ANNUS, Paul [email protected]Analog - to – Digital conversion in measurement and data acquisition systems A / D muundamine mõõte- ja andmehõivesüsteemides http://focus.ti.com/lit/an/slod006b/slod006b.pdf www.analog.com/library/analogDialogue/archives/39-06/ data_conversion_handbook.html
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ANNUS, [email protected] Analog - to – Digital conversion in measurement and data acquisition systems A / D muundamine mõõte- ja andmehõivesüsteemides.
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Füüsikalised Vool ParalleelneKeemilised Pinge Järjestik
kodeeriminePositsioonid skaalal
Võimsus Seeriate loendamine
Numbrilised SagedusAegFaas
ANDUR SÜSTEEMIS ANDMETE SORTIMISE SAAVUTAMNE
Mõõtmine on ?
A “bit” of historyThe earliest recorded binary DAC known is not electronic at all, but hydraulic. Turkey, under the Ottoman Empire, had problems with its public water supply, and sophisticated systems were built to meter water. One of these dates to the 18th Century. An example of an actual dam using this metering system was the Mahmud II dam built in the early 19th century near Istambul.
1954 "DATRAC" 11-bit, 50-kSPS Vacuum Tube ADCDesigned by Bernard M. Gordon at EPSCO
HS-810, 8-bit, 10-MSPS ADC Released byComputer Labs, Inc. in 1966
ADC-12U 12-Bit, 10-μs SAR ADC from Pastoriza Division ofAnalog Devices, 1969
NYQUISTI KRITEERIUM:DISKREETIMISSAGEDUS > 2* KÕRGEM KUI KÕRGEIM
SAGEDUSSIGNAAL
Ajast ja sagedusest
Gabor-Heisenberg uncertainty principle:
Mida rohkem on bitte seda väiksem on kvantimise viga.
KVANTIMISE VIGA +-q/2 V
DAC – digitaalmaailmast analoogsignaaliks
?
GAP/R's K2-W: a vacuum-tube op-amp (1953)
1941: First (vacuum tube) op-amp
1947: First op-amp with an explicit non-inverting input
1963: First monolithic IC op-amp
U.S. Patent 2,401,779 "Summing Amplifier" filed by Karl D. Swartzel Jr. of Bell labs in 1941. This design used three vacuum tubes to achieve a gain of 90 dB and operated on voltage rails of ±350 V. It had a single inverting input rather than differential inverting and non-inverting inputs, as are common in today's op-amps. Throughout World War II, Swartzel's design proved its value by being liberally used in the M9 artillery director designed at Bell Labs. This artillery director worked with the SCR584 radar system to achieve extraordinary hit rates (near 90%) that would not have been possible otherwise.
Kõrge eraldusvõimeSuur kiirusKergelt multiplekseeritav sisendTavaliselt kasutatakse andmehõive kvartidesAlalissignaal
FLASHParalleelmuundur
Kõige kiiremKüps tehnoloogiaKõige kallimKasutatakse digitaal TV, kosmoses
INTEGRATINGIntegreerivVana, hakkab kaduma
Kõrge eraldusvõimeHea müra mahasurumineHea lineaarsusKüps tehnoloogiaAeglane muundamise kiirus (selle tõttu ei kasutata enam tänapäeval)Kasutatakse digitaalmultimeetrites (tester)
DELTA SIGMAOdav ja tõrjub integreeriva väljaKõige uuem
Kõrge eraldusvõimeSuurepärane lineaarsusSisse ehitatud aliase kõrvaldaja (LPF filter)Vahelduvad signaalidKasutatakse audio signaalide digitaaliseerimiseks ja analoogiseerimiseks, helisignaalid
PINGE-SAGEDUS MUUNDUROdav ja võimaldab tulemust hästi edasi kanda
SAR - Successive approximation ADC
SAR algorithm dates back to the... 1500's !
The basic algorithm used in the successive approximation (initially called feedback subtraction) ADC conversion process can be traced back to the 1500s relating to the solution of a certain mathematical puzzle regarding the determination of an unknown weight by a minimal sequence of weighing operations. In this problem, as stated, the object is to determine the least number of weights which would serve to weigh an integral number of pounds from 1 lb to 40 lb using a balance scale.
One solution put forth by the mathematician Tartaglia in 1556, was to use the series of weights 1 lb, 2 lb, 4 lb, 8 lb, 16 lb, and 32 lb. The proposed weighing algorithm is the same as used in modern successive approximation ADCs.
SAR - Successive approximation ADC
SAR - Successive approximation ADC
SAR - Successive approximation ADC
An N-bit conversion takes N steps.
SAR 2
A simple 3-bit capacitor DAC based SAR.
The switches are shown in the track, or sample mode where the analog input voltage, A IN, is constantly charging and discharging the parallel combination of all the capacitors.The hold mode is initiated by opening SIN, leaving the sampled analog input voltage on the capacitor array. Switch SC is then opened allowing the voltage at node A to move as the bit switches are manipulated. If S1, S2, S3, and S4 are all connected to ground, a voltage equal to –AIN appears at node A.Connecting S1 to VREF adds a voltage equal to VREF/2 to –AIN. The comparator then makes the MSB bit decision, and the SAR either leaves S1 connected to VREF or connects it to ground depending on the comparator output (which is high or low depending on whether the voltage at node A is negative or positive, respectively).A similar process is followed for the remaining two bits. At the end of the conversion interval, S1, S2, S3, S4, and SIN are connected to AIN, SC is connected to ground, and the converter is ready for another cycle.
Subranging ADC (Pipeline etc)
Subranging ADC (Pipeline etc)
Subranging ADC (Pipeline etc)
Subranging ADC (Pipeline etc)
Subranging ADC (Pipeline etc)
Võendamine, sampling, reconstruction, taastamine
The sampling theorem
The Scientist and Engineer's Guide to Digital Signal Processing
If a function of time f(t) is limited to the band from 0 to W cycles per second it is completely determined by giving its ordinates at a series of discrete points spaced 1/2W seconds apart
Edmund Taylor Whittaker (1873 – 1956)
Harry Theodor Nyqvist (1889 –1976) Владимир Александрович Котельников, (1908 – 2005)
Gábor Dénes (1900 – 1979)
The sampling theorem
1928 "Certain topics in telegraph transmission theory”
1949 "Communication in the presence of noise”1933 "On the transmission capacity of the 'ether' and of cables in electrical communications"
1915 "Expansions of the Interpolation-Theory", "Theorie der Kardinalfunktionen"
1946 "Theory of communication"
Võendamine, sampling
Võendamine, sampling
Võendamine, sampling
Jean Baptiste Joseph Fourier (1768 –1830)
Mémoire sur la propagation de la chaleur dans les corps solides. (1807)
Uuris soojusnähtusi ja kasutas siinussignaale temperatuuri jaotuste kirjeldamiseks. “...any continuous periodic signal could be represented as the sum of properly chosen sinusoidal waves.”
Data transfer, serialThe first telegraphs came in the form of optical telegraph including the use of smoke signals, beacons or reflected light, which have existed since ancient times.
A semaphore network invented by Claude Chappe operated in France from 1792 through 1846. It helped Napoleon enough to be widely imitated in Europe and the U.S. The Prussian system was put into effect in the 1830s. The last commercial semaphore link ceased operation in Sweden in 1880.
Very early experiment in electrical telegraphy was an electrochemical telegraph created by the German physician, anatomist and inventor Samuel Thomas von Sömmering in 1809, based on an earlier, less robust design of 1804 by Catalan polymath and scientist Francisco Salvá i Campillo.
One of the earliest electromagnetic telegraph designs was created by Baron Schilling in 1832Carl Friedrich Gauss and Wilhelm Weber built and first used for regular communication the electromagnetic telegraph in 1833 in Göttingen, connecting Göttingen Observatory and the Institute of Physics, covering a distance of about 1 km.
An electrical telegraph was independently developed and patented in the United States in 1837 by Samuel Morse. His assistant, Alfred Vail, developed the Morse code signaling alphabet with Morse. America's first telegram was sent by Morse on 6 January 1838, across two miles (3 km) of wire at Speedwell Ironworks near Morristown, New Jersey. The message read "A patient waiter is no loser."
Data transfer, serialBit rate – bps – bits per secondByte rate – Bps – bytes per secondBaud rate - Bd – symbols per second
WAN modems Ethernet LAN WiFi WLAN Mobile data
•1972: Acoustic coupler 300 baud•1977: 1200 baud Vadic and Bell 212A•1986: ISDN introduced with two 64 kbit/s channels (160 kbit/s gross bit rate)•1990: v.32bis modems: 2400 / 4800 / 9600 / 19200 bit/s•1994: v.34 modems with 28.8 kbit/s•1995: v.90 modems with 56 kbit/s downstreams, 33.6 kbit/s upstreams•1999: v.92 modems with 56 kbit/s downstreams, 48 kbit/s upstreams•1998: ADSL up to 8 Mbit/s,•2003: ADSL2 up to 12 Mbit/s•2005: ADSL2+ up to 24 Mbit/s
Data transfer, serial, RS -232Recommended Standard 232, 1962
Serial binary single-ended data and control signals connecting between a DTE (Data Terminal Equipment) and a DCE (Data Circuit-terminating Equipment).
EIA-485, also known as TIA/EIA-485 or RS-485
ASCII-HEX
Parity
7 bits of data(number of 1s)
8 bits including parity
even odd
0000000 (0) 00000000 10000000
1010001 (3) 11010001 01010001
1101001 (4) 01101001 11101001
1111111 (7) 11111111 01111111
XOR sum of the bits (even)
InputOutputA B
0 0 0
0 1 1
1 0 1
1 1 0
Data transfer, serial, SPI“four-wire" serial bus, three-, two-, and one-wire, microwire (NS) SPI bus is a “de facto standard” = igaüks saab omamoodi aru...
Clk - 1–70 MHz
Data transfer, serial, address first versus data first
Data transfer, serial, I2C“two-wire" serial bus, SMB, Philips, 1980, UM10204.pdf
Multimaster, 10 kbps – 4 Mbps
maximum number of nodes is limited by the address space, and also by the total bus capacitance of 400 pF
First byte after start
Protocol!
Data transfer serial - CANCAN-bus started originally in 1983 at Robert Bosch GmbH
Controller–area network (CAN or CAN-bus) is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer.
Each node is able to send and receive messages, but not simultaneously. A message consists primarily of an ID which represents the priority of the message and up to eight data bytes. It is transmitted serially onto the bus. This signal pattern is encoded in NRZ and is sensed by all nodes.
If the bus is free, any node may begin to transmit. If two or more nodes begin sending messages at the same time, the message with the more dominant ID (which has more dominant bits, i.e., zeroes) will overwrite other nodes' less dominant IDs, so that eventually (after this arbitration on the ID) only the dominant message remains and is received by all nodes. This mechanism is referred to as priority based bus arbitration. Messages with numerically smaller values of ID have higher priority and are transmitted first.
Field name Length (bits) Purpose
Start-of-frame 1 Denotes the start of frame transmission
Identifier 11 A (unique) identifier for the data which also represent the message priority
CRC Cyclic Codes for Error DetectionW. W. PETERSON, AND D. T. BROWN, 1960
CRC Cyclic Codes for Error DetectionW. W. PETERSON, AND D. T. BROWN, 1960
A well-constructed CRC polynomial over limited-size data blocks will detect any contiguous burst of errors shorter than the polynomial, any odd number of errors throughout the block, any 2 bit errors anywhere in the block, and most other cases of any possible errors anywhere in the data.
So every possible arrangement of 1, 2, or 3 bit errors will be detected.
Nevertheless, there remains a small possibility that some errors will not be detected. This happens when the pattern of the errors results in a new value which,when divided, produces exactly the same remainder as the correct block.
With a properly constructed 16-bit CRC, there is an average of one error pattern which will not be detected for every 65,535 which would be detected.
That is, with CRC-CCITT, we should detect be able to detect 65535/65536ths or 99.998 percent of all possible errors
Remote I/O - CANCanOpen and DeviceNetCANopen is a network protocol based on CAN bus and has been used in various applications, such as vehicles, industrial machines, building automation, medical devices, maritime applications, restaurant appliances, laboratory equipment & research. It allows for not only broadcasting but also peer to peer data exchange between every CANopen node. DeviceNet based on the CAN bus is one of the world's leading device-level networks for industrial automation.
Function code Node ID RTR Data
length Data
Length 4 bits 7 bits 1 bit 4 bits 0-8 bytes
Contents of a standard CANopen frame:
Common Industrial Protocol or (CIP), which includes the following technologies:EtherNet/IP (take note of the capital 'N', and "IP" here means "Industrial Protocol")ControlNetDeviceNet
The contents of an HDLC frame are shown in the following table:
Zero-bit insertion is a particular type of bit stuffing (in the latter sense) used in some data transmission protocols. It was popularized by IBM's SDLC (later renamed HDLC), to ensure that the Frame Sync Sequence (FSS) never appears in a data frame. An FSS is the method of frame synchronization used by HDLC to indicate the beginning and/or end of a frame.
The bit sequence "01111110" containing six adjacent 1 bits is commonly used as a "Flag byte" or FSS
IPInternet Protocol
LXILAN eXtensions for Instrumentation
The LXI instrumentation platform combines Ethernet-enabled instrumentation with the ubiquity of the World Wide Web and applies them to test and measurement applications.LXI devices can communicate with devices that are not themselves LXI compliant, as well as instruments that employ GPIB, VXI, and PXI, into heterogeneous configurations. In order to simplify communication with non-LXI instruments, the standard mandates that every LXI instrument must have an Interchangeable Virtual Instrument (IVI) driver.
Precision Time Protocol = LXITCP/IP +
IEEE 1588-2008 introduces a clock associated with network equipment used to convey PTP messages. The transparent clock modifies PTP messages as they pass through the device. Timestamps in the messages are corrected for time spent traversing the network equipment. This scheme improves distribution accuracy by compensating for delivery variability across the network.
Precision Time Protocol (PTP)
GPIBIEEE-488 is a short-range digital communications bus specification. It was created for use with automated test equipment in the late 1960s, and is still in use for that purpose. IEEE-488 was created as HP-IB (Hewlett-Packard Interface Bus), and is commonly called GPIB (General Purpose Interface Bus). It has been the subject of several standards
GPIBPhysically the GPIB bus is composed of 16 low-true signal lines. Eight of the lines are bidirectional data lines, DIO1-8. Three of the lines are handshake lines, NRFD, NDAC and DAV, that transfer data from the talker to all devices who are addressed to listen. The talker drives the DAV line, the listeners drive the NDAC and NRFD lines. The remaining five lines are used to control the bus’s operation.
IEEE-488Pin out
Female IEEE-488 connectorPin 1 DIO1 Data input/output bit.Pin 2 DIO2 Data input/output bit.Pin 3 DIO3 Data input/output bit.Pin 4 DIO4 Data input/output bit.Pin 5 EOI End-or-identify.Pin 6 DAV Data valid.Pin 7 NRFD Not ready for data.Pin 8 NDAC Not data accepted.Pin 9 IFC Interface clear.Pin 10 SRQ Service request.Pin 11 ATN Attention.Pin 12 SHIELDPin 13 DIO5 Data input/output bit.Pin 14 DIO6 Data input/output bit.Pin 15 DIO7 Data input/output bit.Pin 16 DIO8 Data input/output bit.Pin 17 REN Remote enable.Pin 18 GND (wire twisted with DAV)Pin 19 GND (wire twisted with NRFD)Pin 20 GND (wire twisted with NDAC)Pin 21 GND (wire twisted with IFC)Pin 22 GND (wire twisted with SRQ)Pin 23 GND (wire twisted with ATN)
# Ultralow noise (0.1 Hz to 10 Hz)ADR440: 1 μV p-pADR441: 1.2 μV p-pADR443: 1.4 μV p-pADR444: 1.8 μV p-pADR445: 2.25 μV p-p# Input range: (VOUT + 500 mV) to 18 V# Superb temperature coefficientA Grade: 10 ppm/°CB Grade: 3 ppm/°C# Low dropout operation: 500 mV# High output source and sink current+10 mA and −5 mA, respectively# Wide temperature range: −40°C to +125°C
Komponendid, takistiMax võimsusTolerants:-+-5% kuni 0,005%Max pingeTC: tüüpiline +-50 ppm/CLineaarsus!
Color 1st band 2nd band3rd band (multiplier)
4th band (tolerance)
Temp. Coefficient
Black 0 0 ×100
Brown 1 1 ×101 ±1% (F) 100 ppm
Red 2 2 ×102 ±2% (G) 50 ppm
Orange 3 3 ×103 15 ppm
Yellow 4 4 ×104 25 ppm
Green 5 5 ×105 ±0.5% (D)
Blue 6 6 ×106 ±0.25% (C)
Violet 7 7 ×107 ±0.1% (B)
Gray 8 8 ×108 ±0.05% (A)
White 9 9 ×109
Gold ×10−1 ±5% (J)
Silver ×10−2 ±10% (K)
None ±20% (M)
The Standard TCR is 5ppm - however, if you need something closer, special TCRs to 1ppm per degree C. are available. Ultra Stability vs. Time - probably your most important consideration - can be conditioned to 0.001% per year. Wide Temperature Span - from -65°C. to +125°C. ... derated to zero wattage at +145°C.. Other technologies are limited to +70°C., which can be a problem in your soldering processes. Special Custom Flexibility - when you need matching TCRs and tolerances with part-to-part repeatability. Non-inductive - All HR & RX standard parts are non-inductive (suffix "N") except the HR103
* C0G or NP0: typically 1 pF to 0.1 µF, 5%. High tolerance and good temperature performance. Larger and more expensive. * X7R: typically 100 pF to 22 µF, 10%. Good for non-critical coupling, timing applications. Subject to microphonics. Temperature up to 125°C * X8R: typically 100 pF to 10 µF, 25-100v, 5-10%. Good for high temperature up to 150°C * Z5U or 2E6: typically 1 nF to 10 µF, 20%. Good for bypass, coupling applications. Low price and small size. Subject to microphonics. * Ceramic chip: 1% accurate, values up to about 1 µF, typically made from Lead zirconate titanate (PZT) ferroelectric ceramic