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Regarding Ultra Low Latency RF Transitive Module for Wireless Flash Trigger

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sakibnaz

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RF for Wireless Camera Flash Trigger

Hi All.

I want to make a Wireless mesh based DSLR Camera Flash Trigger. Where one Transmitter (connected with Camera Hot-Shoe) will trigger one or multiple Receiver (connected with Flash).

Now for the RF Communication I am thinking about BLE (Bluetooth 4.0) but not sure if its the best. As for Flash I need to trigger it very fast when Camera Shutter is clicked so delay needs to be min as possible.

Can anyone advice if BLE is the right choice? Or other RF will be better? If so please advice what RF I can use to get fastest (min latency) communication).

Thank you in advance.
 
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Re: RF for Wireless Camera Flash Trigger

a mesh network means various transmission paths will have different arrival times, depending on how many nodes the signal goes thru. So if you are using multiple flashes, they will actually go off at different times...perhaps up to 60 milliseconds apart per each extra node. Is this ok?

Otherwise, stay with a simple point to point transmission scheme. If you have range issues, look at the new Lora modulated chips, or just use a higher transmit power (momentary transmissions are allowed a higher power level)

https://lora-alliance.org/
 

Re: RF for Wireless Camera Flash Trigger

Hi biff44. Thanks for reply.

For time delay ... 60ms will be huge deviation. In a real example the Camera Shutter can be max 1/8000sec i.e. 0.125ms only. Where the Camera will be connected with RF Transmitter and Receiver (one or multiple) will be connected with Flash (one or multiple). I found the Transmitter can get a pulse from Camera Hot-Shoe Pin 4ms before the Shutter Trigger. So within this 4ms I need to get ready with all Receiver to trigger the Flash at the or almost the same time with Shutter.

There are many Transmitter and Receiver in market doing that and I find some uses 2.4GHz and some low Freq like 430Mhz or so.

Here I think I need to do a fast RF data broadcast from Transmitter type communication so when Receiver received the Broadcast it will trigger the Flash with proper timings.

For Ramge 100m is good enough so I think LoRa will be over-kill.

- How about regular RF 315MHz or 433MHz transmitter-receiver module? How fast they are in latency?

- For BLE is it possible to do a fast and low latency Broadcast?

Thanks again.

Regards.
 

Re: RF for Wireless Camera Flash Trigger

If I needed shortest response time I would transmit a sine carrier at any convenient frequency. I would receive it via a nearby antenna connected to a detector tuned to that frequency. Similar to morse code communication.

Once you press 'transmit' the oscillator might require a few cycles to reach full amplitude. Similarly the receiver might require a few cycles before it resonates to the broadcast frequency.
 

Re: RF for Wireless Camera Flash Trigger

There are cheap 433 MHz ASK receivers on Aliexpress or Ebay, you can use those
 

Re: RF for Wireless Camera Flash Trigger

Hi biff44. Thanks for reply.

For time delay ... 60ms will be huge deviation. In a real example the Camera Shutter can be max 1/8000sec i.e. 0.125ms only. Where the Camera will be connected with RF Transmitter and Receiver (one or multiple) will be connected with Flash (one or multiple). I found the Transmitter can get a pulse from Camera Hot-Shoe Pin 4ms before the Shutter Trigger. So within this 4ms I need to get ready with all Receiver to trigger the Flash at the or almost the same time with Shutter.

There are many Transmitter and Receiver in market doing that and I find some uses 2.4GHz and some low Freq like 430Mhz or so.

Here I think I need to do a fast RF data broadcast from Transmitter type communication so when Receiver received the Broadcast it will trigger the Flash with proper timings.

For Ramge 100m is good enough so I think LoRa will be over-kill.

- How about regular RF 315MHz or 433MHz transmitter-receiver module? How fast they are in latency?

- For BLE is it possible to do a fast and low latency Broadcast?

Thanks again.

Regards.


do you really want to reinvent the wheel ??

there are already many 2.4GHz remote flash units available out there and most of them would be much cheaper and better looking in smaller housing than
what you are likely to be able to build

just one example from a place I buy a lot of camera gear

https://www.digitalcamerawarehouse.com.au/voking-wf820-wireless-flash-trigger-transceiver-set

eBay probably has many more and probably cheaper
 

Re: RF for Wireless Camera Flash Trigger

if you are using a strobe flash...you would never adjust the camera for the shortest shutter time. You can leave the shutter open WAY longer, and let the very short light pulse of the strobe do the actual "timing"
 

Regarding Ultra Low Latency RF Transceiver Module for Wireless Flash Trigger

Hello all.

I am developing a Camera Controller with Wireless Flash trigger. There will be a Master Device (Connected with DSLR Camera Hot-Shoe) and other several (up-to 16) Salve Device (Connected with Flash or SpeedLight). Here Main Device will get signal from Camera Hot-Shoe and do a RF-Broadcast with Control Data which will be received by nearby (within 100m range) Slave Devices and Trigger the Flash.

Now for this I need to use very low latency/delay based RF Communication. I am not sure what max time delay I can allow but I am targeting 1/2 ms to make the Data communication within Master and Slave.

My plan was to use Nordic nRF24LU1+ SoC with its Enhanced Shock-Burst features. But now Nordic not recommending their nRF24 lineup for new design, hence I am looking for other suitable RF Transceiver Platform.

Can anyone advise me a suitable RF Module or SoC considering below:

- Ultra low latency
- Range 100m or more can be achieved with Chip Antenna based design
- Frequency Band I am open to use any from 433MHz to 2.4Gz
- Internal MCU (8051 will be fine) for programming
- Available OEM Module in market will be great


Thanks in advance.

Regards.
 
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You will find this quite difficult. The problem is the need to send some kind of data from the controller to the slave flashes and for them to decode it before acting. You can't just use the presence of a signal because it will trigger from any other source on the frequency. A hot shoe normally triggers the flash without delay.

You will have to experiment but I think you will find the timing is difficult to achieve. It may be easier to do it the other way around and fire the shutter from the same signal and use a remote controller for both camera and flash, that way they all see the same delay.

Brian.
 

not necessarily. You might pick a frequency, and just have an amplitude detector, as suggested above. When you push the button, the frequency starts to oscillate, and a few nanoseconds later the signal is detected. No modulation or coding needed. ADL5506 log detector will have a good dynamic range, AND only take 100 ns to turn on. But if you have to add a bandpass filter in front of it, the latency wil increase as the inverse of the bandpass filter's bandwidth

If you are in a congested area, you might make two receivers, one tuned to say 433 MHz, and the second tuned to 2450 MHz...and you only flash when BOTH of them get turned on

A more complicated way would be to set up a comunications link with modulation, with a high bit rate...say 500 MBPS, and send a short code to fire. That would be much more battery draw intensive though
 

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