![]() The Pi3 does have an on-board audio codec. That will require the use of a faster cpu to avoid fldigi hogging the the code to use the gpio pins on the pi or use the circuit that converts the CW audio to CW keying. Higher speedsĪre possible, but fldigi should be modified to use a CW sample rate ofġ6000 or even 48000 (or native 44100 if that is the codec default). Subject: Re: linuxham fldigi, raspberry pi, qrp cw. That is sufficient for QRQ less than 200 WPM. The default timing for fldigi's audio CW is 125 microseconds The timing resolution is then the reciprocal of the sample rgpio allows remote control of the GPIO on systems running the rgpiod daemon. lgpio is a new C library for Linux Single Board Computers (including the Pi) which allows control of the GPIO. Needs to keep the audio stream current as the codec performs it's d/aįunctions. pi-gpio A dynamic C library to control Raspberry Pi GPIO channels This has equivalent functionality to Pi.GPIO (events excluded). Timing is controlled by the audio codec h/w. ![]() PSK, MFSK, RTTY, CW, etc all perform with precise timing because the ![]() Anything faster is a like going to sea on the Titanic. 30 WPM CW begins to sound QLF (sending with leftįoot). Anything faster and you can hear the effect ofĬpu time slicing. System(s) that do not provide real time or preemptive interrupts. Is executing in user space on multi-tasking / multi-user operating The problem is that of creating the correct timing with code that The reason is not that port control is difficult, it is not,Īlthough a programmer's nightmare when trying to do that on the various The circuit is shown for QSK operation, but is equally applicable for CW keying.ĬW keying via GPIO, serial DTR/RTS, or parallel port is not coded intoįldigi. The interface to convert the right channel 1000 Hz keying tone, or the left channel audio signal, to on/off keying is sublimely simple. That will require the use of a faster cpu to avoid fldigi hogging the cpu cycles. Higher speeds are possible, but fldigi should be modified to use a CW sample rate of 16000 or even 48000 (or native 44100 if that is the codec default). The default timing for fldigi's audio CW is 125 microseconds (1/8000). The timing resolution is then the reciprocal of the sample rate. The application simply needs to keep the audio stream current as the codec performs it's d/a functions. PSK, MFSK, RTTY, CW, etc all perform with precise timing because the timing is controlled by the audio codec h/w. 30 WPM CW begins to sound QLF (sending with left foot). Anything faster and you can hear the effect of cpu time slicing. The problem is that of creating the correct timing with code that is executing in user space on multi-tasking / multi-user operating system(s) that do not provide real time or preemptive interrupts. The reason is not that port control is difficult, it is not, although a programmer's nightmare when trying to do that on the various OS. It reappears every New Year -).ĬW keying via GPIO, serial DTR/RTS, or parallel port is not coded into fldigi.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |