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ell repeater


cattlefarmboy

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Max-Paul wrote:

Iwas told that the ELL radios are on the 2.4 Ghz band. With that if it is true, then you will need to use one of these. Either the 12 or 15 dbi gain antenna. Look at these http://www.l-com.com/item.aspx?id=21869

Then you might need one of these depending on the connector on the ELL.
http://www.l-com.com/item.aspx?id=5348

You do not want to extend the coax cable from the antenna. At this high of a freqency and more cable extended to the antenna and the loss of signal in the cable will take away any gain you get from the antenna. So you will need a water tight box mounted just below the antenna. Then run some Cat 5 to this box from your RS-485. You will want to keep this run as short as possible too.

Not knowing the difference in height between the two houses and how clear the view is once the leaves fall from the trees. I predict you are still going to have a hard time getting a good link. There is a reason that they say you need a good line of sight between the two antennas when working with 2.4 Ghz and above. Also a little known fact of non-radio people is this, and I do not remember at this time the take off angle. But not only do you need the ability to see the other antenna. But the further apart they are the higher above ground they need to be. What I am refering to is this, there is a ice cream cone radiation pattern that radiates from the antenna. And is at its largest at the mid way point between the antennas. If something blocks part of this pattern, even if it is below a laser line between the two antennas. It will degrade the signal. Now I am not talking about short range like 200 feet or less. It becomes more critical the further out the two radios are from each other.

You might only need one, or two or mabye neither will work. But it will be cheaper than the wire. Besides sounds like you already have the two ELLs. The antennas are not that much more to invest. Besides, bet you can unload them on Ebay with no problem..

Disclaimer, The suggested adapter to go from female N to SMA male is just a possible required adapter. You will need to find out what actual connector is on the ELLs and order acordingly.

Max



max,

on the ELL it says on the side of light o rama, "wireless Module 902-928 MHZ". the antennas that comes on the linker looks like this one, http://www.mouser.com/Search/ProductDetail.aspx?qs=hlEtao5wRdr2tiWji%252bnTKQ%3d%3d, if it is the one then it's a RP-SMA Plug for the antenna, i'm also going to send a e-mail to dan, seeing if he could tell me what connector i will need.

james
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I can appreciate the discussion about repeaters in this thread and am always larning stuff and filing it away....

After having said that, though, this thought comes to mind. A question I just have to ask...

The two houses are over 1,000 feet away. It just doesn't seem that they are cose enough together to benefit rom all of this work to sync them. Is there some application / need I'm missing?

Here's what I would do....

Run the same show at each house using separate computers. Configure the two PCs or laptops to use the same NTP server so that their clocks are reasonably synched up. They won't be off more than a tenth of a second, etc. That should provide enough synch that if you drove from one houe to the other, you could see the "continuation" of the sequencing from the previous house...

The controllers at each house can be addressed separately if necessary and the sequences on each computer can contain all the controllers and sequencing for all the channels. Of course, only the controllers at each house will respond to the LOR commands from their respective controllers.

But in the end, I'm just not sure what the benefit is for all this work to sync. Maybe I'm missing something. Well, that's my idea...

Maybe the original poster can explain the need a little bit more....

Thanks, Randy

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Randy wrote:

I can appreciate the discussion about repeaters in this thread and am always larning stuff and filing it away....

After having said that, though, this thought comes to mind. A question I just have to ask...

The two houses are over 1,000 feet away. It just doesn't seem that they are cose enough together to benefit rom all of this work to sync them. Is there some application / need I'm missing?

Here's what I would do....

Run the same show at each house using separate computers. Configure the two PCs or laptops to use the same NTP server so that their clocks are reasonably synched up. They won't be off more than a tenth of a second, etc. That should provide enough synch that if you drove from one houe to the other, you could see the "continuation" of the sequencing from the previous house...

The controllers at each house can be addressed separately if necessary and the sequences on each computer can contain all the controllers and sequencing for all the channels. Of course, only the controllers at each house will respond to the LOR commands from their respective controllers.

But in the end, I'm just not sure what the benefit is for all this work to sync. Maybe I'm missing something. Well, that's my idea...

Maybe the original poster can explain the need a little bit more....

Thanks, Randy


i have thought about having 2 computers running two shows, the problem i'm having with that is my audio from the fm transmitter would only be sync with my main show. if it wasn't for that, i would just do that. and you could almost see both houses at the same time, being in the right place. i appreciate your thought Randy, cause sometimes the simple way is the best way a lot, by the way, i love your display. make sure you tell your son to for me.

thanks james
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Hi James,

Thanks for setting me straight on the frequency. I now have it firm to be in the 900 Mhz range. Well if it is RP-SMA then that antenna will not need an adapter. Some of the benifits of 900 Mhz is that it is some what less LOS demanding. But will still be somewhat affected by trees with leaves, just less so than the 2.4 Ghz.

Just goes to show you cant always believe everything you hear on the net.

Again, thanks for correcting me with the correct info about what frequency those ELLs use. One really good thing about the 900 Mhz is that it will not effect a wireless network in ones home. But might effect a cordless phone if it is still using the 900 Mhz band. And visa versa.

Max

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Max-Paul wrote:

Really good Doctor, what benifits do you presume to achieve by putting a repeater at the head of the cable? Do you really understand what the purpose of the repeater is?

Let me explain a few things about the purpose of a repeater is. First lets look at a different repeater my good man. Radio prepeaters such as us hams use them on the 2 meter band and other bands. If I put a repeater up in the middle of a city and a mobile units is on the north side, they then by the use of the repeater can talk to a mobile unit on the south side of the city. Now, lets say I had put the repeater on the north side of the city. The north mobile unit can access the repeater and due to its higher wattage and usually its antenna is on the top of a 2 or 3 story building. The mobile unit on the south side can hear the repeater. But the mobile unit with lower power and with its antenna closer to the ground is not able to be received by the repeater. Thus the north side mobile unit never hears the south side mobile. So, what was gained by having the repeater near the head of the cable?

Now if you put an isolated repeater after the last controller at his mom's house and a isolated repeater before the first controller at nanny's house. Then I see that you are trying to keep any static charge that might be induced in the long run of cable between the two houses. And that I can understand. But your reason for doing so for the signal strength or voltage drop is, well wrong headed. As I have stated before, RS-485 is good for 4K feet. But like anything else. You should use cable that is rated for RS-485 duty. Meaning you would not put 50 ohm impedence cable on a TV antenna. And you would not put 4 ohm speakers on a stero rated for 16 ohms. If you do on either above examples. Then your system will develop a degraded picture or sound.

You sound like a learned man. I presume you used a scope to look at the single. Cause you mention that the voltage overshot some kind of reference. That is from the L and C componets of the wire that has caused a shift in voltage and current of the signal. But I presume you tuned your probe before hand. Even your probe will give you a false reading if you do not tune it to the frequency of the device under test. A 1Khz square wave will not work for tuning to something that might be very well in the 1Mhz.

I think that is enough for you to chew on for now. And my fingers are getting tired too.. :)

Max
Dr. Jones wrote:
Max - There is no need to put a repeater in the middle. A repeater at the head of the cable will increase the gain of the signal to compensate for the loss over the 1k feet. I would put an optically isolated repeater on both ends to keep from damaging components in the event of a lightning strike.

[snip}

I have a cable that is just shy of 500' and have had no ill effects. it has less than a .5v drop on the output and a slight increase in overshooting on the waveform.



Max

I work with RS-485 networks on an almost daily basis, though not the LOR protocol.

With the protocol, I work with, I have seen issues coming from an output through a couple hundred feet of high quality shielded 120 ohm cable. As a remedy we clean the signal with an opto splitter prior to pushing it down the wire. The data stream must maintain 2V differential, otherwise we recieve corrupt data. On some of the bi-directional runs, we install an opto on both ends of the line to maintain the minimum voltage. - as lor is bi directional, I recommended a repeater at both ends
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