On Tue, Feb 22, 2005 at 02:51:06PM -0700, Daniel Moss wrote: | Can anyone tell me what is meant when a receiver is "Dual Conversion"(DC)? | And are all receives either DC or something else, say Single Conversion? | Thanx
No, there's single conversion. And triple conversion as well, though it's not usually used in R/C receivers. (You see it mentioned more in scanners.) Berg describes the differences between SC and DC a little here -- http://www.bergent.net/SC-DC.pdf. Of course, the article is designed to say why his SC receivers don't suck (as many SC receivers do), but he does explain the gist of how they work too. As a general rule of thumb, most SC R/C receivers suck, with limited range and limited ability to reject interference. This isn't really the fault of the SC design per se -- it's more that when you're trying to make things small and cheap, you tend to gravitate towards SC, as it is simpler. However, there are exceptions. Most JR receivers are SC, and they don't suck. And the Berg receivers are SC, and they don't suck either. There's probably others out there too. DC receivers generally are at least OK. The worst DC receivers are far better than the worst SC receivers, and the best DC and SC recceivers are generally on par with either other. Note that DC and SC receivers take different crystals. This isn't directly related to your question, but I wrote this up for rec.models.rc.air a while back, and it may help answer what your next question may be -- Ultimately, here's the lowdown on single conversion vs. double conversion for you, as simple as I can make it : single conversion: some are bad, some are OK, and some are better. double conversion: just about all are OK or better. Hitec Feather = really bad, single conversion. GWS 4P (and similar) = bad, single conversion. Most PPM JR receivers = OK, single conversion Most PPM Futaba receivers = OK, dual conversion Most PPM Hitec receivers = OK, dual conversion Berg receivers = better, single conversion FMA receivers = better, dual conversion Most PCM JR receivers = better, single conversion (?) Most PCM non-JR receivers = better, dual conversion Got it? :) The `Bad' receivers tend to have bad range, and tend to glitch if anybody else is flying nearby, even on different channels. The `OK' receivers have good range, and generally only glitch if there is direct interference (on the same channel, or only 10 kHz away like might be caused by a pager tower.) The `Better' receivers have good range, and generally do not glitch at all because they discard invalid frames. They are still affected by direct interference like the `OK' receivers, but they handle it better. (Of course, I'm ignoring receivers made before 1991 here because they may not be `narrow band'.) And the real kicker is that the `better' FMA and Berg receivers cost less than the `OK' Futaba and JR receivers, and about the same as the `OK' Hitec receivers. -- Doug McLaren, [EMAIL PROTECTED] Never let school interfere with getting an education. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
