![]() The software is mostly used by amateur radio operators who connect the microphone and headphone connections of an amateur radio SSB or FM transceiver to the computer's headphone and microphone connections, respectively. Two-bit (on/off) keying is much simpler.English, Italian, Spanish, French, German, Polish, Dutchįldigi (short for Fast light digital) is a free and open-source program which allows an ordinary computer's sound card to be used as a simple two-way data modem. I'm just too lazy to use the (easy) math involved. Modulation of the SSB signal produces an ambiguity in center frequency, because the output of the rig is a combo of the dial setting(s), menu settings (carrier insertion point, Hz), and tone modulation frequencies. It's on-off circuit grounding instead of BEEP-BEEP tone output. On 75 meters you'd be slapping a hornet's nest, so why do it?Īs a purist CW op, I'd use the VOX circuit in the FLdigi manual to key the transmitter instead, or use an app that keys the transmitter through the RS-232/COM port or USB port. It's probably better to stick with the rules and reg's mentioned previously, however. FM starting at the top of 10 meters and above AM's okay in any wide-enough phone band with appropriate license level. It's probably okay as long as it fits in allocated bandwidth and mode requirements, e.g. It's probably okay in the phone portion, because it is phone. THAT'S true MCW at least in the military WWII sense. Then, the bandwidth will be too wide (legally) for the CW portion of each band. The hazard is if the newby misunderstands the difference, uses AM or FM mode (with carrier), and modulates that. The only problem I have with typing CW is that I just can't seem to type as fast as I can key LOL! ![]() And the reports of my CW "note" were outstanding since, as KK5YJ mentions, "the modulating wave shape can be very precisely controlled to minimize key clicks, etc." And if you listen to the CW audio coming from FLDigi, it sounds just great. When set up PROPERLY (not triggering ALC whatsoever,) I could drive the radio from QRPp levels to full power output by simply keeping radio set to full power output and varying the audio input through the sound card interface. ![]() I decided to try the CW mode through the sound card interface. I was experimenting with this back in 2012 when I used to run PSK31 with FLDigi. There is no carrier being sent, just the audio signal which you can zero beat like any other CW station. If you're on frequency with another station sending CW over SSB using an audio tone (from FLDigi in this case,) you would never know the difference. Just like with CW, this has the benefit of allowing you to use the dedicated RTTY features of your radio, like special RX filters, etc.Ĭlick to expand.I also agree with K7JEM. If you use a radio that has a dedicated hard-key input for RTTY, this circuit can be used for RTTY, too. I updated this circuit to use more current parts, but either way, using a keying circuit allows one to use one's radio in the dedicated "CW" mode, which lets you use CW-specific filters and features, while still using fldigi for both transmission and reception. The fldigi manual describes a simple circuit that allows the sound card to hard-key the CW input of your transmitter. ![]() If you want to operate CW from fldigi, there is a simpler way to do so that is almost certainly guaranteed to be cleaner for most newer radios. To emit a clean signal, one does need to be careful not to overdrive the transmitter audio stages, avoid compressors, etc. In fact, this method has some advantages if done properly, because the modulating wave shape can be very precisely controlled to minimize key clicks, etc. Is quite correct - there is certainly nothing wrong with using a tone to modulate an SSB transmitter to produce CW. ![]()
0 Comments
Leave a Reply. |