Truly handheld RF spectrum analysers!

Aim-TTi have launched a new series of handheld RF spectrum analysers, the PSA Series II. Available in 1.3GHz and 2.7GHz versions, the new instruments are smaller, lighter and have longer battery life than other handheld RF products.

Whereas a typical “handheld” spectrum analyser weighs over 2kg (4.4lb) and is considerable wider than a hand width, the PSA Series II weighs only 560 grms (20oz) and is just 9.2cm (3.6”) wide, fitting perfectly into the hand.

Despite their small size, the analysers incorporate a 4.3” (11cm) backlit TFT colour display with touch screen. A high capacity rechargeable Li-ion battery gives more than 8 hours operation from a charge.

The PSA1302 has a frequency range of 1MHz to 1300MHz whilst the PSA2702 operates up to 2700MHz. Dynamic range is 80dB with a noise floor approaching -100dBm. Resolution bandwidth is selectable down to 15kHz. Sweep modes include continuous, single, peak hold and sweep average. Sweep parameters can be set in terms of centre plus span or start plus stop to 1kHz resolution. A zero span mode with AM or FM audio demodulation is also provided using a built-in speaker.

Dual markers are incorporated with simultaneous readout of absolute amplitude and frequency plus difference values. Markers can be scrolled manually, or set to automatically find or track peaks. Up to three traces can be displayed (Live, View and Reference) clearly differentiated by colour. Traces or complete screen images can be saved to files.

Advanced features include data logging for traces, data points or screen images. Up to 10,000 entries per file can be stored with triggering from a manual key press, internal timer, external trigger, or the limits comparator. The 1.8GB of internal memory enables many large files to be stored.

Limit lines and limit patterns can be displayed with a full limits comparator enabling audible warnings, output pulses, halting of the trace, or entries into logging files. Compensation tables for antennae or other external transducers can be created and loaded.

The instruments have a full filing system capable of storing up to 1,000 each of traces, screen images, set-ups, logging files, limit patterns or compensation tables under auto incrementing names or user-defined names. USB host and device connectors allow the connection of USB Flash drives or direct connection to a PC.

Control of the analyser is provided by finger operated soft keys created on the touch screen. These form a hierarchical menu system that gives rapid access to the menu functions. Alternatively, all functions can be operated using the hard keys alone.

The ruggedised casing incorporates rubber protection buffer and includes a bench stand and screen protector. For bench-top use, the instrument can be operated continuously from its AC charger. For portable use, the long battery life of eight hours can be further extended by selecting auto-off which turns the instrument off after a delay of 5 to 60 mins. from the last key press whilst retaining all data.

The PSA Series II will offer RF service engineers a cost effective and highly portable tool that will make it practical to a carry a spectrum analyser to areas that have traditionally been difficult to access with bench top instruments and not cost effective when using existing portable products offered by other manufacturers. This can reduce the need for a return visit when it is suspected that a spectrum analyzer is required.

Other engineers working on the bench will appreciate the low cost of the products enabling them to justify the purchase of an RF spectrum analyzer for tasks where the cost would have been previously been difficult to justify.

New type of probe measures current in PCB tracks directly

Aim-TTi has launched an entirely new type of current probe which is cable of measuring currents in PCB tracks.

The Aim I-prober 520 positional current probe uses a patented technology to observe and measure current without the need to break or surround the conductor.

Measurement of current normally requires either the insertion of a shunt resistor, or for the conductor to be passed through a closed magnetic loop. Typically this is done using some form of split clamp device. Whereas this is suitable for individual wires, it is of no use for measuring current in PCB tracks.

The I-prober 520 is a compact hand-held probe which is used with an oscilloscope. By placing the insulated tip of the probe onto a PCB track, the current flowing in the track can be observed and measured.

The probe has a bandwidth of DC to 5 MHz and a dynamic range of 10 mA to 20 A peak to peak. It is safety rated to 300 V Cat II (600 V Cat I) and is suitable for connection to any oscilloscope.

The Aim I-prober 520 operates by sensing the field in very close proximity to the track. To achieve a calibrated measurement, the field sensor must be capable of maintaining a precise distance from the track. To achieve good sensitivity this distance must be very small because field reduces with the square of distance (to a first-order approximation).

To create a practical current measurement probe, a very special type of miniaturised sensor was needed. The requirements included very small size with precision dimensions, DC sensing capability, wide AC bandwidth, and low noise. None of the existing sensor technologies used within field and current probes was suitable for this.

Instead, the I-prober 520 uses a patented miniaturised version of a fluxgate magnetometer, developed in conjunction with Cambridge University. It is the patented miniaturisation that enables it to measure the field at a precise point in space. In addition, the miniature sensor has much lower noise and much wider bandwidth than a conventional fluxgate magnetometer.

As well as measuring currents in PCB tracks, the probe can be used on component leads or any other current-carrying conductor. An interesting example occurs in ground planes, where it can be used to observe circulating currents, interference injection points and “hot spots” in order to optimise design.

The Aim I-prober 520 is supplied with a control box and calibrator, power supply, and a clip-on toroid assembly which can convert it into a convention closed magnetic loop current probe.

Wide range RF signal generator has microhertz resolution

SRS (Stanford Research Systems) has introduced a DC to 4 GHz signal generator that uses a unique and innovative architecture to deliver frequency resolution down to 1 µHz.

A technique known as rational approximation frequency synthesis enables the new instrument to deliver ultra-high frequency resolution, excellent phase noise, and versatile modulation capabilities at a fraction of the cost of competing designs.

The SG384 offers a wide variety of modulation capabilities including amplitude modulation (AM), frequency modulation (FM), phase modulation (ØM) and pulse modulation. There is an internal modulation source as well as an external modulation input. The internal modulation source produces sine, ramp, saw, square and noise waveforms. An external modulation signal may be applied to the rear-panel modulation input.

The generator comes with an oven-controlled crystal oscillator (OCXO) timebase. The timebase uses a third-overtone stress-compensated 10 MHz resonator in a thermostatically controlled oven. The timebase provides very high stability of 0.002 ppm low phase noise and very low aging. An optional rubidium oscillator may be added to reduce frequency aging still further and to improve temperature stability.

Optional I/Q inputs allow I and Q baseband signals to modulate carriers from 400 MHz to 4.05 GHz. This option also allows the I/Q modulator to be driven by an internal noise generator with adjustable amplitude and bandwidth. Rear-panel outputs allow the noise source to be viewed or used for other purposes.

Remote operation of the generator is supported with GPIB, RS-232 and Ethernet interfaces. All instrument functions can be controlled and read over any of the interfaces. Up to nine complete instrument configurations can be saved in non-volatile memory.

The SG384 is available in Britain through TTid (Thurlby Thandar instrument distribution) who represent all engineering test and measurement products from SRS.