"Multi channel" triggering (coded single) & fc

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"Multi channel" triggering (coded single) & fc

Postby kwanyin » Sat Sep 29, 2007 7:00 pm

Hi,

I'm curious about this subject. I like the direction of this topic. I'm a science/ hobbiest. I don't have any background in electronic nor radio.



Base on my very limited knowledge of radio control airplanes, I have some ideas that may be helpfull for our group

Concept:
Coded single in order to 'simulate' "multi channel" while using a limited amount of channels.

Base on these cheap-low-cost Chinese made flash triggers on eBay, I will assume that the triggers use four (4) actual channel. My friend owns one of these. I bought a higher


An LCD display can be used for 99 IDs; however, LCD requires a tiny bit more programming for displaying info... and can be controlled with as little as two (2) buttons


Or simple 5 LED lights for 10 channels: LED 1=On or Off, LED 2-5 -imagine 'binary' display:

LED = O
LED ON = X
LED OFF = O

O OOOO ID 1
O XOOO ID 2
O OXOO ID 3
O OOXO ID 4
O OOOX ID 5
X OOOO ID 6
X XOOO ID 7
X OXOO ID 8
X OOXO ID 9
X OOOX ID 10

The LED concept is not as intuitive but could be easier to program (I'm not a programmer)


Possible problem(s):
Using one channel, multi photographers can interfer with each other's strobe.

Personally, my belief is, given the randomness of life, the use of digitals (allowing for 'Machine gun' photography), the interferance can reduce to 'just an "annoyance"' rather than a 'major problem'. Also, how man Strobist will there be in a given event?



I've not taken apart my friend's Chinese ebay radio trigger... even if I did, I am not sure what to look for. I don't know if they use real channels or some form of encoding method.

If FCC allows for the use of four (4) actuall channels, then we have 4 real channels to play with.

If we have 4 channels to play with, we still can impliment Single ID on top of that; but, narrowing it down to 3 or 4 (or 5)IDs on top of the 4 existing channels.

3 ID x 4 channels = 12 strobist
4 ID x 4 channels = 16 strobist
5 ID x 4 channels = 20 strobist
etc
kwanyin
 
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Simutated chans.

Postby Thonord » Sat Sep 29, 2007 7:26 pm

quote
Base on these cheap-low-cost Chinese made flash triggers on eBay, I will assume that the triggers use four (4) actual channel.
unquote
I may be wrong, but your binary simulated multi chan is exactly what they are doing. They definitely only use one frequency.

Tom
Ppl who agree need normally not reply, those who disagree or have questions do.
Or - just ignore me.
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Location: Norway

Postby strogg » Sat Sep 29, 2007 9:03 pm

I would bet money on this one just yet. Lots of frequencies allot for multiple channels. They might just be using that.

In a week or so, I'll be setup with some equipment to analyze the RF coming out of the ebay triggers. Once I do that, I'll see if I can post some details on how they actually communicate with the receiver.

Edit: Bah.. I mean "I wouldn't bet money on this one just yet.". I hate it when I miss a negation in my sentence.
Last edited by strogg on Sun Sep 30, 2007 2:34 am, edited 1 time in total.
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Postby Rudeofus » Sun Sep 30, 2007 12:03 am

strogg wrote:In a week or so, I'll be setup with some equipment to analyze the RF coming out of the ebay triggers. Once I do that, I'll see if I can post some details on how they actually communicate with the receiver.


Let me guess (since I've never seen such a thing for real): Someone wrote about SAW based oscillators being used in these triggers, so I assume they use an on off keying scheme on one single frequency...
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