14 bit Digitzer optimized for RADAR applications

For engineers requiring a PC based radar signal and antenna position capture card, the German manufacturer Spectrum provides the M2i.4038, which incorporates an ultra high speed 50 MSample/sec signal capture module coupled with a digital input module. Looking closer at the technical details, this card has three inputs available into the analogue section, these being signal input, external clock and external trigger. The card incorporates a high-resolution 14 bit A/D converter with excellent dynamic performance to ensure accurate radar signal recording. Sample clocking can be externally supplied from the users own equipment, or generated internally by the cards own clock engine utilising a low jitter on board oscillator. The trigger input connection also allows full control of the sampling window and an option to allow each trigger to be time-stamped.

 On the digital side of the M2i.4038 the azimuth encoder counter connection is very straight-forward just having 2 lines, one for the encoder pulse signal the other for a reset (North Reference Pulse). The cards pulse counter provides up to 16 bits of resolution, so with the capacity to record up to 65536 pulses on per rotation, this gives the opportunity to acquire with an exceptionally good positional accuracy. Another possibility is for the M2i.4038 to acquire data in parallel on 16 digital channels. This digital port wide capture can be used for antenna elevation as well as azimuth, though each would have to share the 16 bits. Counter input and parallel acquisition can also be individually combined by software command.

 In operation the radar card can be used in two ways. First there is the special multiple record option, where the trigger, either externally derived or from the arrival of the radar pulse, starts a recording window of finite length digitising the pulse and recording the angle positions at the end of the window. Using this mode of operation allows gaps in the recording at times when data is not required or unimportant. This reduces file sizes and bandwidth required for data transfer to the PC. Below is a timing diagram that exemplifies this: here the capture of the radar signal data occurs on the analogue channel. A second method is to run the capture continuously, with a radar pulse recorded along with angle positions on every clock pulse, which at 50 MSample/sec is a 20 nano second repeat period, (note that to suit your requirements this sampling rate may be varied).

 The card can be equipped with up to 2 GSample of on-board memory to cope with the large amounts of data. By choosing either the PCI 33/66 MHz (PCI-X) or PCI Express interface model, continuous data can be streamed to PC RAM, its potential capacity now greatly extended in the new 64 bit Windows and Linux environments. The radar card is also available in a lower cost 20 MSample/sec version, (model number M2i.4028), which still has all the features of the faster card, including the excellent support for Windows and Linux software environments (32 and 64 bit).

 The existing Spectrum drivers are used for programming the board, with the flexibility of the drivers allowing the programmer to build and design an application to exactly meet his requirements. A set of standard programming examples are provided to illustrate the boards main signal capture functions. Extensive support includes Visual C++, Borland C++, Gnu C++, Visual Basic, VB.NET, C#, J# and Delphi code. This special card comes with a 2-year manufacturer guarantee.