QPHY-UWB UWB Serial Data Operator’s Manual Revision C – October, 2008 Relating to the Following Release Versions: • Software Option Rev. 5.7 • UWB Script Rev. 1.4 • Style Sheet Rev. 1.
LeCroy Corporation 700 Chestnut Ridge Road Chestnut Ridge, NY 10977–6499 Tel: (845) 578 6020, Fax: (845) 578 5985 Internet: www.lecroy.com © 2008 by LeCroy Corporation. All rights reserved. LeCroy, ActiveDSO, WaveLink, JitterTrack, WavePro, WaveMaster, WaveSurfer, WaveExpert, WaveRunner and WaveJet are registered trademarks of LeCroy Corporation. Other product or brand names are trademarks or requested trademarks of their respective holders. Information in this publication supersedes all earlier versions.
QPHY-UWB Software Option TABLE OF CONTENTS OVERVIEW ................................................................................................................................ 5 INSTALLATION ......................................................................................................................... 6 Oscilloscope Option Key Installation ..........................................................................................................................
Configuration Dialog ................................................................................................................................................. 29 Edit/View Configuration Dialog ................................................................................................................................. 29 Generating a Report .................................................................................................................................................
QPHY-UWB Software Option OVERVIEW The LeCroy QPHY-UWB option software enables LeCroy Digital Oscilloscopes to perform WiMedia ultra wideband (UWB) physical layer (PHY) transmitter compliance measurements as well as provide analyses and displays for troubleshooting UWB transmitters. This option software performs the analyses and tests in accordance with the following documents available from the WiMedia Alliance (WiMedia.
INSTALLATION The QPHY-UWB option is enabled through installation of an option key. If the option was purchased with the oscilloscope, then the key will already have been installed and nothing further is required to gain access and control of the option. If the option was purchased independently of the oscilloscope and needs installation, then please follow the instructions in the next section.
QPHY-UWB Software Option BASIC SETUP FOR CAPTURING UWB PACKET OVER CABLE Configure the UWB transmitter to be tested to the desired Band group, TFC, and data rate. It will make setup of the trigger easiest if your transmitter can be put in a mode to continuously send out packets. The trigger can still be setup even if you can only send out a finite burst of packets or even only 1 packet at a time, but it is a little more difficult.
CAPTURING A WIRELESS USB DATA PACKET The block diagram below shows a setup that is useful for capturing a UWB packet within the context of a Certified Wireless USB (WUSB) system. Antenna, Amplifier, and Filter The amplifier is needed in order to be able to move the capture antenna out of the near field of the transmit antenna.
QPHY-UWB Software Option OVERVIEW OF UWB ANALYSIS MODE Once installed, the UWB (WiMedia) selection will appear in the Analysis menu. This is the main entry point into the UWB analysis mode. Notice that the packet to be analyzed displayed on the screen below is in Memory 1, M1. Click UWB (WiMedia) to enter the UWB analysis mode.
Upon entering the UWB analysis mode, the UWB Analysis main menu will appear on the bottom third of the screen. The UWB Analysis main menu contains 5 main sections corresponding to the following sections of this manual. Turning the UWB Analysis Mode On and Off Click on the “On” box to turn the UWB Analysis Mode On. Click again to turn it off.
QPHY-UWB Software Option Selecting the Source for the UWB Waveform to be analyzed Selecting Input source control brings up a list of possible sources for waveform analysis. Select the one containing the packet for analysis. Any of the 4 input channels, 4 memories, or 8 math functions can be used as a source. Specifying the MB-OFDM parameters for the packet to be analyzed The section labeled Signal Setup, as follows, is used to specify the MB-OFDM parameters used by the radio when it transmitted the packet.
Setting the Band Group Select the Band Group control to set the Band Group for the packet to be analyzed. • Each Band Group is composed of 3 bands, except for Band Group 5, which has 2 bands • Each Band Group has 10 possible TFC choices except Band Group 5, which has 3 • Each combination of Band Group and TFC is called a Channel Setting the Data Rate Selecting the Data Rate allows you to select the data rate for the payload portion of the packet to be analyzed.
QPHY-UWB Software Option Interpreting the Packet Information Box This box located to the right of the UWB Analysis main menu outputs useful information on the signal being analyzed: • Number of packets displayed • Preamble information • Inter-packet gap time • Number of symbols contained in each packet displayed Selecting the Analysis View and Associated Menus Select one of the analysis buttons to bring up the view and controls for that type of analysis.
SPECTROGRAM ANALYSIS This view displays a spectrogram of the input waveform. Forming a spectrogram does not require UWB processing, so you can zoom in on the source (as shown below) to any part of a packet. A spectrogram is a 3 dimensional plot in which the power is plotted on the z-axis, as a color-graded intensity, as a function of both frequency on the vertical axis and time along the horizontal axis. The time scale for the spectrogram is identical as that for the source waveform.
QPHY-UWB Software Option Dynamic Range Dynamic range controls the vertical dynamic range of the signal displayed in the spectrogram. This sets the number of dB down that the black bins are from the peak power bins of the waveform (plotted in red). Values range from 32 to 48. More noise becomes visible in the spectrogram as the dynamic range is raised but subtle low level signal effects can be hidden as the dynamic range is lowered.
POWER SPECTRAL DENSITY (PSD) ANALYSIS The power spectral density analysis does the following: 1. Performs a packet detect to identify and isolate the individual packets 2. For each packet: o Performs a correlation on the sync preamble of the packet with the expected preamble symbols to determine a first order timing reference and frequency offset. o Use timing information to determine exact locations of symbols.
QPHY-UWB Software Option Modifying the Symbol Timing Window In some radios the switching of the carrier may happen a little late causing excessive carrier leakage into the next symbol out-of-band spectrum. The WiMedia C&I specification allows the FFT gate timing to be offset in order to minimize such prior symbol carrier leakage. The Start offset adjustment is provided for this purpose.
Mask Pass/Fail View This view displays the power spectral density of the active bands in the selected band group and tests the limits against the specified masks. Test result passes if the signals do not violate the corresponding masks. Red circles highlight the areas of mask violation. If there are no violations and the test passes full, then “(Q1 &Q2 &Q3) = True”.
QPHY-UWB Software Option Adjacent Channel Power Ratio (ACPR) View Click on the ACPR values button to switch from the Mask pass/fail view to the ACPR values view. This view shows the pass/fail limit testing on the Adjacent Channel Power Ratio parameters. Each of the six displayed ACPR parameters measures the power ratio between the transmitting band and the two adjacent bands. Test limit is the same for all six channels and equal to 20 dB.
BAND POWER ANALYSIS This analysis shows the power of the symbols in each active band, in dBm, in P1, P2 and P3; and the power of all the symbols in P5. In TFC 5, 6 and 7 only one band is active so only one of P1, P2 and P3 will be shown, and the value in P5 will be the same as that value because all the symbols were in one band. Similarly for TFC 8, 9 and 10 two of P1, P2 and P3 will be shown.
QPHY-UWB Software Option ERROR VECTOR MAGNITUDE (EVM) & CONSTELLATION ANALYSIS This view offers a simultaneous display of: • A time-based display of the complex FFT I and Q samples from each symbol plotted in subcarrier order for each symbol with successive symbols in time order. The I and Q subcarrier samples within a sample are plotted spread over a time equal to the symbol duration.
Real and Imaginary Waveforms (I and Q components) These two waveforms are the result of the discrete Fourier transform (DFT) processing, and display the Real and Imaginary components of all the tones contained in each symbol. The points in these traces are the same as the points in the constellation. These traces have horizontal axis units of time, but 112 points from each symbol are from the same symbol (the same time); i.e., the time scale is # symbols * symbol duration.
QPHY-UWB Software Option The sdev value, because it is shown in the same units as all the values, requires a word of explanation. But first, please note that this measurement has not much value in considering sdev as it’s not required by the test. Linear units must be averaged to find the mean and the sdev. Then both are converted to dB. Sdev reflects the distribution of EVM values from different packets. It is expected to be much smaller than EVM, as shown.
When EVM is computed, the frequency of the signal has been matched; that is, the overall slope of CPE from start to end of each PSDU has been eliminated. Therefore it is only variation of CPE from symbol to symbol that is filtered and causes degradation of EVM values. The inclusion choices are: For compliance testing the appropriate choice is Data and Pilot Tones. Selected Tone In each symbol, there are (-61 to + 61) tones. Tones +/- 5, 15, 25, 35, 45, 55 are pilot tones.
QPHY-UWB Software Option MAGNITUDE AND PHASE ANALYSIS This view displays the Real and Imaginary components (Magnitude and Phase) that result from the DFT processing of the UWB signal after down-converting it to baseband: Selecting a Specific Packet and Symbol to Display You can select a specific packet and the symbol of interest within one specific packet. The default value is packet 1, symbol 43 (beginning of User data) within the packet.
Selecting Subcarrier Types to Display Pilots Only (Magnitude and Phase Traces) There are 12 pilot tones in each symbol (located at ± 5, 15, 25, 35, 45, 55 of the DC center point). When Pilots only is selected, each one of the traces (Magnitude and Phase) displays one data point at each pilot tone. This is a particularly useful view for high data rate signals which use Dual Carrier Modulation.
QPHY-UWB Software Option Setting the Trace Style This control sets the style of the Real and Imaginary plots as either Points only (default) or Line (straight line interpolation between points).
COMMON PHASE ERROR (CPE) VERSUS TIME ANALYSIS This view shows how the Common Phase Error of the carrier frequency of each band in the band group which is used for the selected TFC varies over time, over the Header and the PSDU. This view does require UWB processing to be done, so an entire packet (starting from the beginning, including at least 200ns of the inter packet gap) must be seen.
QPHY-UWB Software Option AUTOMATING UWB MEASUREMENT TAKING WITH QUALIPHY Download the QualiPHY program from the LeCroy website in order to automate test measurements and produce test results reports. As long as the option key that enables the QPHY-UWB package is installed in the oscilloscope, QualiPHY will work. Refer to the QualiPHY Compliance Test Software Operator’s Manual for instructions on how to install the software and operate it.
boxes under the Test Selector tab. Note that in order to control which TFC values you want in the test sequence you need to edit the variable called TFC accessed under the Variable Setup tab. Generating a Report At the end of the test a dialog will ask what type of output report you want. A readable report can be produced in either HTML or PDF format. An XML output can be used if you want to transfer the data into a database program such as Microsoft Access.