The EssexPSK application is deliberately very basic, to encourage newbies to give the mode a try without the hassle or expense of one of the larger PSK31 applications. The EssexPSK app has a button that lets you view common frequencies. Most of the PSK activity is on HF, so you will need to tune your radio to a suitable frequency and check that you can hear the data tones. You can even decode signals by holding a cheap computer microphone in front of your radio’s speaker.
To use the application, you need to connect your amateur radio to your computer – typically, connecting the headphone output to your computer’s Line In socket will do the trick. Using this application, you’ll be able to decode PSK31 data signals and get familiar with the mode EssexPSK – The Essex Ham PSK Decoder by M0PZT How do I use EssexPSK? PSK31 is one of the common of the HF data modes, and is a great mode to get started with.
It’s a free application that can be installed on your Windows computer that decodes PSK and RTTY data signals received on your amateur radio, and lets you decode and view conversations. On this page, you’ll find the latest copy of EssexPSK, a free application that lets you decode data signals on your PC. The "Data" input is also 6 dB less sensitive than "Mod in" making it that much less likely that one will significantly over drive the the transceiver and create distortion in the audio stages ahead of the modulator".New to the world of amateur radio data modes? We can help. Using this input avoids several potential problems - including the constant swapping between mic and digital connections and remembering to turn off the compressor when switching to digital operation. The narrow spans clearly show the benefits of reducing the audio until output power drops 1.5 dB.Īudio was connected to the IC-706mkIIg via the "DATA" jack rather than the mic connector or "Mod In" pin of the ACC jack. I do use a high audio frequency to minimize harmonic issues.įor fun I've attached versions at 70 W in 10K, 5K, and 2K spans. This one isn't too bad but one can see carrier at -50 dBc and opposite sideband at -55 dBc +/. The 10 KHz span shows the one failing of the IC-706mkIIg and other rigs with analog modulation - opposite sideband and carrier leakage. "Two views - the 2 KHz span and a 10 KHz span. The results of those tests are very enlightening.
Joe also performed a series of tests on an Icom 706 mkIIg transceiver. The waterfall, time domain, and spectrum signatures of the transmitted signal look like this: The principal being a reduction in inter symbol interference which gives much improved performance by the receiver. There are performance gains using this approach. Therefore the transmit audio and RF amplifiers must be linear, just like the requirement for PSK signals. The resultant waveform is not an FM type signal of constant amplitude. Each of the generated Mark / Space signals are on-off-keyed (OOK), bandwidth limited signals. It is not limited to the traditional tone pairs around 2100 Hz. fldigi can encode and decode an RTTY signal that is anywhere within the passband of the sideband transceiver. You probably will never have to do that unless you like experimenting with unusual RTTY modes.Īll of the modem signals that fldigi produces are audio signals. "Custom" combinations are set up on the RTTY configuration tab. The 50 baud machines were for the European market and used 50 Hz synchronous motors.įldigi can encode and decode many other symbol rates and bandwidths. The 45.45 baud and 75 baud machines were for the US / Canadian market and used 60 Hz synchronous motors.
These modes were a result of mechanical and electrical designs of the early TTY machines. The three most common in amateur radio use can be selected from the mode menu. The selection of symbol rate and bandwidth is made on the RTTY configuration tab. Chen, W7AY, was a silent contributor to the design by virtue of his excellent technical papers on RTTY modulation and demodulation, which he so generously placed in the public domain.įldigi can operate on a wide range of RTTY symbol rates and bandwidths.
The new design was a cooperative effort of Stefan, DO2SMF, and Dave, W1HKJ with extensive testing performed by Ed, W3NR, and Dick, AA5VU. The RTTY modulator and demodulator have been extensively changed with version 3.21.67.