wireless video tranmitters

[Max Mizov]

This is all for static or outdor use. I want to find schemtic for use for motion in halls. 

[Jon Collins]

Hmmm

I dont think there are specific radio systems for static / indoor / outdoor / motion use? The system in the ebay link is designed with static use between rooms in mind, but would perform equally well (or not) mounted on your camera. Most transmissions are ok with line of side between tx and rx. The problem with microwave frequencies like 2.4ghz it that it is easilly absorbed by the body so walking in the beam can cause drop out. Moveing around inside buildings can cause multipath reflections from steel frames etc. causing cancellations and ghosting. This can also happen outside in the street if cars and large vehicles pass near by. Thats rf for you! decent antennas can help, but greatly, the FM tx and rx stages are all the same.

If have heard good things about this system;

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=6058464005&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1

The lower frequency and higher tx power would be less susceptable to dropout.

Remember though, these systems are only VHS quality and just for a directors monitor etc., at bit of dropout keeps them on their toes!!!

I use a 2.4ghz system, built into decent metal boxes and fitted with 6db wifi antennas, with reasonable results?

Jon

[Tom Wills]

Max, I'm pretty sure you're not going to find a good diversity system for much less than a Modulus. Diversity, while seeming simple in practice, hasn't been done at all by these cheap manufacturers, because it does take some serious work. If you're really serious about high quality video, you've gotta shell out some serious money to get a good system.

Sorry Max, but I just don't see any other way around it, unless you have the equipment and Electrical Engineering background to build your own from scratch.

Also, one of the transmitters mentioned here would work decently for monitoring video, but if you're looking to have something to record signal off of, you're talking about maybe a Canatrans or a microwave system. Canatrans systems run around $4000 for the transmitter only.

[Max Mizov]

To John. I said that this system for static use or outdoor for this reason that in hall the wall reflect the signal which interfered with straight signal. In a different places in the hall this interference is different and this cause, that with motion you will see in monitor(which display signal from receiver) time-changed noise, sometimes you will have clear signal sometimes you will have noisy signal sometimes only noise. The diversity system have a two receivers and comparator choose the strong signal for demodulate. It will delete all the problems with reflected signal. But how, say Tom, these systems are so expensive. May be is a way: buy two receivers and make the comparator which will chose the strong signal. But i dont know the schematics of these receivers and i dont know if the chip inside receiver have a RSSI output. It want a experiments.

[Max Mizov]

To Tom. Yes, the diversity system is expensive and hard to make in home. Because it must work on high frequency. It is not possible make it in home. But i will go to work to firm, which have a needed equipment. I hope, that is possible make a relative cheap system with good parameters. 4000$ is very big cost.

[Max Mizov]

http://www.cocom.com/pages/pro.htm

[Jon Collins]

Hi Max,

If you open up any of theses comercial receivers units, you will find them based on a radio module. I have built many system based on these modules with good results. They also have the RSSI signal strength indicator output. So as you say, 2 receiver modules and a comparator and switch!!! Let me know how you get on? My degree is in electronics and I spent 10 years as a design engineer, not in rf though!

http://www.lprs.co.uk/pdf_directory/2386mylprs1060167956.pdf

Jon

[Max Mizov]

To John. Waw, these modules looks so good! Do you know where i can buy it? How much it can cost?

[Jon Collins]

Hi Max,

I dont know where you are based but LPRS look like they supply world wide?

http://www.lprs.co.uk/main/product.info.php?productid=275

The cost of the module is very good, you would have trouble buying all the bits separatly for the price without the sweat and tears of building and making it work!. I bet you could build your entire diversity receiver for about 100 euros?

Jon

[Mauro Zenoniani]

just arrived today....i tested on a Canon Xl1 and a conventional television.
it works fine, some times seems to have a "dropped frames" effects but it occurs walking from a room to another.
If the transmitter and the receiver are in the same room all is great.

It cannot be used for recording, but if the director wants to look trough your camera....

[Max Mizov]

I buy the 2.4 GHz modules from www.lprs.co.uk i wait for it.      I will try build the samely receiver like on www.cocom.com

[Jon Collins]

Hi Max,

I am right behind you here! let us know how you get on and I will try to build the same?

Jon

[Max Mizov]

Hi John. Of cource i let you know how i bulit it  . I think it will not hard. The biggest problem the make part which choose the strongest signal. This part for two signals is not hard but i make it for three signals and it will be hard 

[Max Mizov]

I still dont have the modules  . Was a any wrong with payment on net. This week i try send fax to www.lprs.co.uk. I hope that it helps to me get the modules!!!
My friend try to help me with design switch block for receiver. For now it designed with logical chips. I think that it not very practical construction. I must to lern programing the microprocessor. 

[Jon Collins]

Hi Max,

Thats strange, I have used LPRS several times, and received the goods within days?

Jon