Packet Communications

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DRAFT (A Work in Progress)

This tutorial presents methods to transmit and receive packet data using burst transmissions. The data can originate from a message source or a stream source. A hardware implementation is shown using BPSK modulation.


Simulating Baseband Packet Processing

In order to grasp the basics of packet processing, this section presents a transmitter and receiver without any modulation or channel impairments.

Building the flowgraph

Build the following flowgraph using the details given below:

Pkt 7 base fg.png

Message Strobe

For the Message Strobe to generate a PDU, the Message PMT must be of the form


This specific vector has a length of 9 and the character values of "GNU Radio".

Variable, Id: hdr_format

The Protocol Formatter uses a Format Object to define its parameters. The one used in this example is

 hdr_format digital.header_format_crc(len_key, num_key)

Protocol Formatter

The entry for the Format Obj. is 'hdr_format'

Protocol Parser

The entry for the Format Obj. is 'hdr_format'


Using BPSK and Hardware

Transmitting a Signal

Receiving a Signal