Wireless Trigger Transmission

There are a number of manufacturers that sell long range RF transceiver modules that also work in the (generally free) frequency bandwidths (country dependent of course) up to a range of about 64km (product and application dependent of course).

You could try the websites for the following companies - Aerocomm, Tekdis, Celsum Technologies Limited, Radiocraft, RF Solutions, Xemics, etc.

Most of these sell RF transceiver modules so you will need additional microprocessors and electronics to turn them into an actual radio link. If this is too difficult (which it likely is) and you want a pre-built RF link you could try companies such the above or specifically McLean Automation or RF Solutions which sell simple pre-built on/off radio links.

http://www.ma1.net.au/

http://www.rfsolutions.co.uk/acatalog/index.html

This is going to be a rather expensive project either way (unless you hire the radio or similar equipment, which is a possibility). A cheaper alternative may be to use a laser source and lenses as the trigger, with an optical receiver connected to the camera trigger unit (if you have line of site).

Microsecond trigger delay is likely going to be a problem with any possible solution. Does your high speed video camera have a delay function that will allow capture of a short period of time before the trigger is received (to take into account trigger delay)?

Can you describe the application in more detail? What exactly are you trying to capture, and why the large distance? How many events are you trying to capture (and over what time frame)?

I guess the biggest question is can you not just start the camera before the event occurs (such as manually, control over internet, cellphone trigger, delay timer, etc) and leave it running until the event is captured? Even basic high-speed cameras have a large memory capacity to allow this (or is the event trigger random)?

Other high-speed camera options that may be of use (especially if you want to capture a random one-time event) are to leave the camera recording (overwrite old memory when full) and use a trigger local to the camera to stop the camera recording.

A simple sketch of your application would be of help.

Thanks for your response.I'll try to find out the pre-built radio link.

You have mentioned of using a laser source and lenses as the trigger;could you please elaborate on this alternative,I mean how to realise the set up???In my project assignment,most of the times it is line of sight case.

Yes,the high speed camera that I'm using is having pretrigger and posttrigger features,which means it can record data before and after the event.However,the total record time is 4 seconds.The event is going to be captured at a rate of 1000 frames per second.The event is the instant at which a high speed projectile(1200m/sec) hits a target around 1200m away.The pre-trigger feature can be used but the delay provided by the communication system must be constant always for accurate calculations post event.

You have mentioned of using a laser source and lenses as the trigger;could you please elaborate on this alternative,I mean how to realise the set up???In my project assignment,most of the times it is line of sight case.

This is just a possible alternative to a radio link. The focused laser is used to strike an optical receiver which then triggers the camera. It has its advantages and disadvantages compared to a radio link and is mentioned as a possible alternative, but unless you have access to a cheap W class (not mW laser pointer) laser, lenses and have the patience and ability to focus the beam for this distance the radio link is you best option.

The pre-trigger feature can be used but the delay provided by the communication system must be constant always for accurate calculations post event.

Whether you use a remote trigger using a radio link or local trigger using the camera pre-trigger you cannot guarantee that the camera timing will always be the same, especially since the triggering of the device launching the projectile will likely add additional time variations. If you are trying to use the camera frame count or time index as the basis of timing your event in and out of camera shot (eg- calculating exactly when the projectile left the barrel) it won't be accurate or repeatable.

A simple radio link and the camera pre-trigger function + 4 seconds of record (4000 frames) should be more than enough to capture the single event. Exactly what are you trying to monitor and measure? If it is the speed of the projectile then this can be measured at the site of the target by monitoring how fast the projectile passes between known points within the camera frame (using the frames per second as the time measurement). This is how this measurement is commonly done, and most other projectile variables (such as projectile motion and interaction with wind, air resistance and gravity) can be accurately calculated (if this data is even necessary).

Check out http://www.hotshotsales.com/

I have used these to activate pumps at significant distances. The receiver is essentially a switch- you would need a source of 5 V at the receiver end to get the TTL signal.