ap/xxxxx/1010

Trimble Lassen SQ and scrying: (2008.06.28:1)

Sat, 28 Jun 2008 21:22:00 +0100

Sample code to switch SQ to NMEA 4800 bps 8N1:

unsigned char gps0[]={0x10,0x7A,0x00,0x01,0x00,0x00,0x00,0x01,0x10,0x03}; // last but two: GGA and GSV also = 0x09 ... just GGA=0x01 //ends 0x01,0x03

unsigned char gps1[]={0x10,0xBC,0xFF,0x06,0x06,0x03,0x00,0x00,0x00,0x02,0x04,0x00,0x10,0x03};

/* output to 2nd serial port */

and further:

http://scrying.svn.sourceforge.net/viewvc/scrying/

scrying and logging notes: (2008.06.26:1)

Thu, 26 Jun 2008 11:20:00 +0100

1] Latest serial/memory logging code:

http://scrying.svn.sourceforge.net/viewvc/scrying/

Programmed with:

avrdude -c avrusb500 -p m128 -P /dev/ttyUSB0 -U lfuse:w:0xFD:m -U hfuse:w:0x99:m -U efuse:w:0xFF:m -U flash:w:serialtest.hex

2] Commands:

xxxxx:help                                                                                        
log: output log                                                                                   
lv: print one sample
nm: show counter
res: reset counter
p: pause
s: start
d1/d2/d3: delays short->long
str: stream
q: quit stream
8bit: char output
10: 10 bit integer output
ant: antenna src
rssi: rssi board src
help: helps

3] As an aside remix of iwspy signal strength logging from:

http://users.skynet.be/chricat/signal/signal-strength.html

iwspy eth0 192.168.1.1

cat iwspy.sh

#!/bin/bash
while true
do
        iwspy eth0
        sleep 1
done | grep Signal

./iwspy.sh > iwtest

cat iwperl.pl

#!/usr/bin/perl
while ($line = <STDIN>)
{
       
        if ($line =~ /level=(-[0-9]+).*level=(-[0-9]+)/)
                {
                print "$1 $2\n";
                chomp($line=<STDIN>);
                }
}

cat iwtest | ./iwperl.pl > iwproc

## and in gnuplot-mode buffer (send buffer with C-c C-b):

set title "iwspy"
set yrange [-120:-50]
set ylabel "dBm"
set xlabel "Sample"
set term png
#
set output 'xxxxx-strength.png'
plot 'iwproc' using :1 title "Signal", 'iwproc' using :2 title "Noise"

Logging code for scrying: (2008.06.20:2)

Fri, 20 Jun 2008 12:25:00 +0100

http://1010.co.uk/serialtest.c

1] Logs 10 bit value from adc0 to SRAM

2] Prompt for the following commands on usart0 (ATmega128):

log: dump log to serial port

live: show live reading of ADC

num: show log counter

reset: reset log counter

3] Data dumped to file by way of minicom and graphed with Octave:

Software defined radio/ITC/Baudline notes and references: (2008.06.20:1)

Fri, 20 Jun 2008 12:14:00 +0100

1] Building and testing GNU Radio (Debian testing):

svn co http://gnuradio.org/svn/gnuradio/trunk gnuradio

apt-get install libtool portaudio19-dev alsa-dev alsa-source python-wxgtk2.6 python-numpy

export PYTHONPATH=/usr/local/lib/python2.4/site-packages/

./bootstrap

./configure

make install

ldconfig

cd ~/gnuradio/gnuradio-examples/python/audio

./audio_fft.py -I hw:0,0 -S

References:

GNU Radio tutorials: http://www.nd.edu/~jnl/sdr/docs/tutorials/1.pdf

http://www.spectrum.ieee.org/oct06/4654/toolsb1

http://www.kd7lmo.net/ground_gnuradio.html

SDR: http://f4dan.free.fr/sdr_eng.html

2] Demodulation using Baudline:

Ref: http://www.domenech.org/homebrew-sdr/receiver-3.htm

http://www.baudline.com/manual/glossary.html

http://www.burtonmackenzie.com/2007/05/poor-mans-spectrum-analyzer.html

http://www.febo.com/pages/baudline/

Use of decimate and down-mixer:

Down-mixer allows us to move across frequency range down-sampling.

What is decimation?

"a technique for reducing the number of samples in a discrete-time signal."

Play deck window - advanced features: high pass and low pass filters, use of shift for demodulation.

3] ITC/EVP ref:

commandline EVP: (2008.06.14:1)

Sat, 14 Jun 2008 20:17:00 +0100

rough port of some features from EVPmaker:

http://www.stefanbion.de/evpmaker/index_e.htm

for cutups of audio recordings, text usw.

gcc evp.c -o evp

cat crying | ./evp 40 10 1000 0

arguments: to, from, window size, overlap (1 or 0)

latest scrying collection: (2008.06.06:1)

Fri, 06 Jun 2008 16:44:00 +0100

RF signal strength meter 100 MHz-2.5GHz (2008.05.22:1)

Thu, 22 May 2008 12:02:00 +0100

Simple design based on Analog Device's AD8313 chip, providing visual display of broadband signal strength and audio level output of demodulated signal.

The circuit detects, demodulates the amplitude and amplifies high frequency electromagnetic emissions (100 MHz to 2.5 GHz approx) for audio frequency output. The main component is the Analog Devices AD8313 IC: RF logarithmic detector and controller, whose output is further amplified by the TL082 op-amp.

Circuit diagram:

Or: http://1010.co.uk/images/rssi_strength.pdf

PCB and all Kicad/GERBER files:

http://1010.co.uk/rssi_strength.tar.gz

References:

http://f6bon.albert.free.fr/Milliwattmetre.html

http://www.analog.com/en/prod/0%2c%2c770_847_AD8313%2c00.html

http://www.turnpoint.net/wireless/cantennahowto.html

http://www.engadget.com/2005/11/15/how-to-build-a-wifi-biquad-dish-antenna/