DSMJ i new countries?

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DSMJ i new countries?

Postby errsemr » Wed May 26, 2010 8:21 am

I have read with great interest your article "JR Now Pushing Its Frequency Hopping System" (http://rcmodelreviews.com/dsmj.shtml) that says JR now pushes DSMJ rather than DSM2 in UK and other countries. I'd be happy if you could give some references as I was unable to verify that claim myself. Searching for DSMJ on http://www.macgregor.co.uk/ turned up nothing.

If true, this would be a bad message to send to current and potential customers. Lack of compatibility between brands is bad enough as it is. If JR (or anyone else) introduces a transmitter that is not compatible with the receivers their current customer base has, then that would tell current and future customers to be careful about buying said brand. Some of the good reasons to buy JR/Spektrum are the rich selection of receivers at competitive prices, large second hand market and lots of people and shops around familiar with the technology. Changing to an incompatible technology would take away those good reasons and make people more inclined to buy another brand or stay with FM. Current customers would probably feel deceived for some time.

You mention "lock-in" but this could as well be a "lock-out" :)

Of course, I think it would be technically possible to make transmitters that support DSM, DSM2 and DSMJ, selectable for each model. Apparently new models coming out are firmware upgradable (JR 11X, Spektrum DX8 and DX10 all have SD card slots, presumably able to carry firmware upgrades). That should make everyone (except perhaps competitors) happy.

Like you, I think it is less likely that US will see DSMJ. The main reason for introducing DSMJ in Europe would be to get around the rules in EN 300 328 that prevents non frequency hopping systems from using more than 10mW eirp. DSM2 which hops between two frequencies only is not considered frequency hopping by those rules. US rules does not discriminate DSM2 the same way. There is therefore less motivation to introduce DSMJ on the US market.

Googling for EN 300 328 1.8.1 turns up some interesting information. If I get this right Europe is about to allow non frequency hopping systems to use 100mW if the transmitters listen before they transmit. As you know, DSM2 systems listen for idle channels before selecting which ones to use. Perhaps that would weaken a large market for DSMJ? I'd be happy if some competent person could write an article on EN 300 328 1.8.1 and its implications for RC.

Please keep us informed as DSMJ gets introduced on new markets!
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