A Merry Chrismas Video to you from BRL Test Staff

Ando AQ6317B Optical Spectrum Analyzer for WDM, LD, LED and FBG. Diverse and Accurate. On Sale at BRL Test for $11,900

Sales and Repairs of Ando AQ6317B at BRL Test.

BRL Test is your optical spectrum analyzer headquarters for sales and repairs.  We've got Ando, HP, Agilent and more.  The Ando AQ6317B is an accurate, diverse and respected instrument.

Click here for data sheet and quote forms at BRLTest.com
Call your BRL Test representative today to lock in on big savings.  407-682-4228

● Wide dynamic range for 50 GHz WDM-Signals
The dynamic range is 70 dB at peak ±0.4 nm, and
60 dB at peak ±0.2 nm.
High-resolution measurement achieves wide dynamic
range with 50 GHz spacing WDM system.
● High wavelength accuracy
Provides ±0.02 nm wavelength accuracy at 1520 to
1580 nm, and ±0.04 nm at 1580 to 1620 nm, with
±0.01 nm wavelength linearity, making it especially useful
for high-precision loss wavelength characteristics and
other evaluation of WDM devices.
The wavelength scale indicates both in air and in
vacuum.
● High wavelength resolution
Achieves wavelength resolution of 0.015 nm.
● Versatile analysis functions
Analysis functions for WDM and other optical devices
(LD, LED, FBG, etc.).
● Synchronous sweep
In conjunction with an AQ4321 Tunable Laser Source,
much higher wavelength resolution/wide dynamic range
can be achieved by high-speed synchronous sweep.
● High sensitivity
High sensitivity allows measurement of light at down to
-90 dBm, covering from 1200 to 1650 nm.
● Low polarization dependency
Measurements such as gain of optical amplifier can be
proceeded accurately because polarization dependency
is suppressed as low as ±0.05 dB.
● High-level accuracy
Accurate within ±0.3 dB.
● High power measurement: Max. +20 dBm
(100 mW)
Even high-power output from an optical amplifier can
be measured directly without an optical attenuator.
● 9.4-inch color LCD
● Pulsed light can be measured
● Three individual trace memories

How to Fix Common EMC Problems

Martin Rowe -September 17, 2014

"I keep running into the same EMC problems over and over," EMC Engineer Kenneth Wyatt told an audience of some 40 engineers at a meeting of the Greater Boston IEEE EMC Society. The meeting took place on September 16 at the Bose Corp. headquarters in Framingham, Mass.

"EMC problems appear because many designers don't understand how to design for EMC," said Wyatt. He then spent 90 minutes discussing the causes of EMC problems such as gaps in return planes, cable resonance, shielding, and bonding as well as troubleshooting techniques and tools. Many of the topics Wyatt discussed are covered in The EMC Blog and in his new book EMI Troubleshooting Cookbook for Product Designers: Concepts, Techniques, and Solutions.

Gaps in return planes are one cause of the common-mode currents that produce unwanted emissions. Why? Because current returning to its source has to go around gaps, which lengthens the return path and enlarges the loop that current has to travel. In the video below, Wyatt explains where gaps occur, the emissions problems they cause, and what to do about them.

Wyatt then showed some examples of products that failed compliance tests and why they failed. Take LCD panels, a common problem. There are often gaps between the displays and their enclosures, which can let radiated energy escape. Figure 1, from Wyatt's presentation (download slides) illustrates the problem.

Wyatt explained why LCD displays can be a source of unwanted emissions because LED drivers use LVDS (low voltage differential signaling), which clocks the data at rates approaching 500 MHz and use fast edge speeds. These high frequency, fast edges, tend to couple common-mode currents onto the display cable and housing, which creates emissions that can escape from gaps between the display and enclosure. This is especially true as the length of the gap approaches a half wavelength of a harmonic frequency.

 

Figure 1. Unwanted emissions can escape from around LCD displays.

Poor bonding of cable through enclosures is another problem. Wyatt showed an industrial application where not only wasn't a cable shield connected to a return or reference location, but cables were routed through an enclosure, leaving gaps. Furthermore connectors used for other cables weren't properly connected. That is, connector shells didn't have solid connections to the enclosure. These and other issue can let emissions from clocks and digital circuits out or let outside emissions in.

Wyatt then demonstrated some of the concepts using a Rhode & Schwarz RTE 1104 oscilloscopewith FFT analysis and near-field probes. Figure 2, taken from Gaps in return planes - yes or no?, shows the test setup where he drove two transmission lines—one where the signal traveled over a gap in a return plane and another that didn't— with a digital pulse stream. The harmonics from the emissions were easy to see when the return trace passed over a gap.

Figure 2. A near-field probe and an oscilloscope using an FFT show how a gap in a return plane can create emissions when carrying digital signals.

To close the presentation, Wyatt showed some of the tools and equipment he uses to troubleshoot EMC problems, be they emissions or immunity. His toolbox included

• Loop probes
• Current probes.
• Log-periodic antennas made from PCBs
• RF generators and circuits that generate test signals such as a chattering relay.
• Gaskets, filters, batteries, connectors, and cables
• Several handheld spectrum analyzers. The EMC Blog contains reviews of these and other troubleshooting products.

The evening even had a mini-trade show. Tektronix was there with the MDO4000 and MDO3000mixed-domain oscilloscopes.

Würth Electronik had a table of EMI filters, chokes, ferrites, and connectors. The company held a raffle at the end of the night, giving away two books and a product kit.

Antennas for EMC EMI - BRL Test has Biconical Antennas, Log Periodic Antenna, Tuned Dipole Antennas, Loop Antennas, Horn Antennas, Waveguide Horn Antenna and Active Monopole Antennas

Antennas for EMC EMI - BRL Test has Biconical Antennas, Log Periodic Antenna, Tuned Dipole Antennas, Loop Antennas, Horn Antennas, Waveguide Horn Antenna and Active Monopole Antennas

	AB-900	Com-Power	30 - 300 MHz Biconical Antenna	$1,029.00
	ABF-900	Com-Power	30 - 300 MHz, Biconical Antenna	$1,750.00
	ABM-6000	Com-Power	1 to 6 GHz, Biconical Antenna	$3,450.00
	AL-100	Com-Power	300 MHz - 1 GHz, Log Periodic Antenna	$1,250.00
	ALP-100	Com-Power	300 MHz - 1 GHz ,Log Periodic Antenna	$1,820.00
	ALC-100	Com-Power	300 MHz - 1 GHz, Log Periodic Antenna	$1,250.00
	AD-100	Com-Power	30 MHz - 1 GHz, Tuned Dipole Antennas	$2,425.00
	AC-220	Com-Power	30 MHz - 2000 MHz, Combilog Antenna	$3,375.00
	AL-130	Com-Power	9 kHz to 30 MHz, Loop Antenna	$2,375.00
	AH-220	Com-Power	200 MHz - 2000 MHz, Horn Antenna	$6,195.00
	AH-8055	Com-Power	800 MHz - 5 GHz, Horn Antenna	$4,800.00
	AH-118	Com-Power	1-18 GHz, Horn Antenna	$2,830.00
	AHA-118	Com-Power	1-18 GHz, Horn Antenna	$6,600.00
	AH-826	Com-Power	18 - 26.5 GHz, Double Ridged Waveguide Horn Antenna	$1,875.00
	AH-640	Com-Power	26.50GHz - 40 GHz, Horn Antenna	$1,775.00
	AH-840	Com-Power	18 GHz - 40 GHz, Double Ridged Waveguide Horn Antenna	$4,025.00
	AM-741	Com-Power	9 kHz - 30 MHz, Active Monopole Antenna	$2,060.00

Thank You!!!

Sensors Everywhere, Privacy Nowhere Says Purdue Prof

	By Steve Tally, tally@purdue.edu West Lafayette, IN — Just as we are coming to grips with having less privacy in our lives thanks to the Internet, a new use of the technology is poised to present new questions about security and privacy, and create a new threat to society. Eugene Spafford, professor of computer science at Purdue University and executive director of the Center for Education and Research in Information Assurance and Security (CERIAS), says the so-called "Internet of Things" will see small microprocessors and sensors placed seemingly everywhere, and these devices will collect much data about us, often without our knowledge. "Instead of a small number of scholars recording data, we will soon have millions and soon billions of tireless digital observers recording everything within reach, and storing it forever," Spafford says. "The benefit will be better decision making about many aspects of our lives, such as energy use, decisions about our health and financial decisions. The downside is that we give up a lot of our privacy, and, in fact, maybe all of it." Ubiquitous Internet microprocessors will soon be in things we encounter every day. Spafford says examples are already appearing. "We have the Nest thermostat, which does a better job of learning how we like to heat or cool our homes than previous thermostats, and we are beginning to see Internet-connected refrigerators, which can let us know when we need to buy groceries and pull together a shopping list for us," he says. The problem is that consumers have little or no control about how the data collected will be used, or even knowledge about what data is being collected. "We put ourselves in a position where we may be manipulated without our consent, and possibly without our knowledge, because connections may be drawn on this data that we don't understand or recognize even about ourselves," Spafford says. "For example the company that makes the Nest thermostat was purchased by Google. Now Google will know when I'm home, can determine how many people are in the house, and that information will be provided to other companies and government agencies. Is that a trade I'm willing to make? To what extent can I control that?" Spafford says what is needed is consumer information equivalent to the drug information that is packaged with each medication. "We need a notice of the level of some of these observations, and which of these observations should we be allowed to opt out of. There needs to be greater transparency about what is done with the information that's collected, the accuracy of the data and where it's going," he says. A second concern with the Internet of Everything is that we may have already crossed a threshold where a large event that would cripple these devices would mean that our current civilization would come to an immediate stop. "Our telephones wouldn't work, hospitals would not be able to do medical tests, at the university we wouldn't be able to post grades," Spafford says. An occurrence of a massive solar flare, like the 1859 Carrington Event, could disable all of these devices. "If something like that were to happen, the Amish would become the only people without a major life upheaval," Spafford says. Info: spaf@purdue.edu

Happy Halloween from BRL Test!!

Happy Halloween from BRL Test!!

Transmission Line Probes Picotest P2100A, P2101A Sales at BRL Test

Transmission Line Probes Picotest P2100A, P2101A Sales at BRL Test

	P2100A		1 Port PDN Transmission Line Probe, Accessory Kit, One DC Blocker	$1,495.00
	P2101A		2 Port PDN Transmission LIne Probe, Accessory Kit, One DC Blocker	$2,495.00
	P21B01		PDN Probe Bundle (1 Port and 2 Port Probes), Accessory Kit, Two P2101A DC Blocker	$3,495.00

The 1-port probe, being a unity gain wide bandwidth probe, allows the measurement of ripple and noise with optimum signal to noise ratio (SNR).  The 2-port probe can be used to transmit a load current step through one port, while measuring the response from the other port, simultaneously.  The probes can both be used to inject noise for the assessment of sensitivity to the power supply for sensitive circuits such as clocks and LNAs. The probes are supported by a wide range of signal injectors and accessories, such as DC blockers, preamplifiers, and high speed current injectors.

The high-bandwidth (DC-1.3GHz), variable-pitch probe tip design enables accurate impedance measurements for high-speed PCB development and manufacturing. It eliminates the need for soldering SMA cables to your board and the risk of damaging fine copper pads or pulling up small components. You can get connectivity to circuit boards and devices without connectors.

The probes are compatible with all equipment including VNAs, oscilloscopes, and spectrum analyzers and come with an accessory kit (see above photo) that includes a variety of probe tips and lead extenders, as well as, a DC blocking device. The probes are also designed to work with the Picotest J2180A low noise preamplifier to improve signal to noise performance and the J2102A common mode transformer which eliminates the DC ground loop.

What’s a Transmission Line Probe

Transmission line probes are a special type of passive probe that replaces the high impedance probe cable found in a traditional passive probe with a precision transmission line, that has a characteristic impedance that matches the oscilloscope’s input (50Ω). This greatly reduces the input capacitance to a fraction of a picofarad, minimizing the loading of high frequency signals.  The probes are referred to as  ‘PDN’ probes, because of their effective use in measuring the low and ultra impedances found in power distribution networks.

The input impedance of the Picotest probes remains nearly constant over their entire frequency range. A traditional ÷10 passive probe has a high input impedance at DC, however, this impedance drops rapidly with frequency, passing below the input impedance of a transmission line probe at <100MHz. The probes are useful in applications that produce fast rising, narrow pulses with amplitudes which exceed the dynamic range of active probes. They also tend to have less parasitic effects on frequency response and so they are ideal for measuring impedance.  By providing a simple yet elegant solution to probing high-frequency signals, Picotest’s one and two port transmission line probes preserve signal fidelity and allow high-bandwidth test equipment to properly measure circuit characteristics.

Impedance Demands New Probe CapabilitiesHigh speed applications put pressure on the measurement of power supply busses to unprecedented frequencies. As an example, the measurement of power distribution network (PDN) impedance for FPGAs generally requires the measurement of impedance levels in the milliohm scale at frequencies exceeding 1GHz. Measuring the high speed step load response in power systems using 2-port impedance is difficult because of the need to connect two 50Ω transmission lines to the output capacitor.  Compounding this difficult task is that these measurements often need to be made in very small circuits such as cell phones, solid state disk drives, and computer tablets; to name just a few examples.