[MLB-WIRELESS] Bullet2 output power, why 1W or 100mW

[Simon Knight]

Or with a low gain omni for an OLSRd or Batmand suburban mesh network :)
Anyone had a play with the bullet2s yet?

On Sun, Mar 1, 2009 at 5:01 PM, Mark Aitken <nodegxt at yahoo.com.au> wrote:
> mw at freenet.net.au wrote:
>> G'day,
>>
>> Yeah, I can't think of many applications that would need a 1Watt
>> transmitter.  That's not to say that there are no applications for one, just
>> that I can't think of many ;-)
>>
>> 1Watt is about 30dBm, which means that your maximum antenna size is just
>> 6dBi to keep within the 36dB EIRP limit.
>>
>> Now, consider a point to point link of about 50Km.  Theoretically you lose
>> about 135dB signal through the air, so if you start with 26dB at the
>> transmit end, by the time you go 20Km, you only have -99 to work with.  If
>> your antenna is a meagre 6dBi, then the best possible result at the receiver
>> is a measly -93: barely enough to do anything with it.
>>
>> BUT, if you used a 170mW transmitter, which is about 22dBm, then you can use
>> a 14dBi antenna.  So over a 50Km link, you could potentially get -85dBm of
>> signal to the receiver.  That's more likely to produce a reasonably usable
>> result.
>>
>> The only reason I can think of that you would want to use a 1W transmitter
>> would be when you want to do a relatively short hop point to point link
>> (like less than 5Km perhaps), and you wanted to use small, aesthetically
>> unobtrusive, antennas.
>>
>> Cheers!
>>
>>
> Or be a Amateur Radio Operator and use the 30dbi into a 24dbi dish
> giving you 54dbi to play with...gotta love it  :)
>
>
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