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disconnected

@sbcglobal.net

Signal Strength Meter for PCS Cellular with -100dBm Sens.

I am preparing to install a grid parabolic dish for 1900MHz (hopefully to produce a usable signal in the building with my Wilson 65dB amplifier, now that the foliage has bloomed and killed the PCS signal I had during the winter). I need something economical, not a $40K spectrum analyzer boat anchor, as I have to do this on a rooftop.

Was looking at something like this »www.cornetmicro.com/ but their sensitivity is only -60dBm, not enough to detect the weak (-105dBm on the roof last January) PCS signal from a tower in the next county southeast of me. In addition, it's not clear that it can be used to connect an external antenna and be used for adjusting antenna orientation.

I'm aiming an Andrew 24dBi 42" grid parabolic antenna, feeding LMR-600 transmission line, down to a Wilson amplifier inside the building. Connectors are N type. I'd like to find a FS meter that can give me a realtime reading of signal strength of the target PCS signal, as I adjust the antenna orientation and direction.

Any suggestions for an inexpensive measuring device. Due to the 8° beamwidth, precision of aiming is fairly critical.


54067323

join:2012-09-25
Tuscaloosa, AL
said by disconnected :

Was looking at something like this »www.cornetmicro.com/ but their sensitivity is only -60dBm, not enough to detect the weak (-105dBm on the roof last January) PCS signal from a tower in the next county southeast of me.

Why not run the signal through the amp and then to the meter?

I have used a similar method using a Blackberry with a signal strength app and a Wi-Ex zBoost to aim yagi’s for the same purpose.


pike
Premium,MVM
join:2001-02-01
Washington, DC
kudos:3

1 edit
reply to disconnected
Sorry, I can't help with your original question but I have a curiosity of my own. Have you ruled out the use of a femtocell? If so, mind if I ask why?

Also, if it's a Sprint signal you're trying to amplify, you may have some relief coming your way. With the impending shutdown of the Nextel iDen network finally happening on June 30th, Sprint will be aggressively refarming their 800MHz SMR spectrum for use on their CDMA 1x-A and LTE networks. In fact much of the hardware is already in place, they're just waiting to flip the switch so to speak. This should help with the range of the tower you're trying to connect to.


disconnected

@sbcglobal.net
reply to 54067323
Part of the problem is the signal strength 'meter' in the phone is delayed by up to a minute. There's an integration algorithm that makes taking readings a very slow averaging process.
The other part, is there's no connector on my Android phone, so I cannot connect it to the Wilson and Wilson warns against connecting any phone to the amplifier at all, under any circumstances.
Ideal would be a spectrum analyzer in the 2GHz range, because with a 20mS sweep, I could watch my desired signal as I rotate the antenna. But size, weight and cost are impractical.
Something hand held would be great.
Failing that, the alternative is dozens of trips in/out of the building to read the phone's signal. But even when the antenna is stationary, the signal level varies by 15dB with wind direction, so that's not a reliable measurement method.


54067323

join:2012-09-25
Tuscaloosa, AL
said by disconnected :

Part of the problem is the signal strength 'meter' in the phone is delayed by up to a minute. There's an integration algorithm that makes taking readings a very slow averaging process.

What I was thinking was connect the amp to the meter you posted a link to.


disconnected

@sbcglobal.net
I know, use the Wilson to make up the gain. While a possibility, I still have to run another cable to the meter, up from the ground floor, where the amp is installed. And it doesn't look like the meter has any N connector, if it has one at all.

BTW, Femptocell requires some sort of landline connection or broadband. If none exists, that won't work. We're dropping the landline as it costs $93/month to keep that going. The wireless is now cheaper. But not until I solve the reception problems.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to disconnected
You can use just a DMM to read DC voltage of an RF power detector. like the AD8313.

That goes down to -80dBm (0.5V DMM reading) but incoming signal should be stronger than that after the high gain antenna.

TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel
reply to disconnected
I don't know where you are located, but in most major cities there are places that offer rental test equipment.

No, not all spectrum analyzers are boat anchors. Technology has advanced significantly and has made portable battery-powered spectrum analyzers and other test equipment possible.

At work I use an Anritsu MS2035B. It's small and light enough to bring it wherever I need to in the field, including to the top of towers.


pike
Premium,MVM
join:2001-02-01
Washington, DC
kudos:3
reply to disconnected
said by disconnected :

BTW, Femptocell requires some sort of landline connection or broadband. If none exists, that won't work. We're dropping the landline as it costs $93/month to keep that going. The wireless is now cheaper. But not until I solve the reception problems.

So you don't have broadband available? Are you currently using dial-up? If you intend on using an aircard or tethering with your phone for internet, you're quickly going to find the $93/mo for a landline to be a bargain compared to the overages for mobile data.


OldCableGuy

@communications.net
Not everyone uses that much data at home. I have 25 meg down internet from my ISP and last month I stayed under a gig.

I work in a data center, with all the bandwidth I can ask for. Why would I want to go home and use the internet?


disconnected

@108.247.170.x
reply to lutful
The AD8313 sounds like an inexpensive and clever solution. Standing on the roof, with the phone in diagnostic info, I'm reading -105 to -119dBm, depending on wind direction and random factors, right now with the trees in bloom.
This installation is a pita because adjusting the azimuth involves taking the mast down, making the adjustment, and putting it back up again. Horizontal is easy enough because I can rotate the mast.
We have no rental centers except for farm equipment. I can rent a backhoe but not a spectrum analyzer around here.
We presently have BB, but it's going away when we shut off the landline, which is costing us $93/month now.
I work from home, running my video production business and amplifier repair business, so I need reliable phones. Hopefully with the grid parabolic, we'll have the sort of signal we enjoyed all winter.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
said by disconnected :

Standing on the roof, with the phone in diagnostic info, I'm reading -105 to -119dBm

Low noise amplifier (LNA) before AD8313 can get you down to that level. Minicircuits sell connectorized versions so you don't even have to solder anything.


disconnected

@108.247.170.x
said by lutful:

said by disconnected :

Standing on the roof, with the phone in diagnostic info, I'm reading -105 to -119dBm

Low noise amplifier (LNA) before AD8313 can get you down to that level. Minicircuits sell connectorized versions so you don't even have to solder anything.

Good idea with the LNA. May be my only option. Antenna arrived yesterday. I installed it today, but orienting it is a crap shoot. Signal is varying by 20dB with the antenna stationary and the phone next to the indoor panel antenna. At one point I had -79dBm, then a minute later, -105dBm! How can I aim an antenna when the trees are moving and causing such wild swings? I need a realtime monitor like a SA display with 20mS update times, so I can watch the peaking move up and down as I swing antenna from side to side.

TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel
If you know where the cell tower is located and its height as well as the location and height of your own antenna, you can actually aim it pretty accurately.

I think you can get cell tower locations and heights by searching the FCC database on the FCC website.

GPS receiver and topographic map to determine the location and height of your own antenna.

With an accurate compass you should be able to set the azimuth of the antenna within a couple degrees of where it should be. A digital level or a simple protractor and plumb-bob can be used to set the tilt appropriately.

That should get you in the ballpark.

Also, the structure (mast) that the antenna is mounted on should obviously be very rigid. If the mast bends or moves at all in the wind, it's NFG for what you're trying to achieve.

Also, it sounds like your antenna can not reach above the tree tops? Definitely not an ideal situation. Any way to get it higher?


disconnected

@108.247.170.x
Due to the curvature of the mountain, I do not have line of site to the tower. The tower is at the bottom of the hill, but I'm not on the facing slope. I'm on top, a ways from the 'edge' where the slope turns downhill. So if you draw a line from my antenna to the tower, it would pass through the mountain ledge on the way. Knife edge diffraction is the only path available, further attenuated by trees.

What really burns me is that there is a multi-site cell/AM/FM tower farm 900' south of me. But if I aim the dish in that direction, my signal at the indoor panel goes to -128dBm. Sprint is not on that tower, despite what their web site says. The only other tower is a few miles away, at the bottom of the mountain, and it's low, mounted on a power pole, not a 180' tower.

I wish I could get my antenna higher, but without a steel structure guyed tower, impossible. 100' oaks and beech trees surround us on all sides. The foliage is so thick, the sun doesn't even reach land here, so my solar footlights don't work except in winter and early spring.

Right now I've done about 50 trips to the roof and moved the rotation of the mast 1° each time, then took 2 minutes and averaged the readings from the phone. It only takes 2° of rotation to lose 8dB. Right now, I'm at -72dBm 3' from the indoor panel antenna. During the winter, it was -58dBm at that location. No service if I shut off the amplifier. That's not much better than the 11dBi log periodic that Wilson provides with 30' of RG6. 25' of CNT-600 and 24.5dBi dish antenna not doing much better, if at all. I wonder if it's the fact that the amplifier is 75 and the cable/antenna dish is 50... 1.5:1 VSWR would mean barely 2dB loss in a RF power transmission system, but this is bi-directional and who knows what the mismatch is doing to the way the amplifier's 'smart logic' system works. I may have to buy the more costly 50 Wilson amplifier and replace this 75 version. Plus the N to F adapter, where the CNT-600 comes to the amplifier, loses some signal (hopefully less than a dB). Over all, it's disappointing performance. I had hoped to see 10dB or better increase in signal over the small log periodic from Wilson. I was able to make a phonecall just now from inside the house, but zero bars of signal makes me nervous that the call will drop.


disconnected

@108.247.170.x
Using mapping software, Sprint's tower map, and Google maps with satellite imagery, I was able to determine that the cell tower my dish is aimed at is not the one closest to me at 3.5 miles, but another, about 18 miles away that is more line of sight. The nearby tower is completely shadowed by the mountain, but when it's daylight and not raining, I'm going to try aiming for that narrow sector anyway, just to see if I can get some sort of signal.
Not good results right now even with the 24.5dBi dish. Service is going on and off on the phone and zero bars of signal. I lose service about every 15-30 seconds with the ebb and flow of the propagation. Very frustrating. I'm going to have to go even higher gain on the amplifier, so it seems. Wilson tech told me that I will need a preamplifier, given my long distance super fringe signal conditions. This is starting to approach a grand in hardware costs just to get marginal signal into the building.


disconnected

@108.247.170.x
Today, I swung the antenna around to get the tower (mounted on a power pole next to a state route) that's completely shadowed, at the base of the mountain. I went from -72-ish to a -58-62dBm as measured with the phone next to the indoor panel antenna.
Downstairs, I went from -115 to about -102dBm. Not enough for data (network error when I run speedtest), but can make and receive some calls now. Also noted that my phone battery no longer goes completely dead in 2 hours and the phone isn't overheating anymore.


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to disconnected
Have you considered the obvious solution - going with a provider that actually works???
AT&T has very good coverage in the area, same for Verizon...


disconnected

@108.247.170.x
I did. I chose Nextel. But they got bought out by Sprint and iDEN was shut down, so I was forced into PCS.

My wife has AT&T. Zero bars of signal in the house WITH the Wilson booster. Our spot is a complete dead spot for any PCS provider. Only iDEN band has ever put in a good 4 bars here.

TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel

1 edit
reply to disconnected
said by disconnected :

Today, I swung the antenna around to get the tower (mounted on a power pole next to a state route) that's completely shadowed, at the base of the mountain. I went from -72-ish to a -58-62dBm as measured with the phone next to the indoor panel antenna.
Downstairs, I went from -115 to about -102dBm. Not enough for data (network error when I run speedtest), but can make and receive some calls now. Also noted that my phone battery no longer goes completely dead in 2 hours and the phone isn't overheating anymore.

Since you're getting a good signal close to panel antenna, this means your parabolic antenna is picking up a good enough signal.

All you need to do now, is add more amplification so you get the signal strength necessary to give you coverage of downstairs.

~40dB is about what I would expect for path loss from the panel antenna to downstairs, assuming an average sized house.

Every 10dB additional amplification will approximately triple the usable range.


disconnected

@108.247.170.x
Click for full size
Current Andrew 24.5dBi 46
I had an even better signal at the panel during the winter. About -48dBm. But then the trees bloomed and the foliage just blocked everything.

Amplifying a weak signal can result in less quality due to noise. That said, I was pondering the idea of getting the Wilson splitter, and installing a second panel antenna downstairs. It almost begs to have a panel in every room. Signal is very good in the hallway, under the panel. Ahead of this splitter, a Wilson 17dB amplifier, intended to boost signal on the INDOOR side of the booster, could be installed to ensure enough power to drive both panels.

I wish Wilson published the patterns for the panel antennas. It would be helpful to know if there are lobes at the corners. I could rotate the antenna a bit and possibly enjoy a significant improvement in areas of the shop where I use the phone most often.

The other issue that may be making things worse now with the new Andrews antenna and the CNT600 transmission line is the fact that the dB Pro amplifier is 75 . Two issues: the use of N to F adapters and impedance mismatch. Normally, that doesn't mean a radical loss in signal, but if the Wilson's self-monitoring logic ratchets down the transmit power as a result, I could be losing a lot more than 3dB due to mismatch alone. Wilson has a "Spec AG Pro" kit with 70dB of gain and all 50 N type connections. If it had outputs for two panel antennas (built in splitter) I would buy it in a heartbeat. As it stands, the $600 pricetag for this amplifier leaves me hesitant.


pike
Premium,MVM
join:2001-02-01
Washington, DC
kudos:3
reply to disconnected
disconnected, I'm not sure if you caught it in my first post, but Sprint is deploying 1xAdvanced on 800MHz SMR (former Nextel spectrum) across their coverage area. You may want to consider getting your hands on an 800-capable device to see if its broadcasting in your area yet as I suspect this would simplify your setup significantly. See s4gru.com for tower maps, market dates, etc.


Disconnected

@108.247.170.x
Only in a few major cities so far. They don't have any upgrade plans for my area in the near future. I regularly sweep the 800mhz band with my hp8568B but no signals exist. LTE is a long ways off.


shdesigns
Powered By Infinite Improbabilty Drive
Premium
join:2000-12-01
Stone Mountain, GA
Reviews:
·EarthLink
·Comcast
·Atlantic Nexus
reply to disconnected
I'm in a similar situation here. Tower is less than a mile away but too many trees and hills. Almost no signal.

Same for UHF TV. No direct line of sight. I get a stronger signal with the antenna pointing any direction other than toward the tower.

The problem is multipath. I may get a decent signal and usually do but a slight wind and the level starts oscillating. Rain, temperature, aircraft, trucks driving by all cause a momentary cancellation.

I have an amplified antenna but it only helps a tiny bit. I see little difference between a highly directional antenna and a bow-tie antenna. Both get agood signal but intermittent nulls.

Unless you can get a LOS setup, I doubt any amp/antenna combination will be reliable. Only a multi-antenna setup with some discriminator would be effective.
--
Scott Henion

Embedded Systems Consultant,
SHDesigns home - DIY Welder

TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel
reply to disconnected
said by disconnected :

Amplifying a weak signal can result in less quality due to noise.

If it's a good low-noise amplifier, the S/N ratio should be relatively unchanged.

said by disconnected :

Ahead of this splitter, a Wilson 17dB amplifier, intended to boost signal on the INDOOR side of the booster, could be installed to ensure enough power to drive both panels.

That's what I was getting at, minus the splitter. But the splitter and two antennas might also work.

said by disconnected :

As it stands, the $600 pricetag for this amplifier leaves me hesitant.

Yeah, I'm starting to question whether the setup will ever pay for itself in the cost savings of not paying for a landline? Sounds like all the hardware required is getting expensive fast.


disconnected

@108.247.170.x
I think 2 antennas is the only way to go. Just not getting enough from upstairs antenna with all the acoustic insulation in the studio ceiling (about 20" of various densities of fiberglass).

It's getting expensive, but I'll save a grand in 2 years on landline charges if I cut the cord, considering the cost of cellular in the picture. Many of my customers call the cell number, but I'm missing 3-4 calls a day now, which is starting to impact my business.


disconnected

@108.247.170.x
reply to shdesigns
Multipath is a killer. And at nearly 2GHz, individual LEAVES become reflectors. Millions of them, fluttering in the breeze.
I noticed yesterday that my signal was above normal for about half a minute. I noticed one of those big army helicopters flying south of me. Must have been reflecting some signal from the tower.
I actually get almost as good a signal from the tower 18 miles away as from the one 3.5 miles away, because the father tower is not so shadowed by the slope of the mountain. I'm on the level plateau, quite a ways from the dropoff, so everything in the valley is shadowed. When the trees are bare, I can see the mountain range on the other side of the valley in the next town over.
Last night, I had -102dBm in the studio, but today, we have very heavy rain and signal dropped to -125dBm. I could strangle the idiots who thought it would be a good idea to rollout PCS in a hilly, forested part of the country.
My idea of a LOS setup would be a multi-stacked J-pole array. But alas, I tried something similar with a sector panel antenna with an 90° beamwidth and an 8° elevation pattern, but it didn't work well compared to the log periodic Wilson antenna (the one in the white radome).
There are still wild swings in signal. This afternoon, standing under the inside panel antenna, I observed the signal dropping to -125dBm for a minute, then it came back up to -93 or so. Either the tower shut off the transmitter momentarily, or that was one heck of a deviation in signal.

TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel
said by disconnected :

I could strangle the idiots who thought it would be a good idea to rollout PCS in a hilly, forested part of the country.

I'm surprised they decided to put the towers down below. Usually carriers like to stick their towers on the tallest hill they can find (within reason).

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to disconnected
said by disconnected :

Multipath is a killer. And at nearly 2GHz, individual LEAVES become reflectors. Millions of them, fluttering in the breeze.

Notice the huge difference between windy and calm days: »Re: RSSI fluctuations

Curiously my very first post in DSLR was about making 2.4Ghz links through foliage ( »Re: Country House to City House (2 mile NLOS) link ) back in 2004. I posted example paths through foliage later on (
»Best way to deal with wet foliage? ) and also provided suggestions to other WISPs to make such links.

The obscure "multi-path" antennas we used in those links had wider beam (because of moderate gain) and was somewhat insensitive to polarization. That explained their seemingly better performance than higher gain fixed polarization antennas.

I did some research in 2006/7 using arrays of single patch antennas (nominally 6.5dBi each) oriented at random angles plus with a low insertion loss combiner and LNA. That worked even better through foliage.



disconnected

@108.247.170.x
That's exactly the concept that I was trying to go after with my 90° beamwidth sector antenna. But then I discovered that the technical advisor from Wilson was right: use the highest gain parabolic dish that you can get. That improve the signal but of course an improvement over the next zilch is not much of a signal still. Right now we're having a band of nasty thunderstorms moving through the northeast it stretches from Canada to Delaware. I saw the signal completely wink out at several points where the phone displayed searching for service. Rain is a real problem when it comes down this hard.