RF Explorer Model 3G Handheld / USB RF Spectrum Analyzer

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jhal94

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Hello all, I was wondering if anyone has had experience with this:

RF Explorer Model 3G-24G Combo — Handheld / USB RF Spectrum Analyzer | RF Explorer - Handheld RF Spectrum Analyzer

I was thinking of getting a used one to map out the cellular coverage of my area (Gainesville, fl) because it is so terrible (along with wardriving). Does anyone know if this is the right tool or if there is something else more appropriate.

Also has anyone had any experience as to whether the 3G/4G boosters/repeaters actually work or if it is just a gimmick. If they do I plan on hooking one up to a high gain 3G/4G larsen or laird antenna.

MODS: please feel free to move this thread to wherever it needs to be, I am unsure of what category it really belongs to.
 

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mmckenna

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I was thinking of getting a used one to map out the cellular coverage of my area (Gainesville, fl) because it is so terrible (along with wardriving). Does anyone know if this is the right tool or if there is something else more appropriate.
No, it's not. The cell sites use a control channel, and the different cells use different frequencies. They get reused occasionally, but not on adjacent sites.
You could find a control channel, and see what the coverage is for a specific site, but it won't hop between sites. You need a cell phone in "field test" mode to do that. You can google your cell phone model and the term "field test" and you can often find directions on how to put your phone into this mode. I can do it with my AT&T iPhone, and it will spit out the cell site info, along with the signal strength in decibels.

Also, a cellular carrier won't really be interested with this information. It might satisfy your curiosity, but the data won't do much else for you, and it won't do anything for the cell carrier. The carriers only care about profit, and if they don't see a profit in improving coverage, they won't do it. Won't matter how much data you provide. What they want is a reliable customer base in that area to make the investment worth it. You can certainly call and complain. It won't hurt (much), but don't expect them to come running out and install a new site.

Also has anyone had any experience as to whether the 3G/4G boosters/repeaters actually work or if it is just a gimmick. If they do I plan on hooking one up to a high gain 3G/4G larsen or laird antenna..
Depends on which ones you get. Cheap Chinese e-Bay ones are going to be a mixed bag. A decent one, like a Wilson, will work pretty well. I used to have one in my truck. It was a Wilson mount that held an iPhone, so no direct antenna connection to the phone. I had an NMO antenna permanently mounted on the roof of the truck. There were places I could go where the cell phone on it's own would not connect to the network. With the Wilson unit, I'd get 2 or 3 "bars" and have no problem making/receiving calls. AT&T was the carrier.

I have a direct connect Wilson that we tried out with one of the call boxes at work. Again, AT&T was the carrier. I installed an NMO mount on the top of the call box, and this amp inside. The call box on it's own would not connect reliably to the network. The Wilson amp helped slightly, but still not a reliable connection. Ended up switching to a Verizon radio and got it all to work just fine.

I've never been really impressed with the Wilson gear. Their antennas are pretty crappy. The iPhone adapter I had worked well, but the housing was really cheap plastic, and the mount was utter and total crap. Had to rebuild it with a "real" mounting. I got rid of the whole mess a few years ago. Sold the amp and antenna (with a mag mount) on e-Bay.
The direct connect unit seems to be built well, but it didn't accomplish the task. Not because it didn't work, but because the AT&T coverage was too crapy.
That is the part you would need to consider. It isn't just about boosting your transmitted signal, you also need to amplify the incoming signal from the cell site. If there isn't enough signal there to overcome the noise floor, no amount of consumer grade amplifier is going to fix it.
 

jhal94

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Yeah I was considering it just for curiosity reasons but I do see your point about it not being very informative/efficient. Right now I am using G-Mon but it only works if you can find a usable signal to begin with. On my HTC One G-Mon shows a loss of -109dBm from the tower (It stops counting at -116dBm) in the only spot in the building that I get any coverage.

I would be happy if T-mobile sold micro cells but they don't....
The tower is about a half mile away but it is in a valley and is too short, I am up on a hill level with it and there's a building in front of it so it blocks the signal.

I looked into those Wilson boosters and they are getting mixed reviews, though I am curious if the bad ones are due to the cheap looking antenna that's supplied (I would assume a high-gain Larson on a large ground plane would make a difference). I guess ill live with it though I may try the direct connected one one of these days.

Thanks for your informative reply. Much appreciated.
 

Razvedchik

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The -109 you're seeing is actually the RSSI (signal strength) value for the BTS (tower) and not a loss. -109 isn't too bad, if you were pretty close to the BTS you would see something like -80 and up. The reason for the -116 is that's the end of the effective range from the BTS to your handset. Your handset would have been handed off to the next BTS before you got the that number, unless you're way out there and there is no other BTS. Those thresholds are provided to your handset by the carrier through the BTS when your handset registers with the network.

As for the amplifiers, I have seen them work well in offices that are located in fringe areas where my phone couldn't find a strong enough signal on its own. Another set of problems related to the amps is the protocols themselves. If you change carriers, the amp may not work because the amp may not support your new carriers protocols. While that was true a few years ago, it may have improved.
 

mmckenna

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I looked into those Wilson boosters and they are getting mixed reviews, though I am curious if the bad ones are due to the cheap looking antenna that's supplied (I would assume a high-gain Larson on a large ground plane would make a difference). I guess ill live with it though I may try the direct connected one one of these days.
If you are trying to improve coverage within a building, you would be better off with a band specific Bi-Directional Amplifier (BDA). You would want to try a fairly high gain directional antenna pointed at a cell site. The BDA would take that signal, amplify it, and send it to an antenna inside the building. There are some "gotcha's" with these, though. You need some good isolation between the indoor and outdoor antennas to prevent the amp from oscillating. Also, they often need to be registered with the carrier to be completely legal.

None of that would be inexpensive. It would be easier to switch carriers as soon as you can get out of your current contract. Indoor pico-cells from the carrier is a good option, too. If you complain hard enough, you can sometimes get them inexpensively from the carrier. You'd need a reliable internet connection for it to work, but it's an option.
Personally, I'd just switch carriers.

The Wilson antenna that came with the iPhone booster was a real piece of crap. RG-174 coax, which is extremely lossy on the cellular frequencies, but makes installation easier for consumers. The antenna itself was just a stripped back piece of coax covered in thick plastic with a magnet on the bottom. I replaced it all with dual shield RG-58, permanent NMO mount, and a good antenna. That may have helped mine work properly.
 
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