radios
01-25-2004, 04:42 AM
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radios
I have several radios,Tower Hobbies,Jr,Hitec and Futuba. I am wanting to norrow them down. Also I am going to buy a new one. My question is what radio to buy. Ihave two Hitec and am leaning toward a new Hitec radio.
Which radio and receiver will work togeather. Also what is the difference between the FM and PCM radio. I am just flying 40 size planes and don't know what i need to buy. All my stuff is used and I want to get it down to one or too radio's. These are probably dumb questions but I am just getting started and have to many different brands of radio's.
Any help would be great.
Which radio and receiver will work togeather. Also what is the difference between the FM and PCM radio. I am just flying 40 size planes and don't know what i need to buy. All my stuff is used and I want to get it down to one or too radio's. These are probably dumb questions but I am just getting started and have to many different brands of radio's.
Any help would be great.
01-25-2004, 05:11 PM
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RE: radios
Try searching around through the existing posts on here. Everyone of your questions has already been answered at length and then some! You'll learn a lot more just reading through those posts than you will from the people that begrudlingly repeat what's already been said =>
01-25-2004, 09:30 PM
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RE: radios
I am sure that with the radios you have you probably have more futaba and hitec compatable receivers, futaba and hitec work on the same system. JR will not work with the hitec or futaba.with that being said I would go with th futaba 9c.the 9c will do pcm or fm but all your receivers are fm so just stick with fm.
Darin
Darin
01-26-2004, 01:09 PM
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RE: radios
PPM (Pulse Proportional Modulation) The signal out of the transmitter is exactly related to the stick positions. You look at the signal on an oscilliscope and you can easilly read where the sticks are directly from the signal.
PCM (Pulse Code Modulation) The signal out of the transmitter is a digital computer code, and looking at it on an oscilliscope its a bunch of visually meaningless junk. You can learn to read it... but it is not easy.
The difference is in the signal encoding and decoding.
BUT... there's more. The PCM signal carries a "Failsafe" setting string in each cycle. If the reciever loses reception (but not power) it will take the last clean failsafe string and move the controls to the positions indicated, regardless of last stick input signal. If you have a PCM system, you NEED to set the failsafes! The default failsafe string is identical to the stick positions. This is rarely where you want the controls to be on loss of Transmitter signal.
When PCM was new, the digital signal was more resistant to interferance than PPM (FM or AM... there are AM based PCM radios, but not many) The modern FM/PPM radios are almost as resistant to interferance as the modern FM/PCM... so little difference its negligible now.
PCM, being a digital signal has digital steps in servo positioning. PPM has analog (no step) positioning. The steps are very small: 1024 steps in appx 120 deg of servo travel is about 0.1 deg per step. Your hand can't reliably move the stick just one step worth. (can't reliably move it to an accruracy of 20 steps)So the steps don't show in the aircraft's performance.
The Failsafes are the most important and most misunderstood part of PCM. you want to set the failsafes to minimze the impact on loss of control. They are NOT there to save the airplane. You can set them with the hope that control will be recovered before the crash, but don't count on it.
For Fixed wing... throttle off or idle, center elevator (maybe a little up... to slow the aircraft) and ailerons and give it some rudder. (so it goes to a circling descent)
For Heli... Collective (throttle + main pitch) just a bit below minimum hover, center cyclics and rudder. OR throttle OFF.
Competition flyers may want to use the hold last input... but it really won't help. the failsafe kicks in at appx 2 sec of lost signal. By that time the maneuver is blown anyway.
Failsafe will do absolutely no good for a dead RX battery
Hope this helps
PCM (Pulse Code Modulation) The signal out of the transmitter is a digital computer code, and looking at it on an oscilliscope its a bunch of visually meaningless junk. You can learn to read it... but it is not easy.
The difference is in the signal encoding and decoding.
BUT... there's more. The PCM signal carries a "Failsafe" setting string in each cycle. If the reciever loses reception (but not power) it will take the last clean failsafe string and move the controls to the positions indicated, regardless of last stick input signal. If you have a PCM system, you NEED to set the failsafes! The default failsafe string is identical to the stick positions. This is rarely where you want the controls to be on loss of Transmitter signal.
When PCM was new, the digital signal was more resistant to interferance than PPM (FM or AM... there are AM based PCM radios, but not many) The modern FM/PPM radios are almost as resistant to interferance as the modern FM/PCM... so little difference its negligible now.
PCM, being a digital signal has digital steps in servo positioning. PPM has analog (no step) positioning. The steps are very small: 1024 steps in appx 120 deg of servo travel is about 0.1 deg per step. Your hand can't reliably move the stick just one step worth. (can't reliably move it to an accruracy of 20 steps)So the steps don't show in the aircraft's performance.
The Failsafes are the most important and most misunderstood part of PCM. you want to set the failsafes to minimze the impact on loss of control. They are NOT there to save the airplane. You can set them with the hope that control will be recovered before the crash, but don't count on it.
For Fixed wing... throttle off or idle, center elevator (maybe a little up... to slow the aircraft) and ailerons and give it some rudder. (so it goes to a circling descent)
For Heli... Collective (throttle + main pitch) just a bit below minimum hover, center cyclics and rudder. OR throttle OFF.
Competition flyers may want to use the hold last input... but it really won't help. the failsafe kicks in at appx 2 sec of lost signal. By that time the maneuver is blown anyway.
Failsafe will do absolutely no good for a dead RX battery
Hope this helps
02-03-2004, 09:36 AM
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RE: radios
Hi, Everyone I would like to know if there is a web site for Jr Radios Home Co. I would like to see pictures & information on a older Jr Radio, I hope they have that information on their site !
Thanks in advance ! Joe
Thanks in advance ! Joe
