----- Forwarded message from Vic_Healey <address@hidden> -----
The JT2000 receiver from AOR provides a fresh look at wide range
receivers. Using the latest DSP technology (Digital-Signal-Processing) in
the i.f. stage (not just audio DSP), the receiver allows very fast FFT
analysis (Fast-Fourier-Transform) of the radio spectrum enabling active
radio channels to be detected and monitored very quickly.
Fundamentally, FFT uses spectral analysis in the time domain to
evaluate which frequencies are active, sections of the radio spectrum are
grabbed within a few tens of milliseconds and a list of active
frequencies prioritised automatically. If compared in conventional terms
to a scanning receiver, JT2000 is capable of scanning several thousand
channels per second! Put in to practice, this means that it is possible
to monitor a frequency on the VHF airband while simultaneously checking
the whole band (every frequency) for new transmissions several times per
second, clearly no activity will be missed with the most elusive,
infrequent and brief transmissions captured. Spectral analysis can
continue during monitoring.
Sensitivity, selectivity and dynamic range will challenge the very
best wide band receivers. A conventional RF stage uses double or triple
conversion (depending on the receive frequency) to provide good image
rejection over a wide reception range from a few kHz to over 2.5 GHz. A
wide bandwidth is maintained throughout both the RF and IF stages and
coupled with a fast, high resolution analogue-to-digital converter
provides the RF signal analysis facilities. Digital filtering with 22-bit
accuracy provides reception bandwidths from a few Hz up to 250 kHz
enabling the DSP to demodulate a wide range of signals. Standard
reception modes include SSB, AM, synchronous AM, FM and wideband
(broadcast) FM, all with selectable IF bandwidths. New features like
dynamic squelch (with manual override) add to the capabilities and ease
of use.
The standard JT2000 is presented in a rugged cabinet (black box) with
internal design to high standards employing six-layer PCBs and custom
parts, control is via a host computer. Connection to a host computer is
via a standard RS232 serial connection and for higher transfer speeds, via
USB (Universal Serial Bus), transfer speed is largely dependant upon the
host computer, the faster the computer, the greater the data - and better
the analysis results. JT2000 provides an extra serial port which allows
direct connection to, and control of an additional, separate monitoring
receiver for hand-off applications. The receivers design is intended to
allow for future functions to be added.
All internal control software and DSP routines are stored in flash memory
which can be re-programmed from the host computer. New signal analysis
methods and different signal demodulation can be implemented with a simple
software download. If new circuitry is required to handle special signals
then there is a spare module slot within the receiver; both analogue IF
signals and a high-speed serial interface to the DSP are available to
support it. A front panel controller is planned with display and keypad
which will provide stand-alone reception and operation in addition to
computer control.
Windows based control software is supplied with the receiver and includes
a database processor and function applets to control receiver settings.
The heart of the control software is a database system that contains
scanning and searching channel information. Unlike other fixed databases,
JT2000 can quickly and dynamically build brand new real-time databases
(from a blank start). The database content is a mixture of signal
information from the user (frequency and identification) and reception
information from the receiver (signal strengths and durations). From this
data the software can produce signal logs and band occupancy information
and the receiver can be controlled to monitor channels based on criteria
of priority, signal strength or signal duration as decided by the user.
Additionally the receiver can automatically produce database entries of
active channels during a period of observation of sections of the radio
spectrum. All database content is in a transportable format so that
further data analysis can be carried out with standard Microsoft Office
applications. Similarly databases of spectrum allocation can be imported
from other formats through these programs.
JT2000 was displayed at the Dayton Hamvention in May'2000 for the first
time in 'proto-concept' format (part way between concept, prototype and
pre-production). The new model is the result of another successful joint
development between AOR and internationally acclaimed UK designer John
Thorpe (design engineer of the award winning AR7030). JT2000 is designed
and built in the UK, production is expected to start at the end of 2001.
Acrobat PDF leaflet (153kB), click here.
Price £ T.B.A. but primarily targeted at the commercial and government
market, possibly around GBP 2.5k