GPS Receiver


welcome friends this is the fourth class on
g p s surveying today i am going to discuss on g p s receiver now users receives g p s
signal from satellite vehicles and this signals are often having very low power as well as
it is it get merged with interference from more powerful signals so ah to make this signals
useful we have to ah undergo many operations on this g p s signals within the g p s receiver
now a g p s receiver primarily composed of three primary elements the ante and antenna
a controller and a receiver hardware so today’s class i will discuss on antenna
followed by controller and g p s hardware receiver and finally on g p s receiver now
as i told you g p s receiver is an electronic instrument it consist of an antenna a controller
and a hardware receiver now the antenna is used for gathering the g p s signal out of
the lot of many electromagnetic signals that are available in the atmosphere once it gathers
it transfers the signal to the g p s receiver hardware now the quality of the g p s signal
that depends on the characteristics of the antenna which we will be using along with
the g p s receiver so the antenna to be selected for use with along with g p s receiver is
very important now this antenna is available in different
forms and commercially available in different either it is available in an independently
that means exclusively we can have the antenna to be attached to be g p s receiver or in
some cases g p s antenna is available along with the g p s receiver now let us take this
case this is a g p s receiver where antenna is encased with in the same framework of the
electronic hardware along with receiver and controller this is another g p s receiver
where also antenna is embedded inside this case along with the controller as well as
receiver now this is an antenna which is attached with
only receiver so no controller has been received with it ah connected with it so again this
is a antenna which is connected to g p s receiver but controller is not associated with it now
there are different antenna available in the market which is independently available which
we can make use along with receivers and controller by using some connectors so example let us
see if these antenna this antenna is an independent unit which can be fixed with the receiver
or the controller using this connector through this another antenna is this small antenna
having a long wire so and this is a connector through this connector we can connect with
the receiver or controller this is again an independent antenna like
that there are so many antenna available in the market which may be useful for our g p
s surveying but we should be very much careful about compatibility between the antenna you
will be accepting or will be choosing for a particular type of receiver now for g p
s surveying it has been found that the antenna having dome shaped will be of good quality
and will generally prefer right hand circularly polarized antenna so whenever you will purchase
an antenna for the g p s surveying one should look for this quality that the ah specifications
says that the antenna is right hand circularly polarized as well as it’s shape is dome shape
top let us say this is an example this is an antenna
where you can say the shape is dome shape and inside it is a circularly polarized which
it’s specification will tell you will not be able to see from outside moreover for very
precise g p s surveying actually you should go for still better type of antenna which
is called known as geodetic geo free antenna like this one where this is an antenna also
again for g p s surveying and this is being used for very precise g p s surveying where
the top of this is also a dome shaped and it is circularly polarized right hand circularly
polarized inside so this is having very powerful it can ah
receive very good quality g p s signals let me now discuss on controller which is is nothing
but a palmtop computer having input output units now commercially the controller may
available in different forms like it may available in an independent way that means it is independent
of receiver as well as antenna or it may be associated with receiver or it may be integrated
with receiver as well as antenna ah let us show some example now this is a controller
where the computer this is the input unit and this is the output display unit so and
this controller has to be connected to antenna as well as to receiver independently though
connector using this input output ports now this is also a controller which is independent
of receiver as well as of antenna but this is a controller also it is attached with receiver
so though it looks like same as before one but it has g p s receiver associated with
it so receiver as well as palmtop computer as well as the input device and output display
unit this is also a controller where g p s receiver associated with it so it is an integrated
unit of receiver as well as controller so like these we may have now as i showned earlier
this is an unit where antenna g p s receiver as well as controller having input unit output
unit is put together so it is an integrated g p s receiver so we
get different types of controller were also available in the market now these controllers
are usually associated with all uploaded with different types of software operating system
software field software and then ah now this software’s actually will be used for carrying
out the work for whole of g p s surveying and through controller we do give the ah instruction
to the receiver as well as to antenna though this software using the connectors and now
we do carry out the g p s surveying also we can find out the condition of the g p s satellites
using this field software so this will show how while demonstrating you the field activities
next the g p s receiver hardware actually as i told you g p s signals are very low in
power as well as it get merged with interference from the higher powerful signals so we need
to improve the power or ah in the signal as well as we need to filter the interference
as well as we need to for the process the signal to get the our desire parameters in
order to get those thing the g p s receiver hardware contains filters amplifiers frequency
unit digital signal processing unit now this as you understand from using filter
it filters the interfered signals from the g p s signals then it will the amplifier amplifies
the amount of power that is has to be associated with the g p s signal to be further processed
in the next stage in the in the frequency unit actually the receiver provides the refines
frequency and time and then also it not only it also fills gave make some filtering as
well as amplification then it converts the analog to digital signal and also these signal
that is received as an input also converted it to intermediate frequency signal that means
the signal will be possible to be processed through digital signal processor
now they bring a whole g p s receiver actually they digital signal processor it will break
up the signal into different channels depending upon the different satellite vehicles and
then process is independently for each satellite vehicle signal and from that together they
will provide thus receiver will provide some fundamental parameters like rate than time
tag than navigational data which will further processed to use our to find out our position
time and navigation parameters so now let me show you some of the g p s receivers
as i told you in case of antenna as well as our controller receivers are also either exist
independently or it exists along with other part of the whole of g p s receiver like as
i told you as i have shown you but in this receiver controller and receiver output together
in this case also antenna as well as receiver is put together and in this case receiver
is put together along with the antenna as well as the controller so these are generally
of low capacity however g p s are also exist as independent unit
now i can show a small g p s chip this is the g p s receiver chip which is used to make
some instrument using g p s receiver another g p s receiver i want to show is this one
which can be connected to antenna through this connector so this is a g p s receiver
which we generally used for making independent instrument using g p s now here is a g p s
you see where which is being used as an independent unit for g p s survey so g p s receiver we
may get either as an independent unit or it is associated with the other parts
now let me discuss on g p s receiver as a whole that means i want to really take into
antenna controller as well as receiver hardware together to work as g p s receiver now commercially
there are different types of g p s receiver available and depending upon the accuracy
how much it can achieve we classify the g p s receiver in the perspective of surveying
into two types one is that core type another is the carrier type now under core type there
are again two fundamental division one is that single core type and another is dual
core type now in a single core type receiver the g p s can decipher only the c a core and
this type of receivers are generally provides list accurate position and generally we use
this type of receiver for recognizing survey now let me show you one of the single code
g p s receiver that would generally use for the recognizing survey is this one however
there are hundreds of varieties of single code g p s receivers are available and most
of the g p s enable mobile phones are also associated with c a code or single code g
p s receiver next it is the dual code or multi code g p
s receiver in dual code or multi code g p s receiver ah one of the code will be the
c a code and other may be any one of the other civil codes like it may be py code it may
be c m code it may be c l code it may be high five code or q five code so one thing is important
to understand that whatever is the g p s receiver it must be or it is capable of deciphering
the c a code because c a code is the primary code most important means fundamental code
which provides the identification of the signal from which satellite is coming also it is
provide it provides the time measurement initial time measurement dual code receiver or multi
code receiver provides positional accuracy of the order of meters one to five meters
and this type of receiver generally we use for small scale mapping purpose
now this is a dual code g p s receiver and this receiver may be used for mapping purpose
now let me discuss on frequency g p s receivers now again frequency g p s receiver may be
of different types depending upon how many frequency it can decipher however all frequency
receivers in the beginning first it will decipher the c a code from c a code only it will get
the identification of the satellite from which the signals are coming and also it will get
the time now the single frequency receiver works with
the l one c a signal now this type of receiver provides accuracy in centimeter level for
positioning and decimeter level in high positioning these types of receivers are useful for lower
order control point positioning as well as large scale mapping purpose let me now demonstrated
you the single frequency g p s receiver now here you can see a receiver where this is
the antenna and this is the receiver and this is the controller receiver and controller
are together and they are connected to antenna using a connector and they are mounted on
a tripod stand so this ah if we take these arrangement outside this room in open sky
then through this antenna we will be able to get the g p s signal and recorded through
this g p s receiver now let me discuss on dual frequency g p s
receiver in dual frequency g p s receiver we do analyze or we can get signals from l
one c a type as well as either l two c or l five signal now this receivers are quite
accurate and very precise position it provides of the order of millimeter in position and
sub millimeter in centimeter in vertical position this type of instrument that means dual frequency
g p s receiver is used for highest order control points highest order baseline measurements
than geodynamic activity as well as for precise measurements of position
now let me demonstrate you dual frequency g p s receiver here you see a dual frequency
receiver where this is the antenna of the receiver and the receiver as well as controller
is this one which is connected using a connector and it is been setup on a on this stand now
if we take this instrument outside in open sky then it will be able to receive signals
dual frequency l one and l two next i will discuss on the triple frequency g p s receiver
this type of g p s receivers receives g p s signals and can decipher signals of l one
c a code l two c as well as l five signal now this is the most robust g p s receiver
because it can decipher all the three civil signals so it is versatile in nature and this
type of receiver provides very precise position this receiver are useful for real time monitoring
well precise ah monitoring system then for continuous monitoring for air navigation and
interrupted air navigation can be done by making use of this type of receiver it is
primarily used for atmospheric study because different type of atmospheric errors may be
quite accurately measured by using g p s signals from this types of receivers
another type of g p s receiver nowadays widely prevalent that is called g n s s receiver
this type of receivers receives signals not only from g p s satellites but also from other
radio navigation system like glonass gallileo bido etcetera now this type of receivers may
receive signal from any combination like it may receive signals from g p s and glonass
or it may from g p s and bido or some other combinations now these type of receivers are
most robust because they provides information from different radio navigation system so
there will be more much more useful for specifically for navigation purpose air navigation purpose
and real time staking out work etcetera now let me demonstrate you a type of g n s
s receiver now this is you can see this is the antenna geodetic geo free antenna this
is the antenna which is useful for very precise measurement of position and this is a receiver
and this is a controller now in these case you can see all the three units are independent
to each other and they are connected using some connectors now this receiver can receive
signals from g p s satellites as well as from glonass satelites as well as from sbas satellites
so ah this is a very powerful receiver the signals can be useful for many precise measurement
activities now let me summarize the total class today’s
class i had discussed about g p s receiver which is an electronic instrument it consist
of three basic components the antenna the controller and a receiver and they are put
together through connectors and this receivers may be appear as a single unit or it may be
a combination of different units which are which exist independently now the controller
antenna receives the g p s signals and transfers it to the receiver hardware as per the instruction
it receives from the controller controller also controls the g p s hardware receiver
by making use of the software that is uploaded within it
now the receiver receives the signals from antenna as per the parameters set by the controller
and then it process the signals and provide us the basic parameters to be used further
now in commercially there are different types of g p s receivers are available and depending
upon the accuracy of the receiver we classify them into two types in code type of receiver
and the frequency type of receivers within the code type we get the single code which
is least accurate and it is useful for recognition survey dual code receiver is useful for mapping
purpose than single frequency we use for low order control point as well as large scale
mapping survey dual frequency used for precise measurement atmospheric study as well as for
ah navigation purpose triple frequency for continuous monitoring and very precise measurement
staking out work and with this i like to conclude today’s class see you again in the next class
in the next class we will be talking on g p s software
thank you

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