Radio with Pure Data

Ever since it was discovered that some cheap DVB-T receivers can be used for generic reception of radio signals, these receivers became more popular among radio enthousiasts. Now there is an interface between these receivers and the Pure Data and Max/MSP audio software packages. The processing of the received signal is mostly done in software, making it ideal in understanding and experimenting with demodulation techniques. This page describes a variety of receivers which work with these packages.

Assortment of DVB_T USB receivers

A collection of DVB-T USB receivers that work with the rtlsdr~ object.

The rtlsdr~ object is written by Tom Zicarelli and is based on the rtl_sdr source for Gnu Radio from OsmoCom. All DVB-T USB devices working with rtl_sdr will work with the rtlsdr~ object. The common element for these sticks is the RTL2832U A/D converter. They differ in the tuner chip used. On Ebay and other sites offer gadgets like DVB-T USB devices, the chip set is sometimes mentioned; the RTL2832U / R820T and RTL2832U / E4000 combinations work. For more (technical) info look at superkuh site.

The receivers with the R820T tuner have a range from 28 MHz to 1700 MHz, the E4000 tuners range from 54 MHz to 2200 MHz with a hole between 1100 to 1250 MHz.

Another small difference between the R820T and E4000 tuner is the result if the demodulation technology each uses. The R820T uses an intermediate frequency, while the E4000 demodulates directly to the base band. The result is that the E4000 tuner always produces a (small) peak in the middle of the received band representing DC, this is at the border of the fft-left and fft-right in the radio-block patch.

Another hint is the description "DVB-T+DAB+FM" or "DVB-T+DAB+FM+SDR". In most cases this is the RTL2832U / R820T chip set. These appear to be the cheapest too.

The receivers usually come with a short antenna, a CD with drivers and a remote control. The price can be lower than $10, including shipping. The packaged drivers are not used by the Pure Data or Max/MSP interfaces.

Typical blister packing

Note there are also DVB-T USB receivers based on different chip sets that do not work with the rtlsdr~ object.



Latest update: 2014-05-03

email: fjkraan@xs4all.nl