Frequency Devices ASC-50 User manual

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ASC-50
Operation
Manual
ASC-50
OPERATION MANUAL
September 2001

TABLE OF CONTENTS
1. ASC-50 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Available types of filter transfer functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Description of front panel controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
4. Using the ASC-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Definition of terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
6. Sample rate control explanation and Chart 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Operational Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8. ASC-50 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
9. Power and fuzing instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
10. Theory of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
11. IIR transfer function curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
12. FIR transfer function curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
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ASC-50
Operation
Manual
I

The ASC-50 is a self-contained signal conditioning filter/amplifier instrument that combines Analog and Digital
Signal Processing (DSP) capabilities hile providing conventional analog signal input and output. Analog and
DSP functions are available ithout the need for computer programming hile familiar analog instrument
operation is maintained. Data entry is accomplished via a “soft front panel” and a t o line Liquid Crystal
Display (LCD) that prompts the user to select among various menu choices.
Features
Wide variety of filter types, functions and frequencies
Precise, stable filter performance
Adjustable gain and attenuation
DC offset control
Choice of single or differential inputs
Special DSP bypass
Analog and DSP clip indicators
Filter performance display
Filter Types
Lo -pass (LP)
High-pass (HP)
Band-pass (BP)
Band-reject (BR)
Filter Functions
Butter orth (Buttr)
Chebyshev (Cheby)
Elliptic-60dB (Ell60)
Elliptic-80dB (Ell80)
FIR-40dB (FIR 0)
FIR-60dB (FIR60)
FIR-80dB (FIR80)
Gain Control
PRE - Analog pre-gain range 0 to +36dB in 6dB steps
POST - Digital post-gain range -48dB to +42dB in 6dB steps
DC Offset Control - Input DC offset range
±5 Volts
Over-Range Indication
Analog saturation, clipping detection (←← CLIP)
Digital saturation, clipping detection (CLIP →→)
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ASC-50
Operation
Manual
1

Available Low-Pass, High-Pass Transfer Functions
ANALOG
Butter orth 4,6,8,10 Pole
Chebychev (0.1dB Ripple) 4,6,8,10 Pole
Elliptic-60 dB (0.1dB Ripple) 4,6,8,10 Pole
Elliptic-80 dB (0.1dB Ripple) 4,6,8,10 Pole
DIGITAL
FIR-40 dB
FIR-60 dB
FIR-80 dB
Band-Pass, Band-Reject Transfer Functions
ANALOG
Butter orth 3,4 Pole-Pair Q = 2,5,10,20
Chebychev 3,4 Pole-Pair Q = 2,5,10,20
Elliptic-60 dB (0.1dB Ripple) 3,4 Pole-Pair Q = 2,5,10,20
Elliptic-80 dB (0.1dB Ripple) 3,4 Pole-Pair Q = 2,5,10,20
DIGITAL
FIR-40 dB BW1,BW2,BW3,BW4
FIR-60 dB BW1,BW2,BW3,BW4
FIR-80 dB BW1,BW2,BW3,BW4
LOCATION OF FRONT PANEL CONTROLS AND TERMINATIONS
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ASC-50
Operation
Manual
2
ASC50
MODEENTERBYP
I
N
O
U
T
RESET

Power-On/Off
A t o-position toggle s itch located on the rear panel turns the AC po er on and off. Upon po er-on, the front
panel ill display MODE 1 of the set-up present at the time po er as turned off.
A. Mode Key
Many more functions are controlled than could be displayed on one screen. Four modes of operation are
utilized. Each press of the MODE key displays a different mode (1 through 4). Four consecutive presses of
the MODE key ill return the display to the initial mode.
B. Enter Key
In order to load the filter chosen via the arro keys, it is necessary to press the Enter key. Until this is done
the present filter is still operating. This allo s the operator to spool through the available choices before making
a selection. When in MODE 1, to arn the user that a ne filter selection has not yet been made operational,
the Warning: <ENT> flashes. It is extinguished by pressing the ENTER key hich loads the selected filter.
C. Arrow Keys
Four arrow (←←, →→, ↑↑, ↓↓) keypads are available to highlight fields and make selections. The left ←←and right
→→arrows allo movement ithin fields and are used to select the field to be modified. Continuous looping
through all the fields ill occur as the left ←←or right →→arrow key is repeatedly pressed. The up ↑↑and down
↓↓arrows cycle bet een the various choices available in each field. Changes that require use of the ENTER
key are indicated by the flashing <ENT> symbol (MODE 1 only).
D. Reset Key
During the filter selection process and before pressing Enter or hile the arning <ENT> flashes, the user can
return the display to the current active filter mode by pressing RESET.
E. Bypass Key
The internal DSP filter can be bypassed by pressing the BYP key. This ill bypass the DSP filter, but not the
input anti-alias (AA) and output reconstruction (RC) filters. The BYP key toggles bet een the active and
bypass modes (denoted ACT and BYP on the display) and al ays returns the display to MODE 1. This permits
the operator to monitor the effects of the DSP filter.
F. Input Connectors
T o shielded, female BNC input (+IN and -IN) connectors are present on the front panel. An input signal
connected to the +IN provides single-ended input. To operate in the differential input mode, differential input
signals must be connected to the +IN and -IN connectors. The -IN connector is only used for the differential
input-operating mode.
G. Output Connector
One shielded female BNC output connector is present on the front panel.
H. LCD Display
A t o-line display indicates the setup choices available as ell as providing the user selected characteristics.
Fields that are controllable are presented to the display for vie ing (a flashing cursor ithin a field indicates
the specific parameter that can be modified by utilizing the arro keys). Selected performance characteristics
are also identified. A Menu Options chart is included (see Attachment 1) to indicate ho selections are
made ithin modes and fields. . User choices are made via the arrow (←←,, →→,, ↑↑,, ↓↓) and Enter Keys.
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ASC-50
Operation
Manual
3

USING THE ASC-50
User Interface
User entry is accomplished by means of a “soft front panel” ith the user entry prompted by the display.
Left ←←and Right →→Arrows - place the blinking cursor on the function that is to be changed.
Up ↑↑and Down ↓↓Arrows - make changes to the current setup.
<ENT> - In MODE 1 a blinking <ENT> on the display reminds the user that ne functions are not implemented
until the ENTER button is pressed.
MODE - selects hich menu is displayed. MODE makes no changes to the current setup. By repeatedly
pressing MODE the entire setup can be revie ed ithout making any changes.
ENTER - implements the selected setup.
BYP - provides a special DSP bypass operation, its use is signaled on the display.
RESET - allo s the previous setup to be restored.
Flashing Cursor
AFlashing Cursor indicates hich field is a aiting update.
DISPLAY MODES
Three display modes register the complete range of operational choices; the fourth mode provides filter
characteristics. Pressing the MODE key a maximum of three times ill display the modes in succession. The
fourth time MODE is pressed the original display is returned.
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ASC-50
Operation
Manual
4

Mode 1
Field 1 - Filter type
A. LP (Lo -pass)
B. HP (High-pass)
C. BP (Band-pass)
D. BR (Band-reject)
Field 2 - Filter function
A. Buttr (Butter orth)
B. Cheby (Chebyshev)
C. Ell60 (Elliptic-60dB)
D. Ell80 (Elliptic-80dB)
E. FIR40 (Finite Impulse Response 40dB)
F. FIR60 (Finite Impulse Response 60dB)
G. FIR80 (Finite Impulse Response 80dB)
Field 3 - Number of Poles
(Does not apply for FIR filters
A. 4P (4 Pole)
B. 6P (6 Pole)
C. 8P (8 Pole)
D. 10P (10 Pole)
E. 3PP (3 Pole Pair)
F. 4PP (4 Pole Pair)
Mode 2
Field 1 - Analog Pre-gain Control
A. Pre-gain ( 0dB to +36dB)
Mode 3
Field 1 - Single / Differential Input Control
A. SNG (Single Ended Input)
B. DIF (Differential Mode Input)
Mode
Field 1 - Filter Performance,
Shape Factor/Transition Band
A. Shape Factor - Shape Factor Ratio
B. Trans BW-Transition Band idth (Hz)
C. Pass BW-Pass-band Band idth (Hz)
D. Stop BW-Stop-band band idth (Hz)
E. Warning - 1, 2, 3
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Operation
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5
Field - Q/Band idth
A. Q2 (Q=2) Does not apply to FIR40, FIR60,
FIR80
B. Q5 (Q=5) Does not apply to FIR40, FIR60,
FIR80
C. Q10 (Q=10) Does not apply to FIR40, FIR60,
FIR80
D. Q20 (Q=20) Does not apply to FIR40, FIR60,
FIR80
E. BW1 (FIR BW #1) Does not apply to Buttr,
Cheby, Ell60, Ell80
F. BW2 (FIR BW #2) Does not apply to Buttr,
Cheby, Ell60, Ell80
G. BW3 (FIR BW #3) Does not apply to Buttr,
Cheby, Ell60, Ell80
H. BW4 (FIR BW #4) Does not apply to Buttr,
Cheby, Ell60, Ell80
Field 5 – Active/Bypass
A. Active mode (ACT)
B. DSP Bypass mode (BYP)
Field 6 – Corner Frequency
A. 0.10 Hz - 0.99 Hz (0.01 Hz Steps)
B. 1 Hz - 9.9 Hz (0.1 Hz Steps)
C. 10 Hz - 99 Hz (1 Hz Steps)
D. 100 Hz - 990 Hz (10 Hz Steps)
E. 1,000 Hz - 9,900 Hz (100 Hz Steps)
F. 10,000 Hz - 30,000 Hz (1000 Hz Steps)
Field 2 - DSP Post-gain Control
A. Post-gain (-48dB to +42dB)
Field 2 - Input DC Offset Control, relative DC
offset
A. ±5V range in ⊃0.15mV steps
Field 2 – Stop-band Band idth
A. BW (Hz)

Filter performance characteristics presented to the display are not available for change but rather indicate
relative performance of the various filters (See Attachment 2 for plots of the available filter transfer functions).
Shape Factor (SF)
Used for analog filters to indicate the ratio of corner frequency of the filter to attenuation floor frequency. In the
case of Butter orth (Buttr) and Chebychev (Cheby) filters an attenuation level of 80dB is assumed. Band-pass
(BP) and Band-reject (BR) filters exhibit the same attenuation slope on both the upper and lo er sides of the
response (symmetric).
Transition Bandwidth (Trans BW)
Lo -pass (LP) and high-pass (HP) digital filters are labeled ith a band idth (Hz) that expresses the difference
bet een the attenuation floor frequency and the upper (LP) or lo er (HP) limit of the pass-band frequency.
Pass-band Bandwidth (Pass BW)
Band-pass (BP) and Band-reject (BR) digital FIR filters are labeled ith a band idth (Hz) that expresses the
difference bet een the t o pass-band frequencies. The band-pass (BP) passes frequencies over the range
(Fc ± BW/2). The band-reject (BR) passes frequencies outside the range (Fc ± BW/2).
Stop-band Bandwidth (Stop BW)
Band-pass (BP) and band-reject (BR) digital FIR filters are labeled ith a band idth (Hz) that expresses the
difference bet een the t o stop-band frequencies. The band-pass (BP) filter rejects frequencies outside of the
range (Fc ± BW/2). The band-reject (BR) rejects frequencies over the range (Fc ± BW/2).
WARNING MESSAGES
Warning Messages indicate that a filter is operating outside of normal limits.
Warning 1 - HP FIR (Attenuation @ DC)
This message is displayed hen the selected FIR high-pass filter is unable to achieve the desired level of
attenuation at a frequency of 0 Hz (DC).
Warning 2 - BP FIR (Attenuation @ DC)
This message is displayed hen the selected FIR band-pass filter is unable to achieve the desired level of
attenuation at a frequency of 0 Hz (DC).
Warning 3 - BR FIR (Attenuation @ DC)
This message is displayed hen the selected FIR band-reject filter is unable to achieve the desired level of
attenuation at a frequency of 0 Hz (DC).
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ASC-50
Operation
Manual
6

Sampling Rate Control
The maximum band idth of any DSP system is limited to less than one-half of the sampling frequency. In the
case of the ASC-50 the maximum band idth is one-quarter of the sampling frequency. In order to provide the
highest performance from the available band idth the ASC-50 provides an automatic-sampling rate selection
control. A sampling frequency bet een 36Hz and 150kHz is chosen depending on the filter type, function and
frequency (See CHART 1 belo ).
Filter Filter Corner Sample System
Function Type Frequency Frequency BW
LP,HP Analog/Digital Fc < 0.735 Hz 36.7 Hz 9 Hz
BP,BR Analog/Digital Fc < 1.47 Hz 36.7 Hz 9 Hz
LP,HP Analog/Digital 1.47 Hz > Fc >= 0.735 Hz 73.5 Hz 18 Hz
BP,BR Analog/Digital 2.94 Hz > Fc >= 1.47 Hz 73.5 Hz 18 Hz
LP,HP Analog/Digital 2.94 Hz > Fc >= 1.47 Hz 147.1 Hz 36 Hz
BP,BR Analog/Digital 5.88 Hz > Fc >= 2.94 Hz 147.1 Hz 36 Hz
LP,HP Analog/Digital 5.88 Hz > Fc >= 2.94 Hz 294.1 Hz 73.5 Hz
BP,BR Analog/Digital 11.76 Hz > Fc >= 5.88 Hz 294.1 Hz 73.5 Hz
LP,HP Analog/Digital 11.76 Hz > Fc >= 5.88 Hz 588.3 Hz 147 Hz
BP,BR Analog/Digital 23.53 Hz > Fc >= 11.76 Hz 588.3 Hz 147 Hz
LP,HP Analog/Digital 23.53 Hz > Fc >= 11.76 Hz 1.17 kHz 294 Hz
BP,BR Analog/Digital 47.06 Hz > Fc >= 23.53 Hz 1.17 kHz 294 Hz
LP,HP Analog/Digital 47.06 Hz > Fc >= 23.53 Hz 2.35 kHz 588 Hz
BP,BR Analog/Digital 94.12 Hz > Fc >= 47.06 Hz 2.35 kHz 588 Hz
LP,HP Analog/Digital 94.12 Hz > Fc > = 47.06 Hz 4.71 kHz 1.17 kHz
BP,BR Analog/Digital 188.25 Hz > Fc >= 94.12 Hz 4.71 kHz 1.17 kHz
LP,HP Analog/Digital 188.25 Hz > Fc >=94.12 Hz 9.41 kHz 2.35 kHz
BP,BR Analog/Digital 376.50 Hz > Fc >= 188.25 Hz 9.41 kHz 2.35 kHz
LP,HP Analog/Digital 376.50 Hz > Fc >= 188.25 Hz 18.8 kHz 4.71 kHz
BP,BR Analog/Digital 753.00 Hz > Fc >= 376.50 Hz 18.8 kHz 4.71 kHz
LP,HP Analog 753.00 Hz > Fc>= 376.50 Hz 37.6 kHz 9.41 kHz
LP,HP Digital 1.506 kHz > Fc >= 376.50 Hz 37.6 kHz 9.41 kHz
BP,BR Analog 1.506 kHz > Fc >= 753.00 Hz 37.6 kHz 9.41 kHz
BP,BR Digital 3.012 kHz > Fc>= 753.00 Hz 37.6 kHz 9.41 kHz
LP,HP Analog 1.506 kHz > Fc >= 753.00 Hz 75.3 kHz 18.8 kHz
LP,HP Digital 6.024 kHz > Fc >= 1.506 kHz 75.3 kHz 18.8 kHz
BP,BR Analog 3.012 kHz > Fc >= 1.506 kHz 75.3 kHz 18.8 kHz
BP,BR Digital 12.048 kHz > Fc >= 3.012 kHz 75.3 kHz 18.8 kHz
LP,HP Analog 30.000 kHz > Fc >= 1.506 kHz 150.6 kHz 37.6 kHz
LP,HP Digital 30.000 kHz > Fc >= 6.024 kHz 150.6 kHz 37.6 kHz
BP,BR Analog 30.000 kHz > Fc >= 3.012 kHz 150.6 kHz 37.6 kHz
BP,BR Digital 30.000 kHz > Fc >= 12.048 kHz 150.6 kHz 37.6 kHz
CHART 1
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ASC-50
Operation
Manual
7

OPERATIONAL CONSIDERATIONS
Anti Alias and Reconstruction Filters
The automatic sample control is transparent to the user and operates the internal input anti-alias (AA) and
output reconstruction (RC) filters. These filters, operating in cascade, determine the system band idth and
phase characteristics.
The system band idth (amplitude response) is al ays limited to one-quarter of the sampling frequency in use.
CHART 1 (above) sho s the sample rate and system band idth for the available filter configurations. For lo -
pass (LP) and band-pass (BP) filters this is of little consequence because the cutoff frequency is internally
programmed to be ithin the system band idth. Ho ever, the high frequency amplitude response of high-pass
and band-reject filters is limited to the system band idth.
The phase response of the AA and RC filters is al ays added to the filter function that is selected via the front
panel. This effect is more pronounced on analog filter transfer functions than on the digital (FIR) filter transfer
functions and hen the filter selected is programmed to a frequency close to the sample rate. The delay, in
digital (FIR) transfer functions, hich appears as linear phase shift, is generally large enough that the phase
contributed by the AA and RC filters is not significant. Figure 1 illustrates the effects of this additional phase
on typical Butter orth lo -pass filters ith corner frequencies of 10% and 80% of system band idth.
FIGURE 1
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0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
Normalized Frequency (system band idth)
-1600
-1400
-1200
-1000
-800
-600
-400
-200
0
Phase (deg)
6 Pole Butter orth Lo pass Phase response
fc = 10% of system band idth
/o aaf & reconstruction filter
/ aaf & reconstruction filter
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
Normalized Frequency (system band idth)
-1600
-1400
-1200
-1000
-800
-600
-400
-200
0
Phase (deg)
6 Pole Butter orth Lo pass Phase response
fc = 80% of system band idth
/o aaf & reconstruction filter
/ aaf & reconstruction filter
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
Normalized Frequency (system band idth)
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
Amplitude (dB)
Anti-Alias & Reconstruction Filter
Frequency Response
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
Normalized Frequency (system band idth)
-1400
-1200
-1000
-800
-600
-400
-200
0
Phase (deg)
Anti-Alias & Reconstruction Filter
Phase Response

Instrument Gain and Offset Considerations
The user is provided ith ide latitude in the selection of pre-gain (PRE) and post-gain (POST). Practical
considerations should be recognized, since the linear operating range of both the input and output analog
circuitry is limited to ±10V peaks (7.07Vrms in the case of a sine ave) hence amplitudes greater than this
amount ill result in saturation of the input or output. A large value of pre-gain may result in the saturation of
the analog input stages and no-amount of post-gain correction ill restore linear operation. Like ise very large
values of post-gain may result in the saturation of the DSP output section. Very small values for post-gain may
create poor signal-to-noise ratios as the DSP output is severely attenuated.
Clip Indications
To assist the user in identifying potential saturation, (non-linear operating condition), t o clip-indicators are
provided.
An analog clip indicator (←←CLIP) indicates that the input voltage after the application of pre-gain (PRE)
exceeds the maximum linear (±10 Volt) range of the instrument. This is an approximate detector. Depending
on the frequency and type of aveform applied to the input, non-linear operation may occur ithout an analog
clip indication.
A digital clip indicator (CLIP →→)is activated hen the peak-to-peak level of the output DSP aveform exceeds
the digital-to-analog converters maximum range after the application of post-gains (POST).
Input Voltage Range
The ASC-50 has a maximum input operating voltage range of ±10Volts. Operation beyond this range ill result
is the display of one or both CLIP indicators. Maximum safe input range (non-operating) is noted in the
specification.
DC Offset Capability
The DC offset capability allo s the ASC-50 to accept input aveforms ith DC levels that ould other ise
cause the instrument to saturate, especially at high gain levels. The offset value displayed represents the
approximate voltage that the input stage is offset from zero (0) Volts. Some external means of measuring the
effect of a DC offset change is needed, such as a voltmeter or oscilloscope. The value presented is
approximate, effects of drift must be recognized. Amplified dc offset can cause internal saturation and activation
of the clip indicator.
DSP Bypass Control
The overall frequency response of the ASC-50 is the cascade of the anti-alias and reconstruction filters as ell
as the DSP filter chosen. DSP Bypass (BYP) allo s the operator to remove the DSP filter from the cascade
hile retaining frequency sampling along ith anti-alias and reconstruction filtering.
Several uses for bypass are indicated. In order to judge the effect of the channel band idth, the DSP filter is
temporarily removed, allo ing a measurement to be made. Gain and phase responses can be obtained for
DSP filters alone or by “normalizing” (using a relative 0dB gain and 0°phase) for sampling anti-alias and
reconstruction filters. It must be remembered that Bypass does not bypass the entire ASC-50 but merely
the internal DSP filter.
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ASC-50
Operation
Manual
9

SPECIFICATIONS
(@25°C and Rated Power Input)
Input Characteristics
Impedance 1MΩ|| 47pF to Analog Ground (each input)
Input Configuration Single Ended or Differential
Analog Clipping Indicator Threshold ±10V
DC Offset ±5V DC
Analog Pre-Gain Range 0 to +36dB (6 dB steps)
CMMR >60 dB @ 1 kHz
Output Characteristics
Impedance <1 Ω
Output Configuration Single Ended
Digital Clipping Indicator Threshold ± Full Scale (Digital to Analog Converter)
Digital Post-Gain Range -48dB to +42dB (6 dB steps)
Linear Signal Level ±10V Peak (7.07Vrms) max.
Safe Signal Level ±60V Peak max.
Total Harmonic Distortion -70dBV typical @ 7.07Vrms 1kHz
(Bypass Condition 30kHz BW)
Noise -90dBV typical Input Grounded
(Bypass Condition 30kHz BW)
We hope the information given here ill be helpful. The information is based on data and our best kno ledge, and e consider the information to be true and accurate. Please read all goods supplied
by us. We assume no responsibility for the use of these statements, recommendations or suggestions, nor do e intend them as a recommendation for any use, hich ould infringe any,
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ASC-50
Operation
Manual
10

INSTRUCTIONS TO CHANGE VOLTAGE
ASC-50 BACK PANEL POWER ENTRY MODULE
1. Disconnect po er
2. Remove black plastic cover next to po er cord connection.
3. Check fuses and replace blo n fuse ith 250V fuse.
4. Remove pc-board ith hite plastic tab and position pc-board and tab for 230V or 240V operating
voltage. White dot ill sho in indo hen correctly positioned.
5. Replace black plastic cover that contains ne fuse.
6. Plug-in to electrical outlet and verify performance.
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Operation
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Theory of Operation
Referring to the block diagram (Figure 2), the operation of the ASC-50 can be explained in terms of the various
functional blocks.
Figure 2
Micro-controller
The micro-controller acts as a central administrator for all functional elements. Keypad operations are
transformed into a format that the Digital Signal Processor (DSP) can recognize and display characters
generated by the micro-controller.
Input Amplifier
Gain settings, single/differential input control, and DC offset level functions are incorporated ithin the input
amplifier.
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In
In
A
Gain
Control
DC
Offset
DIF/SNG
Control
Analog
Saturation
Detection
Freq
Anti-Alias
Filter
(Programmable)
A/D DSP D/A
Reconstruction
Filter
(Programmable) Out
Freq
Digital
Saturation
Detection
Filter,
Bypass,
Gain Control,
Performance
Microcontroller
DISPLAY
RESET
ENTER
BYP
MODE
ASC-50 Block Diagram
ASC-50 Block Diagram

Saturation Detectors
Analog and digital saturation detectors are routed from their sources to the display indicators.
Anti-alias Filter
Limits the input band idth to one-fourth of the sampling frequency, preventing corruption from out-of-band
signals.
Analog to Digital Converter
The analog to digital converter (A/D) provides the Digital Signal Processor (DSP) ith sampled amplitude data.
Digital Signal Processor (DSP)
The Digital Signal Processor (DSP) creates filter functions based upon micro-controller command, permits
transition bet een active (ACT) and bypass (BYP) modes, and produces filter performance characteristics for
display. With the exception of filter or frequency change, the sampled data stream from/to the DSP is not
interrupted by micro-controller - DSP communication. The DSP determines the sample frequencies, loads and
stores the filter coefficients, begins filter operation.
Digital to Analog Converter
The digital to analog converter (D/A) restores an analog aveform from the DSP output data ord.
Reconstruction Filter
Smoothes the D/A aveform, removing sampling noise by limiting band idth to one-fourth the sampling
frequency.
Keypads
Keypads provide the user interface by means of left/right arro parameter selection and up/do n arro choice.
In addition RESET restores a filter setup that as a aiting activation via the ENTER key. Bypass (BYP)
activates the special DSP bypass operation. The MODE key allo s vie ing of all display screens.
Display
Permits vie ing of filter setup choices clip indicators and performance characteristics ithin four modes.
25 Locust St, Haverhill, Massachusetts 01830 • Tel: [phone] • FAX: [phone]
e-mail: [e-mail] •Web Address: http://www.freqdev.com
ASC-50
Operation
Manual
13

25 Locust St, Haverhill, Massachusetts 01830 • Tel: [phone] • FAX: [phone]
e-mail: [e-mail] •Web Address: http://www.freqdev.com
ASC-50
Operation
Manual
14
Buttr
Cheby
Ell60
FIR40
FIR60
LP
HP
BP
BR
Ell80
FIR80
4P
6P
8P
10P
Frequency
Lowpass and Highpass Filter
Menu Options
Low-Pass
High-Pass
Filter
Type
Number
of Poles
Left or right arrow
Up or down arrow
Attachment 1
Menu 1 of 2
ASC50

25 Locust St, Haverhill, Massachusetts 01830 •Tel: [phone] •FAX: [phone]
e-mail: [e-mail] •Web Address: http://www.freqdev.com
ASC-50
Operation
Manual
15
LP
HP
BP
BR
Buttr
Cheby
Ell60
FIR40
FIR60
Ell80
3PP
4PP
Q2
Q5
Q10
Q20
BW1
BW2
BW3
BW4
FIR80
Frequency
Bandpass and Bandreject Filter
Attachment 1
Menu 2 of 2
Left or right arrow
Up or down arrow
Menu Options
Filter
Type
Pole
Pairs
Filter
Q
Band-Pass
Band-Reject
ASC50

AVAILABLE IIR TRANSFER FUNCTIONS
25 Locust St, Haverhill, Massachusetts 01830 •Tel: [phone] •FAX: [phone]
e-mail: [e-mail] •Web Address: http://www.freqdev.com
ASC-50
Operation
Manual
16
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4,6,8,10 Pole Butterworth
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4,6,8,10 Pole Chebychev
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4 Pole 60dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
6 Pole 60dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
8 Pole 60dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
10 Pole 60dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4 Pole 80dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
6 Pole 80dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
8 Pole 80dB Elliptic

AVAILABLE IIR TRANSFER FUNCTIONS
25 Locust St, Haverhill, Massachusetts 01830 •Tel: [phone] •FAX: [phone]
e-mail: [e-mail] •Web Address: http://www.freqdev.com
ASC-50
Operation
Manual
17
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
10 Pole 80dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4,6,8,10 Pole Butterworth
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4,6,8,10 Pole Chebychev
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4 Pole 60dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
6 Pole 60dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
8 Pole 60dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
10 Pole 60dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4 Pole 80dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
6 Pole 80dB Elliptic

AVAILABLE IIR TRANSFER FUNCTIONS
25 Locust St, Haverhill, Massachusetts 01830 •Tel: [phone] •FAX: [phone]
e-mail: [e-mail] •Web Address: http://www.freqdev.com
ASC-50
Operation
Manual
18
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
8 Pole 80dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
10 Pole 80dB Elliptic
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
3PP Butterworth Q2,5,10,20
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4PP Butterworth Q2,5,10,20
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
3PP Chebychev Q2,5,10,20
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
4PP Chebychev Q2,5,10,20
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
3 PP 60dB Elliptic Q2
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
3 PP 60dB Elliptic Q5
Normalized Frequency (Hz)
0.1 1.0 10.0
2345678 234567
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Amplitude (dB)
3 PP 60dB Elliptic Q10