Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: UWB PA transmitted power and spectrum mask?
Posted: Wed Nov 30, 2005 9:30 pm
I have seen some
specificaiton stated that the spectrum mask of the UWB is -41.3dBm/MHz.
For the average Tx power is -10.3dBm. I want to ask how is the -10.3dBm
get? I am so trouble about these two values. Is it means that the transmitted
output power from PA must need to reach to -10.3dBm?
Post subject: UWB powerPosted:
Thu Dec 01, 2005 12:34 pm
In the US, these are legal maximum limits
- not required powers!
The spectral mask is there merely to assure
that the power is spread over the assigned bandwidth equally, which
will reduce interference with existing (licensed!) services. Please
notice the very low power: -10.3 dBm is 93.3 microwatts. This level
of power can often be generated directly, without the need for an amplifier.
Post subject: Posted:
Wed Jan 04, 2006 11:35 pm
Joined: Sat Dec
31, 2005 9:19 am
With a spectral density limit of -41.3
dBm/MHz the TX power of -10.3 dBm is a 30 dB difference. This means
the TX bandwidth is three orders of magnitude larger than the 1MHz spectral
density, so the -10.3 dBm TX power is for a 1GHz bandwidth (-10.3 dBm/GHz).
For UWB the maximum bandwidth is 7GHz for the 3-10 GHz band so the
maximum TX power allowed should be about -2.8 dBm.
Post subject: Posted:
Tue Jun 26, 2007 1:40 pm
Joined: Tue Jun
26, 2007 10:27 am
Location: Dallas, TX
802.15.3a the specification states that the maximum transmit power for
a UWB signal is -41.3 dBm/MHz. Each UWB band is 528 MHz as stated in
the MB-OFDM proposal (which has seemed to take over compared to the
DS-CDMA proposal). There are 14 band groups allocated in the UWB proposal
located from 3.1 to 10.6 GHz, but right now most companies and researchers
are only concerned with what is called "Mode I" of UWB which focuses
on the 3 band groups located between 3.1 and 4.7 GHz. Therefore, we
calculate the maximum average transmit power for a Mode I UWB device
-41.3 + 10*log10(3*528)= -9.3 dBm
we operate at 1 dB backoff to make sure we stay below the FCC regulation
and we end up with a maximum transmit power of -10.3 dBm.
we talk about average transmit power for all 14 bands with a 1 dB power
backoff we will obtain:
-41.3 + 10*log10(14*528) - 1 = -3.6