Fldigi and cw operation software#
Fldigi and cw operation code#

Overdriving the transmitter can cause multiple audio signals within the SSB passband, and cause unwanted interference to other ops. your transmitter must never be overdriven and it should have excellent opposite sideband suppression.

Fldigi and cw operation software#

The CW generated this way has a nearly ideal attack and decay time, controlled by the software modem. If fldigi is tracking and receiving a CW signal on the waterfall your transmitted signal will be exactly on the frequency of the other operator.

The actual transmitted signal will be at the USB carrier + the audio frequency, or the LSB carrier - the audio frequency. The CW signal is completely generated in the software so it is possible to control many aspects of the CW signal. The transceiver should be operated in either USB (preferred) or LSB mode. Press the '*' again to return to back to the CW speed that you were previously using.įldigi generates CW by inserting a keyed tone at the current waterfall audio frequency.

Fldigi and cw operation code#

If during a QSO you needed to slow down to give the other op a better chance to copy what you are sending, just hit the '*' on the numeric keypad and the CW code will immediately switch to sending CW at the set default value (18 wpm in this example). As shown above the TxWPM is 30 and the default is 18. The 'Default' control on the CW tab sets that default value. Numeric keypad '*' toggles between the selected TxWPM and a default WPM Numeric keypad '-' decreases the TxWPM by 1 Numeric keypad '+' increases the TxWPM by 1 The transmit encoder settings for WPM can also be adjusted with three hot keys: The Lower/Upper controls are in in 5 WPM increments. The resolution of the TxWPM slider is 1 WPM. 'Lower' sets the lower limit of the slider and 'Upper' sets the upper limit of the slider. To make the setting easier two additional controls are provided. The TxWPM sliding controller is used to set the transmit WPM. It can increase the probability of correctly identifying the text character under very noisy conditions. 'SOM decoding' provides a fuzzy logic implementation to match the RX stream detected on-off sequence to a 'best fit' character. The RxWPM control is an indicator and is not used for setting the operation of the CW decoder. You can control the attack and decay squelch parameters of the detector, slow - medium - fast, for both attack and decay. When tracking is enabled the tracking filter is reset every time the transmit WPM is adjusted.ĬW detection is basically an amplitude demodulator with an automatic threshold adjustment. The tracking range (+/- Hz around the TxWPM setting) can be set using the 'Rx Trkg Rng' control. Enable Rx WPM tracking by enabling the check box 'Enable Tx Trkg'.

Increasing the filter bandwidth might improve detection in that QRN environment.įldigi can track the incoming signal. A lot of impuse noise (static) can cause the filter to ring. Select 'Matched' filter to optimize the filter width for the current transmit WPM setting. The FFT filter is optimum when receiving CW in a white noise environment. This is a very steep sided low pass filter. The CW decoder uses a Fast Fourier Transform (FFT) filter implemented with a sin(x)/x impulse response. It is the digital equivalent of tuning an analog USB transceiver so that the carrier is exactly at the CW carrier frequency. The CW signals are converted to a baseband signal. During operation the Rx and Tx WPM settings are annunciated on the status bar in the two boxes next to the mode indicator. You can also open up the CW tab by first selecting CW as the operating mode and then clicking on the left-most item 'CW' on the status bar at the bottom of the fldigi main window. You can open that tab by selecting the 'Configure/Modems' menu item and the clicking on the Modems/CW tab. The operating controls for CW are found on the Config/CW tab.

Fldigi can send and receive morse code from 5 wpm to 200 wpm.