This work deals with analysis of protocol APRS Automatic Positioning System for telemetry. There is analyzed the structure of the most important frames and their application. It discusses the processing of GPS data and subsequent modulation of the selected frequency. This work also describes and discusses the proposed peripheral devices and the used firmware.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The NMSUSat is part of the AFRL/NASA University Nanosatellite program. The constellation will consist of a main microsatellite that will have a command link from ground and a telemetry link to ground while a picosatellite will act as a sensor reporting data to the microsatellite. Innovative command and data handling will be incorporated at low cost and greater accessibility. In this paper we present the necessary communications and control architecture for the space segment and the ground segment of the nanosatellite.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / A position beaconing system for tracking small mammals, such as the Golden Lion Tamarin, was developed and tested. GPS acquires location of the animal. The system utilizes a VHF radio transmitter tuned to 144.390 MHz, which is located in the amateur radio band. APRS was selected as the protocol for position, transmission, and recovery. This allows users to benefit from any existing APRS enabled devices. The beacon was designed by attempting to optimize operational longevity and minimize size. Consequently, the system is implemented on a single board and enclosed for protection. As the system must be comfortable for the mammal, it was manufactured from lightweight components and enclosed in a plastic housing. To attach the case to the mammal, it is connected to a flexible, zig-zag, wearable antenna, which functions as a collar.

The Automatic Packet Reporting System (APRS) is an amateur radio packet network that has evolved over the last several decades in tandem with, and then arguably beyond, the lifetime of other VHF/UHF amateur packet networks, to the point where it is one of very few packet networks left on the amateur VHF/UHF bands. This is proving to be problematic due to the loss of institutional knowledge as older amateur radio operators who designed and built APRS and other AX.25-based packet networks abandon the hobby or pass away. The purpose of this document is to collect and curate a sufficient body of knowledge to ensure the continued usefulness of the APRS network, and re-examining the engineering decisions made during the network’s evolution to look for possible improvements and identify deficiencies in documentation of the existing network.

FM transmitter APRS of telemetric data is device able to measure telemetric values from its ambient. It is able to send this data to user on earth by radio frequency channel. This device can create data frames, with proper formatting allowing sending data. It operates in 435 MHz band, uses FSK and AFSK modulation. This work describes basic information of used protocols, electronic connection of this transmitter and software equipment.

A low-cost radio direction finding (RDF) VHF receiver has been investigated for development into a radio direction finding network (RDFN) with a particular focus towards public service and commercial asset tracking applications. The primary design criteria were reproducibility, low-cost, and simplicity such that public service and volunteer organizations can benefit from the technology. Two receiver designs were built and tested to allow for comparison of practicality, cost, and accuracy. A pseudo-Doppler RDF and a time difference of arrival (TDOA) receiver were built as proof-of-concept for a system design based on commercial off-the-shelf (COTS) components. The pseudo-Doppler system is a less practical implementation due to the necessity for custom hardware, a large antenna system, and an increased directional error due to multipath and weak signals. The TDOA system has potential as a very simple and low-cost RDFN implementation, but requires extremely accurate time synchronization that is difficult to achieve using COTS GPS receiver modules. The final proposed solution takes advantage of the simple TDOA hardware and multiple detection techniques (including signal strength) to produce improved locational data and ultimately provide a more accurate estimate of position. Further development and improvements to this receiver design have the potential for implementation as a low-cost radio direction finding network.

This thesis presents the design, simulation and analysis of a new network based on the Automatic Packet Reporting System (APRS) concept to enhance communications of CubeSat. Created in the 1980s, APRS is arguably one of the world’s largest Radio Frequency (RF) networks maintained by a community of licensed amateur radio volunteers for a variety of terrestrial purposes. Using these established nodes we can create a virtualized ground station network for satellite downlinks. Based on literature reviews of CubeSat communications systems and their orbital elements, as well as direct surveys of the amateur radio community, comprehensive far-field antenna models were created in 4nec2 for both the ground and space sections of the CubeSat downlink. The ground station antenna models include: a directional AMSAT/OSCAR Yagi-Uda, an omnidirectional J-pole, ground plane, and a whip antenna. The CubeSat antenna models used include dipoles, monopoles, and turnstiles. These models were evaluated and then imported into the Analytical Graphics Inc (AGI) Systems Tool Kit (STK) to form a discrete event simulation based on nonhomogeneous WGS84 location data extracted from real world APRS Internet Gateway (I-Gate) packets. All objects within the simulation use realistic antenna models, node locations, propagation models and satellite orbital mechanics. This simulation can act as a suite of generally applicable example satellites models (ExampleSat) for analytical comparisons that include link budgets, access times, differing data rates, antenna designs, orbital altitudes and ground station locations. Furthermore, it represents a North American continental scale RF satellite communications downlink network model. Using the virtual ground station network alters the net probability distribution of the received signal from the spacecraft. Specifically, the thesis compares non-stationary time series analysis methods upon the net received signal. The virtualized ground station network enables the aggregated received signal to appear stationary. This in turn may allow for alternative signals analysis techniques to improve a CubeSat’s downlink performance. The simulation allows us to generate representative received signals from ExampleSat to the ground station nodes for exploratory analysis, utilizing less arbitrary assumptions. This simulation and the set of models enable a more rapid start to trade-off studies for link budget design. This set of ExampleSat downlink models can be used by new designers of small-satellite communications systems. / February 2017

APRS system is described are sent toin my essay, which is used for sending and receiving text messages. The text messages frequenc 144 MHz by using the modulation scheme AFSK. APRS communicate by using the protocol AX 25, which sends and receives the text messages in the area where are carried despatches and control bits as well. The whole area of high frequency part is in one integrated circuit. The control, coding and decoding of the area is the microcontroller’s job.

APRS system is described are sent toin my essay, which is used for sending and receiving text messages. The text messages frequenc 144 MHz by using the modulation scheme AFSK. APRS communicate by using the protocol AX 25, which sends and receives the text messages in the area where are carried despatches and control bits as well. The whole area of high frequency part is in one integrated circuit. The control, coding and decoding of the area is the microcontroller’s job.