Complete circuit design capability means going from schematic to product. With our years of experience embedding a wide variety of micro-controllers, DSPs, and programmable logic, we can hook you up to the 'real world' with 'real-time' results.
The transceivers used by emergency personnel inside a subway tunnel, shopping mall or sky scrapper cannot communicate with their base stations because the surrounding structure is impervious to radio frequencies. To provide communication coverage in these structures, a rebroadcast system is used. DSP Tools, Inc. just developed an FPGA based, digital signal processing module and FPGA code to provide the needed signal processing. The system including several of these modules is being deployed at the Garden State Plaza in New Jersey, World Trade Center Tower 4 in New York City and will be used in the San Francisco subway system which undergoing a major upgrade.
In a rebroadcast system, a distributed antenna is run throughout the building or subway tunnels to receive the handheld transceiver's output and after the digital signal processing described below, passes selected channels via fiber optic cable to an outside transceiver and antenna. Each of several channels used by police, fire and other emergency personnel needs to be digitally filtered, level normalized and keyed-on or off using either carrier, CTCSS tone, or Digitally Coded Squelch.
DSP Tools designed the module shown below and also the Xilinx Artix 7 FPGA internal design.
To provide a control system for an un-manned 'helicopter,' DSP Tools partnered with Applied Micro Design to develop a miniature DSP-based autopilot about the size of a credit card for Allied Aerospace Industries.
Both size and the ability to reprogram the firmware 'on-the-fly' were key to this design.
DSP Tools completed the initial hardware and software design, and then trained the client's engineer so that they were able to continue with future software add-ons of their own, allowing them to respond rapidly to their customers' needs.
One of the projects DSP Tools, Inc. did during 2012 and 2013 was the design of a Software Defined Radio HF receiver that is small enough to be attractive for small UAV applications. Our work included product architecture, schematic design, PCB layout, FPGA design, application programming interface and GUI software. The design included a soft processor implemented inside the FPGA and programmed in C. The software for that processor implemented scanning and more than 100 commands for receiver tuning, demodulation mode, bandwidth, AGC control, squelch and other control functions. It also implemented a command and data streaming interface over Ethernet using UDP and TCP/IP.
The following figure shows the Software Defined Radio board including 125 MHz ADC and driver, Xilinx Spartan 6 FPGA, USB 2.0 interface, Gigabit Ethernet interface, stereo audio chip for headphone and line outputs, a DAC for RF output and power regulators:
DSP Tools, Inc. has developed Data Acquisition (DAQ) boards for several Flow Cytometers for three medical instrument companies. A flow cytometer is a blood cell analysis device in which a sample of blood that has been treated with reagents is passed in a stream through a tiny orifice. The orifice is so small that the individual cells pass in single file. The stream is illuminated at four points along its length by lasers of different colors. The reagents attach to the different types of cells and fluoresce in different colors depending on the type of cell in each laser beam. The light emitted at each laser illumination point is captured using optics and color filters and turned into electrical pulses by sixteen photo-multiplier tubes. The PMT signals pass through preamplifiers to 16 ADC converters on the DAQ board for analysis leading to the identification of each cell in a stream of as many as 35,000 cells per second.
We provided architecture, parts selection, board schematic design, PCB layout, quick turn board fab and assembly using a local ISO9000 contract manufacturer, FPGA algorithm design, and PC application programming interface. The following figure shows the 16 channel DAQ board with the A/D shields removed. It contains a USB 3.0 interface (Cypress FX3) and a Xilinx Spartan-6 FPGA in a 900 ball BGA package.
The FPGA design of a Flow Cytometer DAQ board contains 16 signal paths that are filtered, time aligned, corrected for baseline offsets in the Photo-multiplier tubes and preamps. There is FPGA circuitry that extracts key pulse shape parameters from each cell pulse as they pass through at a 35,000 per second rate. In order to debug that circuitry as well as the optics, Photo-multiplier tubes and preamps we design test capabilities into the FPGA. They allow display of the signal waveforms at each signal processing stage. The following screen capture shows that debug GUI.
DSP Tools designed and built production board functional testers for all the circuit boards in a Flow Cytometer. One of the testers is shown in the following figure being tested in the DSP Tools lab:
One interesting recent project was the design of a very small TI OMAP based H.264 digital video encoder / decoder running Linux for UAV video display. The Texas Instruments OMAP is a DSP & Arm processor in an unusual "package on package" design. The DSP & Arm chip has a BGA second chip mounted on its top surface. The second chip contains DRAM and Flash memories. We used a system on module made by Logic PD. That module removed the difficult job of mounting the exotic OMAP directly on our board.
One project for SAIC was for High Frequency I & Q recording to disk. This project used a commercially available PCIe board containing an FPGA and a large DRAM. The FPGA design implemented a wideband digital down converter and a very large FIFO made by adding address counters and other control logic for the large DRAM. It was designed to allow as much as the entire 30 MHz HF Band to be recorded to disk as I & Q streams. Here the work was concept, design of RF front end and A/D add-on board, layout, prototype build, the FPGA design and software for the PC. It is shown in the following figure:
One interesting research project DSP Tools did was to attempt locating a bugging device using FPGA hardware and a MATLAB program. The MATLAB program was used to cross correlate the waveforms from four antennas two at a time and use time difference of arrival to locate the RF emitter in an office environment. The cross correlation yielded the difference in arrival times of the signals from two antennas. The plot of points with a constant difference from two points is a hyperbola. There are six pairs of antennas so we obtained six hyperbolas. Where they intersected was the location of the transmitter. The following photo shows the hardware used for the feasibility study. The hardware used four mag-mounted antennas wired to four L band receivers. The output signals from four L band receivers were wired to four synchronized DSP boards which were in turn connected to a USB hub.
Sometimes DSP Tools is called upon to develop and prototype commercial products. The following picture shows the board that is about 2 inches in diameter for a hand held laser device used to treat arthritis:
Our earliest HF receiver design was on a PCMCIA board. The design used a quad digital down converter by Graychip, a Sharc DSP and an FPGA on the back side of the board implementing the PCMCIA interface. This figure shows one of the HF receiver board designs. Others included a total of 16 digital tuners by using four Graychips. Another included an AMBE voice compression chip.
Sometimes DSP Tools' customers utilize our ability to design, program and also produce small runs of boards. We use an excellent ISO 9000 certified contract manufacturer and can do the parts purchasing and expediting to get working prototypes in our customer's hands quickly. Here are some examples: