What sound cards do you recommend?

M-Audio Delta PCI sound cards are recommended for use with UltraMSK. A card such as the Delta 44 has 4 analog inputs - enough for the GPS 1 PPS signal, an electric field antenna and two loop antennas.

Update July 2016. The M-audio Delta cards are no longer in production. USB soundcards such as the Focusrite Scarlett range are also a good choice.

01 Oct 2016

How do I get the best phase measurements?

UltraMSK measures the phase of the received radio signal by combining the long term accuracy of the GPS 1 PPS signal with the short term frequency stability of the crystal oscillator on the sound card. By thermally insulating the sound card oscillator, its frequency stability is greatly improved and the quality of the received signal phase measurements will be improved.

This can be achieved by attaching a small piece of foam to the top and bottom of the sound card at the location of the crystal oscillator. The foam can be either clamped in place as shown below or attached using 3M double sided foam mounting tape. You will need to trim the foam for the top side so that it fits neatly within the electronic components.

M-Audio Delta1010LT with foam insulation attached using an Excel plastic clamp

10 Jul 2006