RTL-SDR: Difference between revisions

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| '''Impedance ||50 ||50 ||50 ||50 ||50 ||75 ||50 ||50 ||50 ||50 ||50 ||75 ||50 ||50 ||50 ||50
| '''Impedance ||50 ||50 ||50 ||50 ||50 ||75 ||50 ||50 ||50 ||50 ||50 ||75 ||50 ||50 ||50 ||50
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| '''Loss 100 Mhz per 100’ ''' || 0.8 ||1.5 ||1.22 ||1.4 ||1.4 ||1.46 ||1.40 ||1 ||2.1 ||2.1 ||2.1 ||2.9 ||3.9 ||4.4 ||4.9|| 11
| '''Loss 100 MHz<br/> per 100’ ''' || 0.8 ||1.5 ||1.22 ||1.4 ||1.4 ||1.46 ||1.40 ||1 ||2.1 ||2.1 ||2.1 ||2.9 ||3.9 ||4.4 ||4.9|| 11
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| '''Loss 1000 MHz per 100' ''' || 2.6 ||3.9 ||4.33 ||4.4 ||4 ||5.85 ||5.12 ||5 ||7.3 ||7.6 ||8 ||11 ||12.9 ||14.7 ||20 ||38
| '''Loss 1000 MHz<br/> per 100' ''' || 2.6 ||3.9 ||4.33 ||4.4 ||4 ||5.85 ||5.12 ||5 ||7.3 ||7.6 ||8 ||11 ||12.9 ||14.7 ||20 ||38
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Revision as of 16:30, 2 December 2025

This page is a preliminary release.

SDR


RTL-SDR

Be Very Very careful to purchase the Rtl-Sdr from reputable suppliers - there are many fake and hacked units. The real ones are alleged to have a nut on the SMA connector and are all in aluminium cases (grey and black). There are also multiple versions with the bias-T; these require different software configuration. The V2 bias T has been well proven - do research on the V4 [1] [2] bias T SDR before purchasing.

review

clones

Be careful, there are clones on the market that do not perform like the originals!

The RTL-SDR clones do not have a nut on the SMA connector! See https://www.rtl-sdr.com/rtl-sdr-blog-v-3-dongles-user-guide/

Radio TLS SDR USB Tuner Receiver RTLS2832U+R820T2 100 kHz-1.7Ghz

parts

AirSpy

LNA

filters

915 MHz Bandpass filter

This BPF is nearly perfect for GSM band and would help remove out of band channel interference of SDR receivers.

OGN technical data

Open Glider Network.

FLARM frequencies

Frequency Location
868.2-868.4 MHz Europe
Africa
869.2 MHz New Zealand
902-928 MHz North America
916.2 MHz Israel
917-926.6 MHz Australia
South America

Firmware

OGN software is installed on a raspberrypi with an overlay filesystem.

Antennas

These antennas provide a d.c. short to the input. This is undesireable for portable equipment where the LNA may need to be removed and the people are not aware or unable to turn the bias-tee off in the RTL dongle.

These do not provide a d.c. short to the input:

Measuring the velocity factor:

Measuring ferrites:

tracking

antenna design

Extract this data into a table. File:Antenna.xls Coax suppliers:

Rf power tap and metering

coax

Coax LMR-600 RG-8X EcoFlex 10 Belden 9913
RG8/U		 LMR-400 RG-11 Westflex 103 RG-218 LMR-300 LMR-240 RG-213 RG-6 RG-142 RG-400 RG-58 RG-316
Inner solid BCCAI SC stranded C solid BC S BC BC SC SC SBC Solid BC SC S C Copper Silver stranded TC
Dielectric foam PE foam PE low loss PE PE foam PE foam PE PE air PE PE foam foam PE PE foam PE PTFE PE
Outer Outer tape and tinned copper AL tape tinned braid Copper tape copper braid Tri-laminate AL and braid Tinned Copper CCS CCS Copper Braid Al tape tinned C braid Al tape and tinned copper copper Al tape Copper braid Silver platted Copper Braid Tinned Copper braid
dia centre 4.47 2.74 2.85 2.7432 2.74 ? 2.62 4.95 1.78 1.42 2.29 0.74 0.93 ? ? ?
dimens dielectric 11.96 7.24 7.25 7.24 7.39 7.2 17.27 4.83 3.81 7.24 4.7 2.95 ? ? ?
Outer 12.45 8.13 < 10.2 8.13 8.13 9 5.72 4.52 7.98 6.3 3.96
V.F. 0.85 0.85 0.84 0.84 0.84 0.81 0.66 0.85 0.83 0.66 0.66 0.7 0.695 0.659 0.69
Impedance 50 50 50 50 50 75 50 50 50 50 50 75 50 50 50 50
Loss 100 MHz
per 100’ 		0.8 1.5 1.22 1.4 1.4 1.46 1.40 1 2.1 2.1 2.1 2.9 3.9 4.4 4.9 11
Loss 1000 MHz
per 100' 		2.6 3.9 4.33 4.4 4 5.85 5.12 5 7.3 7.6 8 11 12.9 14.7 20 38

urls

SMA attentuators

engineer SCGC FLARM RX

  • scan for raspberry pi on SCGC WiFi router:
sudo nmap -sS 192.168.0/24
  • look at stats
http://192.168.0.192:8080
http://192.168.0.192:8081
  • login
ssh pi@192.168.0.192
runway06

overlay fs

Receiver Software

categories

  1. ↑ RTL-SDR V4 https://www.rtl-sdr.com/v4/
  2. ↑ RTLSDR V4 datasheet https://www.rtl-sdr.com/wp-content/uploads/2024/12/RTLSDR_V4_Datasheet_V_1_0.pdf
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