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SRS Labs SIM965 Operation And Service Manual

Bessel & butterworth filter
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Operation and Service Manual
Bessel & Butterworth Filter
SIM965
Stanford Research Systems
Revision 1.7
August 3, 2011

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  • Page 1 Operation and Service Manual Bessel & Butterworth Filter SIM965 Stanford Research Systems Revision 1.7 August 3, 2011...
  • Page 2 Copyright c Stanford Research Systems, Inc., 2005 – 2011. All rights reserved. Stanford Research Systems, Inc. 1290–D Reamwood Avenue Sunnyvale, CA 94089 USA Phone: (408) 744-9040 Fax: (408) 744-9049 www.thinkSRS.com e-mail: info@thinkSRS.com Printed in U.S.A. Document number 9-01597-903 SIM965 Bessel & Butterworth Filter...

  • Page 3: Table Of Contents

    Contents General Information Safety and Preparation for Use ....Symbols ......Notation .
  • Page 4 Contents SIM965 Bessel & Butterworth Filter...

  • Page 5: General Information

    Do not install substitute parts or perform unauthorized modifications to this instrument. The SIM965 is a single-wide module designed to be used inside the SIM900 Mainframe. Do not turn on the power until the module is completely inserted into the mainframe and locked in place.

  • Page 6: Symbols

    Symbols you may Find on SRS Products Symbol Description Alternating current Caution - risk of electric shock Frame or chassis terminal Caution - refer to accompanying documents Earth (ground) terminal Battery Fuse On (supply) Off (supply) SIM965 Bessel & Butterworth Filter...

  • Page 7: Notation

    Literal text other than command names is set as OFF. Remote command examples will all be set in monospaced font. In these examples, data sent by the host computer to the SIM965 are set as straight teletype font, while responses received by the host computer from the SIM965 are set as slanted teletype font.

  • Page 8: Specifications

    Supply current, 5 V 15 V General Characteristics Interface Serial (RS-232) through SIM interface Connectors BNC (2 front, 1 rear) DB–15 (male) SIM interface Weight 3 lbs Dimensions 1 5 W 3 6 H 7 0 D SIM965 Bessel & Butterworth Filter...

  • Page 9: Operation

    1 Operation This chapter gives you the necessary information to get started quickly with the SIM965 Analog Filter. In This Chapter 1.1 Overview ......1 – 2 Nominal transfer functions .

  • Page 10: Overview

    The SIM965 Analog Filter is a continuous-time, digitally-programmable filter with fully analog signal paths. By using a modified state- variable circuit design, the SIM965 provides a variety of programmed filter configurations. From the front panel, the user can select a But- terworth filter, for maximum passband gain flatness, or a Bessel...

  • Page 11: Nominal Transfer Functions

    1.2 Nominal transfer functions 1 – 3 1.2 Nominal transfer functions The SIM965 circuitry is configured to provide a near-ideal Butter- worth or Bessel filter transfer function for the user. 1.2.1 Butterworth filters For a Butterworth filter, the nominal transfer function for an nth- order low pass filter is given by:...
  • Page 12 filters of various orders. All filters are tuned to f 1 kHz. 48 dB/octave Time (ms) Figure 1.3: The nominal step response for Butterworth low-pass filters of various orders. All filters are tuned to f 1 kHz. SIM965 Bessel & Butterworth Filter...
  • Page 13 All filters are tuned to f 1 kHz. 48 dB/octave Time (ms) Figure 1.5: The nominal step response for Bessel low-pass filters of various orders. All filters are tuned to f 1 kHz. SIM965 Bessel & Butterworth Filter...

  • Page 14: High-Pass Filters

    For example, a 6–pole high-pass Bessel filter with f 100 Hz can be calculated using f 0 21409, or 467.09 Hz. Figures 1.6 and 1.7 show the frequency response for Butterworth and Bessel high-pass filters. SIM965 Bessel & Butterworth Filter...
  • Page 15 filters of various orders. All filters are tuned to f 1 kHz. 12 dB/octave 48 dB/octave 100 Hz 1 kHz 10 kHz Frequency Figure 1.7: The nominal frequency response for Bessel high-pass filters of various orders. All filters are tuned to f 1 kHz. SIM965 Bessel & Butterworth Filter...

  • Page 16: Front-Panel Operation

    1 – 8 Operation 1.3 Front-Panel Operation All settings of the SIM965 can be set from the front panel (see Fig- ure 1.1). 1.3.1 Frequency The cuto frequency can be incremented or decremented using the [Freq. ] buttons. Pressing either [Freq. ] or [Freq. ] once will cause the least significant digit in the display to increment (or decrement)

  • Page 17: Clock Stopping

    Each output is (separately) connected the filter circuitry through an internal 50 resistor. 1.4 Clock Stopping The microprocessor clock of the SIM965 stops if the module is idle, “freezing” the digital circuitry. The following actions “wake up” the clock: 1. A power-on.

  • Page 18: Sim Interface

    SIM900 Mainframe via this connection, either through one of the internal Mainframe slots, or the remote cable interface. It is also possible to operate the SIM965 directly, without using the SIM900 Mainframe. This section provides details on the interface.
  • Page 19 RS-232 serial port of a personal computer. Connect RXD from the SIM965 directly to RD on the PC, TXD directly to TD. In other words, a null-modem style cable is not needed. To interface directly to the DB–9 male (DTE) RS-232 port typically found on contemporary personal computers, a cable must be made with a female DB–15 socket to mate with the SIM965, and a female...
  • Page 20 1 – 12 Operation 1.5.2.2 Serial settings The initial serial port settings at power-on are: 9600 Baud, 8–bits, no parity, 1 stop bit, and no flow control. The parity can be changed with the PARI remote command. SIM965 Bessel & Butterworth Filter...

  • Page 21: Remote Operation

    2 Remote Operation This chapter describes operating the SIM965 over the serial interface. In This Chapter 2.1 Index of Common Commands ... . . 2 – 2 Alphabetic List of Commands ... . . 2 – 4 Introduction .

  • Page 22: Index Of Common Commands

    2 – 13 Awake mode LEXE? 2 – 13 Execution Error LCME? 2 – 14 Command Error LBTN? 2 – 14 Button TOKN(?) z 2 – 15 Token Mode TERM(?) z 2 – 15 Response Termination SIM965 Bessel & Butterworth Filter...
  • Page 23 2.1 Index of Common Commands 2 – 3 SIM965 Bessel & Butterworth Filter...

  • Page 24: Alphabetic List Of Commands

    2 – 9 Filter pass band PSTA(?) z 2 – 11 Pulse STATUS Mode SLPE(?) i 2 – 9 Filter slope TERM(?) z 2 – 15 Response Termination TOKN(?) z 2 – 15 Token Mode SIM965 Bessel & Butterworth Filter...
  • Page 25 2.2 Alphabetic List of Commands 2 – 5 TYPE(?) z 2 – 9 Filter type SIM965 Bessel & Butterworth Filter...

  • Page 26: Introduction

    2 – 6 Remote Operation 2.3 Introduction Remote operation of the SIM965 is through a simple command lan- guage documented in this chapter. Both set and query forms of most commands are supported, allowing the user complete control of the filter from a remote computer, either through the SIM900 Mainframe...

  • Page 27: Command Syntax

    CR LF , the following two commands are equivalent: TERM CRLF —or— TERM 3 For queries that return token values, the return format (keyword or integer) is specified with the TOKN command. SIM965 Bessel & Butterworth Filter...

  • Page 28: Notation

    In these examples, all data sent by the host computer to the SIM965 are set as straight teletype font, while responses received the host computer from the SIM965 are set as slanted teletype font. The usage examples vary with respect to set query, optional param- eters, and token formats.

  • Page 29: Filter Commands

    Set (query) the filter stop band rollo rate to i (12, 24, 36, 48 dB octave) . Example: SLPE 24 SLPE? COUP(?) z Input coupling Set (query) the SIM965 input coupling to z (DC 0, AC 1) . Example: COUP 1 COUP? SIM965 Bessel & Butterworth Filter...

  • Page 30: Serial Communication Commands

    Example: PARI EVEN 2.4.6 Status Commands The Status commands query and configure registers associated with status reporting of the SIM965. *STB? [i] Status Byte Reads the Status Byte register [bit i]. Execution of the *STB? query (without the optinal bit i) always causes the STATUS signal to be deasserted.
  • Page 31 CESE? OVLD? Overload Query the current overload condition. The SIM965 responds with 1 during a signal overload, and 0 at all other times. OVLD? always returns the realtime value of overload, independent of the value of the OVLD bit in the Status Byte.

  • Page 32: Interface Commands

    2 – 12 Remote Operation 2.4.7 Interface Commands Interface commands provide generic control over the interface be- tween the SIM965 and the host computer. *RST Reset Reset the SIM965 to default configuration. The following commands are internally executed upon *RST: FREQ 1.00E+3...
  • Page 33 Set (query) the SIM965 keep-awake mode to z (OFF 0, ON 1) . Ordinarily, the clock oscillator for the SIM965 microcontroller is held in a stopped state, and only enabled during processing of events (Section 1.4). Setting AWAK ON forces the clock to stay running, and is useful only for diagnostic purposes.
  • Page 34 Query the last button-press code. A query of LBTN? always clears the button code, so a subsequent LBTN? will return 0. Valid codes are: Value Definition no button pressed since last LBTN? [Freq. ] [Type] [Freq. ] [Slope] [Filter] [Coupling] Example: LBTN? SIM965 Bessel & Butterworth Filter...
  • Page 35 ASCII character(s) 13 (car- riage return) and 10 (line feed). The token mnemonic gives the sequence of characters. At power-on, TERM is set to CRLF. Example: TERM? SIM965 Bessel & Butterworth Filter...

  • Page 36: Status Model

    OVLD Figure 2.1: Status Register Model for the SIM965. There are two categories of registers in the SIM965 status model: Event Registers : These read-only registers record the occurrence of defined events. When the event occurs, the corresponding bit is set to 1.

  • Page 37: Status Byte (Sb)

    2 – 17 2.5.1 Status Byte (SB) The Status Byte is the top-level summary of the SIM965 status model. When masked by the Service Request Enable register, a bit set in the Status Byte causes the STATUS signal to be asserted on the rear- panel SIM interface connector.

  • Page 38: Service Request Enable (Sre)

    Input Bu er. QYE : Query Error. Indicates data in the Output Queue has been lost. DDE : Device Dependent Error. Not implemented in the SIM965. EXE : Execution Error. Indicates an error in a command that was successfully parsed. Out-of-range parameters are an example.

  • Page 39: Communication Error Status (Cesr)

    RTSH : RTS Holdo Event. Not implemented in the SIM965. CTSH : CTS Holdo Event. Not implemented in the SIM965. DCAS : Device Clear. Indicates the SIM965 received the Device Clear signal (an RS-232 break ). Clears the Input Bu er and Output Queue, and resets the command parser.
  • Page 40 2 – 20 Remote Operation SIM965 Bessel & Butterworth Filter...
  • Page 41 3 Parts Lists and Schematics This chapter presents a brief description of the SIM965 circuit design. A complete parts list and circuit schematics are included. In This Chapter 3.1 Circuit Descriptions ....3 – 2 3.1.1...

  • Page 42: Circuitry

    When the microcontroller has completed all pending activity, it drives the STOP signal high (pin 8 of U104), e ectively halting its own processor clock. In this way, the SIM965 guarantees no digital clock artifacts can be generated during quiescent operation.

  • Page 43: Front Panel Display

    The integrator DACs allow for trimming of the cuto frequency. An attractive feature of the state-variable filter architecture is that it provides output “taps” for low pass, high pass, and band pass filters. SIM965 Bessel & Butterworth Filter...

  • Page 44: Parts Lists

    13 V. By then, analog circuitry have settled, permitting the output signal to be connected to the output BNCs without large transients. Until switch U305 closes, the SIM965 output is referenced to ground via R320 (100 k). 3.2 Parts Lists The parts list for the analog board is separate from the digital &...

  • Page 45: Digital Board & Front Panel

    3-00601 MMBT3904LT1 U304 3-01289 LT1363CS8 Q306 3-00580 MMBT3906LT1 U305 3-01488 AQY221R2S R101,R105,R110,R111,R124, 4-01519 47K U306,U307 3-01218 AD825AR R125 X101,X102,X103,X104,X105, 5-00299 .1U R102,R112 4-01479 1.0K X106,X107,X108,X109,X301, R103 4-01052 210 X302,X303,X304,X305,X306, R104,R113,R114,R123 4-01527 100K X307,X308,X309,X310 R106 4-01431 10 SIM965 Bessel & Butterworth Filter...

  • Page 46: Schematic Diagrams

    3-01171 AD5415YRU C430,C529,C530 U409,U507,U509 C231,C232,C331,C332,C431, 5-00619 .22U / 100V U210,U310,U410,U510 3-01367 DG419DY C432,C531,C532 U211,U311,U411,U511 3-01369 DG409DY C235,C236,C335,C336,C435, 5-00615 4.7U / 63V 5% X201-X220,X301-X320, 5-00299 .1U C436,C535,C536 X401-X420,X501-X520 3.3 Schematic Diagrams Schematic diagrams follow this page. SIM965 Bessel & Butterworth Filter...
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