What Is DISEQC
DISEQC stands for Digital Satellite Equipment Control. DISEQC switch allow us to use more than one LNB for a single satellite receiver.These two LNB can be both Ku band LNBs or 1 C band and other one Ku band.
Earlier we were using one individual output port for each one of LNBs to receive the signal in our satellite receiver.But when DISEQC standard came then use one DISEQC to connect more than one LNBs for a single output to our satellite receiver.
The polarization depend upon the supply given by the satellite receiver to LNB. If the supply DC voltage is in between 12.5 v to 14.5 V then the polarization is vertical.If it is in between 15 v to 24 v then the polarization is horizontal.
DISEQC allow us to select Polarity,frequency band and satellite position.
Installation Of DISEQC Switch
As shown above in the figure the DISEQC switch is connected with 4 LNBs. These are the four inputs of DISEQC switch while it gives one output.This output goes into the satellite receiver.
Thus by using DISEQC switch we can use more than one LNB for a single satellite receiver.
A 22 khz tone is send to the LNB to receive high frequency signals. So if LNB receive this tone then its internal 9.75 GHz oscillator gets activate.If this 22 KHz tone is not received by the LNB then LNB receive low frequency signals.So this 22 KHz tone generator is inside the satellite receiver which sends this tone.
There are also many kinds of satellite receiver in which we need to input the frequency only. Then satellite receiver automatically decides weather it should send the 22 KHz tone or not.
DISEQC Versions
There are three versions of DISEQC.
DISEQC Version 1.0
This is used to operate 2 way or 4 way DISEQC switch,
DISEQC Version 1.2
This version is more improved version of 1.0.In this version it control the LNB as well as provides the power from the satellite receiver to motor to steer the dish. The size of this dish can be 1 meter.
DISEQC Version 2.0
This version provides the two way communication.This is responsible for diagnose and control the switching functions.
So if you are using 4 LNBs then DISEQC Version 1.0 is sufficient.While to steer the dish there is need for at least DISEQC Version 1.2.
Working Of DISEQC Switch
DISEQC messages are sent in a sequence short burst of 22 KHz tone.Messages are sent in digital bytes.This byte contain 8 bits.These bits can be 0 or 1 for a byte that depends on the information send in signal.
First byte is called the framing byte.Suppose if the information is like 11100 then it means this is to listen the slave device. If the 6th bit is 0 then it is command from master to slave and if this bit is 1 then it means slave is replying.If there is requirement for response then 7th bit is 1 otherwise it is 0. 8th bit is to re retransmission of message because reply have not received of last message.
The second byte defines that this message is of which device’s family.First 8 bit defines the type of device it can be switch and LNB etc. While a type is used for last 4 bits.While if in this address message if we use 0 it means this message is open for all.
Third byte is called the command byte it also contains data byte.This byte gives the command to slave.
DISEQC MOTOR
If we do not want to tune our dish again and again.Also we do not want to have complexity of wires the we can go for DISEQC motor.We need to simply tune our satellite receiver for a satellite. Then these signals goes from satellite receiver to slave devices to tune dish on that particular degree.
These dishes are more expensive than fixed dish. It also required more maintenance than fixed dishes.Also we needs to wait while dish is tuning from one satellite to other satellite.In this period there will be downtime of services for us.
This is all about the DISEQC Switches.
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