified by the LNA built with Q2 that assures
a high amplification factor (over 20 dB). Another helical filter follows (FL2), giving a
total of more than 70 dB attenuation of the first image frequency.