ENGN4521/6521

Embedded Wireless

An LIPD Band RF Front End for DATV

V3.0Copyright 2014-2015 G.G. Borg College of Engineering and Computer Science. Australian

National University

1

Contents

1 Foreword 3

2 Assessment 3

3 Introduction 3

4 Description 3

5 Exercises 5

2

1 Foreword

The ENGN4521 term project introduces digital amateur television (DATV). Amateurradio gives radio hobbyists a way to experiment with radio wave communications1. Wewill build a DATV radio to transmit video to an existing software defined receiver usingthe satellite digital video broadcast standard (dvb-s)2.

2 Assessment

The project is worth 40% of the course mark and will be covered entirely in labs. Thebroad aim is to implement a working wireless video link with the help of an rtl-sdr softwareradio receiver (sdr) - based DTV receiver 3. There are two separate projects. Thisdocument describes the RF front end. It is worth 20% of the course total mark.

The appendix also contains an introduction to LINUX which will be using in the rest ofthe course. One of the exercises in this project includes an exercise in C programming.

3 Introduction

This project is an rf electronics exercise involving the construction of (a) an rf up/down-converter to cross-band translate the 24.00-24.89MHz lipd (Low Interference PotentialDevice) band to an intermediate frequency (if) and (b) an rf power amplifier based on acommon emitter amplifier using a BF199 VHF transistor. Note that because the LIPDband only permits 10mW (20dBm) EIRP (Equivalent Isotropic Radiated Power), theamplfier is really a low power common-emitter BJT amplifier.

The information contained in this description and the solutions to a few short exercisesprovide the basis for a 5-10 page report. There is more to DATV communications systemthan is in the scope of the project. Students only need to concentrate on the assess-ment areas and their specific requirements. The report submission deadline is the endof semester. Emphasis should be placed mostly on providing worked solutions to thequestions and demonstrating that you understand the principle of operation of the radioand the design choices.

4 Description

A block diagram of the radio is shown in Fig. 1.

1https : //en.wikipedia.org/wiki/Amateurradio2https://www.datv-express.com/3http://www.rtl-sdr.com/introduction-to-signal-analysis-baltimore-course-live-stream-and-recorded-

videos/

3

24MHz

50MHz

74MHzQPSK IF

LO IF RF

LO

RFIF

MIXER

LOW PASS BAND PASS

QPSK IF55MHz

QPSK IF55MHz

55MHz

BAND PASS

Figure 1: Circuit schematic of the up converter. The inset shows the architecture of thedouble balanced ring diode mixer. There are two possible rf-ucs the main figure shows the24MHz system which requires a mixer to convert from 74MHz to 24MHz and the lowerfigure shows 55MHz version which does not need a mixer.

4

Vdd

R1

50R

(12V)

50RRbias

b

e

c

Lchoke = 10uH

1 2

3

BF199

R2

Figure 2: Circuit schematic of the rfpa.

5 Exercises

1. Design, build and test an rfpa based on the BF199 VHF transistor for 12V powersupply and 20-80MHz and 20dB gain. Your report should contain sections describ-ing,

• Use of solve to model the amplifier. Be careful to design the amplifier for aninput and output impedance of 50Ω.

• The construction process. Using components supplied in the lab build theamplifier on on a double sided FR4 PCB. Be sure to leave enough room formatching and input/output BNC connectors.

• Test results. Measurements of gain (transfer function).

(8 marks)

5

2. Design, build and test a 74MHz low pass filter for an impedance of 50Ω. Be sure toinclude all design steps, performance predictions and test results in your report. (3marks)

3. Design, build and test a 24MHz band pass filter of bandwidth 2MHz and an impedanceof 50Ω. Be sure to include all design steps, performance predictions and test resultsin your report. (3 marks)

4. Make an RF up/down-converter by laying out the filters on a PCB with a MINICIR-CUITS ADEX-10 mixer (see appendix B) and a 5V-50MHz clock / local oscillator.Make measurements of the filter response (transfer function) and input impedance.Connect in the power amplifier and remake the measurements. (3 marks)

5. Read appendix A on linux, implement the udp talker / listener and demonstratecommunications on a localhost. (3 marks)

6

APPENDIX A: LINUX

When you connect to the LINUX O.S. using PUTTY (secure shell), you are presentedwith a terminal interface. This is an old-fashioned but very effective way to interact witha computer. In this section we describe the structure of LINUX file system and how youcan use LINUX.

First off type ls /. You should see the following.

debian@beaglebone:~$ ls /

bin dev home lost+found mnt proc run selinux sys usr

boot etc lib media opt root sbin srv tmp var

/ refers to the root file system. This is the top folder or directory. There are a number ofsubfolders as follows:

bin Contains many of the binary files that constitute the commands in the O.S.

boot Contains kernel images and configutation files. The kernel refers to the LINUXoperating system itself.

dev Contains system interfaces (files) to the LINUX character and block devices (butnot the network devices). Take a look at them by typing ls /dev. These devicescan be opened as files by programs and allow the program to access LINUX devicedrivers. Can you think of what any of the devices refer to?

etc Is where most of the system configuration scripts are located.

home Is the home folder where the files are located of users who can access the system.There is only one user on my BBB system with uID debian. When you log in youarrive directly at your home folder. Here this is /home/debian.

lib These are where the binary libraries are located. On WINDOWS think dlls.

media This is where external storage devices can be mounted. Such devices include CD-ROMS, flash and external hard drives. Note tha term mount. The mount commandis used to connect a folder (usually but not necessarily located in /media) to ablock device in /dev. This allows the block device to be accessed as a folder. Thismay seem strange for MAC and WINDOWS users where mounting is performedtransparently by the O.S.

mnt serves a similar purpose to media

proc Is actually a file system that is not located on the hard drive - or any block de-vice. proc is located in RAM and is a volatile folder containing all of the systeminformation. For example try cat /proc/cpuinfo to see what is contained in thisfile.

7

sbin is the superuser binary director. This is where the administrator-only commandsare stored.

usr is the usual place where new commands and other system files get stored when auser installs new software on LINUX.

The following is a short list of basic unix commands that can be executed in the xterm.These commands are big programs usually with many options and can be very powerful.If you wish to learn more about a command type, man COMMAND−NAME >. The’man’ refers to the manual or man page for the command. ’man’ produces a scrollableinterface inside the xterm. To navigate, simply use the arrow keys. To quit type < quit >.

• ls− l list the files in the current directory in detailed format.

• cat FILE −NAME.txt dumps the contents of a text file to the terminal.

• grep STRING FILE−NAME.txt. List all occurrences of STRING in file FILE−

NAME. Note that wildcards are possible: grep STRING ∗ .txt.

• cp FILE − NAME TARGET . Copy file FILE − NAME to TARGET whereTARGET could be another file or a directory. In this case the file FILE−NAMEis left in tact.

• mv FILE−NAME TARGET . Move the file FILE−NAME to TARGET whereTARGET could be another file or a directory. In this case the file FILE−NAMEis removed.

• rm FILE−NAME. Delete the file FILE−NAME. Be careful of this command.The ’rm’ command does not transport files to a safe haven such as the trash can.Instead it wipes them completely from the disk.

• mkdir DIR−NAME. Create a directory DIR−NAME.

• rmdir DIR−NAME. Delete the directory DIR−NAME. Only works if DIR−

NAME is empty.

• cd DIR − NAME change to folder DIR − NAME. format. The command cdtakes you to your home folder.

• df . List total disk usage. Superfast way of finding out how much of your hard drivespace is left.

• mount is used to mount file systems e.g. mount /dev/sdb1 /media/disk

8

• ssh allows you to make a connection to another LINUX computer. Example 1: con-nect to user debian on a machine at IP address 192.168.7.2: ssh debian@192.168.7.2

Example 2: Do the same but also allow an x-session: ssh −X debian@192.168.7.2

Example 3: Copy a file FILE −NAME located in folder DIR1−NAME on thelocal machine to folder DIR2−NAME on debian@192.168.7.2

scp DIR1−NAME/FILE−NAME debian@192.168.7.2 : /DIR2−NAME/FILE−

NAME

note that DIR2−NAME has to be an absolute path. DIR1−NAME can be anabsolute path but may be a relative path e.g. ./ is the current folder.

• nano is a simple screen text-editor with a built-in description of its ten only com-mands. The figure below shows how to use nano to create a simple c-program thatprints ’Hello World!’ to the terminal.

• gcc − o myfile myfile.c: compile C-program myfile.c into executable myfile.To run myfile, cd to the folder where it is located and type ./myfile.

If you are running ’X-windows’ the following are useful commands.

• /usr/bin/sofficeWordDoc.docx to open a WORD document

• /usr/bin/evincePDFFile.pdf open a PDF

• /sbin/ifconfig: display the status of network devices. An example is shown below.Note that there are three network interfaces: eth0 the main ethernet interface,lo the loopback interface and usb0 the USB network interface (providing ethernetconnectivity).

debian@beaglebone:~$ /sbin/ifconfig

eth0 Link encap:Ethernet HWaddr 90:59:af:5b:cd:c3

inet addr:10.0.0.211 Bcast:10.0.0.255 Mask:255.255.255.0

UP BROADCAST MULTICAST MTU:1500 Metric:1

RX packets:0 errors:0 dropped:0 overruns:0 frame:0

TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

Interrupt:40

lo Link encap:Local Loopback

inet addr:127.0.0.1 Mask:255.0.0.0

inet6 addr: ::1/128 Scope:Host

UP LOOPBACK RUNNING MTU:65536 Metric:1

RX packets:68 errors:0 dropped:0 overruns:0 frame:0

TX packets:68 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:0

9

RX bytes:6434 (6.2 KiB) TX bytes:6434 (6.2 KiB)

usb0 Link encap:Ethernet HWaddr c6:fe:62:d7:9a:82

inet addr:192.168.7.2 Bcast:192.168.7.3 Mask:255.255.255.252

inet6 addr: fe80::c4fe:62ff:fed7:9a82/64 Scope:Link

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:630 errors:0 dropped:0 overruns:0 frame:0

TX packets:448 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:51153 (49.9 KiB) TX bytes:96967 (94.6 KiB)

• Finally there is /usr/bin/sudo. This command can be used to execute superusercommands by a regular user - provider the uID is stored in /etc/sudoers. Youeven need /usr/bin/sudo just to look at the file /etc/sudoers. A useful commandrequiring /usr/bin/sudo is /usr/bin/sudo halt which shuts down LINUX.

Notice that these comands have been invoked from the folders where they are lo-cated. It is unnecessary to do this if these folders are in the PATH . PATH is anenvironment variable that can be found using the command echo $PATH .

10

Figure 3: Screenshot of nano in action

UDP code

/*

** talker.c -- a datagram "client" demo

*/

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <netdb.h>

11

#define SERVERPORT "9999" // the port users will be connecting to

int main(int argc, char *argv[])

int sockfd;

struct addrinfo hints, *servinfo, *p;

int rv;

int numbytes;

if (argc != 3)

fprintf(stderr,"usage: talker hostname message\n");

exit(1);

memset(&hints, 0, sizeof hints);

hints.ai_family = AF_UNSPEC;

hints.ai_socktype = SOCK_DGRAM;

if ((rv = getaddrinfo(argv[1], SERVERPORT, &hints, &servinfo)) != 0)

fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));

return 1;

// loop through all the results and make a socket

for(p = servinfo; p != NULL; p = p->ai_next)

if ((sockfd = socket(p->ai_family, p->ai_socktype,

p->ai_protocol)) == -1)

perror("talker: socket");

continue;

break;

if (p == NULL)

fprintf(stderr, "talker: failed to bind socket\n");

return 2;

if ((numbytes = sendto(sockfd, argv[2], strlen(argv[2]), 0,

p->ai_addr, p->ai_addrlen)) == -1)

perror("talker: sendto");

12

exit(1);

freeaddrinfo(servinfo);

printf("talker: sent %d bytes to %s\n", numbytes, argv[1]);

close(sockfd);

return 0;

/*

** listener.c -- a datagram sockets "server" demo

*/

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <netdb.h>

#define MYPORT "9999" // the port users will be connecting to

#define MAXBUFLEN 100

// get sockaddr, IPv4 or IPv6:

void *get_in_addr(struct sockaddr *sa)

if (sa->sa_family == AF_INET)

return &(((struct sockaddr_in*)sa)->sin_addr);

return &(((struct sockaddr_in6*)sa)->sin6_addr);

int main(void)

int sockfd;

13

struct addrinfo hints, *servinfo, *p;

int rv;

int numbytes;

struct sockaddr_storage their_addr;

char buf[MAXBUFLEN];

socklen_t addr_len;

char s[INET6_ADDRSTRLEN];

memset(&hints, 0, sizeof hints);

hints.ai_family = AF_UNSPEC; // set to AF_INET to force IPv4

hints.ai_socktype = SOCK_DGRAM;

hints.ai_flags = AI_PASSIVE; // use my IP

if ((rv = getaddrinfo(NULL, MYPORT, &hints, &servinfo)) != 0)

fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));

return 1;

// loop through all the results and bind to the first we can

for(p = servinfo; p != NULL; p = p->ai_next)

if ((sockfd = socket(p->ai_family, p->ai_socktype,

p->ai_protocol)) == -1)

perror("listener: socket");

continue;

if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1)

close(sockfd);

perror("listener: bind");

continue;

break;

if (p == NULL)

fprintf(stderr, "listener: failed to bind socket\n");

return 2;

freeaddrinfo(servinfo);

printf("listener: waiting to recvfrom...\n");

14

addr_len = sizeof their_addr;

if ((numbytes = recvfrom(sockfd, buf, MAXBUFLEN-1 , 0,

(struct sockaddr *)&their_addr, &addr_len)) == -1)

perror("recvfrom");

exit(1);

printf("listener: got packet from %s\n",

inet_ntop(their_addr.ss_family,

get_in_addr((struct sockaddr *)&their_addr),

s, sizeof s));

printf("listener: packet is %d bytes long\n", numbytes);

buf[numbytes] = ’\0’;

printf("listener: packet contains \"%s\"\n", buf);

close(sockfd);

return 0;

/*

** rtl_decode.c -- decodes rtl-sdr binary IQ to HEX

*/

#include <errno.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

main(int argc, char **argv)

char infilename[200];

char outfilename[200];

char *name;

FILE *infile;

FILE *outfile;

unsigned char Ichar, Qchar;

int flag;

int sample_counts;

int Nbytes;

15

printf("Usage: ./rtl_decode infile outfile Nbytes\n");

printf("Default filename=file.in Nbytes = 200\n");

if( argc < 4 )

strcpy(infilename,"file.in");

strcpy(outfilename,"file.out");

Nbytes = 200;

else

strcpy(infilename,argv[1]);

printf("infile = %s\n",infilename);

strcpy(outfilename,argv[2]);

printf("outfile = %s\n",outfilename);

Nbytes=(int)atoi(argv[3]);

printf("%d\n",Nbytes);

infile = fopen(infilename,"r");

if( infile == NULL)

printf("Could not open file\n");

exit(EXIT_FAILURE);

outfile = fopen(outfilename,"w");

if( outfile == NULL)

printf("Could not open file\n");

exit(EXIT_FAILURE);

flag = fscanf( infile, "%c", &Ichar);

flag = fscanf( infile, "%c", &Qchar);

// while( EOF != flag )

for(sample_counts=0;sample_counts<Nbytes;sample_counts++)

fprintf(outfile, "%d,%d\n", (int)Ichar-128,(int)Qchar-128);

flag = fscanf( infile, "%c", &Ichar);

flag = fscanf( infile, "%c", &Qchar);

16

fclose(infile);

fclose(outfile);

17

APPENDIX B: ADEX-10H Mixer

18

APPENDIX C: AEL9710CSN-50MHz Crystal Clock

19

I N T E R N E T h t t p : / / w w w . m i n i c i r c u i t s . c o m

P . O . B o x 3 5 0 1 6 6 , B r o o k l y n , N e w Y o r k 1 1 2 3 5 - 0 0 0 3 ( 7 1 8 ) 9 3 4 - 4 5 0 0 F a x ( 7 1 8 ) 3 3 2 - 4 6 6 1

D i s t r i b u t i o n C e n t e r s N O R T H A M E R I C A 8 0 0 - 6 5 4 - 7 9 4 9 • 4 1 7 - 3 3 5 - 5 9 3 5 • F a x 4 1 7 - 3 3 5 - 5 9 4 5 • E UR O P E 4 4 - 1 2 5 2 - 8 3 2 6 0 0 • F a x 4 4 - 1 2 5 2 - 8 3 7 0 1 0

M i n i - C i r c u i t s®

I S O 9 0 0 1 C E R T I F I E D

ADEX-10H

Typical Performance Data

REV. ORM79465ED-9813/1ADEX-10HDJ/TD/CP011217

Features• EXcellent L-R isolation, 54 dB typ.• EXcellent flat conversion loss ±0.35 dB typ. over entire band• low conversion loss, 7.0 dB typ.• good VSWR, 1.4:1 typ. for LO, 1.6:1typ. for RF, 1.4:1 typ. for IF• good performance to 1500 MHz• solder plated leads for excellent solderability• low profile package, US Patent 6133525

Outline Drawing

RFMHz

LOMHz

Conversion Loss(dB)LO

+17dBm

Isolation L-R(dB)LO

+17dBmLO

+17dBm

Isolation L-I(dB)

VSWR RF port(:1)

VSWR LO port(:1)LO

+17dBmLO

+17dBm

Frequency MixerLevel 17 (LO Power +17 dBm) 10 to 1000 MHz

Surface Mount

A B C D E F G H.280 .310 .220 .100 .112 .055 .100 .0307.11 7.87 5.58 2.54 2.84 1.40 2.54 0.76

J K L wt.–– .065 .300 grams–– 1.65 7.62 .40

Outline Dimensions ( )inchinchinchinchinchmmmmmmmmmm

Maximum RatingsOperating Temperature -40°C to 85°C

Storage Temperature -55°C to 100°C

RF Power 200mW

IF Current 40mA

Pin ConfigurationLO 6

RF 3

IF 2

GROUND 1,4,5

Applications• cellular• PCN

EVALUATION BOARD P/N: TB-03

Frequency

CASE STYLE: CD542PRICE: $3.45 ea.

QTY.: (10-49)

Electrical SpecificationsLO-RF ISOLATION

(dB)LO-IF ISOLATION

(dB)

TotalRangeMax.

CONVERSION LOSS*(dB)

Max.

Mid-Bandm_

x

FREQUENCY(MHz)

IFLO/RF

fL- fU

LTyp. Min.σσσσσ

IP3@centerbandTyp.

(dBm)MTyp. Min.

UTyp. Min.

10-1000 DC-800 7.0 0.1 8.5 9.5 68 55 55 40 47 31 46 30 32 20 26 13 22 0.5

1dB Compr.: +14 dBm typ.E= [IP3(dBm)-LO Power(dBm)]/10*Conversion loss increases 0.5 dB when IF is above 150 MHz.

EFACTOR

LTyp. Min.

MTyp. Min.

UTyp. Min.

NEW!NEW!

L = low range [fL to 10 f

L] M = mid range [10 f

L to f

U/2] U = upper range [f

U/2 to f

U]

m= mid band [2fL to f

U/2]

10.00 40.00 7.31 74.12 50.79 1.12 1.6022.00 52.00 7.22 71.77 48.34 1.11 1.5840.00 70.00 7.27 69.34 45.86 1.14 1.5552.00 82.00 7.28 68.06 44.49 1.15 1.5770.00 100.00 7.25 66.74 42.68 1.17 1.53

88.00 118.00 7.25 65.95 41.20 1.20 1.5494.00 124.00 7.23 65.79 40.80 1.21 1.53

100.00 130.00 7.22 65.51 40.41 1.21 1.52160.00 190.00 7.18 61.66 36.78 1.26 1.52280.00 310.00 7.05 56.68 32.77 1.31 1.50

400.00 430.00 7.18 57.28 32.20 1.33 1.51580.00 610.00 7.29 49.11 30.60 1.44 1.52700.00 730.00 7.70 45.63 29.87 1.53 1.57940.00 970.00 7.45 36.58 23.49 1.85 1.41

1000.00 1030.00 7.42 35.39 22.50 1.98 1.33

ADEX-10HCONVERSION LOSS

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

0 100 200 300 400 500 600 700 800 900 1000

FREQUENCY (MHz)

CO

NV

ER

SIO

N L

OS

S (

dB)

LO +14dBm LO +17dBm LO +20dBm

at IF Freq of 30 MHz

ADEX-10HISOLATION L-R

20

30

40

50

60

70

80

0 100 200 300 400 500 600 700 800 900 1000

FREQUENCY (MHz)

ISO

LAT

ION

(dB

)

LO +14 dBm LO +17dBm LO +20dBm

at LO DRIVE of +14/+17/+20 dBm

ADEX-10HVSWR

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

0 100 200 300 400 500 600 700 800 900 1000

FREQUENCY (MHz)

VS

WR

#LO VSWR #RF VSWR

at LO DRIVE of +17 dBm

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