[ANSS-netops] 2.4GHZ problems

Thu Feb 3 19:29:30 UTC 2011

Hi Juan,

That's a question we all have to deal with and could lead to an 
entire NetOps session!  Greg Steiner shared good comments about what 
you might try to stay in the 2.4 band and save some cash now having 
to replace all your radios.

The NCSN completely abandoned the 2.4GHz band in the San Francisco 
Bay Area years ago.  Interestingly--and fortunately--900MHz still 
works here so that is exclusively what we use for low-bandwidth 
operation.  For higher bandwidth applications (relay sites) we have 
had good luck with 5.8GHz even in the metropolitan Bay Area, but time 
will only tell if we will be able to stay there.  I bet some of the 
success is from exactly what Greg mentioned about highly directional antennas.

We just had a nice meeting with the folks at Reno and they are trying 
to get into the licensed 4.9GHz band (public safety).  I think they 
are going to be pretty successful there and could be a smart 
move.  They have found some really nice radios from a company named 
Ubiquiti that are cheep (!).  Ubiquiti also makes radios in many 
other bands which we are going to explore.

There is a bit of a catch 22 with going to licensed frequencies right 
now, though.  With the feds considering the sale of another 500MHz of 
spectrum in the next 5-10 years (out of a 2500MHz of available 
spectrum), it may be difficult to justify going that 
direction.  We'll know more in the coming months.  At the same time 
it is getting more and more crowded in the non-licensed bands.  Got a coin?

Juan, there are several companies that make radio modems that work in 
the VHF and UHF bands but there are two primary reasons why we have 
not adopted any of them for real-world use:  they are VERY power 
hungry and with the 12.5kHz that we are allotted they can only make 
9600 baud throughput.  Some can even do Ethernet over VHF and 
UHF.  So, if you have commercial power and you only want to transmit 
3 channels at 100sps, you could make use of them.  We are actively 
working on a way to get around some of those things, but we're not 
there yet.  Some of the companies that we know about are Satel, 
Pacific Crest, Teledesign Systems, and CalAmp.  There are others.

Hope this helps.  Good luck.
Dave

At 05:56 AM 2/2/2011, Juan B Lugo Toro wrote:
>Hi
>
>We, at PRSN has been using the 2.4ghz radios but some weeks ago we 
>started having problems in some sites. I understand that because it 
>is an open frequency it is too busy. I was thinking to move to 
>5.0ghz but it will be a matter of time to start having problems. I 
>will appreciate any suggestion. I am thinking on a private frequency 
>but I will like to know first if there is already a government 
>frequency available on that range like the VHF and UHF bands that we can use.
>
>Thanks in advance
>Juan Lugo
>
>--
>Juan Lugo
>Tel: (787)833-8433
>Fax: (787)265-1684
>
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