Print Strength Bandwidth

PSK31 signal traces samples

This page demonstrates a range of real signals taken from 20m QSOs during early December 2002, as received in Southern California, USA. The captured screen shots are using Logger32 by Bob K4CY.

The IMD noted on the images are taken directly from the value calculated by Logger32. Care was taken to pick fairly strong signals and to capture the picture during an idle point in the transmission.

Whilst this method is not thought to be especially scientific, it is believed to provide a useful relative reference.

Good quality transmission

The image below shows a range of signals, with the chosen signal in the waterfall highlighted between the two red parallel lines, just to the left of the text "14071".

The spectrum display shows the clean profile of this signal, attaining an IMD figure of -26dB.

This trace would rate a  Q9 report according to the reporting tables.

Example of very good quality signal trace

Typical quality transmission

The image below shows a range of signals, with the chosen signal in the waterfall highlighted between the two red parallel lines, just to the right of the text "14071".

The spectrum display shows one pair of unwanted sidebands, attaining an IMD figure of -20dB.

This trace would rate a  Q7 report.

Example of typical quality signal trace

Poor quality transmission

The image shown below demonstrates a bad signal, unfortunately all too commonly seen!

The signal is generating multiple sidebands, taking up more bandwidth than necessary, and likely causing interference to fellow amateurs.

The spectrum display clearly shows the multiple unwanted sidebands emitting from this station.

This trace would rate a  Q1 report.

Example of very poor quality signal trace

Non real-world signals

To see a range of non real-world traces, click here.

Sound samples

Below are a couple of  .WAV audio files, highlighting the difference between a good and bad PSK signal.

Click on each one to download the sound sample - but remember to turn your volume setting down first!

Capturing the audio to a wave file, and then e-mailing to operators who are sending poor signals may assist them to better recognise their problem. Experience has shown that this type of feedback is appreciated.