[Prism54-users] Output power regulation - SMC2802W

[Martin Vítězník]

Luis,
thanx for tons of information.

>Not sure though. Can someone advise?

I am interested in HAM and electronic, so I know what means dBm etc...
I try to explain it to you:

dB (deciBell) is relative unit for gain and loss - 
for voltage: a = 20 * log(U2/U1) where a[db] is gain, U2=output voltage, U1=input voltage
There is the same formula for curent.

FOR POWER: a = 10 * log(P2/P1)
output +3dB is 2x input, -3dB is 0,5x input etc.

P1 is a reference, in our case it is 1 mW, so it means that if output-power is 100mW, the output-power in dB(dBm) is 10*log(100)=20dbM.

With deciBells you can easily add or substract powers and gains. For example: I have yagi-15dB, and in my country I cannot have total gain bigger than 20dBm (simplified) so I have to regulate output power of my card to (20-15)=5dBm.

>This is the OID to use.
>
>> > Output power in units of 0.25 dBm.
>
>Perhaps this means for each unit you put on that address you get 0.25 dBm.

With iwpriv? - something like iwpriv eth1 OID_INL_OUTPUTPOWER FF02000F xxx (xxx=outputpower in dBm*4)? I don t know what does it mean.

Thanx, Martin


---------- Original Message ----------------------------------
From: "Luis R. Rodriguez" <mcgrof@ruslug.rutgers.edu>
Date: Tue, 6 Jan 2004 15:18:24 -0500 (EST)

>
>Martin,
>
>On Tue, 6 Jan 2004, Martin Viteznik wrote:
>
>> Hi,
>> can anyone tell me how to regulate output power of SMC2802W?
>> In old p54 forum I found this:
>>
>> OID_INL_OUTPUTPOWER FF02000F
>
>This is the OID to use.
>
>> > Output power in units of 0.25 dBm.
>
>Perhaps this means for each unit you put on that address you get 0.25 dBm.
>Not sure though. Can someone advise?
>
>> > The highest maximum output power is restricted to the value at which the
>> > card was calibrated to. And also the regulatory restrictions of the
>> > country domain.
>
>Probably means that even if you go on setting the output power really
>high, it will only reach certain threshold which is equal to a restricted
>regulatory value which was preset (hardcoded/calibrated) onto the specific
>card you have (country regulations may vary).
>
>> > Looks like the OID is readable and writeable and not
>> > latched.
>
>Means you can read and also write the value, so its not hardcoded.
>
>>From The Free On-line Dictionary of Computing (09 FEB 02) [foldoc]:
>
>  latch
>
>     A digital logic circuit used to store one or more bits.  A
>     latch has a data input, a clock input and an output.  When the
>     clock input is active, data on the input is "latched" or
>     stored and transfered to the output either immediately or when
>     the clock input goes inactive.  The output will then retain
>     its value until the clock goes active again.
>
>     See also {flip-flop}.
>
>	Luis
>
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