Sekonic radio transmitter European Frequency

[will_wenzel]

I use quantum freewires for radio slaves, and noticed that they

operate at about the same frequency as the european pocket wizards.

Do any of you Euros know if the Sekonic radio transmitter can

trigger the freewires? Or a similiar question that might yield the

same answer - ever have a European pocket wizard accidentally fire

your freewire slaves?

 

Thanks for any help!

[john falkenstine]

Ever tried of just checking with Sekonic?

[timberwolf1]

this is heresay: I remember reading on the internet that there was some frequency

conflict with radio slaves. As a result, one brand was favored over the other in the US.

Then the opposite was true in Europe. I am not naming brands here. You will have to find

out the rest of the story. This is an issue with wedding photographers.

[hal_bissinger]

They are digital coded. Even if they were on the exact same frequency there would be no problem.

[patrick_clow]

I think I can answer this as I work for LPA Design (makers of the PocketWizard systems including the Sekonic modules).

 

In a nutshell, they won't and shouldn't trigger each other. Read on for the technical reasons.

 

There are 3 important components that make up a digital radio signal; frequency, bandwidth, and signalling.

 

The center frequency for the FreeWire is 433.92 MHz. The PocketWizard CE Plus units are 433.62 MHz and the CE MultiMAX adds another freq at 434.22 MHz. You notice that the PocketWizard units are NOT directly on 434 MHz. This is ON PURPOSE. The reason is that there a lot of "off the shelf" chipsets that use that frequency and we want to be as far as legally possible away from it to avoid interference issues. Interference affects performance.

 

Bandwidth is how wide your signal is. PocketWizards have a bandwidth of around 200-250 KHz. That means it hears things best on its center frequency, but could hear things up to 125 KHz (0.125 MHz) away. The farther off frequency, the less likely it will hear it however. This is where narrow bandwidth is good -- it filters out other things. The FreeWire bandwidth is also relatively narrowband at around 300-400 KHz. It will hear things up to 200 KHz away (anything in between 433.72 through 434.12 Mhz). Numbers making you dizzy? Suffice it to say that neither the PocketWizards nor the FreeWires can really hear each other. There might technically be some overlap at the extremes of each, but the signal is so weak that it would barely register as anything more than low level ambient radio noise or background distant static.

 

Signalling is another way of saying, "The width and speed of the data that is sent or the size and shape of the bits." PocketWizard and FreeWire data streams or bit recognition are simply not compatible.

 

Every one of those factors would have to align perfectly for a trigger to happen.

 

I haven't included discussions of power level or sensitivity. Those are more about range and not raw triggering compatibility. This is to keep within the gist of the original question.

 

Hope someone finds this helpful.

[patrick_clow]

Hal is talking signalling (go Hal!). While correct in one sense, it is important to note that any 2 devices on the exact same frequency will reduce each other's effective range. They might not set each other off, but their receivers will have to work harder to filter out what isn't theirs on a specific frequency. This is true of all radio technology, even spread spectrum to some degree (those less so with that tech).

 

Receivers do most of the work in radios -- that's where the mojo lies.

[hal_bissinger]

Thanks Pat, You said it much better than I could. Nice to hear from you again!

[craig_bridge]

Pat might be correct if the transmitters were on the exact same frequence and were keyed all the time; however, they aren't. They only send out short bursts of coded packets at the event times and the signals are repeated a few times improve reception and detection.

 

The signals are separated in frequence/bandwidth, space/physical palacement (in most cases), encoding, and time (in most cases).

[patrick_clow]

Craig is correct about the short burst packets and the clever repetition. In the US that's a piece of the Part 15 FCC rules we comply with (similar CE laws apply). Neither PocketWizard nor Quantum can make a transmitter that continuously triggers programatically. YOU, as a user, can mash and hold the button down, but we can't automate that. By law it must be an intermittent transmission device or our end users have to become licensed radio ops. Not a problem really, becuase even with a dozen photographers in the same area the likelihood of more than one person triggering during the same 500us (microseconds -- 1/2000) is pretty much nil anyway.

 

But that super-fast timing is good for flash triggering only. Remote camera operation, on the other hand, is more likely to be an interference issue. At sporting events you can have a phalanx of photographers all mashing their transmit buttons continuously over the same event, motor drives whirring away. That would cause intereference, but not between PocketWizards and FreeWires because of the three reasons I said above.

 

 

An interesting thing to note is that a Receiver can also be a Transmitter. I'm not talking transceiver, here. Some receiver technologies have to generate (transmit) a frequency near where it wants to receive and perform a kind of down-mixing.

 

I have had problems in the past when one company's receiver was physically mounted close to one of ours. Their receiver was putting out such a strong continuous transmission on our frequency that our Receiver just could not hear its Transmitter. Super regenerative technology does this to a great degree but it's really old hat and illegal in Europe, I believe, but was really common in the radio slave world in past decades.

 

Again, the mojo is in the Receiver. Moving the Receiver away from the transmission source (placement as Craig pointed out) was the only solution. Discovering that the transmission source was something with the word RECEIVER painted on the side was sort of surprising to me at the time. Also a faulty receive unit of some kind could be a unintentional continuous transmitter.

 

I guess my point is that 2 devices operating on the same frequency may affect each other and that happens more than you think because some things are transmitters that you wouldn't suspect, especially radio receivers. And other things are out there transmitting that don't say TRANSMITTER on the side. Like some laser printers. And the Chicago Bulls Arena shot clock wire. Oh the things I've seen in this wacky radio world ...

 

Bottom line and on topic, the likelihood of a FreeWire interfering with a European CE PocketWizard, or vice versa, is statistically improabable due to very short burst packet durations (Craig), incompatible triggering patterns (Hal), location (Craig again), different center frequencies, and effectively non-overlapping bandwidths.

 

Most of those reasons are why they are also incompatible.

 

The last one is completely eliminated in the US because US PocketWizards are on totally different frequencies (344.04 - 354.00 MHz) for those who are wondering.