Electrical Engineering Crossword (Issue 287)

The answers to Circuit Cellar’s April electronics engineering crossword puzzle are now available.287 crossword (key)

Across

1. BEAMFORMING—Signal processing technique

7. HETERODYNERECEIVER—Converts a signal to an intermediate frequency [two words]

8. AMIGA—A high-resolution PC based on Motorola’s 6800 microprocessor family

9. NAGLING—Creates “Russian doll”-type packets to improve a TCP/IP network’s performance

10. SERVERBLADE—A thin circuit board designed for one specific application [two words]

15. FUZZING—Tests for coding and security errors

17. PHASECHANGE—Nonvolatile RAM [two words]

18. WALLEDGARDEN—Restricts access to Web content and services [two words]

19. SERIALBACKPACK—A PCB interface that goes between a parallel LCD and a microcontroller [two words]

20. SLACKWARE—Open-source, Linux-based OS

Down

2. ROOTMEANSQUARE—Determines an AC wave’s voltage [three words]

3. ROENTGEN—IBM’s active matrix LCD

4. KERNELPANIC—Happens when a fatal error is detected [two words]

5. BIPHASEENCODING—Requires a state transition at the end of every data bit [two words]

6. PERMITTIVITY—Ability to be polarized

11. VOODOO—Helps create realistic 3-D graphics

12. FLANGING—An audio process that combines signals to create a comb filter effect

13. BREADBOARDING—Used for circuit design experimentation

14. STATOHM—Five of these equal approximately 4.5 × 1012

16. TELEDACTYL—Utilizes human speech to code

 

Electrical Engineering Crossword (Issue 286)

The answers to Circuit Cellar’s April electronics engineering crossword puzzle are now available.

Crossword-CC286-May14

Across

2. SAMBA—This networking protocol enables you to write to an embedded file system from a Windows PC

7. ELECTROMAGNETICFIELD—Used for data transfer [two words]

8. CAPACITOR—These types of microphones were commonly called “condensers” until about 1970

9. HOMODYNE—A receiver with direct amplification

13. BLENDER—Contains several modeling features and an integrated game engine

15. PULSESHAPING—Used to improve wired or wireless communication link performance [two words]

17. BRILLOUINSCATTERING—Occurs when certain types of light change their frequency and route [two words]

18. CLOCKSIGNAL—Used to coordinate circuits’ actions [two words]

19. RASPBERRYPI—Designed to encourage scholastic computer science lessons [two words]

Down

1. NONRETURNTOZERO—Typically 1s are a positive voltage and 0s are a negative voltage [four words]

3. BITARRAY—Provides compact storage for computing and digital communications [two words]

4. DOUBLEDATARATE—Coordinates the rising and falling edges of an [18 Across] to transfer data [three words]

5. ANECHOIC—Absent of sound

6. FIRSTINFIRSTOUT—Oldest requests receive priority [four words]

10. INTERFERENCE—The “I” in SQUID

11. CROSSTALK—Occurs when accidental coupling causes unwanted signals

12. BINISTOR—An electronic oscillator component

14. NANCY—Receiver that intercepts or demodulates IR radiation

16. BEAGLEA good breed of analyzer for I2C and SPI designs

 

Issue 284: EQ Answers

PROBLEM 1
Can you name all of the signals in the original 25-pin RS-232 connector?

ANSWER 1
Pins 9, 10, 11, 18, and 25 are unassigned/reserved. The rest are:

Pin Abbreviation Source Description
1 PG - Protective ground
2 TD DTE Transmitted data
3 RD DCE Received data
4 RTS DTE Request to send
5 CTS DCE Clear to send
6 DSR DCE Data Set Ready
7 SG - Signal ground
8 CD DCE Carrier detect
12 SCD DCE Secondary carrier detect
13 SCTS DCE Secondary clear to send
14 STD DTE Secondary transmitted data
15 TC DCE Transmitter clock
16 SRD DCE Secondary received data
17 RC DCE Receiver clock
19 SRTS DTE Secondary request to send
20 DTR DTE Data terminal ready
21 SQ DCE Signal quality
22 RI DCE Ring indicator
23 - DTE Data rate selector
24 ETC DTE External transmitter clock

 

PROBLEM 2
What is the key difference between a Moore state machine and a Mealy state machine?

ANSWER 2
The key difference between Moore and Mealy is that in a Moore state machine, the outputs depend only on the current state, while in a Mealy state machine, the outputs can also be affected directly by the inputs.

 

PROBLEM 3
What are some practical reasons you might choose one state machine over the other?

ANSWER 3
In practice, the difference between Moore and Mealy in most situations is not very important. However, when you’re trying to optimize the design in certain ways, it sometimes is.

Generally speaking, a Mealy machine can have fewer state variables than the corresponding Moore machine, which will save physical resources on a chip. This can be important in low-power designs.

On the other hand, a Moore machine will typically have shorter logic paths between flip-flops (total combinatorial gate delays), which will enable it to run at a higher clock speed than the corresponding Mealy machine.

 

PROBLEM 4
What is the key feature that distinguishes a DSP from any other general-purpose CPU?

ANSWER 4
Usually, the key distinguishing feature of a DSP when compared with a general-purpose CPU is that the DSP can execute certain signal-processing operations with few, if any, CPU cycles wasted on instructions that do not compute results.

One of the most basic operations in many key DSP algorithms is the MAC (multiply-accumulate) operation, which is the fundamental step used in matrix dot and cross products, FIR and IIR filters, and fast Fourier transforms (FFTs). A DSP will typically have a register and/or memory organization and a data path that enables it to do at least 64 MAC operations (and often many more) on unique data pairs in a row without any clocks wasted on loop overhead or data movement. General-purpose CPUs do not generally have enough registers to accomplish this without using additional instructions to move data between registers and memory.

Electrical Engineering Crossword (Issue 285)

The answers to Circuit Cellar’s April electronics engineering crossword puzzle are now available.

285-crossword-keyAcross

2.    STOKESSHIFT—Can reduce photon energy [two words]
8.    HYSTERESISLOOP—Its area measures the energy dispersed during a magnetization cycle [two words]
11.    NANDGATE—A shoe in when playing “true or false?” [two words]
13.    YOCTOPROJECT—An open-source alliance designed to help Linux aficionados [two words]
15.    RANKINE—°R
17.    INTERNALNET—A network that resides in and around you
18.    SEQUENTIALCIRCUIT—Dependent on past input [two words]
19.    NANOHENRY—Its abbreviation is the same as the state bordered by Massachusetts, Maine, and Vermont
20.    BINARYCODEDDECIMAL—Makes good use of a 4- or 8-bit nibble [three words]

Down

1.    BIREFRINGENCE—Divides light into ordinary and extraordinary rays
3.    SQUIRREL—An object-oriented programming language
4.    SMARTMETER—Records and shares energy usage information [two words]
5.    MESHANALYSIS—A circuit evaluation method [two words]
6.    LYOTFILTER—Uses [1. Down] to produce a narrow frequency range of wavelengths [two words]
7.    LINEARREGULATOR—Keeps things steady [two words]
9.    BRAGGDIFFRACTION—Occurs when electromagnetic radiation disperses [two words]
10.    AUTODYNE—An amplifying vacuum tube-based circuit
12.    FEMTOWATT—10–15 W
14.    UNIJUCTION—Can be used to measure magnetic flux
16.    PEAKER—Increases gain at higher frequencies

Electrical Engineering Crossword (Issue 284)

The answers to Circuit Cellar’s March electronics engineering crossword puzzle are now available.

284-crossword-key

Across

1.    CROSSEDFIELDAMPLIFIER—This vacuum tube is capable of high output power [three words]
3.    HYPERVISOR—Produces and runs virtual machines
5.    DYNATRON—Uses negative resistance to keep a tuned circuit oscillating
8.    ULTRAVIOLETLIGHT—Gives some substances “a healthy glow” [two words]
13.    ZEROMOMENTPOINT—A moment of respite for robots [three words]
14.    THERMOSONIC—Connects to silicon ICs
17.    CATSWHISKER—An outdated electronic component mainly used in antique radios [two words]
18.    FLEMINGVALVE—Invented in the early 1900s, this was known as the first vacuum tube [two words]
19.    BACKBONE—Makes LANs connect

Down

2.    DEMODULATOR—Recovers information from a regulated waveform
4.    SQUEGGING—This type of circuit oscillates erratically
5.    DOWNMIXING—Audio manipulation process
6.    REYNOLDSNUMBER—Used for flow pattern predictions [two words]
7.    LATENCY—Used with bandwidth to ascertain network connection speed
9.    THICKFILM—This type of chip resistor is commonly used in electronic and electrical devices [two words]
10.    DYNAMIC—Its memory is volatile
11.    CRYOTRON—Operates via superconductivity
12.    NETMASK—Creates neighborhoods of IP addresses
15.    HOROLOGY—E.g., clepsydras, chronometers, and sundials
16.    SEEBECK—An effect that creates electricity