Multiple Modems - Direct Connect v.s. Wireless v.s. Combiner

JoeCHecht · EVDO Junkie Joined: 05 Jan 2008 Posts: 342

Hello,

With my MBR1000 now load balancing between a Sprint U727 and an Alltel UM-150, I gotta problem with my mobile installation.

I currently have a direct connect amp hooked to a omni trucker antenna.

I can't add another antenna for the second modem (however, I could add another amp).

I want both modems to be amplified, and run them though the omni antenna.

I have a couple of possible solutions, and would like to hear opinions.

Solution A: Get a combiner. This allows two modems to be fed to the single direct connect amplifier/antenna system. Pros: Cheap and easy. Cons: At least a -3db loss.

Solution B: Can you feed two direct connect amps into a combiner? Will this result in less loss? Since the amp is supposed to vary the power based on the cell tower, would two amps work any better/worse than one?

Solution C: Get one of the wireless amps that are supposed to allow multiple devices (phones and modems) to work. Pros: really easy, works with our cell phones as well. Cons: Expensive. Device must be in very close proximity to inside antenna. Connection to modem probably not as good as as a direct connection.

Also, does the combiner and/or the wireless amp have any trouble when connecting to multiple carriers at the same time?

Finally, does anyone have any experience with both the direct connect and wireless amps? Care to share? How much better is the direct connection (if any). Does it really work well with multiple devices at the same time? I can see times when two modems and two cell phones would be running all at the same time, using multiple carriers.

Thanks in advance for your thoughts!

Joe

Alex · Posted: Fri Aug 29, 2008 12:51 pm Post subject:

Ever since the MBR1000 1.3.1 firmware has been released, i've been stealing ESN's from staff to do testing with 3 sprint and 3 verizon devices. (shh. don't tell them thats why their devices keep failing.)

I was faced with the same dilemma as you described, but have the luxury of having many toys to play with.

I tried the splitter/combiner, and while it worked better for me than repeater did, i needed signal gain to three devices, not two.

My opinion is that for maximum gain to just two devices, the splitter we sell is the best choice.

However, for my testing, the in-vehicle repeater with proximity antenna sitting on top of the MBR1000 was what gave me best results.
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JoeCHecht · EVDO Junkie Joined: 05 Jan 2008 Posts: 342

Thanks Alex!

Did you try it with multiple carriers at the same time?

How much difference is there between the splitter (actually it's a combiner) and the wireless?

As I recall, the proximity antenna is good for about 18 inches?

Thanks again,

J

Alex · Posted: Fri Aug 29, 2008 1:48 pm Post subject:

i tried with sprint and verizon at same time, yes.

i was never in "really bad" signal area, so its hard to say whether splitter was "better" than wireless, at any point.

if there was a difference at all, it was not dramatically obvious to me.

maybe operating under really bad signal conditions would make it more obvious.

thing is, i was trying to find a tower that had more than T-1 pipe to both carriers, and i only found towers with more than T-1 to either carrier in city/urban settings which tend to mean pretty good signal to begin with.

btw, when i finally found a tower with better than T-1 to sprint and verizon (like 1600/1800 kbps down on each), i spent hours testing bittorrent speeds to see if multiple devices from same carrier would ever be as good as multiple devices from different carriers.

as i suspected, the only way to truly benefit from load balancing across multiple devices is to have each device from a different carrier, and hope that each carrier at that tower, is "well fed".

curious about peak bittorrent rate? Wink

3022.85 Kbps = 369 kB/s = 3.02 Mbps = 0.37 MB/sec

that was with Sprint EX720 and Verizon UM175, but swapping to other active devices proved to me, no device has any speed advantage.
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