Re: [PATCH] wireless-regdb: Update regulatory info including bandwidth for Trinidad and Tobago (TT) for 2025

Chen-Yu Tsai <[email protected]> wrote:
>
> Hi,
>
> On Wed, Sep 24, 2025 at 10:22 AM Ping-Ke Shih <[email protected]> wrote:
> >
> > From: Ping-Ke Shih <[email protected]>
> >
> > The Telecommunications Authority of Trinidad and Tobago [1] provides
> > Schedule of Devices Eligible for Use under a Class Licence [2]. The
> > type 1 (End-user devices or customer premise equipment) with Schedule B.1
> > and B.2 shows
> >
> >  - 2400 - 2483.5 MHz
> >    * 30 dBm
> >  - 5150 - 5250 MHz
> >    * 24 dBm
> >  - 5250 - 5350 MHz
> >    * 24 dBm
> >  - 5470 - 5725 MHz
> >    * 24 dBm
>
> For these bands, the rules specify ERP, or effective radiated power.
> However it states "Maximum Effective Radiated Power ERP (from RF
> transmitter)", so I think it is meant to "maximum conducted output
> power" as seen in FCC rules?
>
> This is not the same as EIRP, or effective isotropic radiated power.
> AFAIK the latter is what is supposed to be used in the database. This
> discrepancy is found in many rules originating from the FCC rules. The
> FCC rules specify maximum conducted power (TX power) plus max antenna
> gain in dBi.
>
> So there is some conversion involved. I think the values should be
> "max conducted power" + "max gain in dBi". This assumes no cable loss.
>
> I think we would also need to revisit the US rules.

Thanks for the detail, but I still not clear if I should use ERP +
antenna gain as
EIRP, or should I apply FCC requirements as hard power limit?

By [1], it also mentioned limits of maximum power spectral density, if we also
apply the limits, the values will be almost what I wrote, which are also almost
the same as US country in db.txt.

[1] https://www.law.cornell.edu/cfr/text/47/15.407

>
> >    * extend 5 MHz to 5730 MHz for channel 144
> >  - 5725 - 5850 MHz
> >    * 30 dBm
> >  - 5925 - 6425 MHz
> >    * 24 dBm
>
> These two bands have 0 dBi for max antenna gain, so max TX power ==
> max EIRP.
>
>
> ChenYu
>
> > [1] https://tatt.org.tt/licensing/class-license/
> > [2] https://tatt.org.tt/wp-content/uploads/2025/07/Schedule-B_Schedule-of-Devices-Eligible-for-Use-under-a-Class-Licence-25th-July-2025.pdf
> >
> > Signed-off-by: Ping-Ke Shih <[email protected]>
> > ---
> > Hints to find these entries: by searching "Wi-Fi" with type 1 in [2].
> > ---
> >  db.txt | 13 ++++++++-----
> >  1 file changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/db.txt b/db.txt
> > index 6e1ad30222a4..90ffa4e0d5d7 100644
> > --- a/db.txt
> > +++ b/db.txt
> > @@ -1946,12 +1946,15 @@ country TR: DFS-ETSI
> >         # 60 GHz band channels 1-4, ref: Etsi En 302 567
> >         (57000 - 66000 @ 2160), (40)
> >
> > +# Source:
> > +# https://tatt.org.tt/wp-content/uploads/2025/07/Schedule-B_Schedule-of-Devices-Eligible-for-Use-under-a-Class-Licence-25th-July-2025.pdf
> >  country TT: DFS-FCC
> > -       (2402 - 2482 @ 40), (20)
> > -       (5170 - 5250 @ 80), (17), AUTO-BW
> > -       (5250 - 5330 @ 80), (24), DFS, AUTO-BW
> > -       (5490 - 5730 @ 160), (24), DFS
> > -       (5735 - 5835 @ 80), (30)
> > +       (2400 - 2483.5 @ 40), (30)
> > +       (5150 - 5250 @ 80), (24), AUTO-BW
> > +       (5250 - 5350 @ 80), (24), DFS, AUTO-BW
> > +       (5470 - 5730 @ 160), (24), DFS
> > +       (5730 - 5850 @ 80), (30)
> > +       (5925 - 6425 @ 320), (24)
> >
> >  # Source:
> >  # Table of Frequency Allocations of Republic of China (Taiwan) / Feb 2017:
> > --
> > 2.25.1
> >