[HamWAN PSDR] VOTE: 900MHz service experiment
Bart Kus
me at bartk.us
Sun Mar 8 12:30:58 PDT 2015
I didn't go, nor would I trust HamWAN money to sketchy antennas.
I purchased the 3 modems recently approved (1 replacement 5GHz and the 2
900MHz modems) and saved money by combining shipping. There is $118.12
left in approved funds to get a 900MHz antenna solution. Baltic is
asking for *$204.59 to make the OD9-8 antenna happen* (shipping
included). Laird's lower gain antennas also have crazy high shipping
costs, and they quickly approach isotropic gain. I don't think it's a
good idea to spend $125 on shipping for what was supposed to be a low
cost / low performance test antenna. Longer-term, we would very likely
employ a cross polarized MIMO system since bandwidth @ 900MHz is very
limited and it's therefore important to maximize bit/Hz. There is only
one antenna on the market that I'm aware of that fits the bill: Ubiquiti
AM-9M13. It's a 13dBi 120 degree dual polarity sector. I'm pretty sure
they add the dBi from H+V polarizations to arrive at 13dBi, so it's
probably 10dBi / polarization. Still, 2dB better than the 8dBi OD9-8.
This antenna is physically smaller, so the shipping is much cheaper. *It
costs $278.36 shipped*. We'll also need a pigtail cable to adapt from
the RP-SMA terminals on the antenna to the N-male on the modem.
Now, there are a couple advantages to going this route:
1) We can re-use this antenna if we do deploy a 900MHz service since
it's the only one I'm aware of that fits the bill.
2) The experimental phase can test both vertical and horizontal polarity
performance independently by simply switching a cable.
So here's the modification:
1x Credit from removing OD9-8 = ($118.12)
1x Ubiquiti AM-9M13 @ $252.00/ea = $252.00
1x RP-SMA to N patch cable (1m) @ $9.95/ea = $9.95
1x NF-NF barrel adapter @ $4.25/ea = $4.25
1x Shipping @ $36.60 = $36.60
*Total additional funds requested: **$184.68*
If we don't end up doing a 900MHz service, or it doesn't use these
components, we'll return or eBay the parts and credit the HamWAN balance.
--Bart
On 3/6/2015 7:59 PM, Tom Hayward wrote:
>
> Try the swap meet tomorrow?
>
> On Mar 6, 2015 7:55 PM, "Bart Kus" <me at bartk.us <mailto:me at bartk.us>>
> wrote:
>
> Turns out the shipping on that 8dBi vertical is $125.
>
> I'm open to suggestions at this point.
>
> --Bart
>
>
> On 3/6/2015 11:23 AM, Bart Kus wrote:
>> I just sent you all the relevant invoices.
>>
>> Thanks, board! I guess I'm placing all the orders now.
>>
>> --Bart
>>
>>
>> On 3/6/2015 11:19 AM, Cory (NQ1E) wrote:
>>> Bart,
>>>
>>> I also vote YAY on the contingency that you get caught up on the
>>> paperwork. I still don't have the invoices on file from your
>>> last two purchases. ;)
>>>
>>> That makes it unanimous, so I guess the voting is complete.
>>>
>>> -Cory
>>> NQ1E
>>>
>>> On Fri, Mar 6, 2015 at 10:49 AM, Ryan Elliott Turner
>>> <ryan.e.t at gmail.com <mailto:ryan.e.t at gmail.com>> wrote:
>>>
>>> Thanks, Bart. I vote yay.
>>>
>>> On Fri, Mar 6, 2015 at 12:47 PM, gary.k7ek at yahoo.com
>>> <mailto:gary.k7ek at yahoo.com> <gary.k7ek at yahoo.com
>>> <mailto:gary.k7ek at yahoo.com>> wrote:
>>>
>>> I'd be interested in experimenting with 900 mhz gear at
>>> my Spanaway residence, and possibly at my Graham Hill
>>> repeater site. I believe 900 mhz would provide better
>>> overall results than 5 Ghz, which proved to be marginal
>>> to barely usable during our recent site survey.
>>>
>>> Best regards,
>>>
>>> Gary, K7EK
>>>
>>>
>>> Sent from my Verizon Wireless 4G LTE Smartphone
>>>
>>> ----- Reply message -----
>>> From: "Bart Kus" <me at bartk.us <mailto:me at bartk.us>>
>>> To: "Puget Sound Data Ring" <psdr at hamwan.org
>>> <mailto:psdr at hamwan.org>>
>>> Subject: [HamWAN PSDR] VOTE: 900MHz service experiment
>>> Date: Fri, Mar 6, 2015 10:38
>>>
>>> Hello,
>>>
>>> 5.9GHz is awesome when it works. The speeds are great, and it carries
>>> as far as the eye can see with very low ambient noise floor. It does
>>> however have problems when it needs to penetrate trees and buildings.
>>> To alleviate this, I'd like HamWAN to offer a slower but deeper
>>> penetrating 900MHz service. 900MHz is the lowest frequency ham band
>>> without bandwidth or modulation rate restrictions. Before we deploy a
>>> full cell site, I'd like to get some real-world experience with 900MHz
>>> penetration, propagation and ambient noise conditions. Here's the
>>> cheapest appropriate hardware we can use for this:
>>>
>>> 1x Vpol omni antenna @ $79.50/ea = $79.50
>>> (http://www.balticnetworks.com/laird-antenna-omni-8dbi-900mhz-n-female-integrated.html)
>>> 2x 9HPn modem @ $108.00/ea = $216.00
>>> (http://www.balticnetworks.com/mikrotik-metal-9hpn.html)
>>> 1x Shipping @ $UNKNOWN (quote not showing?! Need to call them.) =
>>> $40.00 ???
>>>
>>> Total: $335.50
>>>
>>> I already have a 900MHz high gain Yagi-Uda in my inventory and can use
>>> that to do various field tests. These can be directly compared against
>>> 5.9GHz performance since the gear will be deployed to one of our
>>> existing 5.9GHz cell sites. The results of such comparisons will give
>>> us a good idea of how well 900MHz might do for HamWAN.
>>>
>>> Disclaimer: These may not be the right modems or antennas for us
>>> long-term. A real deployment might use Ubiquiti Rocket M900 with their
>>> sector antennas. These Ubiquiti items are far more expensive though,
>>> and their software doesn't integrate as easily into our network, so for
>>> the purposes of the test I believe the set of hardware I proposed will
>>> do well at deploying fast and keeping costs down.
>>>
>>> NOTE: If both the votes are approved, I will combine shipping from
>>> Baltic to save money.
>>>
>>> --Bart
>>>
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>>>
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>>>
>>>
>>>
>>> --
>>>
>>> Ryan Turner
>>>
>>>
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>>>
>>>
>>>
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>>
>>
>>
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