| Electronics > RF, Microwave, Ham Radio |
| Ubiquiti SR71-USB Range Question |
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| bostonman:
I have a Ubiquiti SR71-USB that I played with for the first time tonight to see if it got better reception than my laptop WiFi. Looking at the datasheet, it's good for 300m (984ft or 0.19miles) indoors and 10km (6.2miles) outdoors. Does this mean I can tap off my friend's WiFi that's about 1/2mile away (but through trees and a few houses) if I place the antenna outside? I took the laptop outside, however, I don't believe I saw their WiFi name in the list. Most likely the spec requires direct line of site, but thought I'd get some clarification. Here is the datasheet: https://download.discomp.cz/Ubiquiti/Datasheets/sr71usb_datasheet.pdf |
| Halcyon:
For reliable throughput at 800 metres (1/2 mile), you'll need a lot more than a couple of dipoles. You would be looking at high-gain directional patch or cage type antenna on both ends. Using standard consumer parts, with a clear line of sight on 2.4 GHz, you might get somewhere in the 50-100 metres range. Ubiquiti's outdoor long range antennas will typically give you coverage to about 150 metres, using an omni-directional antenna. So-called "Bridging antennas" will usually get you up to about 500 metres maximum. |
| bostonman:
Why do they list 10km then? Does that mean it will work providing the hardware has a high level of power? I knew this wouldn't pick up signals 10km away; else I would have seen many more networks than the ones in the general area, but wondering what the 10km spec means. |
| Halcyon:
--- Quote from: bostonman on January 03, 2025, 02:21:07 pm ---Why do they list 10km then? Does that mean it will work providing the hardware has a high level of power? I knew this wouldn't pick up signals 10km away; else I would have seen many more networks than the ones in the general area, but wondering what the 10km spec means. --- End quote --- You MIGHT get 10 km with a decent radio/antenna at both ends and perfect conditions (think in the middle of nowhere with some high gain, directional antennas). The specs sheet itself says "antenna dependant". You won't get that with a couple of cheap dipoles thrown into the box. The power limits are strict and vary from country to country. Talking louder (increasing power/gain) needs to happen on both ends. The other issue you have is all the other crap on the 2.4 GHz band along your link path (including Fresnel zones). It's a crowded band and that stuff doesn't just disappear, both ends will pick that up. You can't just "talk over" other networks, Wi-Fi doesn't work that way. Even in a regional area, you can forget about it on 2.4 GHz, or even 5 GHz. If you're looking at Point-to-Point, you want to be looking at equipment that operates in the 60 GHz band, but you won't get that in a PC card or dongle. This is network level stuff. |
| RoV:
I have used Ubiquiti equipment in the past (in particular the Bullet-M series) to reach long distances. They can easily cover 10 km or more in clear line of sight when using high gain antennas. I personally tested them in a mountain environment with ~1 m diameter parabolic dishes. However, going above 100-150 m requires to override the standard timeout of Wi-Fi modems, otherwise the RF signal arrives, but the communication link is not established or fails regularly. Ubiquiti modems have a customized timeout setting for this purpose in their configuration page, but the link works only if both parties increase the timeout, so you won't normally be able to talk to a generic access point using your Ubiquiti above 100-150 m, even if you get a clear signal: you see the access point listed, but you don't manage to connect and/or exchange data. All works ok with two Ubiquiti devices. |
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