Heblo Everybody I've just read through Dane's review of the DigiTech AR1946 multiband receiver. I wanted to make some comments frimarily to him, but maybe others might find them useful too. I hope from the outset that my comments will be taken in the spirit of constructive feedback on an article which, refreshingly, was the work of the original sender.
Firstly, Dane makes comment regarding the telescopic antena. He puts much emphasis upon the "length" of the tubes, for want of a better description. Dane then goes on to state that the antenna is "thick". Actually, Dane, I think you will probably find that these two elements can be said to compensate for one another. Most likely, inside the tubes will but a spring-like coil of thin single-core feeder. Usually, the telescopic design is used in high-end radios to house the actual antenna, rather than functioning as the antena itself. Although sometimes it serves both purposes. In this case, in all probability, the coil will be an "air coil", whose dimentions have been customised to suit a multi-band antenna design. The problem with this kind of receiver is exactly that. In order to produce an antenna which resonates in a multi-band environment, the user should normally experiness with the antenna, adjusting both the polarity of the antenna and also extending and destending it to find the best performance on the band in use at the time. It is a common mistake that many people make to presume that pulling the antenna fully up and just leaving it in a vertical orientation will work best for all bands. That is actually rarely the case. Neither is the assumption that the antenna will produce inferior performance to a "longer" or "larger" antenna correct. Non-Resonance of an antenna at a given frequency usually manifests itself as noise and weak signal. It's actually amazing how much one can improve an internal antenna's performance with a given signal and at a given frequency by adjusting the antenna by use of the old-fashioned, but still very effective knuckle-jostt at the base of the antenna. So, my suggesttion, for whatever it's worth to you, would be to experiment with specific signals to try and obtain the best results. A receiver's sensitivity can often be dramatically improved by the correct orientation of the antenna. In point of fact, that is a crucial element with any RF device, whether a transmitter or a receiver. The environment of these devices is usually another vital factor in its performance. Sadly, those people who design devices like computers, particularly those housed in cases which offer no screening from RF emmission, can also play a huge part in a receiver's performance. I'm sure you'll have encounteded this factor many times before now. You and I, Dane, have discussed this topic many times privately. The technologies used here in the UK are quite different to those used in Australia, New Zealand, the US and Canada. I think that each system presents it's own challenges and it's own plusses. Although we over here use very different frequencies to those used where you are, probably primarily for topographical reasons. I'm certainly not trying to suggest that ours is superior, because there are undesputed advantages to each. In our case, the technologies we use allow the broadcaster to play "nanny". This is necessary because of licensing restrictions which every broadcaster must abide by. We use a system known as "multiplexing". Each transponder on a multiplexer can handle 6 signals. Thus, Although to the listener, when tuning a digital radio or TV station, it appears that the radio or TV is changing frequency as with a traditional annalogue transmission, what is actually happening is that the receiver simply changes from one multiplexer or transponder to another. Thus, it is possible to compress a DAB signal alongside other signals, and the receiver simply decompresses the signal and we hear or to ee the results. Your system is quite different, as you know. In point of fact, I don't profess to fully understanding the technical methods your systems use, and that is why I make no claims whatsoever as to which system wins the battle. I am very well aware that geographical and topographical factors play a large part in governing the most advantageous systems for use in that kind of environment. I can certainly see many advantages to your system, not the least of which is the capacity for far greater bandwidth of a signal, thus DAB+ becomes a reality. But anyway, I may very well go and research this radio, as it may help me to solve a longstanding problem here. ============================== My Compliments And Kindest Regards Gordon Smith 'Accessibility And Information Technology Support Specialist ------------------------------
