okay we're gonna get started
with the the the next paper on flexible digital modulation testing for
satellite regenerate payloads my name
is Darren mclennan I'm a product marketing
I leave for the actually system new software
speaking on behalf for the the author Greg you and
in this tutorial presentation we're gonna look
a little bit at a a a evolution within the satellite
industry from an old first-generation so the satellites
to newer capability and some other testing and design
issues associated with that generational change inside like capability
and some ways to overcome those issues on
in a in a traditional or older architectures
the the so-called bent pipe a
earth station will upload a signal to a satellite
which receives it and retransmit sat down to the ground for the problem being
solved
is avoiding the years curvature sending
a signal to a wider distribution area a
that and just bouncing it off space station so in the older
satellite generation there's a a lot of the considerations were
analog issues you a take the signal
you re amplified and broadcast it to the ground on
so you're looking at a flatness
and linearity and there's a number of issues over fix pan with what's happened
with the newer generation of satellites
on is that with with the
newer a multi-antenna beamforming
you can provide signals unique to certain spot
areas you can provide different levels of services you can reconfigure the band
with
to have so much go to this a
service provider so much go to another service provider
spaces become I P packet I
so there's networks in space on you take
signals from the ground d modulate them get the bits
route them and remodel ate them in broadcast them
and route them to different locations to provide these
overlay let up level of services on the ground so
this complexity a reallocating spectrum
reformatting things has put a lot of the
a intelligence up into the into the
into the birds themselves so without there's another set of design challenges
and testing challenges that go along with
this new capability so in this new capability
where you may have been measuring frequency response or
or flatness and ripple group delay
you now measuring different quantities are measuring
air vector magnitude you're measuring bit error rate
I'm you're counting for more sophisticated block diagrams
and actually treating the satellite itself
as a receiver and transmitter on so there's
there's a whole range a additional
capability that goes along with the the new generations of satellites which
calls for on a new
understanding of what measurements to make so
in older formats a they would
generally use more simple modulation schemes
I here BPSK
is pretty bulletproof it will go from to
between two states on generally because of the limited power using a constant
envelope
typeof modulation system so PF
a 8psk going up to 16 and 32
a a PSK are the newer formats
what you find now is that higher modulation
a mod formats are being used
to do to pack more bits per symbol
to to deliver more data per unit time
give for a given amount of spectrum so the spectrum occupancies
is very very high now in in these
formats you you have additional challenges
with measurement quality so before when you're just
hopping frequencies frequency shift keying
or using simple modulation formats you you care
a little bit less about so many things with as you packed these
these modulation rings tighter you begin
to need to worry about how far each of these
States is from each other so noise
and nonlinearities and different things a fact
the quality of the States some other things that can go wrong that you want
to measure
are gain in balance the difference in the game between I'm cue
because you're working in a and I'm cue plane
you working on skew rotation
phase noise 10th to speed up or slow down your carrier
which rotates you randomly or along a circle smears you wanna
along a circle there's also for amplifier people you start having to
worry about
gain compression effect and again
turning into an angle error or an amplitude air
needs to be corrected as well and all these things
there's an ideal state where you'd like to be
and where years your information is
actually and that difference is called in a row vector magnitude
and that's an important measure up Quality Inn in a lot of the system
on one of the I challenges
love up doing aerator air vector magnitude
is the ability to troubleshoot
to with bit error rate all of a sudden you get to the end
and you either have a good trip better a very favorable
a bit error rate no heirs we have a lot if you have a airs
where they come from what where's the smoking gun what what's causing the air
so it could be a nonlinear PA
it could be flatness it could be spur
it could be a rated a converter and clock skew and all kinds of wonderful
things about 80 converters
it could be in your signal processing in the baseband
on to depart this one handy thing is to be able to use the exact same software
measurement tools at every place and
the as well actually provides equipment for every place
logic analyzer scope for for analog baseband
modulated carrier now says with the instrument and even
before you even do any this simulation you can you can use
the BSA software from a spectrum analyzer
you can actually use that inside the logic analyzer scope
or in the simulation software so by using the same measurement technique
the same filtering the same kind of algorithms that every place in the chain
you can eliminate you do apples to apples measurements and eliminate some
the air City
it makes the troubleshooting is here so here
here's an example using the BSA in
a logic analyzer situation where we have a twenty-one
a pin ribbon cable looking at this
as I links vertex looking at the Pan
and it takes the individual pins of the bus
and reconstructs what sampled way for value would be
because realize you probably have a serial stream up data
and reconstructs the communication information
from the wrong data stream so
that's a formatting issue when you get a modulated carriers
on you still using the same tool but now you're working of our
a time-varying are carrier
now making signals is another challenge on
for simple are kinds of signals and investigations people use an expensive
tools that they've they've made and download them to the instrument
on there's also inexpensive sought test and measurement software to do this
wave as a way for creator another
a a scheme that you're saying here is with a a system simulator that
system view a that Agilent
in the case I cells and you can see that you can choose from a whole range
modulation and and also the modulation formats as a
forty and you can make more you like
you can make any signal at any kind of filtering
and and impairments other signals aggregate other signals
and download those anything in the simulation that hits
one of these components is downloaded to a connected instrument
and with a wideband are this particular are
is capable of 5 gigahertz analog band with
you can then a make a very wide band signal
typically 100 megahertz in the case of us SATCOM
and uploaded to whatever I millimeter-wave
a or expand frequency that you'd like
here's a picture of this system is actually running
the cats offers running on a controller inside this card cage
and its feeding the are through the back playing with data
and they are a bit making the signal at uploaded
the PSG and then digitized with a 63 gigahertz
oscilloscope event of an oscilloscope
is you save it down conversion you directly digitizing the signal
so that have on some advantages as well
so for for for a lot of satellite
signals that are on the orders of hundreds of megahertz wide
and then may have multi-channel applications
some the traditional 160 Mac wide
on measurement platforms may or may not be able to do that
and so you need at least a wide and digitizer with the down cover
or a scope with fairly wide band with
to be able to to to capture those
actually it turns out that you can capture the signals and bring a back
into the simulation software and continued
motley kind of an interesting trip
here's a case where I i spoke
earlier love in the newer generation of satellites
you can reconfigure the van with dynamically
on to reallocate for certain service levels to different
on people not to do that you're often looking at creating
multiple concurrent signals side by side
and to do that on it's possible to set up
multimillion situations and combine them with the resample where there's a resale
for component in this cat software
the system use of or that will take all
other carriers Reese resample them
to a common time step so that they're all one
wideband signal and download that wideband signal
and really make that signal
and and this is a picture of it so if you digitize this
on whether the wideband digitizers bring it into you know the analysis
the engine %uh the PSA software you can actually
room in anti modulate any those individually or look
at the power the a CPR a
and different mediums in quality metrics for
any other channels individually I'm saying
it's important to exercise their power amps with realistic
on conditions that they they'd really see
another aspect is bit error rate on
this is showing a a personality for
making both the modulation and the modulation
one thing that show in years packet error rate on Versus noise
signal to noise ratio packet error rate is
different than bit error rate in that if you have
maybe a a six thousand simple payload per frame
you'll have a lot of data bits in one frame
does the frame have any air instead of just one bit so it's actually harder to
do that over a whole frame
your packet error rates are going to be higher but again you get into the city
but
thing a you know where where was the problem
another issue is coding and decoding
you don't just have naked analog components anymore
you have forward air correction
and pre distortion and a lot of signal processing applied
to make the signal survive
marginal analog conditions so
on this on this case the attacking her in a bit error rate
very often will go from up being
a poor quality at very low marginal conditions
and all of a sudden the the the air correction will kick in
and correct a lot of the air and
so I some other modern techniques like low-density parity-check
on that make the at correction factors and make the signal very
noise like on to approach the Shannon limit to how much information you can
pack
per hurts for a given signal to noise ratio
is really pushing the envelope a what's physically achievable
so that just makes design and
and debug I just a little bit more difficult because you have to consider
the sector
a is extra factors so to summarize
the newer generation satellites require
an additional said a diagnostic and design techniques
on you can combine a simulation software
and the instruments
to create fairly complex scenarios have not only multimillionaires
but lots of impairments interferes
and assimilate more complete conditions
to really ring out satellite
qualification because once it's in orbit
what you gonna do saying there's a lot of testing that goes
on had a time vs a software and
the system via software can be used throughout the process in R&D
from concept all the way through on
debug and it's a qualification and
the the ability to add known amounts of garbage
impairments IQ offset nonlinearity interferes in
and noise and different different fading conditions allows you
in the R&D situation to really ring out a design
I much earlier in R&D
before you finish the design
that concludes the remarks if there's any questions i'm happy to take
questions or
weekend go back to the the the Atlantic
exhibit and happy to show you any
okay thanks very much