• on Audio/Video/Photography
  • Published in issue 4/2012 on page 46
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AVR Software Defined Radio (2)

Part 2: Sampling signals

AVR Software Defined Radio (2)
As this series shows, the popular AVR microcontroller can be used for digital signal processing tasks. Here we will use an ATmega88 to sample amplitude- and phase-modulated signals which we can either synthesise ourselves or fish out of the ether. We can even operate at frequencies of above 100 kHz. How does it work? Read the article to find out, in theory and in practice. Learn moreMissed the Elektor Academy/element 14 AVR Software Defined Radio webinar? Click here for the recorded session!
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Download the BOM list
The BOM (Bill of Materials) is the technically exhaustive listing of parts and other hardware items used to produce the working and tested prototype of any Elektor Labs project. The BOM file contains deeper information than the Component List published for the same project in Elektor Magazine. If required the BOM gets updated directly by our lab engineers. As a reader, you can download the list here.
Want to learn more about our BOM list? Read the BOM list article for extra information.

Resistors (5%)
R1 = 2.7kOhm
R2,R22 = 10Ohm
R3 = 220Ohm
R4,R11 = 100kOhm
R5,R14 = 470Ohm
R6,R13 = 2.2kOhm
R7,R8,R10 = 470kOhm
R9,R15,R16 = 1kOhm
R12 = 2.2MOhm
R17,R18,R19,R20 = 4.7kOhm
R21 = 33Ohm
P1 = 1kOhm 20%, 0.15W trimpot
P2,P3 =10kOhm 20%, 0.15W trimpot
C1 = 100µF 25V, radial
C2,C3,C21 = 10µF 63V, radial
C4,C5,C7,C18,C19,C20 = 100nF 50V
C6,C13 = 470nF 63V
C8 = 5.5–65pF 150V trimmer
C9,C11 = 100pF 5% 100V
C10 = 27pF 2% 100V
C12 = 5.6pF ±0.25pF 100V
C14,C15,C16,C17 = 10nF 5% 50V
L1 = 4.7µH, 190mA, 1.7 Ohm
L2,L3 = 1µH, 270mA, 0.8 Ohm
D1 = 1N4007
D2,D3,D5–D12 = LED, red
D4 = SB1100
D13,D14 = 1N5817
T1 = BC560C
T2 = BF245B
IC1 = 7805
IC2 = ATmega88-20PU, programmed
IC3 = 74HC04
IC4 = 20MHz oscillator module
X1 = 20MHz quartz crystal, 50ppm
S1 = pushbutton SPST-NO, 6mm footprint
K1 = low voltage adapter socket
K2,K6,K8 = 2-pin pinheader, right angled, lead pitch 0.1 in. (2.54mm)
K3,K9–K12,JP3 = 2-pin pinheader, lead pitch 0.1 in. (2.54mm)
K4,K5,JP1,JP2 = 3-pin pinheader, lead pitch 0.1 in. (2.54mm)
K7 = 6-pin pinheader, lead pitch 0.1 in. (2.54mm)
JP1,JP2,JP3 = jumper 0.1 in. (2.54mm)
CLKout,TP1 = PCB solder pin
4 IC pin receptacles (for IC4)
Mod = 5-way pinheader for Elektor BOB-FT232R-001
LCD1 = 4x20 LCD e.g. HC200401C-YF62L-VA
PCB # 100181-1

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