DIY cell repeater/booster, or recommended forums/vendors.
May 6, 2015 10:59 PM   Subscribe

I need a repeater, and tend to not trust integrated units. I'm perfectly comfy with soldering and assembling an über-repeater by sourcing the various parts ala a handbuilt PC. I just don't know what to buy!

- Verizon, NYC, Williamsburg, basically a concrete bunker.
- I *might* have access to the roof, definitely could run coax from my space to the building facade (~150ft), and could mount an ext. antenna at ~15' level.
- Reception isn't even very good at the front door. Walk a few hundred feet and calls drop.

I've found at least one project w/parts list, but I feel like NYC is maybe more challenging terrain, and I might need to be a bit more finicky about antennas & gain.

I'm wary of integrated repeaters without ext. antenna hookups, so.. I'd love to hear some recommendations on various parts, forums where I might find similar project rundowns, quality vendors, or just great integrated units that actually are aces.

Also curious as to how I find my best tower to boost... surely I don't need to war-drive with 3G/LTE equivalent of Netstumbler?
posted by Jack Karaoke to Technology (3 answers total) 1 user marked this as a favorite
A handbuilt repeater isn't going to be FCC-certified, and as such, isn't a good idea.

More, the FCC recently changed things so that you need to register cell repeaters with your carrier.

Generally Wilson is considered to be a reputable vendor for this sort of thing.
posted by jgreco at 7:34 AM on May 7, 2015

Best answer: You are going to lose a *lot* of signal in a 150' cable run at cellular frequencies (~ 700 - 2100 MHz), even in fairly thick and expensive cable like LMR-400. Just as an example, at 900 MHz, LMR-400 loses 3.9 dB of signal over a 100' run - that's more than half of your signal right there.

I too am skeptical of the units that you are supposed to stick next to the window or whatever, that don't have a remote antenna connection. That said, I've never actually experimented with one so I can't offer any first-hand experience.

In line with what jgreco said, you are not going to "build" a cellular repeater/amplifier. It's outside of your skill level (and mine, and that of many electrical/electronics engineers), and even if it weren't, the resulting product would not be FCC- or carrier-approved. That said, if what you are wanting to do is something more along the lines of your "project w/parts list" link, then yeah, that type of thing is perfectly fine.

I also agree that Wilson is a reputable source of cellular amplifiers and antennas. I'm not sure whether they sell bulk cable, but you can find that online without much trouble.

Properly mounting and aiming a directional (e.g. Yagi) antenna for your outdoor unit can be a real pain. If there is decent signal where you plan to put the outdoor antenna, you might be better off using an omnidirectional antenna there and relying on the combination of outdoor antenna location and amplifier gain instead of trying to get a lot of directional gain into the mix as well.

If you do end up buying some kind of amplifier, be sure it supports the frequency bands that Verizon uses. At the moment, these are:
  • 850 MHz (CDMA band class 0) for 2G/3G voice/data
  • 1900 MHz (CDMA band class 1) for 2G/3G voice/data
  • 700 MHz (band 13) for LTE
  • 2100/1700 MHz (band 4) for LTE (in most areas)
  • 1900 MHz (band 2) for LTE (in some areas)
This Wilson amplifier covers all the relevant bands, but it is possible that it only comes as a kit, which is not what you want:

This one is beefier and more expensive, but does come standalone, and covers all the relevant bands:

If you do end up needing a long run of coax cable in your eventual setup, it is *probably* better to have the long length between your indoor antenna and the amplifier as opposed to having it between the amplifier and your outdoor antenna, but you may need to end up doing some trial and error or consulting with an actual RF person on-site to know for sure.

I hope this helps.
posted by Juffo-Wup at 1:09 PM on May 7, 2015

Best answer: A friend pointed out that you might mean something other than what I was thinking of when you said you don't trust "integrated units without external antenna hookups".

I too don't trust actual radio repeaters without external antenna hookups. However, there is another kind of device, generically called a femtocell or microcell, which uses your Internet connection to connect to your cell phone company, and it then broadcasts its own clean, strong cell signal.

These units (Verizon calls theirs a "Verizon Network Extender") work very well in my experience and are what I would most likely recommend for you instead of an actual amplifier/repeater. The advantages of the femtocell are that it is much cheaper, it is more or less guaranteed to work, it gives a cleaner signal, and you don't have to mess around with long and expensive runs of coax cable.

These units *do* require a GPS lock in order to operate (for technical timing-related reasons in addition to E911 requirements), so there is that consideration. Also, at present, the Verizon Network Extender only transmits a 2G/3G signal, not an LTE signal. Rumors are swirling that an updated version with LTE support will be released "soon," but I have no idea when that might be.
posted by Juffo-Wup at 1:23 PM on May 7, 2015

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