I have been a radio enthusiast for a number of years now (noting that my late great uncle-in-law got me interested in the subject when i was a child) and i am particularly fond of pager/POCSAG/data systems (or more precisely the encoding schemes utilized to facilitate such communications).
Likewise, for the last few years I have been occasionally involved with creating/decoding such communications (whether it be for work, research, or pleasure) and i have (on occasion) found myself in a situation where i thought, "it would sure be nice if a piece of signal generation code could be implemented on a web platform for easy access".
Conversely, for a number of years now such notions were not easily implementable (strictly within JavaScript) so i did most of my signal generation within python; however, since the introduction of HTML 5 and the AudioContex standard, such notions are now possible and i decided it was time to create an application (something simplistic to begin with) in order to determine the overall feasibility of more complex signal generation/processing projects.
In general, this web application requires a AudioContex capable web browser (Internet Explorer currently does not support this standard so later versions of Chrome/Firefox/Safari are required for this application to work correctly) and it can be utilized to emulate Dual-tone multi-frequency signaling (DTMF) tones commonly heard in residential/commercial telephone systems.
Likewise, this application is divided into four parts:
The DTMF Keypad Tool provides the user with a DTMF keypad (similar to those found on a telephone) that produces a DTMF tone upon pressing the associated keypad key.
The Quick DTMF Dialer Tool provides the user with the ability to quickly dial a series of keypad keys (like a phone number) at a user defined speed (noting that this tool knows how to handle common telephone prefixes (like brackets, spaces, and dashes). Additionally, this tool utilizes continuous DTMF tones during the key synthesization process and as a result frequently has audible distortions during key transitions (making this tool ill-suited for high tolerance DTMF applications).
The Pure DTMF Dialer Tool provides the user with the ability to dial a series of keypad keys (like a phone number) at a user defined speed (noting that this tool knows how to handle common telephone prefixes (like brackets, spaces, and dashes). Likewise, this tool generates the keypad sequence mathematically (rather than assembling continuous DTMF tones individually) in order to create a pure DTMF signal and this process can consume a large amount of resources if the key sequence is very large or the delay between keys is very long. Additionally, the sequence generated (by this tool) can be downloaded as a wav file for use in high tolerance DTMF applications.
The Precise Tones Tool provides the user with the ability to generate a number of common precise tones found frequently within residential/commercial telephone systems.
