"Line of sight" question

[mick53 0]

Hi,

 

This question concerns setting up an OUTDOOR wireless camera system.

 

I keep reading the best set-up for any wireless system is to have an unobstructed direct line of sight between the camera and the receiver. Is this correct?

 

An outdoor wireless camera is obviously designed to be used outdoors.

 

How is an "unobstructed line of sight" possible with the camera outside and the receiver inside? I mean 99 times out of 100 the signal is going to have to go through a wall or door to get from the outside to the inside, right?

 

I gotta tell yal, i feel stupid asking this question, but I just don't get it. I see outdoor wireless cameras advertised all the time.

 

Why would anybody buy one if they have to have no obstructions between the camera and the receiver which has to connect to a monitor which will have to be in an enclosed structure?

 

 

Should an outdoor camera be able to transmit its signal just a very short distance? I mean like 6 or 8 feet. It would be a straight line but the signal will have to go through a 2" wooden door.

 

Thanks,

 

Mike

[rory 0]

Okay Im not expert on wireless like a couple others on here (wireless eye for one), but here is what I have learned from a couple wireless jobs Ive done.

 

Should be a Transmitter and a Receiver. The camera is just a camera.

The Transmitter and Receiver can be inside something, with the antenna outside. If they are inside a plastic waterproof box, they will still work with an internal antenna.

 

Line of site means no obstructions, the more obstructions you add to the wireless path, the less distance is achieved. Certain Objects such as trees etc, or anything that contain water, can obstruct the line of site also. Metal will definitely block the line of site, including anything from Iron inside walls, to AC Duct, etc.

 

If the wireless path is not high enough above vehicles, when a vehicle passes through it you will also loose video.

 

So basically doesn't matter where the receiver and transmitter are, it depends on where the antennas are; unless it has an internal antenna.

 

If it is a Wireless camera so to speak, with a TX built in etc, then typically it is DIY gear, and that is going to be tough anyway. Professional setups will use cameras, and then Wireless gear separately.

[WirelessEye 0]

Rory is correct. You can have your wireless gear outside, (with your electronics weatherproofed) and cable leads to both the antennae, (mounted outside as well) and the Cat5e will run to the other end.

 

The X10 type garbage, which has the wireless integrated on the other hand- can probably go through a typical residential wall (allbeit a short distance), but distances and wall types are two huge variables. Some houses have a lot of metal in the walls from studs or stucco mesh, so you could have issues.

 

One thing you have to remember, no matter what the frequency is of the wireless, a clear line of sight is always desirable. Even if they advertise 900Mhz "obstruction penetrating" video links, obstructions will still greatly diminish wireless signal. 900Mhz is less prone to being killed completely by 1 solid object than a higher frequency, but with wireless everything is variable.

[scorpion 0]

I usually get a service call from the DIY ers who need us to come in and fix their southern engineering.

 

I agree with everyone on these posts.

 

The package say 300 feet. I usually use this analogy with these customers.

 

If we use a flashlight with 2 AAA batteries and we are standing on a football field can we see the opposite goal post in the complete darkness?

They say no. I then ask, if we move closer can we see it? They say yes. Now I want to see the color of the goal post in good detail what should we do? They say "move closer". Great! Now they get the idea!

 

There was a service call some time back that I could not figure over the phone. As she described it the system should have worked! I arrived at her house and started to trouble shoot her husbands installation and I finally figured it out. The receiver was in the master bedroom and the camera was in the garage. In her master bath she had wrap around mirrors! The silver lining that creates the mirror was blocking the signal! Moving the camera in to the laundry pass through allowed the system to work!

[videobruce 0]

The biggest issue I see with most of these 'wireless' systems are omni directional antennas as in a single rod (rubber duckie if you will). Instead of all the 'RF' going in one direction (where you want it), it gets dispersed 360 degrees. This goes for the receiving antenna also. It receives from 360 degrees.

 

Of course this doesn't apply to 'yagi' or 'dish' type antennas on the much more expensive systems.

[WirelessEye 0]

Another problem with omni-directional antenna setups is that they seen noise in a 360 degree plane which greatly reduces signal strength and reliability. Unfortunately, these DIY setups have to take into account that most end users have no experience with wireless, so they have to make them this way. Booo.

[Scruit 0]

Another problem with omni-directional antenna setups is that they seen noise in a 360 degree plane which greatly reduces signal strength and reliability. Unfortunately, these DIY setups have to take into account that most end users have no experience with wireless, so they have to make them this way. Booo.

 

 

I'm not a professional, just a home user.

 

 

Generally I don't use wireless anywhere I can run a wire. This is partly for quality (I don't have the expertise to make it work 100%) and partly for privacy. I don't want someone to sit outside my house and see my video signals.

 

 

 

Two stories about range:

 

1) I bought a Swann Microcam III camera so that I could attach a camera to my RC plane and record the video on the ground. First time I plugged it all together I got a strange image that was mostly snow but included some repeating patterns of light that started in the center of the screen and moved outwards. I adjusted the antenna a little and could see the moving lights more clearly and thought to myself; "That looks just like the windows StarField screen saver..."

 

I stepped outside with the receiver and my 7" LCD test screen and the image got clearer until it was obvious that it WAS the star field screen saver. At that moment the imaged changed to a paypal login screen. I started to walk up and down the street using my body to block the antenna and try to make it a little more directional until I found the house that was xmitting the signal. I knocked on his door (I know him) and showed him that I could see his computer screen.

 

Turns out he was using a video xmitter to send his PC signal to a big screen TV in his den, and using a wireless keybard and mouse also. AS soon as hea realised I could see his computer screen clearly he freaked out a little, asking how long I'd been watching. 5 mins,I said; long enough to track him down. I get the feeling he might have been visiting some website earlier that he maybe didn't want me to know about...

 

BTW, his house is HALF A MILE from mine. And his xmitter was rated for 300 feet. The signal only had to go through one wall at his house, one wall at my house and the rest of the distance was open air.

 

 

2) Once I got my wireless camera set up on my RC plane, I got this quality image even from a plane that was half a mile laterally and about 400' in the air.

 

 

 

This is with the camera mounted upside down on the bottom of the plane, and the receiver on the top of the roof of my house so there is 100% line of sight. Even mounting the camera on the side of the plane wrecks the image when the plane banks and puts a wing between the antennas.

[WirelessEye 0]

What you have to remember with wireless, is that it is not some "plug and play" technology (for the most part). It is a technology that has been around since WW1 and has changed quite a bit between then and now. Aiming antennae at each other for the best signal is about the only thing that hasn't changed....

 

Radios and the hardware they run on change every day, and standards for implementation are lacking. Most DIY wireless gear, probably like what you and your neighbor are using operates on a common frequency... probably in the 400's or 900's. Channel selection in those frequencies are limited and thus are quite insecure and also crowded.

 

Once you go up to technologies like OFDM and implement even common security measures (not broadcasting your SSID, WEP, WPA, Radius, Mac Filtering, etc.), you not only wouldn't have "stumbled" upon his computer screen in your setup, you wouldn't have even know it was there.

 

But you have just found out that wireless is just like everything else in CCTV land: "you get what you pay for".

 

If you are worried about privacy, take the time, do your homework, then reach deep into your pockets.

 

Cool pic from the airplane though, we need you to mount a thermal cam on there so you can get some freaky imagery.

[scorpion 0]

I sell a lot of the wireless cameras that Scruit mentioned. We have an Insitute of Technology nearby and they take flying lessons and alot of them have model rockets, and planes. They really enjoy putting the MC III on these!

 

For this application these cam/xmtr/rcvr work great! These can be trouble some for some cctv applications.

 

Those that wonder why the video works at those distances has learned why they mount antennas really high on most applications.

 

Around these parts of East Coast Florida if you own a high rise building you are bombarded by every radio, amature radio, cell phone, business radio etc etc.