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| | #255 (permalink) | ||||||||||||||||||
| Low Altidude ![]() Join Date: Nov 2006 Location: Costa Mesa, Calif Age: 59
Posts: 38
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Pete (with tongue in cheek) | ||||||||||||||||||
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| | #257 (permalink) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Hey y'all, watch THIS! ![]() Join Date: Feb 2006 Location: Raleigh, NC Age: 51
Posts: 995
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For PPM, the information transmitted is in the form of a serial pulse stream. First, there is a reset pulse that is 2.5 or more milliseconds long. This is the pulse that syncronizes the receiver with the transmitter. Then, for every channel, there is a pulse, the width of that pulse (normally from 1 to 2 milliseconds wide) determines the position of the servo for that channels. So, for an 8 channel radio, the pulse stream could be as long as 20ms. The servo positions can't be updated any quicker than about 20ms. Enter PCM, where the servo positions are digitized and the servo position information is encoded as binary data, 10 bits per channel (for a 1024 system). I don't know the format of the PCM data stream, but I have heard that the original PCM systems transmitted in two frames, with half the channels in each frame, and the update rate was longer than 20ms. I have also heard that some newer PCM systems give priority to channels that have changed positions (no need to transmit data as often if it has not changed). I don't know this for a fact, however, but it does make sense. This would be the best way, IMHO, to improve latency. This requires a variable frame format so that different channels can be sent at any time. I suspect this is how the "servo grouping" option works, where both aileron or both elevator servo positions can be grouped together and sent at the same time (in the same frame) so that one aileron or elevator channel will not lag behind the other while moving positions. Probably the main reason that newer PCM formats have improved latency is because of data compression or the variable frame format I mentioned above. I'm not sure. But, those kinds of improvements in technology have been made possible because of the improvement in processing speed of the microprocessors available for use in the transmitters and receivers. If I made any wrong assumptions in the above, I'm sure someone will be kind enough to correct me.
However, vibration can cause marginal connections to fail, and that will affect things regardless of the frequency in use. This goes for glow engines as well. What I really want to know is PRICE!!! Bob R.
__________________ ![]() Raleigh-Durham Radio Control Extreme Flight RC Vess Propellors RadioActive Airshows | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| | #258 (permalink) |
| That's a Zero!! ![]() Join Date: Jan 2006 Location: SOCAL, CA Age: 54
Posts: 1,895
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Everything you ever need to know about PCM and PPM and radios in general: http://www.torreypinesgulls.org/radios.htm
__________________ ****************** Team Futaba Go FASST or Go Home ![]() |
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| | #259 (permalink) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ====================== ![]() Join Date: Feb 2006 Location: Stralya - down there aye bloke
Posts: 3,714
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So wait a second i got lost, the radio on the front of this thread with a module and aerial change (assumed) can transmit on 72mhz or 36mhz in my region over here, which was kinda my original question without saying it. If so how does the aerial get changed..
__________________ 3Dubya Australia www.modeldesign.com.au Click here for me current logic imac program all cleaned up for sharing mode one only sorry.. Last edited by 3dubya; 04-10-2007 at 01:23 AM. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| | #260 (permalink) |
| That's a Zero!! ![]() Join Date: Jan 2006 Location: SOCAL, CA Age: 54
Posts: 1,895
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I've heard two different possibilities. 1 - The photo is an artist's rendering. The 12FG will use modules, just like the 12Z and 14MZ. You will select which module you want - SS, 50/72 (US -others as allowed). 2 - There will be 2 versions. 1 dedicated to SS, the other that allows you to switch out. I think #1 is more likely. Futaba put up a chart that compares the three (and ALL their radios): http://www.futaba-rc.com/radios/feature-compare.html SS is not mentioned at all. It does say that the 12FG is a module system. BTW - the way I understand that the modules will fit is that they are very low profile. The antenna will be tight to the transmitter back and will come up between the back and the handle.
__________________ ****************** Team Futaba Go FASST or Go Home ![]() Last edited by Judge; 04-10-2007 at 09:40 AM. Reason: added module info |
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| | #262 (permalink) |
| That's a Zero!! ![]() Join Date: Jan 2006 Location: SOCAL, CA Age: 54
Posts: 1,895
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Robbe in Europe also has ads out for the 12FG, all in the G3 version. I suspect that the 12FG will indeed use the same module as the other two high end radios to get on SS. Based on the way the module appears to fit this is not big deal to me. In fact, I like the idea that I can transition while still using my 14MZ on 72 and ham band. That way I do not need to buy a boatload of RXs all at once. The really interesting thing is how little difference there is between the 12FG and 12Z when it comes to actual programming features.
__________________ ****************** Team Futaba Go FASST or Go Home ![]() |
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| | #264 (permalink) | ||||||||||||||||||
| That's a Zero!! ![]() Join Date: Jan 2006 Location: SOCAL, CA Age: 54
Posts: 1,895
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__________________ ****************** Team Futaba Go FASST or Go Home ![]() | ||||||||||||||||||
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