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Z90 & Z91 SpectraScreen Panadapters
and Z90 Control Software
The Z90 and Z91 are planned receiver panadapters, to allow amateur radio and short wave listeners to see a visual display of signals. Both the Z90 and Z91 are currently in prototype stage and and were shown at the 2006 Dayton Hamvention at the Telepostinc table (table no. 517, across the aisle from
SteppIR.)
Update
– for the current status of the Z90 project go to Updates.
To see modulation samples displayed on the Z91, go to Modulation.
Click on any image to view a
large version
What
is a Panadapter?
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A "panadapter" is a specialized device connected to a receiver's intermediate frequency auxiliary output displaying signals near those to which the receiver is tuned. The horizontal axis is frequency (centered on the receiver's current frequency) and the vertical axis is signal strength, in decibels.
(Screen resolution issues may cause the illustration to show only
some of the 8 x 10 grid lines.)
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Z90 and Z91 Differences
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I've designed the SpectraScreen panadapter in two
versions—the Z90 with both a data output and an integrated 5.6 inch (diagonal) liquid crystal display, and the Z91, with data only output, to be used with display software such as the Windows® compatible Z90 Display software. The Z90 Display software offers interactive control of both the Z90 and Z91 models.
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Z90
- With LCD Screen
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Front view of the Z90, with no signal received.
All control functions are exercised through the six "soft keys" to the left of the screen.
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Z90
Rear:
From left to right:
- Auxiliary signal generator output
- RS-232 control\DC Power in (13.5 VDC @ 1 A)
- Attenuator 20 dB
- Attenuator 10 dB
- Signal Input
- Power Switch
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Entering the custom (user-determined) IF frequencies from one of the Z90's setup screens.
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Screen image of WWV during the
500 Hz modulation interval. WWV's tone modulation is at 50%, so each sideband should be down approximately 12 dB below the carrier.
The two sidebands are not equal due to selective fading.
This image is from the first PCB prototype.
The LCD is backlighted with a CCFL.
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An early Z90 prototype printed circuit board, without silk screen and solder mask. Later units
have a separate DDS daughter board. Production units will have both solder mask and silk screen.
The same PCB and microcontroller firmware is used in the Z90 and Z91, permitting a later upgrade to the Z90 version by adding the omitted components and installing it in a new cabinet.
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Z91
- Computer Only - No LCD
The Z91 is identical with the Z90 in all performance specifications, except that it does not have an LCD screen. Rather, the received data is sent over an RS-232 serial line to your Windows 2000 or Windows XP equipped computer, where it is displayed in the Z90 Display Program.
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The Z91, front view.
Production units will have a status LED on the front panel that alternates red/green to show scan starts.
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The rear of the Z91 is identical with the Z90.
From left to right:
- Auxiliary signal generator output
- RS-232 control
- DC Power in (13.5 VDC @ 0.5 A)
- Attenuator 20 dB
- Attenuator 10 dB
- Signal Input
- Power Switch
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Most recent prototype board, late prototype board, with DDS Daughter board visible at left center of photography.
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Z90
Display Software
The Z90 Display software operates with either the Z90 or the Z91 SpectraScreen units. If used with the Z90, control is interactive, i.e., if you change a parameter via the Z90's soft keys, the Z90 Display software changes to match your soft key selection. Likewise, changing a parameter using Z90 Display software correspondingly changes the LCD display.
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Z90 Display is known compatible with Windows 2000 and Windows XP. It requires a serial port capable of operation at 115200 b/s. It is known to work with direct hardware ports and the Keyspan USB-serial adapter. Other adapters may work as well.
The interface mimics the soft keys but with a Windows flavor.
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Z90 Display software supports copy (image is copied to clipboard to be pasted into other programs), print to printer, save image as bitmap or JPG and save data.
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Condensed
Specifications
Condensed
Specifications – Applies to both Z90 and Z91, except as noted
PRELIMINARY
– SUBJECT TO CHANGE WITHOUT NOTICE
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Input
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Horizontal
(cont)
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Input
Impedance
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50
ohms
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User-definable
span
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3,
may be set to any value between 2.5 KHz and 250 KHz
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Minimum
Discernible Signal
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-100
dBm (1 KHz RBW)
(approx
2uV)
-94
dBm (200 Hz RBW)
(approx
4uV)
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Time
Per Sweep
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Typically
approximately 3 sweeps per second; in maximum resolution mode, approx
1.2 seconds/sweep.
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Max
Recommended Level
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-30
dBm/span>
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Frequency
Accuracy
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After
user calibration typically 10 PPM over normal temperature excursion
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Frequency
Range
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Vertical
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Frequency
Range
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50
KHz to 50 MHz
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Dynamic
Range
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>
55 dB
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Pre-defined
Standard IF frequencies
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450,
455, 500 KHz, 4914, 8215,
8830, 10700 & 21400 KHz
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Third
Order Intermod
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With
two equal signals of -43 dBm, third order products are > 55 dB
below carrier; with two equal signals of -33 dBm, third order
products are 42 dB below carrier
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User-definable
IF frequencies
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3,
may be set to any frequencies within the 50 KHz – 60 MHz range. Less
than 3 dB loss in sensitivity for IF up through 73.62 MHz.
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Steps
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10
dB or 2 dB/div
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Data
Port
and Control
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Accuracy
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±
1 dB typical, ±2 dB over 60 dB range
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Data
port
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RS232
serial, two-way, permits control of Z90 and data capture from Z90.
Speed fixed at 115,200 b/s/
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Bandwidth
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200
Hz or 1000 Hz, user selectable or automatic selection via firmware
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General
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Filter
Type
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8
MHz, 4 pole crystal filters, Gaussian response
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Power
Required
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13.6V
nominal, 12V minimum, 15V maximum (never exceed) at 1.0 Ampere (Z90)
or 450 mA (Z91)
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Display
Z90
only
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240
x 320 (quarter VGA) blue/white LCD display with CCFL illumination.
Active area 5.6 inches diagonal.
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Horizontal
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Signal
Generator Mode
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Pre-defined
Span (sweep width)
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5,
10, 20, 50, 100 & 200 KHz
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Signal
Output
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Buffered
output from DDS available at rear panel. Approx. level +5 dBm between
100 KHz and 60 MHz. Usable outside these frequencies with reduced
output.
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Project
Status
In
late June, I submitted two draft articles to the American Radio Relay League
to consider for QEX:
Here's
how I described them in the cover letter:
The
main article, The
Z90 and Z91 Digital Panadapters,
describes two micro-controller based panadapters that I’ve recently
constructed—one with a liquid crystal graphic display and the other intended
for computer control via a Windows display program that can also be used with
the graphical display unit.
The
second article, Designing
the Z90’s Gaussian Crystal Filter,
is an in-depth examination of one part of the Z90’s design, the crystal
filter. It covers measuring motional parameters as well as the filter’s
design, matching and testing.
My
plans are to continue developing the Z90, Z91 and Z90 Display software and
to offer both units as both kits and fully assembled units around September or
Octover 2006.
Pricing
will depend upon the level of interest, as significant economies of scale are
possible for major components, such as the LCD and cabinets. Both the Z90 and
Z91 use some surface mount components, and the most difficult component
for kit building, the AD9851 DDS, will be available as an optional
"assembled and tested" module to plug into a user-assembled board.
Please
let me know if you are interested in the Z90/Z91 and I will add your name and
E-mail address for periodic updates.
You
can also check the Updates
page for the project's current status.
Contact
E-mail me
at Jack.Smith@CliftonLaboratories.com
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The 18F4620 PIC Microcontroller in the Z90 and Z91 SpectraScreen is programmed
with Mecanique's
Swordfish compiler |
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