Introduction to Radio Waves Training Course

[Sonarman77]

I want to start off by saying that I think this is a really great video, and I like it a lot. I've already reccomended it to some people. But I think your simplex/duplex explanation is a little misleading. Simplex refers to a link or equipment where transmission occurs in only one direction, like in a remote-controlled car. Duplex is where full transmission occurs back and forth between two terminals, like on a phone.

[carlchapmantech]

@Sonarman77 Thanks for the comment. The ITU definition is "a simplex circuit is one where signals can flow in only one direction at a time." Traditionally there are 3 types of systems. Simplex - using the same frequency, can be one way or two way but only one direction at one time (e.g 28MHz CB). Half - Duplex - Usually Two frequencies, but only one at a time (e.g commercial two way radio) but flexible description, full Duplex - two frequencies simultaneously (eg a cell phone).

[Sonarman77]

@carlchapmantech (1/3) I don't traditionally use the ITU definitions, the definitions I use are ANSI. Your definition of simplex sounds a lot like half-duplex to me (which I didn't mention in the original comment because it didn't come up in the video), but the confusion might be because of the different definitions standards. I usually don't concern myself with if there's a frequency difference in terms of that determination.

[carlchapmantech]

@Sonarman77 Thanks again for the comments. It often comes down to who you talk to, and half-duplex is flexible. You are correct about landlines and cellphones being full duplex. Two way radio is defined differently due to the Push-to-Talk (PTT) feature which means only one channel is active at one time, where full-duplex channels broadcast simultaneously. Most commercial two-way systems have a different transmit and receive frequencies, but marine and CB two-way radios have the same frequency.

[Sonarman77]

@carlchapmantech No problem, it's awesome to have such fast replies. Like I said, I like the video a lot, I guess we've just grown up using different definitions standards for our RF (The infamous potato/potato debate!). Thanks for the good video and the fast responses. It's always great to see educational videos on YouTube instead of just cats. Not that I don't like cats. Have a great day.

[Sonarman77]

@carlchapmantech (2/3) I consider a landline phone conversation duplex in the same way as a cell phone conversation. What I look at when determining the status of the link is whether or not communications between terminals is mutual on a certain link. I'm admittedly not very familiar with CB radio, or commercial two-way radio (or any non-cellular PCS technology, actually), but I don't see why they would be different.

[Sonarman77]

@carlchapmantech (3/3) From the words alone, I would imagine that "commercial two-way radio" would cover things like bridge-to-bridge maritime VHF frequencies and walkie-talkies, which operate back and forth on the same frequencies. . . .

[FantasiaDelight]

how high can a satellite be, in theory, and still receive the uhf signal?

[carlchapmantech]

@FantasiaDelight Thanks for the comment.

The UHF signal can go much higher than any satellite orbit... some people use UHF signal to bounce off the moon....or go further....

... the problem is the low power from any sat-phone on earth.... Satellites that are closer give a stronger signal to the phone on earth, but they are always moving.... the satellites most far away have an altitude of 35,786 km (22,236 mi) above the earth and are called geostationary (they appear to stay in the same place).

[yotas312]

Thanks dude..please upload more videos like this..greetings from Kenya.!!

[idratherbflying]

really appreciated your effort on picking n explaining this topic so well !!

[FSXIV]

Caffeinated Hampster Lmfao. Great!



[TheRandomGuy664]

Thanks SO much for this! It helped me with my science fair project.

P.S. this video link will be in my sources page

[carlchapmantech]

@TheRandomGuy664 Thanks for your comment... Glad we could be of help... I did a couple of science fair projects in my earlier years ... good luck.