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== Hardware == There are a number of alternatives for hardware to capture a P25 baseband signal. These include: * USRP (using TVRX daughterboard and appropriate antenna). * SSRP with an appropriate radio front-end and antenna. * Custom interface to existing scanner using soundcard for quadrature sampling. * Custom PSK to serial interface hardware. For those without any hardware it is possible to investigate using signal samples which are available on the DemodulatorPage. === USRP === Initial work is proceeding using the USRP which because it is available from [[http://ettus.com Ettus Research LLC]]. The USRP is capable of wideband reception and requires no special-purpose hardware as everything is done in software. hardware. A USRP with the TVRX daughterboard and an appropriate antenna is all that is required. === SSRP === The SSRP is a promising alternative to the USRP from [[http://oscar.dcarr.org/ssrp/index.php David Carr]] required and is significantly cheaper. The sampling rate is reduced in comparison to the USRP and it is not nearly so mature but may be a good bet in future for mobile use or where the expense of the USRP cannot be justified. === Sound Card Sampling === The ADC built into many home computers is capable of sampling at rates up to 200KHz. Depending on the scanner much more than just intercepting P25. For those without any hardware it maybe is possible to quadrature sample the discriminator output investigate using the soundcard. This approach may require some custom interface circuitry and filtering within signal samples which are available on the scanner may limit reception to a single channel. === Custom hardware === DemodulatorPage. Another approach for interfacing to existing scanners is to feed the discriminator output to a custom hardware circuit. Some are available built and tested from a variety of sources such as [[http://www.discriminator.nl/index-en.html discriminator.nl]]. This approach is low cost and pretty straightforward although limited to reception of a single-channel at a time.
