On Thu, Oct 25, 2001 at 10:01:52PM +0100, Derek Fawcus wrote:
> On Thu, Oct 25, 2001 at 04:42:15PM -0400, Jim Veneskey wrote:
> > I believe your radio is using the ETSI channelset?
> > As far as I know, ETSI is limited to 50mw output power.
>
> From memory I thought that the ETSI Class Licence was for 100mW EIRP?

Let's see just found ETS 300 328:

Section 5.2.2: Effective radiated power

"The effective radiated power shall be equal to or less than - 10 dBW (100 mW)
 eirp"

7.2.3: Effective radiated power

Duty Cycle (x) = (Tx on / (Tx on + Tx off))

Also x is limited: (0.1 <= x <= 1),

EIRP = A + G + 10log(1/x)

Where A = Power in dBm, G = antenna gain in dBi

--
Now ignoring the I(sotropic) for the moment,  and just considering the ERP,
I could take my 340 PCI card,  add an antenna with a gain of say 16 (11dBi)
and end up with an ERP of 480mW.  So ultimatly it's up to the user to
ensure they operate the equipment within the terms of the class licence. [1]
Anyway with the PCM350,  I'm note sure that the value of the antenna gain
is - I could assume 2.2dBi as for the rubber duck supplied with the PCI
cards.
This would mean limiting them to 50mW,  gives an ERP that is limited to
82mW,  and that if one were to allow 100mW then the ERP would be 166mW.
However that is ignoring the duty cycle portion of the calculation.
If my understanding of this is correct,  then this will always tend
to increase the EIRP.  Huh?
OK - that seems weird to my poor brain.  The less time within a given
period for which you're tranmitting,   the greater your EIRP is
considered to be?
on for only half of a given duty cycle means you've got double the transmit
power?
So have I gone astray in any of the above?
DF
[1] Well actually,  if I renewed my amateur licence,  I have access to the
    same band range (communicating with other amateurs) at a power limit
    of 400W.  That's 400W of power,  not 400W of ERP or EIRP.
    
    As much antenna gain as I can throw at it allowed!
    
    Mind,  getting a linear amp to give 400W of transmit power for that
    frequency range would be a challenge.
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