Newb question again.

I know what Mhz are regarding transmitters and receivers, but what exactly is a channel? I just bought a transmitter on Channel 60 in the 72 Mhz band. What exactly does that mean?

Regarding the transmitter, I hope I didn't make a mistake. I saw a deal on eBay and bid on it not really thinking I was going to get it. Stupid me didn't even ask any questions. Basically it's a JR Max 4 channel transmitter on channel 60 (whatever that is) and 72 Mhz. Here's a link w/picture:

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEBWN:IT

I only paid $20 for it which is what makes me nervous. It must be a bad transmitter if no one else was wanting it. In any case, its just a temporary one until I come across the funds to buy a nice transmitter and plane.

Thanks,
Mark

Channel can mean two things in RC. On has to do with the frequency channel the other has to do with control channels. Your radio operates in the 72MH band, but on that band, RC airplanes are allowed to use 50 different frequencies. In order to make things simple for folk, the frequencies are numbered 11 to 60. Yours happens to be on channel 60 which is 72.990 MHz. You radio has four control channels, i.e., it can control four devices or servos. This is an older model TX, so $20 is a fair price for the radio.

Frequency chart: http://members.citynet.net/kbrown/Fm...FreqChart.html

The CORRECT use of the term "Channel" would be which servo you are trying to make move (Channel 1 = aileron, Channel 2 = Elevator.....)

The COMMON mususe of channel to refer to the Frequency numbers and thus the actual frequencies the radios use... I'm not sure how it got started, but it was a mistake. It started about the time of the new frequency allocations in the 1980's.

Before 1978, (maybe 1976.. close enough.) we needed a LICENCE to operate a R/C transmitter in the 72 mhz or 75 mhz bands. The massive amount of licence applications for CB's is one reason they dropped the requirement. The FCC expected the same boom in R/C transmitter use. (didn't happen.)
However the CB user's misnomer of calling thier frequincy numbers "Channels" may have something to do with how R/C enthusiasts began using the same misnomer.

As FHHuber said, the term 'channel' is often misused. I try to say 'frequency' instead when I want to know which of the 50 numbers (11 thru 60) a pilot is using. But actually '60' (or 11, or whatever) isn't really a 'frequency' either. 72.990 is a frequency. So technically, I'm wrong too, but we gotta call 'em something, and 'What's the number on the little plastic flag on your transmitter?' sounds pretty dorky!

You probably got that transmitter so cheap because it didn't come with a matching receiver or servos. And also it's only a four channel (uh-oh, here we go with the channel stuff again!). If you buy the transmitter, receiver, servos, battery, switch, etc. separately, you will end up paying a lot more than if you bought the whole set at once. Usually, the cost of everything except the transmitter will add up to the cost of an entire set (including the transmitter). So, if you think of it that way, the transmitter is free!

But you can still use that extra transmitter as a buddy box. In that respect, it's well worth the money! Happy Flying!

I didn't know that using the word "Channel" was incorrect when referring to a frequency. I just looked at all my transmitters and every one of them has a "channel" number but doesn't actually use the word channel. So what is the correct term for the number assigned to a frequency? Are you sure you're right about this FH?

The correct word is channel. It's not a "Misused Term", It's just a single word that gets used for two applications, and unfortunately, we use BOTH applications.

If it were a misused term, then TV and Radio misuse it too.

Both are fair. Just depends which context your in using. Sort of like, on one of my harder landings when I make a channel down the centre of the field.

Just so that we really mix things up, a channel 60 TX (72.990MHz) only transmits at 72.990 MHZ for about 75% of the time (sticks at neutral). The rest of the time it is either at 72.995 for the JR types, and 72.985 for the futaba types.!!!!

According to the excellent writeup at: http://www.torreypinesgulls.org/Radios.htm , out FM radios use 2 frequencies, the base frequence +5Khz for the Positive shift folk, and base -5KHz for the negative folk.

Go figure.....


gus

I like to think of radios (and computers too for that matter) like Sausages:

The less I know about what's inside them, the more comfortable I am.

PS. Great definition Gord!

To say "Channel" as a representation of a frequency is right. Most of telecomunication world use this way, cellular, boadband, microwave links, you name it.
It would maybe easier to call the frequency "carrier" and the number of servos it can control as "channel", or say that your transmitter operates "ON" channel 60 and has 4 control channels, like someone already said here.

Nilo

I always though of a "channel" as a collection of frequencies, or a frequency range, packaged together for easy reference. IE channel 60 for us is really 72.985Mhz-72.995Mhz, meaning your radio is working in that range, and anything else in that range could be considered "on your channel" and likely to mess with your signal. It's not a technical definition, but it works.

Frequency, of course is the number of cycles per second of the waveform.

Channel in reference to control functon on our systems, ie, a "6 channel radio" is, in fact, annoying. I suspect the usage started back in the reed days, when differnet control functions were, in fact, on different frequencies, as I understand it (before my time, that's based on stuff I've read). But it's still an annoying nameing convention.

Lucky for us, the most "channels" you see on one radio is 10 (normally), and the lowest 72Mhz channel number is 11. So, there's no danger of your 6-channel radio on channel 5 interfering iwth the 4 channel radio on channel 2, but not the 3 chanel sytem on channel 6.

That's a band

Yes, technically, you're right, it's a band.

Of course, you also have the "bandwidth" of the "channel". I'm getting a headache

Semantics... sheesh! I see nothing wrong with calling a assigned frequency number a channel. I also see nothing wrong with calling other stuff channels, such as a left and right speakers can be called channels. My TV has channels, both frequency and audio (left/right.) Same basic principle applies to RC radios.

Beginners: If you say may radio is on channel 40, everyone should know what you mean. If you say my radio is a 6 channel radio, again, everyone should know what you mean.

This is funny. Why not call one a "frequency channel" and the other a "control channel"? I mean, isn't that what adjectives are for? Otherwise we would have to come up with an individual noun for every object in the universe.

We better fly than keeping discussing this!
I could had flew couple tanks already!

Nilo