Analogue signals are great in that they are simple enough to generate and demodulate, but they suffer in that the signal quality degrades when sent over a noisy radio link. With radio voice systems, this is heard as pops, crackle, hiss etc. Human ears do a remarkably good job of dealing with noise but it can get tiring when listening for long periods. Way back in , Claude Shannon proposed that digital coding systems can be designed in such a way that error-free transmission can occur even through a very noisy channel.
HF Digital Voice
Digital Voice Project – Temple University Amateur Radio Club K3TU
An international resource for radio operators for. We don't believe it is necessary to re-invent the HF data wheel for digital communications protocol, or desirable to invent a completely new ham-only standard digital data protocol built from the ground up, especially when we can leverage a suite of existing USA and global HF standards to provide an excellent working protocol for the ham community. Another consideration is that the protocols should bear in mind that such common standards last for decades, and thus should not be tied or limited to today's hardware capability or a unique platform, bandwidth, or present regulatory symbol rate limit. We can leverage and be the beneficiary to the vast research and development that has been expended. In this document, we offer the following recommendations and research to support our comments:. With regard to PSK and MFSK, the power levels of the transmitted signal are at nearly constant high amplitude, and the nature of the signal at high speeds does not require the kind of careful transmitter adjustments, high specifications, and linearities that OFDM with amplitude modulation needs for maximum throughput and signal integrity. Since amateur radio equipment of all types will be used by operators, it is important that the physical layer of the data formats be robust and clean with little need for special ALC constraints or stringent IM3 specifications.
Category Archives: D-Star
This event is an opportunity to meet each other in person and share our knowledge and love of ham radio and related topics. This year we have a fantastic lineup of great speakers talking about many topics from software defined radio, to microwave contesting, Raspberry Pi's, APRS, digital voice repeaters, and even an intro to setting up your own ham radio blog This event is open to all radio amateurs and anyone interested in these radio topics. Admission is free but space is limited so please order your free tickets on line.
The function of an Amateur Radio Repeater is to receive an incoming RF signal from a radio operator such as hand portable, mobile or base, regenerate the audio and then retransmit in real time on a different frequency. By allowing the repeater to amplify the signal, they allow transmissions to travel a much greater distance or into areas such as valleys, or populated areas where buildings would normally not allow line of sight transmissions. An Amateur Radio Repeater is essentially a receiver and transmitter, with interfacing logic and more importantly some special RF filtering such as a set of cavities or duplexer.