P300

[katsumi_seki]

I conducted a test using two rucks P300. The AP distance is around 20 cm and they face same direction each other. The result of speedflex showed about 20Mbps. But when the distance is about 5m,10m 20m, the results showed more than 100Mbps. 
My question is that why when the distance is very short, the speedflex result is poor?

Thank you

[DarrelRhodes]

Hi Katsumi,

I would suggest that because the units are so close together (obviously they were not designed to be utilsed 20cm apart!) that the low throughput is due to saturation of the receiver in both devices, effectively causing signal distortion (like an extremely loud sound from a speaker can sound distorted if too close to your ear).

Additionally at such short distances the MIMO functionality of the devices won't work as signals from the different antennas can't be differentiated as this is usually the result of propogation and/or signals bouncing off objects in the RF path (multipath).

I hope that helps explain.

Regards,
Darrel.

[katsumi_seki]

Thanks for answering my question
Does it mean that this antenna is designed for long distances and radio waves interfere?

[DarrelRhodes]

Hi Kat,
Yes, the the P300 is designed for long distance links - that is links upto 8KM.  It's a dedicated Point-to-(Multi)Point bridge link and it would be highly unusual for the link to be less than 5 metres.

If you need to have an extremely short link then you could turn down the TX (transmit) power on both units and that would help.

My description above wasn't about interference but signal distortion.  The recievers on the P300 are very sensitive to help with long-distance (weak signal) reception.

I hope that helps clarify.

Thanks,
Darrel.

[katsumi_seki]

Hi Darrel
Thanks for answering again. Actually it's no need to have short distance communication this time but after this test, I was really curious and wanted to know the reason for the phenomenon.


Thank you!!
Kat