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How can I optimize my 2.4GHz Link?
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| CCTV_Solutions |
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Posts: 6
Joined: 17 Jun 2008
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Posted: Tue Jun 17, 2008 5:22 pm
Post subject: How can I optimize my 2.4GHz Link?
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Hello all,
Found this forum doing some research online. Glad to be here, looks like a great place!!
I have just installed a simple system with 2 cameras that are located in a truck yard. Because I could not get cable to them for video I figured I could use the simple 2.4GHz TX/Rx systems. Of course as you already know these are not quite that simple. Does anyone have and tips for maximizing reception. Im getting a little bit of static on the screen. Its only about a 100ft LOS from TX to RX and I seperated the transmitters by 150 ft so they didnt kill each other. I am using the standard "rubber duck" andtennas that came with them.
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| Rooney |
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Posts: 84
Joined: 27 Sep 2006
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Posted: Tue Jun 17, 2008 6:41 pm
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Are the transmitters and receivers addressable? If they are, make sure they are on different channels. If not, you are probably getting cross feed. Try to isolate the 2 different systems from each other by shielding the antennas so the rx is only seeing the tx for that rx.
_________________
Portable systems. Security should be placed where needed.
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| wisp_engineer |
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Posts: 45
Joined: 28 Apr 2008
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Posted: Tue Jun 17, 2008 7:40 pm
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Having two different RF links means you need to have each link on its own channel. There are 11 channels available in the unlicensed spectrum here in the USA.
There are only 3 useable channels: 1 6 and 11
You can however use a combination of 11 channels, like 2 and 7 or 3 and 8, or 10 and 2, etc etc. You need 4 channels of separation in the middle, to really ensure you do not run into interference problems.
Keep in mind that there are other 2.4GHz products out there so you are contending with those as well.
Having rubber duck antennas on your transmitters puts another nail in your coffin, as you not only hear the transmitter on the other end that you are supposed to hear, but every other 2.4GHz transmitter and device in that frequency range as well. This is why I advocate (and engineer my own jobs) using sector antennas and high-gain directional antennas like yagi's, panels, and dishes.
So.... Step one: see which channels you are on and try and change them around, but make sure you have adequate spacing between them.
Step two: Try and see if you can do a spectrum analysis in your area to see what other devices are in operation and on what frequency. Doing this may help you in deciding what channels to pick for your equipment.
Step three: If one and two does not help, try a more directional antenna on each radio. Maybe start out with a low-gain yagi, perhaps maybe a 9dB or 12dB model on both ends. You can also change the polarization of the antenna so it runs horizontally. This helps in that most sources of interference (like 2.4GHz routers and what not) are vertically polarized. You will get 25dB or so of isolation doing this. It will help out immensely if you are experiencing interference to do this.
Come back for more questions/answers if one and two do not work out, as there is a bit more planning involved to do step three.
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| CCTV_Solutions |
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Posts: 6
Joined: 17 Jun 2008
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Posted: Tue Jun 17, 2008 11:40 pm
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The transmitters are addressable 1-4. I used channels 2 and 4. I will try 1 and 4. I also tried disconnecting one of the transmitters and still got some minor interferance, so im not sure its the transmitters beating each other up. I will try to get some panel 2.4 ghz antennas, but my dealer (Eclipse) has been sold out/backordered for 2 months so far....
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| wisp_engineer |
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Posts: 45
Joined: 28 Apr 2008
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Posted: Wed Jun 18, 2008 12:04 am
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What kind of connector is on the radio?
N or SMA?
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| CCTV_Solutions |
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Posts: 6
Joined: 17 Jun 2008
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Posted: Wed Jun 18, 2008 8:41 am
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| wisp_engineer |
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Posts: 45
Joined: 28 Apr 2008
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Posted: Wed Jun 18, 2008 9:39 am
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| CCTV_Solutions |
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Posts: 6
Joined: 17 Jun 2008
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Posted: Wed Jun 18, 2008 3:51 pm
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Those look great, and good pricing! They are outside in 2 locations, I ran about 100ft of coax off each one to the TX right to the fence line closest to the building. That way I only have about 120 feet of LOS transmition. I was trying to get a good signal, guess that didnt work as planned. Ill get a picture and post it.
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| scorpion |
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Posts: 2722
Joined: 26 Mar 2007
Location: Melbourne Florida
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Posted: Wed Jun 18, 2008 6:30 pm
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| wisp_engineer |
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Posts: 45
Joined: 28 Apr 2008
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Posted: Wed Jun 18, 2008 7:00 pm
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Nice find Scorpion. These are awesome too, especially at their price point. Anyone using 802.11b/g equipment should invest in one if they cannot afford the price for a regular analyzer.
http://www.metageek.net/
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| wisp_engineer |
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Posts: 45
Joined: 28 Apr 2008
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Posted: Wed Jun 18, 2008 7:02 pm
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OP, you said you ran 120 feet of coax to the radio is that right? This is RG59 for the video, not for the RF link right?
Those antennas are quality antennas for the price. I think they would even outperform the antennas that you are looking at ordering, but that is hard to say.
Just what ever you do, do not add amplifiers. 
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| CCTV_Solutions |
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Posts: 6
Joined: 17 Jun 2008
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Posted: Wed Jun 18, 2008 7:10 pm
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Correct
As in
CAM<======120ft coax======>TRANSMITTER w/antenna <--100ft LOS--> RECIEVER
Any good ideas to shield the rubber duck antennas from other 2.4 interference? Im just trying to wrap this project up already..... Any sorft of metal housing to block RF from other directions??!
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| wisp_engineer |
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Posts: 45
Joined: 28 Apr 2008
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Posted: Wed Jun 18, 2008 7:13 pm
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You'll change the radiation pattern if you try and shield the antennas from interference. This may or may not be good. You could skew it all messy, and add in reflections which would cause serious problems.
Get some external antennas on those radios if you at all can. 100 feet pure LOS to the eye and to the radio should be cake with some directionals. I've got some 30 mile 2.4GHz links that have run for years that distribute internet to far-off locations. Keep in mind that these use directional antennas (big antennas, not yagi antennas) and special 2.4GHz radios. 100 feet is nothing.....
I'd like to see some pictures so that I can suggest exactly how to proceed with the install. 
Last edited by wisp_engineer on Wed Jun 18, 2008 7:16 pm; edited 1 time in total
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| wisp_engineer |
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Posts: 45
Joined: 28 Apr 2008
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Posted: Wed Jun 18, 2008 7:14 pm
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Check your private messages too.....
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| wisp_engineer |
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Posts: 45
Joined: 28 Apr 2008
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Posted: Fri Jun 20, 2008 6:44 pm
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How is everything going? Any updates?
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