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kaefer
EVDO User
Joined: 05 Dec 2005
Posts: 65
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 Posted: Thu Jun 01, 2006 1:11 pm Post subject: Evdo amplifiers in series? |
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Has anyone attached 2 amplifiers in series to help boost signal strength, specifically in fringe reception areas?
I was thinking about attaching an amp with 12 inches of an antenna, then running the 60 feet or so of cable into the building which would attach to a second amp, and finally attaching the second amp to an evdo card.
Would this setup be any better than 1 amp attached near the card and having a 60 feet run of cable to the antenna?
Thanks for the help,
-Scott |
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MaximumSignal
EVDO Vendor
Joined: 08 Apr 2005
Posts: 586
Location: Cheektowaga, NY
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| Posted: Thu Jun 01, 2006 1:54 pm Post subject: Re: Evdo amplifiers in series? |
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| kaefer wrote: | Has anyone attached 2 amplifiers in series to help boost signal strength, specifically in fringe reception areas?
I was thinking about attaching an amp with 12 inches of an antenna, then running the 60 feet or so of cable into the building which would attach to a second amp, and finally attaching the second amp to an evdo card.
Would this setup be any better than 1 amp attached near the card and having a 60 feet run of cable to the antenna?
Thanks for the help,
-Scott |
Can't be done. If you use our * amplifier. It compensates for RF Loss in the cabling and connections.1 amplifier attcahed near the card is all you need |
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jstjohnz
EVDO Fledgling
Joined: 04 Apr 2006
Posts: 25
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| Posted: Thu Jun 01, 2006 8:41 pm Post subject: Re: Evdo amplifiers in series? |
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| kaefer wrote: | Has anyone attached 2 amplifiers in series to help boost signal strength, specifically in fringe reception areas?
I was thinking about attaching an amp with 12 inches of an antenna, then running the 60 feet or so of cable into the building which would attach to a second amp, and finally attaching the second amp to an evdo card.
Would this setup be any better than 1 amp attached near the card and having a 60 feet run of cable to the antenna?
Thanks for the help,
-Scott |
Regardless of persistent claims to the contrary, received signal loss in the feedline is *not* recoverable by an amplifier located near the card. Once that received signal level drops below the noise level of the preamp, it is obviously gone for good.
In general, a preamp located at the card is pretty useless unless it's noise figure is better than that of the card's built-in preamp, and that's not likely. Receive-side gain is incredibly cheap, and if it was a benefit to have more of it, the card manufacturers would spend a few extra pennies to add more gain to their preamps.
The point of course is that quantity of signal isn't terribly relevant, it's quality of signal that counts.
An external preamp may give you a higher indicated signal strength, but the preamp is amplifying both the desired signal and the noise, so it can't improve the quality of the signal (the ratio of signal to noise) and in fact is quite likely to degrade it, given the fairly noisy front-ends of typical external preamps.
A good analogy is trying to pick up a weak signal on an AM radio. A preamp at the card is like cranking up the volume, sure the signal gets louder, but so does the noise, and the reception quality doesn't change.
As far as the transmit side goes, again it is *generally* better to have the amplifier located near the antenna. These amplifiers have a fairly low maximum output (typically 1/2 to 1 watt or so), and as with the receive side, once that transmitted power is lost in the cable it is gone. The problem is that amplifiers designed for evdo adjust their gain according to the signal level they see coming from the card, and this function won't work properly if there is a lot of cable loss between card and amplifier.
Your idea of using 2 amplifiers might just work. All of this assumes of course that you are getting a useable signal at your antenna. If I were you I would be inclined to try an external antenna, mounted as high as possible, with some high quality coax. You may not need an amplifier at all.
-jim- |
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MaximumSignal
EVDO Vendor
Joined: 08 Apr 2005
Posts: 586
Location: Cheektowaga, NY
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| Posted: Thu Jun 01, 2006 8:56 pm Post subject: Re: Evdo amplifiers in series? |
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| jstjohnz wrote: | | kaefer wrote: | Has anyone attached 2 amplifiers in series to help boost signal strength, specifically in fringe reception areas?
I was thinking about attaching an amp with 12 inches of an antenna, then running the 60 feet or so of cable into the building which would attach to a second amp, and finally attaching the second amp to an evdo card.
Would this setup be any better than 1 amp attached near the card and having a 60 feet run of cable to the antenna?
Thanks for the help,
-Scott |
Regardless of persistent claims to the contrary, received signal loss in the feedline is *not* recoverable by an amplifier located near the card. Once that received signal level drops below the noise level of the preamp, it is obviously gone for good.
In general, a preamp located at the card is pretty useless unless it's noise figure is better than that of the card's built-in preamp, and that's not likely. Receive-side gain is incredibly cheap, and if it was a benefit to have more of it, the card manufacturers would spend a few extra pennies to add more gain to their preamps.
The point of course is that quantity of signal isn't terribly relevant, it's quality of signal that counts.
An external preamp may give you a higher indicated signal strength, but the preamp is amplifying both the desired signal and the noise, so it can't improve the quality of the signal (the ratio of signal to noise) and in fact is quite likely to degrade it, given the fairly noisy front-ends of typical external preamps.
A good analogy is trying to pick up a weak signal on an AM radio. A preamp at the card is like cranking up the volume, sure the signal gets louder, but so does the noise, and the reception quality doesn't change.
As far as the transmit side goes, again it is *generally* better to have the amplifier located near the antenna. These amplifiers have a fairly low maximum output (typically 1/2 to 1 watt or so), and as with the receive side, once that transmitted power is lost in the cable it is gone. The problem is that amplifiers designed for evdo adjust their gain according to the signal level they see coming from the card, and this function won't work properly if there is a lot of cable loss between card and amplifier.
Your idea of using 2 amplifiers might just work. All of this assumes of course that you are getting a useable signal at your antenna. If I were you I would be inclined to try an external antenna, mounted as high as possible, with some high quality coax. You may not need an amplifier at all.
-jim- |
The lost signal is recoverable when the amplifier communicates with the device to determine the power needed for the optimum signal. Other amplifiers communicate with the tower, the * amplifier communicates with the device. It is software driven amplifcation as opposed to hardware driven as others on the market. One gentleman here attested to the performance of his amplifier and EVDO card with a 110 foot cable run.You have never used one of our amplifiers so please stop speculating that our amplifier does not work in this manner
Getting back to the original post,the only way your configuration would work in theory are on a single band older style amplifiers that just goes straight to 3 watts and are not variable power . The only units around like that anymore with the old archaic technology are Smoothtalkers. You might want get your hands on a couple of 1900 mhz units from them to try your little experiment . I would ask them what they think of it and see if it is possible in thier eyes. |
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jstjohnz
EVDO Fledgling
Joined: 04 Apr 2006
Posts: 25
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| Posted: Thu Jun 01, 2006 9:54 pm Post subject: Re: Evdo amplifiers in series? |
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| MaximumSignal wrote: | | jstjohnz wrote: | | kaefer wrote: | Has anyone attached 2 amplifiers in series to help boost signal strength, specifically in fringe reception areas?
I was thinking about attaching an amp with 12 inches of an antenna, then running the 60 feet or so of cable into the building which would attach to a second amp, and finally attaching the second amp to an evdo card.
Would this setup be any better than 1 amp attached near the card and having a 60 feet run of cable to the antenna?
Thanks for the help,
-Scott |
Regardless of persistent claims to the contrary, received signal loss in the feedline is *not* recoverable by an amplifier located near the card. Once that received signal level drops below the noise level of the preamp, it is obviously gone for good.
In general, a preamp located at the card is pretty useless unless it's noise figure is better than that of the card's built-in preamp, and that's not likely. Receive-side gain is incredibly cheap, and if it was a benefit to have more of it, the card manufacturers would spend a few extra pennies to add more gain to their preamps.
The point of course is that quantity of signal isn't terribly relevant, it's quality of signal that counts.
An external preamp may give you a higher indicated signal strength, but the preamp is amplifying both the desired signal and the noise, so it can't improve the quality of the signal (the ratio of signal to noise) and in fact is quite likely to degrade it, given the fairly noisy front-ends of typical external preamps.
A good analogy is trying to pick up a weak signal on an AM radio. A preamp at the card is like cranking up the volume, sure the signal gets louder, but so does the noise, and the reception quality doesn't change.
As far as the transmit side goes, again it is *generally* better to have the amplifier located near the antenna. These amplifiers have a fairly low maximum output (typically 1/2 to 1 watt or so), and as with the receive side, once that transmitted power is lost in the cable it is gone. The problem is that amplifiers designed for evdo adjust their gain according to the signal level they see coming from the card, and this function won't work properly if there is a lot of cable loss between card and amplifier.
Your idea of using 2 amplifiers might just work. All of this assumes of course that you are getting a useable signal at your antenna. If I were you I would be inclined to try an external antenna, mounted as high as possible, with some high quality coax. You may not need an amplifier at all.
-jim- |
The lost signal is recoverable when the amplifier communicates with the device to determine the power needed for the optimum signal. Other amplifiers communicate with the tower, the * amplifier communicates with the device. It is software driven amplifcation as opposed to hardware driven as others on the market. One gentleman here attested to the performance of his amplifier and EVDO card with a 110 foot cable run.You have never used one of our amplifiers so please stop speculating that our amplifier does not work in this manner
Getting back to the original post,the only way your configuration would work in theory are on a single band older style amplifiers that just goes straight to 3 watts and are not variable power . The only units around like that anymore with the old archaic technology are Smoothtalkers. You might want get your hands on a couple of 1900 mhz units from them to try your little experiment . I would ask them what they think of it and see if it is possible in thier eyes. |
No amplifiers "communicate with the tower". Nor do they need to. Nor is it even possible. I will leave it to others to decide which of us is speculating.
You are confusing the transmit and receive modes. For the *receive* signal path there is *NO* dynamic gain adjustment (none is needed), the receive preamp gain is fixed.
Look at your amplifier's specs: "Receiver Sensitivity: -110dbm (maximum)"
If you have -100dbm received signal at the antenna (very useable level), and 20db of loss in the coax, the signal at the receive preamplifier will be -120dbm, beneath the amplifiers sensitivity threshold, and unuseable. No amount of pixie dust will recover it.
Do a google search for "mast mounted preamps" and you will find all the info you will ever need.
-jim- |
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MaximumSignal
EVDO Vendor
Joined: 08 Apr 2005
Posts: 586
Location: Cheektowaga, NY
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| Posted: Thu Jun 01, 2006 10:10 pm Post subject: |
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| Enough already . You know nothing about the product and have never used it . Not everything about a product is posted in Specs . It does work as advertised. Why have you gone on this campaign again. Our product works as advertised and all your innuendo that it does not. Will not change the facts. And we are about to devulge our patented software technology to appease your narcissism. |
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MaximumSignal
EVDO Vendor
Joined: 08 Apr 2005
Posts: 586
Location: Cheektowaga, NY
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| Posted: Thu Jun 01, 2006 11:09 pm Post subject: Enough |
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| Enough already . You know nothing about the product and have never used it . Not everything about a product is posted in Specs . It does work as advertised. Why have you gone on this campaign again. Our product works as advertised and all your innuendo that it does not. Will not change the facts. And we are not about to devulge our patented software technology to appease your narcissism. |
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jstjohnz
EVDO Fledgling
Joined: 04 Apr 2006
Posts: 25
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| Posted: Fri Jun 02, 2006 4:43 pm Post subject: Re: Enough |
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| MaximumSignal wrote: | | Enough already . You know nothing about the product and have never used it . Not everything about a product is posted in Specs . It does work as advertised. Why have you gone on this campaign again. Our product works as advertised and all your innuendo that it does not. Will not change the facts. And we are not about to devulge our patented software technology to appease your narcissism. |
I have never knocked the product Gordon, I have never claimed that it doesn't work. I only question your claims as to how it works.
BTW, your last sentence speaks volumes: "And we are not about to devulge (sic) our patented software technology to appease your narcissism".
Hint: You can't patent something (even software) without divulging how it works!
Since this thread is becoming unproductive, I will cease now and give you the final word...
-jim- |
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kaefer
EVDO User
Joined: 05 Dec 2005
Posts: 65
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| Posted: Mon Jun 05, 2006 11:19 am Post subject: Re: Evdo amplifiers in series? |
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Yep, I agree with what you said.
I guess I should mention that at this fringe location I need (and use) an external antenna to help capture the -90dbm (unamplified Sierra 580 card signal reading outside the building) evdo signal. I've tested omni's, yagi's, trucker antennas, amps, and repeaters. Currently I use a marine-grade omni antenna as it seems to work better in this enviroment than a yagi.
I got to thinking an amp located at the antenna would capture the cleanest signal available, then send it down the 50+ feet of cable. Then the second amp closest to the evdo card would gather the signal (being stronger and cleaner since there is an upstream amp near the antenna) and pump it into the evdo card.
My main reasoning for a second amp located at the antenna would be to help overcome signal loss and degradation through the cable run. I also happen to have a second amp sitting in a box doing nothing that I could test.
-Scott
| jstjohnz wrote: |
Regardless of persistent claims to the contrary, received signal loss in the feedline is *not* recoverable by an amplifier located near the card. Once that received signal level drops below the noise level of the preamp, it is obviously gone for good.
In general, a preamp located at the card is pretty useless unless it's noise figure is better than that of the card's built-in preamp, and that's not likely. Receive-side gain is incredibly cheap, and if it was a benefit to have more of it, the card manufacturers would spend a few extra pennies to add more gain to their preamps.
The point of course is that quantity of signal isn't terribly relevant, it's quality of signal that counts.
An external preamp may give you a higher indicated signal strength, but the preamp is amplifying both the desired signal and the noise, so it can't improve the quality of the signal (the ratio of signal to noise) and in fact is quite likely to degrade it, given the fairly noisy front-ends of typical external preamps.
A good analogy is trying to pick up a weak signal on an AM radio. A preamp at the card is like cranking up the volume, sure the signal gets louder, but so does the noise, and the reception quality doesn't change.
As far as the transmit side goes, again it is *generally* better to have the amplifier located near the antenna. These amplifiers have a fairly low maximum output (typically 1/2 to 1 watt or so), and as with the receive side, once that transmitted power is lost in the cable it is gone. The problem is that amplifiers designed for evdo adjust their gain according to the signal level they see coming from the card, and this function won't work properly if there is a lot of cable loss between card and amplifier.
Your idea of using 2 amplifiers might just work. All of this assumes of course that you are getting a useable signal at your antenna. If I were you I would be inclined to try an external antenna, mounted as high as possible, with some high quality coax. You may not need an amplifier at all.
-jim- |
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kaefer
EVDO User
Joined: 05 Dec 2005
Posts: 65
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| Posted: Tue Jun 27, 2006 5:31 am Post subject: |
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My time is short at the moment but I started this test last night. I was able to get the strongest evdo signal I've ever had in this fringe area (-58dbm vs. the previous -78 to -90dbm) but then I saw something I've seen before:
-During the initial connection for about 5 minutes the signal strength is awesome. Then I watch the evdo signal scale back to -110dbm or so. Then it stays in this range.
I saw this when I first hookep up an amp w/ external antenna at this location. Anyone know why this signal reduction happens?
More info later.
-Scott |
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kaefer
EVDO User
Joined: 05 Dec 2005
Posts: 65
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| Posted: Fri Jun 30, 2006 1:21 pm Post subject: |
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Update #2.
This is nice stuff. From now on I'm going to start recommending to people to mount the amp as close to the antenna as possible (instead of near the card). Other wifi folks have been recommending this setup for years. I don't know why the evdo setup has been looked at differently!?
Anyways, the signal issue I see seems to be the reason the evdo providers don't list my area as having evdo coverage. The signal simply comes and goes. When I have it my signal can be as strong as -58dbm. Other times when don't have the signal I simply don't have a signal. This is possibly due to tree movement or other variables.
Next week I'm going to try and eliminate the amp located near the card and just try using the amp near the antenna. I'm also strongly considering a wonderpole for my antenna. I'll say this - this has been an addictive project. I started with a -110dbm signal and now I can get as good as -58dbm. More importantly I'm seeing faster speeds.
I do know for now that using 2 amps, 1 at each end of a 40' cable, is effective when I have an evdo signal in this fringe area. I think the wintertime should be a non-issue (no leaves on the trees = better signal). Basically I've seen about a 30dbm gain from adding the second amp near the antenna. Plus I'm guessing the signal is cleaner (less noisy).
So to sum it up....I like 2 amps but you can't amplify a non-existant evdo signal. When I have the signal it's strong but the signal does come and go.
Perhaps with the Sprint/Alltell roaming agreement I may be able to pick up a closer evdo tower. |
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