Radiometrix Ltd.

United States

Radiometrix Ltd.

United States

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Dormer M.,Radiometrix Ltd.
Electronics World | Year: 2012

Any electronic system using non-steady state signals will, by definition, radiate wide-band noise, covering tens or hundreds of MHz. This 'radio frequency effluent' is usually within the legal RFI limits for the device, leaving no recourse to complain to its supplier or the regulatory bodies, but is still more than sufficient to noticeably de-sense any radio link located within a couple of meters of the device. Identifying this form of interference is quite easy, once you know what to look for. It is rarely possible to see such signals on spectrum analyzer/wide-band aerial setups so elimination tests are the best way forward: A typical narrowband receiver might have a working sensitivity of -120dBm. Assemble a 'range comparison trial' prototype, using the same radio link, data structures and aerial but without the customer's digital hardware.


Dormer M.,Radiometrix Ltd
Electronics World | Year: 2010

Myk Dormer shares his views about the latest developments appearing in the low-power radio module market. It has been observed that the simpler section of the market is being rep aced by the improving range of single chip radio devices, offered by a number of silicon vendors. These devices offer the non-RE specialist engineer a good opportunity of implementing a workable, cost-efficient, wireless link without recourse to a module. These devices are presented in the familiar radio module formats, but consist internally of one of the major-vendor radio chips, along with a frequency reference part and some decoupling. Myk Dormer suggests that a properly designed module offers reliability, ease of use, rapid time to market, and superior RE performance.


Dormer M.,Radiometrix Ltd
Electronics World | Year: 2010

Myk Dormer, Senior BE Design Engineer, Radiometrix Limited, shares his views on the low data rate transmission. A given module is capable of transmitting a 128kbit/s data stream then it is inherently superior to a unit operating at, such as 5kbit/s. For radio links, in the simplest sense, data rate, transmit power and operating range constitute three competing factors within which the design must find a compromise. Short range radio modules offer 64kbit/s or higher data speed while large, expensive radio modems increase transmitter power to push 5 to 10 kbaud data streams 5km or more. Basic communications theory predicts a 3dB improvement in S/N (and hence signaling sensitivity) with each halving of the signal bandwidth. A basic data communication link, typical of simple ISM band practice, was assembled. A simple program running on the lab PC generates (and displays) a constant sequence of eight byte test transmissions.


Dormer M.,Radiometrix Ltd
Electronics World | Year: 2010

Myk Dormer, Senior RF Design Engineer at Radiometrix Ltd. defines the global recession or the credit crunch on the low power wireless market. The generally weak linkage between this industry area and the financial/consumer sectors provided a degree of insulation. While the market for low power wireless devices has not completely collapsed, order levels are down and scheduled or repeat orders are being postponed, delayed or canceled. This, in turn, has reduced the immediate income of what are in this industry area generally small-to-medium sized manufacturers, forcing economies in both staffing and capital investment. While the current depressed state seems fairly stable as the market begins to reinstate and order levels rise, there are a few effects that must be watched. The industry must minimize the long term damage caused by external conditions and directives, by using part time working. Customers should anticipate longer than usual lead times.


Dormer M.,Radiometrix Ltd.
Electronics World | Year: 2010

Techniques employed for the increased sensitivity of ISM band radio modules are discussed. A reference link is established using a simple biphase remote control chipset (CTR44, operating at 1kbit/s) and a -120dBm sensitivity receiver. Reliable signaling is observed at -122dBm signal level while halving the data speed yields a 2dB gain in performance. A simple modification is made to the receiver, connecting the data extractor to the RSSI output instead of the discriminator, which results in a simple OOK receiver. The improvised receiver at 250bit/s could reliably operate at -125dBm, while a 30 bit per second test responds at -127dBm, although the response time of the system is several seconds. The use of squarewave modulation waveforms at very low modulation frequencies, where the deviation is several orders of magnitude greater than the baseband rate ensures that the spectrum of an FM signal resolves to a pair of carriers, at ±F(dev).


Dormer M.,Radiometrix Ltd
Electronics World | Year: 2010

Most modules will draw a fairly constant current, irrespective of the voltage, but a few will employ much more efficient switching supplies, which draw a constant power. Unfortunately, it also suffers periodic glitches, interruptions and brown-outs and, most damaging of all, it can suffer alternator load dump transients of 45-60V or more for several milliseconds. Frequently, the easiest solution is to build-in a separate voltage regulator to provide a cleaned-up, safe supply rail for the radio. Many semiconductor suppliers have parts specifically rated for automotive applications and there are some effective 'supply conditioning' modules available. Allow adequate current capacity and sufficient voltage headroom, over all possible operating conditions. Supply issues are easier to diagnose than some of the more awkward RF related faults.


Dormer M.,Radiometrix Ltd.
Electronics World | Year: 2010

Myk Dormer, Senior RF design engineer at Radiometrix Limited shares his views on the engineering. According to him, financial organizations that can see beyond the next month's profit figures and who can understand the need for a company to invest in its future. Suppliers who manufacture sufficient numbers of their products for the demands of their market, so shortages and allocations are occasional accidents, rather than a regularly used technique to hold artificially high prices and excuse long lead-times. Sales and marketing executives who treat a new design as a new possibility for valuable new orders, rather than looking on it as an attack on their self-created, comfy, well-ordered, artificial, little worlds. A reliable, easy to use desktop computer which, when replaced by a model with twice the memory and four times the processing newer.


Dormer M.,Radiometrix Ltd.
Electronics World | Year: 2011

Myk Dormer, Senior RF Design Engineer at Radiometrix Ltd., examines wireless networks from a different perspective. He suggests that it is better to look at such networks from first principles where the simplest possible data communication system will be a link between two radios. Information is coded to produce a viable baseband signal, which is transmitted between the radios, and demodulated and decoded to recover the original data at the receive end. The information can be a continuous data stream but it is expected to consist of discrete 'packets' of data, including synchronization sequences and error handling codes, such as checksums, and address information. It is essential to remember that a point to point link is necessarily limited by the range of the radio link hardware used, and that there will be absolute limits to the range of the basic radio link in any given situation.


Dormer M.,Radiometrix Ltd.
Electronics World | Year: 2012

Myk Dormer, senior RF design engineer at Radiometrix Ltd., explains the term duobinary, which is a public domain technique. It is the coding technique used in the audio/data channels of the D2-MAC digital TV broadcasting standard. It is used in some fibre optic systems; and in certain magnetic recording formats. It is sometimes, possibly inaccurately, also referred to as alternate mark invert coding. Recovering a duobinary stream is also easier, as there is no requirement to generate and decode bit pairs, or to realize accurate inverse-Gaussian filter shapes. It provides the bandwidth compression of four level coded two bits per period for a three level code, with the obvious improvement in S/N. It offers a degree of inherent error detection, in that the sequences 0U0U and 0D0D.

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