Page 35

EETE APR 2014

Follow-us on @EETimesEurope Effective methods for dealing with interference The first requirement in dealing with interference problems is to locate and identify the source of the interference, whether it be CCI, PIM, a jammer, or (in the case of digital video broadcast) LTE transmissions. Many types of RF test instrument can potentially be used for this. Dedicated interference detection equipment, however, will save the user a great deal of time, because of the precision with which it locates and analyses the source of interference. For PIM problems, the Anritsu MW8219A PIM Master is ideal: it can generate two tones of up to 40W into the transmission system, and measure precisely the occurrences of passive intermodulation. Its ‘Distance to PIM’ feature lets the user exactly locate the source of the interference. The MA2700A Interference Hunter is equally helpful for other kinds of interference. Once located, the interference can normally be eliminated easily. In the case of DVB-C broadcasts, filtering is ineffective because the technology uses overlapping frequency bands. The correct approach here is to specify the receiver, cables, modem and other components with high resistance to interferers. As for DVB-T, it can be helpful to replace an omni-directional antenna with a uni-directional antenna (the smaller the beam width, the better). This is not a guaranteed fix: it will make no difference if the LTE base station is located in the same direction as the DVB-T transmitter. And in general, the best cure for interference is prevention: using excellent components and installing them properly eliminates almost all risk of interference. But since no real-world operation is ever perfect, it is useful to know that precise and accurate instruments are available that will quickly find the source of an interference problem when it occurs. Bus analyser examines detail of CAN bus loading The PCAN-Diag from PEAK-System Technik GmbH is a handheld device for the diagnostics of CAN busses on OSI layers 1 and 2. With updated firmware now at version 1.7, the device acquires new features; it now displays the busload associated to the transmission of error frames. This is done in a split view parallel to the busload caused by regular CAN frames. If the oscilloscope function identifies the sampled signal stream as a CAN frame, the report function shows detailed characteristics of that frame, enabling users to draw conclusions about the CAN network. Two display modes are now available for multiplexer variables: Either all variables of a multiplexer are shown together or they are displayed separately for each multiplexer state. Software is available for download from PEAK-System’s website that contains the firmware 1.7.0, device Help, Windows tools for the PCANDiag, and documentation. PCAN-Diag displays data traffic from a connected CAN bus in a basic manner in hexadecimal format as well as in symbolic form. It also transmits CAN messages for maintenance purposes. For a later review of the data stream, there’s a trace function for recording. When faulty communication occurs, the diagnostics can be refined with busload measurements or, on hardware layer, with termination and voltage measurements. Peak-System www.peak-system.com www.electronics-eetimes.com Electronic Engineering Times Europe April 2014 35


EETE APR 2014
To see the actual publication please follow the link above