Vaunix Technology Corporation
Lab Brick® Family of Digital Attenuators
Operation Manual
and
Programming Guide
Revision B
Vaunix Technology Corporation
Vaunix Technology Corporation certifies that this product met its published specifications at the time of shipment from the factory.
Lab Brick Signal Generators are warranted against defects in material and workmanship for a period of one year from the date of shipment.
The foregoing warranty does not apply to connectors that have failed due to
normal wear. Also, the warranty does not apply to defects resulting from improper or inadequate maintenance by the Buyer, unauthorized modification or
misuse, or operation outside of the environmental specifications of the product.
No other warranty is expressed or implied, and the remedies provided herein are
the Buyer’s sole and exclusive remedies. Vaunix Technology Corporation shall
not be liable for any direct, indirect, special, incidental, or consequential damages, whether based on contract, tort, or any other legal theory.
Lab Brick Digital Attenuator
Certification
Warranty
LIMITATION OF WARRANTY
NOTICE
Vaunix has prepared this manual for use by Vaunix Company personnel and
customers as a guide for the proper installation, operation, and maintenance of
Vaunix equipment and computer programs. The drawings, specifications, and
information contained herein are the property of Vaunix Technology Corporation,
and any unauthorized use or disclosure of these drawings, specifications, and
information is prohibited; they shall not be reproduced, copied, or used in whole
or in part as the basis for manufacture or sale of the equipment or software
programs without the prior written consent of Vaunix Technology Corporation.
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This ISM apparatus meets all requirements of the Canadian Interference-Causing
Equipment regulations.
Ce generateur de fequence radio ISM respecte toutes les exigences du Reglement
sur le materiel brouilleur du Canada.
Waste Electrical and Electronic Equipment (WEEE) Directive 2002/96/EC
This instruction complies with the WEEE Directive (2002/96/EC) marking requirement. This affixed product label indicates that you must not discard this electrical/
electronic product in domestic household waste.
To return an unwanted instrument, contact Vaunix Technology Corporation.
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Lab Brick Digital Attenuator
Table of Contents
1.0 GENERAL INFORMATION..................................................................... 5
1.1 General Safety Information .................................................................................. 5
2.0 GETTING STARTED................................................................................. 6
2.1 System Requirements ........................................................................................... 6
2.2 Installation of the Graphical User Interface (GUI).............................................. 6
2.3 Using the Lab Brick Digital Attenuator ................................................................ 6
2.4 Using Multiple Lab Brick Digital Attenuators ..................................................... 7
3.0 OPERATING FEATURES AND CONTROLS ....................................... 8
3.1 Attenuation ............................................................................................................. 8
3.1.1 Manual Attenuation ............................................................................................... 8
3.1.2 Configuring the Manual Attenuation Step Size .................................................... 9
3.1.3 Configuring the Automated Attenuation Step Function ........................................ 9
3.1.4 Configuring the Attenuation Profile .................................................................... 10
3.3 Setting the Initial Operating State ...................................................................... 11
4.0 SPECIFICATIONS ................................................................................... 12
5.0 OPTIONAL ACCESSORIES .................................................................. 13
6.0 PROGRAMMING GUIDE ...................................................................... 14
6.1 Identifying the Lab Brick Digital Attenuators ................................................... 14
6.2 Controlling the Lab Brick Digital Attenuators ................................................... 16
6.2.1 Commands ............................................................................................................ 16
6.2.2 Responses ............................................................................................................ 20
6.3 Tips and Suggestions ........................................................................................... 23
7.0 MECHANICAL OUTLINE ...................................................................... 24
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1.0 GENERAL INFORMATION
This guide contains information on the installation , operation and specifications of
the Lab Brick® Family of Digital Attenuators.
1.1 General Safety Information
To prevent the risk of personal injury and loss related to equipment malfunction,
Vaunix Technology Corporation provides the following safety information. For you
own safety please read this section before operating the equipment.
Warning
Before connecting your Lab Brick Digital Attenuator to other instruments ensure
that all instruments are connected to earth ground. Any interruption of the earth
grounding may cause a potential shock hazard.
Lab Brick Digital AttenuatorVaunix Technology Corporation
Caution
• The Lab Brick Digital Attenuator contains components which are sensitive to
Electro Static Discharge (ESD). Proper ESD precautions must be maintained
at all times while using this equipment.
• This equipment has no serviceable parts.
• To prevent the risk of electrical shock or damage to precision components, do
not remove the equipment covers.
• Unauthorized entry into the unit voids all warranties.
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2.0 GETTING STARTED
Prior to installing your Lab Brick Digital Attenuator, verify the contents of the package. The package should contain:
Quantity 1 Lab Brick Digital Attenuator
Quantity 1 Cable - USB Type A male/ Mini-B male
Quantity 1 Flash Drive containing the manual and the Graphical User Interface
program
2.1 System Requirements
The Lab Brick Digital Attenuator runs from a standard PC or lap top computer with
the following minimum requirements:
• Operating System - Windows® 2000, Windows® XP, Windows® Vista, Windows® 7, Windows® 8
• A minimum of one USB port
No other AC or DC supply is required as the power for this unit is delivered from a
USB port on the computer or a self powered USB hub.
Lab Brick Digital Attenuator
2.2 Installation of the Graphical User Interface (GUI)
The Lab Brick is controlled through the GUI program supplied on the provided USB
flash drive. To install the GUI proceed with the following steps:
• Insert the supplied USB flash drive into an available USB port on the computer
• Run the program “Setup.exe”
• Follow the instructions on the screen
• After Installation is complete, remove the USB flash drive
2.3 Using the Lab Brick Digital Attenuator
Start the Lab Brick program by selecting the Lab Brick Icon or selecting the Lab
Brick program from the Start Menu on the computer. Attach the supplied USB
cable to the Lab Brick Digital Attenuator and the USB port on the computer. The
green LED on the Lab Brick will illuminate as communication with the computer is
automatically established. The GUI program will recognize the device and display
the model number and serial number in the title bar and lower left corners respectively. The Lab Brick is now ready for operation.
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2.4 Using Multiple Lab Brick Digital Attenuators
Users may operate and control multiple Lab Bricks from a single computer. Start
the Lab Brick GUI as described in section 2.3 for each Lab Brick Digital Attenuator
that you will control from the computer. Connect each Lab Brick either directly to
the USB port or through a self powered USB hub to the USB port of the computer.
The green LED on each Lab Brick will illuminate as communication with the computer is automatically established. Each GUI application will automatically connect
to one Lab Brick. The GUI will display the model number and serial number of the
connected device in the title bar and lower left corners respectively.
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3.0 OPERATING FEATURES AND CONTROLS
The general operation of the Lab Brick Digital Attenuator is designed by the Vaunix
engineers to be intuitive and easy to use. This section describes the available
features of the Lab Brick Digital Attenuator.
3.1 Attenuation
Attenuation Setting
Lab Brick Digital Attenuator
Manual Attenuation
Stepping
3.1. 1 Manual Attenuation
The output power is set using the Attenuation field found on the top of the GUI.
Simply type the desired attenuation level into the window and hit the “Enter” key on
your computer keyboard. The attenuation level will immediately be set.
Attenuation Step Size
Automatic Attenuation
Stepping
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3.1.2 Configuring the Manual Attenuation Step Size
The attenuation may also be controlled by using the up and down arrows adjacent
to the Power field. Use the controls directly below the Attenuation field to set the
desired step size. Quick select buttons are available for fixed step sizes of 10 dB and
1 dB. Custom step sizes may also be used by selecting “Other” and entering the
desired step sizes.
3.1.3 Configuring the Automated Attenuation Step Function
The Lab Brick can be configured to automatically step through a range of attenuation.
The user must specify the starting attenuation level, final attenuation level, step size,
dwell time and time between repeating sweeps. The starting and ending attenuation
levels can be configured over the full attenuation range of the device. The dwell time
may be configured from 10 milliseconds to 20000 milliseconds per step. The step
size is configured as described in section 3.1.2. The attenuation level may increase
of decrease during the sweep depending if the starting attenuation is higher or lower
than the ending attenuation setting.
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When the bidirectional ramp box is selected, the bidirectional dwell time and hold time
must be specified. The bidirectional dwell time defines the time at each attenuation
setting from the end attenuation to the start attenuation. The Hold time refers to the
time to wait after the ramp is completed.
By selecting the “One Time” control button, the Lab Brick attenuatorwill sweep from the
start to the end attenuation level. Upon completing the sweep, the Lab Brick output
will stay at the end attenuation setting. The user may stop the sweep at any time by
selecting the “Stop” button.
By selecting the “Repeat” control button, the Lab Brick will repeatedly sweep from the
start to the end attenuation level. The user may stop the sweep at any time by selecting the “Stop” button.
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3.1.4 Configuring the Attenuation Profile
Lab Brick Digital Attenuator
The attenuation profile can be loaded with a .txt or .prf file. The file format is:
dwell time = time in seconds (ex. 0.200)
idle time = time in seconds (ex. 5.000)
length = number of attenuation points to follow (up to 100)
atten 1
atten 2
atten 3
etc.
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To load a profile, select Load from the GUI. Locate the desired profile file and select
Open. A picture of the prfile will appear on the GUI. The dwell and idle times may be
modified on the GUI.
3.3 Setting the Initial Operating State
After configuring the attenuation parameters, the user may select to save the current
settings. From the File menu select Save Current Settings.
These settings will be stored within the Lab Brick device. The Lab Brick will now
power on in this predefined state when plugged into a USB port on any computer or
USB self powered hub. The user may change the saved state at any time by repeating the process.
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4.0 SPECIFICATIONS
Lab Brick Digital Attenuator
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5.0 OPTIONAL ACCESSORIES
Vaunix offers the following optional accessories for the Lab Brick Digital Attenuator
family. Please consult your sales representative or visit Vaunix.com for up to date
pricing and availability.
4 Port USB Hub with external power adapter
USB cable TypeA male/Mini-B male - 3 feet
USB cable TypeA male/Mini-B male - 6 feet
USB cable TypeA male/Mini-B male - 9 feet
USB cable TypeA male/Mini-B male - 15 feet
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6.0 PROGRAMMING GUIDE
The Lab Brick Digital Attenuators are designed to be easily controlled from either
their included control software or from applications programs that directly access
the digital attenuators. The Lab Bricks use the USB HID class so that applications
software can send commands and receive responses and status messages without
the need to install any drivers or other special software components.
As with any USB HID device, there are two phases to working with the Lab Bricks.
The first phase is the process of identifying the device you want to work with, and
then opening the device to send and receive commands and status messages from
it. The second phase is communicating with the device, using its commands to
control it and reading its responses and status messages to determine the state of
the Lab Brick.
This documentation includes examples from the Microsoft Windows™ environment. Similar strategies are used to communicate with USB HID devices under
other operating systems, and this documentation will provide you with a general
understanding of how to control the Lab Bricks under any operating system which
supports USB HID class devices.
Lab Brick Digital Attenuator
6.1 Identifying the Lab Brick Digital Attenuators
The Lab Brick Digital Attenuators are identified by their Vendor ID (“VID”) and
Product ID (“PID”). Each Lab Brick also has a unique serial number, so that individual digital attenuators can be identified and selected in situations where multiple, otherwise identical Lab Bricks are connected to one computer.
Model Description VID PID
LDA-102 .1 - 1000 MHz, 0.5 dB 0x041F 0x1207
LDA-602 6 - 1000 MHz, 0.5 dB 0x041F 0x1208
LDA-302P-H 10 - 3000 MHz, 0.5 dB 0x041F 0x120D
LDA-302P-1 10 - 3000 MHz, 1.0 dB 0x041F 0x120E
LDA-302P-2 10 - 3000 MHz, 2.0 dB 0x041F 0x120F
Normally, in the Microsoft Windows environment, USB devices are identified by repeatedly calling the SetupDiEnumDeviceInterfaces function and then getting the
symbolic link name for the HID device’s interface with the
SetupDiGetDeviceInterfaceDetail function. There are a number of publications that
explain this technique, Writing Windows WDM Device Drivers by Chris Cant is a
good starting point. Also, the Wiimote library by Brian Peek, (http://
www.codeplex.com/WiimoteLib) is a good example of code for identifying and communicating with a USB HID device in a Microsoft Windows environment.
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Lab Brick Digital AttenuatorVaunix Technology Corporation
Use the SetupDiGetDeviceInterfaceDetail function to get the symbolic link name for
the interface, which the operating system uses to encode its enumeration information describing the device. The string contains the VID and PID of the device found
by the operating system. Test each string to find the one (or more if you have
multiple Lab Bricks attached) that contains the VID and PID values in it. For the
Microsoft Windows environment, the portion of the device strings containing the
VID and PID are in the format:
sDevSubstring1 = “vid_041f&pid_1207”; // VID and PID for LDA-102
sDevSubstring2 = “vid_041f&pid_1208”; // VID and PID for LDA-602
Once you have identified a Lab Brick, open it by using the DevicePath from the
Interface Device Detail Data structure, using the normal CreateFile function. Once you
have opened the device1 you can read the Lab Brick’s serial number using the
HidD_GetSerialNumberString function.
WCHAR *pBuffer = new WCHAR [32]; // this buffer must be large enough to hold
// any serial number
HidD_GetSerialNumberString(hDevice, pBuffer, 32);
If you are using multiple Lab Bricks you will need to identify the Lab Bricks, open them
all, and then use the serial numbers returned by each of the devices to map the device
handles to the specific Lab Bricks.
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6.2 Controlling the Lab Brick Digital Attenuators
6.2.1 Commands
The Lab Brick Digital Attenuators use a simplified HID based set of commands. The
commands, and the responses from the Lab Brick, are designed so that they can be
easily created or parsed directly by your applications software. It is not necessary to
use the normal HID API parsing functions.
Each Lab Brick command consists of an eight byte packet with the following format:
typedef struct
{
Lab Brick Digital Attenuator
BYTE command;
BYTE count;
BYTE byteblock[6];
} HID_REPORT_OUT;
(Note that in the Microsoft Windows environment, the HID driver stack requires a prepended 0 byte on packets written, and pre-pends a 0 byte to packets received, so
your applications software needs to use a structure which has an additional BYTE
before the command, and is therefore 9 bytes long.)
The command byte determines the meaning of the bytes within the byteblock. The
count byte contains a count of the number of valid bytes in the byteblock. The values
and the meaning of the bytes in the byteblock are set forth in the table below. For most
commands the byteblock contains a 32bit DWORD quantity, several instances use a
single byte quantity.
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1
Actually, due to the architecture of USB HID devices, Interfaces on the device are opened and closed. A
single HID device can have multiple Interfaces, and it is the Interfaces that are exposed by the HID Class
driver for user level processes to interact with.
Lab Brick Digital AttenuatorVaunix Technology Corporation
The most significant bit of the command byte determines whether the command gets
or sets the parameter. To set the parameter, set the most significant bit. For example,
to set the Lab Brick LDA-102 to an attenuation of 10 dB you would send the following
command:
Command Byte Count Byteblock Contents
0x8D 4 0x28, 00, 00, 00, 00, 00
The command to get the current attenuation setting is:
Command Byte Count Byteblock Contents
0x0D 0 xx, xx, xx, xx, xx, xx
The Lab Brick responds with a report that contains the command byte in its status
field, along with a count of 1 byte and a byte representing the current attenuation
setting in the byteblock of the response. Attenuation is represented as a byte quantity
where the least significant bit is 0.25 dB of attenuatin. The attenuator operates in
steps of 0.5 dB, so the least significant bit is ignored. As an example, an attenuation
of 0.5 dB is represented by 0x02, 63 dB is represented by 0xFC, and 0x00 represents 0 dB of attenuation.
Note that the attenuation value is passed in a DWORD quantity for the commands
that define the start, step, and stop attenuation levels for attenuation ramps. This is
to simplify the development of software which controls ramps and/or sweeps, since
attenuation sweeps require DWORD quantities to represent the attenuation.
The format of certain responses will be described in more detail in the next section.
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Command Set
Lab Brick Digital Attenuator
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As an example, this C code function sets the starting attenuation level of a ramp to 32
dB
static long AtnStart = 4 * 32; // the attenuation ramp starts at 32 db
void SetRampStart(HANDLE hDevice)
{
unsigned char *ptr = (unsigned char *) &AtnStart;
if (SendReport(hDevice, VNX_ASTART | VNX_SET, ptr, 4)){
printf(“ sending the ramp start attenuation value\n”);
}
}
SetRampStart(hDevice);
Applications programs should ensure that commands are sent with a minimum
delay of 30ms between commands, in order that the Lab Brick can generate and
send its responses.
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6.2.2 Responses
The Lab Brick Digital Attenuators send status reports to the host computer periodically while they are operating, and in response to some commands. Applications
programs should normally set up and maintain a read thread to capture responses
and status reports from the device. The status reports are designed to be easily
parsed directly by the applications program.
Each Lab Brick response consists of an eight byte packet with the following format:
typedef struct
{
BYTE status;
Lab Brick Digital Attenuator
BYTE count;
BYTE byteblock[6];
} HID_REPORT1;
The status byte contains a value indicating the type of status report, like the commands the contents of the byteblock varies depending on the value in the status byte.
For command responses, the value of the status byte is equal to the command. So for
example, the response to the Get Attenuation command shown above would have a
status byte of 0x04, a count of 1 corresponding to the 1 byte used by the attenuation
value in the byteblock, and a value of 0x37DC, or .5 db.
Status Byte Count Byteblock
0x04 1 0x02, 00, 00, 00, 00, 00
The Lab Bricks report their status periodically, at an interval equal to the dwell time set
for attenuation ramps, whether or not a ramp is active. During a ramp, the status
report occurs when the attenuation level changes2. This allows an applications program to track the attenuation level of the Lab Brick during the ramp. This allows an
applications program to track the attenuation level of the Lab Brick during the ramp.
The format for the periodic status report is:
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typedef struct
{
BYTE pkt_status; // = 0x0E
BYTE count; // = 6
Lab Brick Digital AttenuatorVaunix Technology Corporation
DWORD frequency;
BYTE dev_status;
signed char power;
} VNX_STATUS_REPORT;
Status Byte Count Byteblock
0x0E 6 reserved, dev_status, power
The dev_status byte contains a set of flags which describe the current state of the Lab
Brick:
#define STATUS_PLL_LOCK 0x80 // MASK: PLL lock status bit, unused by
attenuator
#define STATUS_NEW_PARAM 0x40 // MASK: A parameter was set since the last
// “Save Settings” command
#define STATUS_OK 0x20 // MASK: A command completed
#define STATUS_ON 0x08 // MASK: The RF HW is on
// Bit masks and equates for the Ramp command byte (stored in Ramp_mode, and
reported also in Status)
#define SWP_DIRECTION 0x04 // MASK: bit = 0 for sweep up, 1 for
sweep down
#define SWP_CONTINUOUS 0x02 // MASK: bit = 1 for continuous
sweeping
#define SWP_ONCE 0x01 // MASK: bit = 1 for single sweep
Power is the current value of the attenuation level as set by the Power Level command.
Since Lab Brick status reports occur asynchronously with respect to command responses, the applications code handling reports from the Lab Brick should be able to
accept either a command response report or a status report.
2
The timing of the status reports will vary somewhat depending on the timing of the USB bus transactions, and
software processes within the operating system, particularly for dwell times less than 100 milliseconds.
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Command Response Report Formats
Lab Brick Digital Attenuator
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6.3 Tips and Suggestions
Remember to handle the error cases for device removal, and close the device
handles when you are done interacting with the device.
Remember that in the Microsoft Windows environment, the operating system pads the
reports with a byte at the beginning of the report. Make sure to adjust your structures
accordingly.
If you are programming in C or C++ you can create a set of unions to allow for
convenient access to and conversion of the fields of the reports. For other languages, ensure that the byte order of a 32 bit unsigned integer is the same as the
byte order used in the reports, which has the least significant byte stored in the lowest
address.
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7.0 MECHANICAL OUTLINE
Lab Brick Digital Attenuator
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