asymmetric SNRs
asymmetric SNRs
So there is a router 3.7 miles from my house that i can hear between 2 and 5 SNR but its hearing my transmissions between -4 and -18 SNR with a -10 average (5 traceroute tests). Shouldn't it be able to hear me just as well as I can hear it? I can only think of two possible causes for this.
- The router has a much higher noise floor than I do
- The router antenna is more than 33cm tall and has directional lobes and null zones.
However, that second explanation seems off simply because if it wasn't transmitting my direction, I shouldn't be able to hear it as well as I can.
Thoughts?
Edit:
- My antenna is not a full 33cm So does not radiate the signal efficiently.
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No. Sending and receiving are two separate processes. While you yourself might hear a train whistle over a Kilometer, don't expect that the train hears you shouting at it.
True, but since this is license-free, the radios should be putting out about the same amount of power. I would totally understand it if this were a licensed band and the router was putting out much more power than the client, such as repeaters on amateur radio being able to put out 50 or 100 watts where my HT can only put out 5 watts.
Do you have the exact same hardware on both sides?
No, router is a WisBlock 4631 with a 2.5 wavelength antenna (according to a local) and my node is a SeeedStudio SenseCAP T1000-E with what i think is an 1/8th wave antenna.
Maybe at some point I will buy another node that will allow for an external antenna and put a full wavelength antenna on it, which should boost the radiated power pretty significantly.
Is it a 2.5 wavelength or a 2.5 dB omni? A 2.5 wavelength is much larger than 33 cm and will have dead spots.
But in general it will be harder for it to hear a transmission from the internal T1000-E compared to any significant external antenna.
According to the local, it's a 2.5 wavelength, which is larger than 33 cm, and is going to have dead spots because of that. But, since I'm using the internal antenna on the card tracker, I'm not surprised that it's not hearing me very well either.