The Octopus

The Octopus transceiver card family presents a state of the art digital radar capability that forms the basis of all of our ISR products. It utilizes the miniaturization of radio frequency components, driven by the cellular telephone market, in the design of new radar capabilities. The Octopus provides a transmit and receive capability on one PCI card. It offers programmable pulse generation capability with .1 to 100 MHz bandwidth programmability, and eight digital receiver channels using 8-bit A/D converters for the receiver section for the first step of acquisition, followed by additional on-board processing that increases the dynamic range of the recorded signal. A single Octopus supports an 8-element receive array, and can be used with up to three additional OctalRec receiver cards to increase the receive aperture to as many as 32 elements. Receiver output data are two byte words, achieved by either repetitive pulse averaging or digital down conversion I/Q data generation. In the case of averaging, up to 256 consecutive echoes can be averaged, providing 2-byte output real data. For DDC processing, the gain is the ratio of 95 MHz divided by the desired output rate (~ pulse bandwidth). For an 8-ms pulse, 125 KHz bandwidth, a gain of 95/.125=760 is achieved, with I/Q pairs generated and stored at 4-bytes output format. On-board averaging is also available to more fully utilize the 4- byte output word size.

The waveform generation capability ranges from a few kilohertz to 100 MHz, with user-defined programmable pulse envelope control, in addition to ISR provided cosine-squared, square wave, and triangle envelopes. The signals are generated using Direct Digital Synthesizer chips with a square waveform, fed to a mixer with a user-defined pulse envelope, resulting in a pulse waveform with rf spectrum characteristics that will satisfy FCC requirements in the HF band.

A software graphical-user-interface is provided that allows the user to program the transceiver according to the desired specifications for the application at hand, stores the parameter file for future use, and then executes the acquisition. The program can be run on a periodic basis using a task scheduler for continuous data collection.

Currently, the Octopus is sold only as part of ISR radar systems, but partnering opportunities will be considered for applications not yet offered by ISR. We offer the system as a digital receiver system, imbedded in a rackmount Intel family computer running Linux, with networking capabilities for transferring data to a user’s processing computer. Post processing software is offered for some radar operations. See our software products section for more details. The digital receiver system offers new educational opportunities for university radar courses, and special pricing is available to the educational field.

Some of the system's features include:

Analog section

  • 8 available channels (individually activated or deactivated by software)
  • 100mV to 2V input (50 Ohm input impedance) with 6 ranges available
  • Each channel can be individually configured with 0dB, 6dB, or 12dB attenuation. Each channel may also use a gain of 20dB in conjunction with any of the three attenuation settings.
  • 12-bit fine offset and 10-bit fine gain control
  • Acquisition length- 128 to 65,536 samples in 128 sample steps

A/D Converter

  • Analogue Devices AD9762ARU 8-bit resolution A/D converter
  • 1 to 100MHz software configurable sampling rate

Transmitted signal, pulse shaping, and filters

  • Pulse-to-pulse frequency selection on an interleaved basis
  • Analogue Devices AD9852ASQ Direct Digital Synthesizer chip programmability, including simple pulse, frequency modulated chirp, phase modulation, and random noise.
  • The DDS output pulse can be run through an onboard mixer which can shape the pulse according to any desired function. Currently a cos squared shape is used, but a custom shape can be designed. Consult ISR regarding your signal shaping needs.
  • 1 of 3 lowpass filters (or none) are automatically selected based upon the frequencies transmitted
  • Transmitted pulse and signal mixing profile may be monitored through an SMA port and recorded directly to recording channels.

System triggering

  • Pulse-Repetition-Frequency (PRF) of 1 to 5,000 Hz available with 25-bit precision
  • Trigger pulse length of 1us to 200 us in 50 ns steps
  • Post trigger delay- 1 to 200 us in 50 ns steps
  • Board can process 1 to 224 triggers without CPU intervention
  • Triggering available via:
    • Software trigger
    • Internally generated by the reference clock (divisor of the reference clock is programmable)
    • 10kHz GPS clock
    • External trigger (in/out)
    • Common trigger (in/out) (allows multiple boards in a system to share a trigger signal)
    • Auxiliary (parallel port) trigger

Clocks

  • Clock signal available via:
    • 20 MHz PLL
    • 50 MHz internal clock
    • Rubidium clock (10 MHz) OR x2 clock (20 MHz) (SEPARATE PURCHASE OPTION)
    • External TTL clock (SMA port available for input or output)
    • DDS chip used to generate A/D sampling rate clock with frequencies available from DC to 120MHz with 1 uHz resolution

Data

  • Data is available in both unsigned binary
  • Up to 256 waveforms can be averaged together to compress data and increase dynamic range

Memory, DSP, and Control

  • 2 digital down converters (one for upper four channels, one for lower four channels) with data rates up to 95 MHz
  • 64K x 16-bit summing/ storage memory onboard
  • 64K bit EEPROM for calibration data storage

PC Platform

  • The Octopus card currently operates under Microsoft Windows 98 and Linux platforms, with some file size constraints using Windows 98.
  • Octopus fits in a standard full-sized PCI slot (full height and length card)
  • Utilizes PLX technology with a PCI9054 chip to communicate with PCI bus

Mechanical

  • 8 SMA ports for data input
  • 1 SMA port for clock input
  • 1 SMA port for trigger input
  • Wing bracket with SMA ports for:
  • 1PPS signal (in/out)
  • GPS antenna input
  • Mixer output
  • Unmixed signal output
  • Blanking signal
  • Profile (envelope) output
  • Rubidium input
  • Common trigger port (for multiple board applications

Programmability

  • GUI interface provided with instructions
  • More sophisticated options developed under separate contract.

Other Models

Quadrapus

The Quadrapus transceiver is a four-channel version of the Octopus and is designed for use with our DOA radar that uses four or fewer receive antennas. All other characteristics of this model are identical to the Octopus.


OctalRec Receiver

The OctRec is a receiver card, with basically the same design as the Octopus without the transmitter capability. It is designed for use in our larger Phased Array radars, where 16 to 32 elements are desired. One or more OctRec receiver cards are then used in tandem with an Octopus transceiver, which generates master A/D timing for the OctalRec cards. In the future, we will be offering other passive sensing systems based on the OctalRec digital receiver.


QuadRec Receiver

The QuadRec receiver card is basically a Quadrapus card without the transmitter capabilities.


Exciter Board

The Exciter board is a subset of the Octopus without any receiver elements. See the Octopus description above for characteristics of the transmitter section.