1. BASE BAND DECODER Project Team Gurrampati Venkatakrishna Reddy
Mokrala Srikrishna Chaitanya
Under the guidance
Bengt Oelmann

2. BASE BAND DECODER Introduction Over view of the System
Coding Techniques
Interfacing of the system
Results
Conclusion

3. BASE BAND DECODER Introduction
The Base band decoder project is a part of ZigBee Lite Receiver.
Zig bee is new global standard for wireless connectivity focusing on standardizing and enabling interoperability of products with in home control, building automation and industrial control and monitoring. Most wireless sensors use too much power. By resolving this problem we develop the Zigbee.
The purpose of this project is to design and implement a hardware module that decodes the bit-stream and convert into bytes to be transmitted.
A decoder is a device that decodes a scrambled electronic signal to make it interpretable
The function of base band decoder in zig bee is as shown below .

4. BASE BAND DECODER BLOCK DIAGRAM

5. BASE BAND DECODER WISHBONE INTERFACE:
The interface to the microcontroller should be Wishbone.
Input parameters S3 & S2 helps in selecting the frequency of the data rate.
Input parameters S0 & S1 helps in selecting the type of coding which is to be generated. S3 S2
Freq(Kbps) 10 1 20 40 80 S0 S1
Type of coding
NRZ 1 RZ
MANCHESTER
DIFFERENTIAL

6. BASE BAND DECODER
FREQUENCY GENERATOR:
The function of whole system depends on the Frequency Generator
Generation of Data rate
Generation of Pclk2
Frequency Generator output is connected to the MULTIPLEXER and SERIAL to PARALLEL converter
Data Rate
No of Samples/bit 10
4000 20
2000 40
1000 80
500
4000
2000

7. BASE BAND DECODER RZ Coding: 0 - Absence of pulse
NRZ Coding:
0 - Absence of the pulse
1 - Presence of the pulse
NRZ coding in Base band Decoder :
Data in = Data out
RZ Coding:
0 - Absence of pulse
1 - Presence of pulse in the first half of the bit duration ,the light level returns to zero during the second half
RZ coding in Base band Decoder :
If start is set to ’1’, the arriving input is the output for twice the max value of count.

8. BASE BAND DECODER Manchester coding:
0 - Upward transition at bit center.
1 - Downward transition at bit center.
Manchester coding in Base band Decoder:
The synchronization is obtained by comparing the previous bit with any bit and also
counting the duration of half pulse period.
when transition is value occurs the count is decreased for the second half of the pulse
until it becomes ’0’ when a start bit is sent to indicate the Next pulse starting.

9. BASE BAND DECODER Differential manchester coding:
0 - first half of the signal opposite to last half of the previous signal .
1 - first half of the signal equals to the last half of the previous signal.
Diff Manchester coding in Base band Decoder:
The synchronization is obtained by comparing the previous bit with any bit and also
counting the duration of half pulse period.
when transition is value occurs the count is decreased for the second half of the pulse
until it becomes ’0’ when a start bit is sent to indicate the Next pulse starting.

10. BASE BAND DECODER Multiplexer:
Here, the 40 M-Hz clock and the data rate clock are compared. The transition occurs anywhere in 40 M-Hz clock with respect to the data rate clock’s bit rate and generates the output.
The output is sent to serial to parallel converter.
Serial to Parallel Converter:
It takes 1bit of data at a time as input and generates the output after 8bits of data are stored in it , parallelly.
The output is generated in form of serial data in (byte form).

11. BASE BAND DECODER RESULTS: Total memory usage is 73300 kilobytes.
The outputs of matlab and vhdl are compared and both are same.
Total memory usage is kilobytes.
The decoded digital output can be obtained at four different data rates as per the requirement.
synthesis report:
Number of 4 input LUTs: out of %
Minimum period: ns (maximum frequency : MHZ)
Minimum input arrival time before clock: ns
Maximum output required time after clock: 5.106ns

12. BASE BAND DECODER Conclusion:
We have successfully obtained the required type of decoding data at the out put as well the signal is continuos.
Requirements of the customer have been fulfilled.

13. BASE BAND DECODER THANKS:
we thank our supervisor Bengt oelmann for his constant vigil and encouragement and all our friends for their support.