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To back up my claims of low noise floor, here's 5 minutes of airtime
sampled from a 900MHz antenna @ Haystack, aimed roughly at Everett
(287 degrees):<br>
<br>
<img src="cid:part1.19296C5A.AEBEC1E3@bartk.us" alt=""><br>
<br>
I don't use this system anymore, so I'm making it available for
HamWAN experimentation for the next few weeks/months. To use it:<br>
<br>
Modem: Rocket M900 / M9, or compatible, dual-polarity MIMO.<br>
Antenna: <a href="https://www.ui.com/airmax/airmax-yagi-antenna/">https://www.ui.com/airmax/airmax-yagi-antenna/</a><br>
SSID: HamWAN<br>
Frequency: 917MHz<br>
Bandwidth: 5MHz<br>
Mode: AirMAX TDMA<br>
Security: None<br>
IP: DHCP<br>
<br>
Please let me know if you're attempting to connect, regardless of
success or failure, as both results are useful.<br>
<br>
--Bart<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 5/23/2019 10:16 AM, Bart Kus wrote:<br>
</div>
<blockquote type="cite"
cite="mid:dd5a5e8e-fdef-1b78-6eec-d000bcdc9358@bartk.us">Another
thing to mention about 900MHz usage is that it's very close to
really powerful paging / cell systems. We had to use an 8-cavity
super-narrow bandpass filter to make the 900MHz installation @
Gold Mtn work. The initial deploy didn't use said filter, and the
adjacent QRM was so bad that I couldn't even connect to the AP
from the base of the tower! I have several more filters in stock
to support any possible future site deployments.
<br>
<br>
In my surveys, I haven't observed the high in-band noise floor
that others are reporting.
<br>
<br>
Due to the lower gain and directivity of 900MHz antennas, the
signal levels are low, and higher power would be useful. Sadly,
900MHz bidirectional amplifiers are still prohibitively
expensive. If I recall correctly, the math models I did for
900MHz mobile coverage required something like 500W peak amplifier
performance to get decent data rates.
<br>
<br>
Sad to hear about the EOL of the 9HPn. :( In light of that news,
it probably makes sense to re-work that system with available
gear, such as UBNT.
<br>
<br>
--Bart
<br>
<br>
<br>
On 5/23/2019 10:03 AM, Bryan Fields wrote:
<br>
<blockquote type="cite">On 5/23/19 12:57 PM, Steve wrote:
<br>
<blockquote type="cite">The 900 MHz noise floor is pretty bad
around the populated areas. Lots of
<br>
utility's use it now.
<br>
<br>
The narrower the better.
<br>
</blockquote>
If it's just a ptp use, a M2 yagi will help.
<br>
<br>
Also, there are radios from the mid 2000's mabe by alvarion:
<br>
<a class="moz-txt-link-freetext" href="https://www.ebay.com/itm/162895142474">https://www.ebay.com/itm/162895142474</a>
<br>
They are a 2 mhz channel and will do about 1.5 Mbit/s and 550
packets/sec.
<br>
It's not a lot but if it's behind trees, it's just fine for a
link or a few
<br>
phones.
<br>
<br>
73's
<br>
</blockquote>
<br>
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<br>
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<br>
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<br>
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<br>
</blockquote>
<br>
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