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

[Chen-Yu Tsai]

On Wed, Oct 8, 2025 at 11:32 AM Ping-Ke Shih <pkshih at gmail.com> wrote:
>
> Chen-Yu Tsai <wens at kernel.org> wrote:
> >
> > Hi,
> >
> > On Wed, Sep 24, 2025 at 10:22 AM Ping-Ke Shih <pkshih at gmail.com> wrote:
> > >
> > > From: Ping-Ke Shih <pkshih at realtek.com>
> > >
> > > 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?

This old slide deck [1'] from the FCC (?) suggests that EIRP is max
conducted power + 6 dBi antenna gain.

> 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.

The PSD requirements also translate to the wording for some of the bands:

For the 5.25-5.35 GHz and 5.47-5.725 GHz bands, the maximum conducted
output power over the frequency bands of operation shall not exceed the
lesser of 250 mW or 11 dBm + 10 log B, where B is the 26 dB emission
bandwidth in megahertz. In addition, the maximum power spectral density
shall not exceed 11 dBm in any 1 megahertz band.

"11 dBm + 10 log B" is basically describing the PSD limit.

If in doubt, maybe you could ask how certification labs interpret the
text? I think that doubly applies to the Trinidad and Tobago case, where
the text is somewhat mixing the terms ERP and max conducted power.


Thanks
ChenYu

P.S. The FCC website seems to be more or less unavailable due to the gov't
shutdown, so it's hard to dig up more information at this time.

[1'] https://transition.fcc.gov/bureaus/oet/ea/presentations/files/oct14/51-New-Rules-for-UNII-Bands,-Oct-2014-TN.pdf



> [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 <pkshih at realtek.com>
> > > ---
> > > 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
> > >