What’s New in Spectrum Analysers

There are general-purpose spectrum analysers, and then there are specialised ones. What kind of a spectrum analyser do you need? The answer to this question basically depends on the maximum frequency range that you want to measure, after including the harmonics and intermodulation products of the wanted signals. Although you can get a lab-grade oscilloscope that can analyse low audio frequencies up to microwave, this is overkill if you are going to use it with audio equipment. On the other hand, if you are working on very high frequencies, you might need an analyser that has a resolution good enough to differentiate between the smaller frequencies.

N9344C handheld spectrum analyser

Some new releases in this space are:
1. Tektronix MDO4000 mixed-domain oscilloscope, which is claimed to be the world’s first oscilloscope with built-in spectrum analyser.
2. R&S FSW-K91ac signal and spectrum analyser, which supports the new IEEE 802.11ac WLAN standard.
3. Anritsu MS2830A + OML MxxHWD, which has a  frequency coverage of up to 325 GHz.
4. Agilent N9344C HSA—an MIL PRF 28800 Class 2 compliant handheld spectrum analyser.
5. Scientech DSA800 Series spectrum analyser, which comes with a wide-screen display and is targeted at hobbyists.

The innovative lot includes:
1. Aronia X-Series USB RF spectrum analyser. Featuring specifications and performance similar to the equivalent Spectran handheld spectrum analysers, these RF spectrum analysers are controlled entirely via the USB interface using the real-time RF analysis software included with every unit.

2. Metageek WiSPY DBX—a pocket-sized tool designed for enterprise-level troubleshooting of WiFi environments. It has an amplitude range of –6.5 dBm to –100 dBm and amplitude resolution of 0.5 dBm. The device features an RP-SMA antenna too.

Purchasing an instrument for spectrum analysis being a major investment, make sure that you buy one that not only meets your today’s requirements but can also cope-up with the demands of tomorrow. With this in mind, selecting the ideal instrument should be a well-thought-out affair, with sufficient inputs from the people who are going to use it. Here are some pointers.

 1 Working with the IEEE 802.11ac WLAN standard?
If your project requires you to work with the upcoming 802.11ac WLAN standard, go for an analyser that is capable of analysing these signals. Although 802.11ac is still being defined, companies that chair the WiFi alliance have already brought out their own solutions using this standard.

The new standard requires 256 quadrature amplitude modulation (QAM), up to eight MIMO data streams, and a higher frequency band, along with wide bandwidths of up to 80 MHz. (The 160MHz bandwidth in this standard is achieved by using 80+80MHz mode.) Moreover, due to the 256 QAM, this standard requires an error vector magnitude (EVM) of -32 dB. The R&S FSW-K91ac tool features a very low EVM of less than -45 dB.


Announced on 20th June this year from Munich, the FSW-K91ac option enables the R&S signal and spectrum analyser to record and demodulate the full bandwidth of a WLAN signal in line with the new standard. It has a 31cm (12.1-inch) touchscreen with MultiView. MultiView provides users with simultaneous view of multiple measurements and applications. Pricing is available only on request.



 2 Spectrum analysers for education and hobbyists
Spectrum analysers for educational use and hobbyists should not only let them experiment with measurement testing but also act as a standard industrial instrument.

The DSA800 series from Scientech includes compact, light-weight and low-cost spectrum analysers that suit the education and hobbyist applications. The digital IF technology of this series helps in radio frequency (RF) applications like measurement of an RF amplifier’s characteristics, measurement of an RF bandpass filter’s characteristics, and measurement of voltage standing wave ratio.

The analysers offer a minimum resolution bandwidth of 100 kHz and are available with or without tracking generator. Their widescreen display, advanced measurement functions, electromagnetic interference (EMI) filter and quasi-peak detector kit, up to -135dBm displayed average noise level, phase noise of -80 dBc/Hz at 10kHz offset, total amplitude uncertainty of less than 1.5 dB, and the capability to interface through LAN, USB host, USB device and GPIB make them suitable for a majority of education and hobbyist applications.

The series comprises spectrum analysers to be used in basic electronics, basis communication, antenna and wireless communication labs.


 3 Millimetre-wave analysers
Millimetre-wave (mm-wave) analysers are intended for spectrum and signal analysis of emerging wideband communication systems. Using new capabilities, engineers can evaluate, characterise and manufacture products designed for emerging wideband standards, such as WiGig, including FCC Part 15 compliance emission testing requirements from 40 GHz to 200 GHz.

The MxxHWD harmonic mixer, based on a single-diode design, is available in waveguide bands from 26.5 GHz to 325 GHz. The harmonic mixer is a two-port frequency extension product with mm-wave interface for device-under-test (DUT) connection. The Anritsu MS2830A signal analyser, when coupled with the OML MxxHWD harmonic mixer, offers mm-wave frequency coverage from 26.5 GHz to 325 GHz.

 4 Radar, electronic warfare, EMI/EMC testing

Rapid advances in radar and electronic warfare technology have created the need for leading-edge testing technology and tools. Robust radar test equipment reduce uncertainty during the design process and deliver confidence in the integrity of increasingly complex designs.

Traditional signal analysers are unable to trigger on transient problems and the maximum available acquisition bandwidth in the mid-range is just 40 MHz.

To capture transients for analysis, Tektronix RSA5000 series offers frequency mask, frequency-edge, density, time-qualified and runt triggers. It can also be used to isolate hard-to-find hardware and software anomalies with cross domain triggering between multiple instruments. It can capture a seamless time record of RF frequencies into deep memory for up to 7 seconds at 85MHz bandwidth.


 5 Built for the field
For this kind of application, you require a spectrum analyser that is rugged, portable and performs well enough to get the job done. Compliance to MIL-PRF-28800 Class 2 is also important. This specification covers the general requirements for equipment used for testing and calibration of electrical and electronic equipment. The test equipment may be of commercial design and include general-purpose, special-purpose, peculiar, console-mounted, automatic test equipment and calibration standards.

The Agilent N9344C handheld spectrum analyser is built for the field. It features a channel scanner that can measure up to 20 channels simultaneously, as well as a spectrum monitor with spectogram display, record and playback. Moreover, it features AM/FM/ASK/FSK modulation analysis and time-gated spectrum analysis, which allows intermittent or burst signal spectrum measurement.

The Agilent N9344C is priced at ` 1,329,530 for the no-frills version, while a typical configuration would cost you ` 1,339,269.

Sourced By: EFY: Author name:  DILIN ANAND

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Seven-Colour LED Lighting Circuit Diagram

Presented here is a simple circuit that uses six red, green and blue (RGB) LEDs to generate a running-light effect in seven colours—blue, green, red, cyan, yellow, magenta and white. The RGB LEDs have four pins, one for each colour and a common cathode. Different colours can be produced by mixing the primary colours (i.e., red, green and blue).

Fig. 1: colours produced by three basic colours

Circuit and working
The circuit diagram for the seven-colour LED lighting is shown in Fig. 2. The circuit is built around timer NE555 (IC1), decade counter CD4017B (IC2), four-bit binary counter 7493 (IC3), driver IC ULN2003 (IC4), six RGB LEDs (RGB1 through RGB6), three BC547 transistors (T1 through T3) along with some basic components.

Fig. 2: Circuit of seven-colour LED lighting

The timer IC NE555 (IC1) is wired in astable multivibrator mode. It provides low-frequency clock pulses, the frequency of which is decided by timing components R1, VR1 and C2. The frequency of the timer can be varied using the preset VR1.

The output of IC1 at pin 3 is fed to decade counter CD4017B (IC2). IC2 has ten outputs, which go high in sequence when a source of pulses is connected to its CLK input (pin 14). Q0 through Q5 of IC2 are connected to IN1 through IN6 of IC4. Pin Q6 of IC2 is connected back to its reset pin 15 and input pin 1 of IC3 via diode D1. When Q6 pin of IC2 goes high, it resets IC2 and, at the same time, provides the high input clock to IC3 each time after the sixth clock of IC1.

IC3 is a four-bit binary counter, and its outputs QB through QD are connected to the bases of transistors T1 through T3 via resistors R21 through R23, respectively. The binary outputs of IC3 make corresponding transistors conduct and select a different colour after each cycle (see Table I).

The common-cathode pins of each RGB LED are connected to the outputs of IC4 as shown in Fig. 2. ULN2003 is used for driving these LEDs. You can add even more RGB LEDs in parallel to the existing ones to make a larger lighting system.

The working of the circuit is simple. When the circuit is switched on, the clock pulse is generated from pin 3 of the timer IC1, making outputs of IC2 high, sequentially, which decides the switching rate of LEDs that can be changed through VR1. The colours are selected by the binary output of IC3, which changes after every sixth pulse from IC1.

Fig. 3: A single-side PCB layout in actual size for seven-colour LED lighting circuit

Fig. 4: component layout for the PCB

Construction and testing
A single-side PCB for seven-colour LED lighting is shown in actual size in Fig. 3, and its component layout is shown in Fig. 4. After assembling the circuit on a PCB, enclose it in a suitable case. You can wire LEDs the way you like and connect on the PCB. The circuit uses a 5V DC supply.

To test if the circuit is functioning properly, check the input supply at TP1 with respect to TP0. The output pulses generated by IC1 can be checked at TP2 with the help of an oscilloscope. The frequency of these clock pulses can be varied by VR1. The clock pulse to the binary counter IC3 can be checked at TP3.

Sourced By: EFY: Author : Riju Thazhathuveettil.

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Simple Headphone Amplifier Circuit Diagram

This is the Simple Headphone Amplifier Circuit Diagram. You can use any NPN transistor. You can drive this circuit with a 9V batery. .

Simple Headphone Amplifier Circuit Diagram

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