© Brooke Clarke 2021

    Spectrum Analyzer & Discone Antenna


Because I live in Northern California in an area that's seen fires very close by for the past few years I pay a lot of attention to FlightRadar24 (link has my Lon-Lat so it comes up showing my local area).  It allows me to see where the first responding fire fighting aircraft are going.  Today I hears a helicopter and it turned out to be N499DF practicing.  Because I live in a canyon on top of a mountain I do not have good line of signt visability to the horizon so FR24 does not want to loan me one of their ADSB receivers.  But they have suggested that I build my own.  They have a web page describing how build an ADSB receiver.  Also a page on Share your ADS-B data, with a manual.pdf.

FlightAware also has a web page on making your own PiAware ADS-B Ground Station, WiFi_expert on eBay.  But their free on line map is much much poorer than the FR24 map.

So I'm making this web page to look into what's involved.
ADS-B: Automatic Dependent Surveillance-Broadcast

In order to burn the FlightRadar24 Pi24 .img file onto the microSD card you need to download WIN32 Disk Imager.


Required Components

Raspberry Pi 3b or newer

The Raspberry Pi (Wiki) comes in many flavors, but as of Oct 2021 the Pi4 B ( Pi4 web page) seems to be the most powerful and feature loaded and versions 1.2 or higher have the bugs removed.  It comes in 1, 2 or 4 GB memory configurations.

Astro Pi - there are a couple of these on the Space Station and citizens can propose experiments. - Mk II Hardware - Sensors -

Raspberry Pi Foundation  - UK foundation promoting computers for young adults, including sophisticated video games.
CanaKit Raspberry Pi 4 4GB Starter PRO Kit - 4GB RAM
Raspberry Pi Beginner's Guide 4th Edition (Pdf) - I have the hard copy on order.

Kit Includes (Fig 2):
  1. Raspberry Pi 4 4GB Model B with 1.5GHz 64-bit quad-core CPU (4GB RAM)
  2. 32GB Samsung EVO+ Micro SD Card (Class 10) Pre-loaded with NOOBS
  3. CanaKit Premium High-Gloss Raspberry Pi 4 Case with Integrated Fan Mount, CanaKit Low Noise Bearing System Fan
  4. CanaKit 3.5A USB-C Raspberry Pi 4 Power Supply (US Plug) with Noise Filter
  5. Set of Heat Sinks
  6. Micro HDMI to HDMI Cable - 6 foot (Supports up to 4K 60p)
  7. CanaKit USB-C PiSwitch (On/Off Power Switch for Raspberry Pi 4)
  8. USB-A MicroSD Card Reader
  9. Fan
  10. Quick-Start Guide
  11. Raspberry Pi J8 Pinout Card
  12. Read Me First Card
YouTube: CanaKit Starter Kit for the Raspberry Pi 4 4GB Setup with Heat Sink+Fan install & Test!, 11:19 -
@3:34 Assembly - @3:52 Heat Sinks - @6:22 Install microSD card, @6:33 Connect Cables (USB-C, HDMI0, USB2.0=Keyboard, Mouse, HDMI Monitor), @7:31 Boot (~5 minutes to install), @9:07 Fan check,

CanaKitVideos: CanaKit Raspberry Pi B+ Case Installation, 1:33 - PCB into case, @0:37 Camera Fitting (either Fan or Camera if lid mounted),

Power Supply for the Pi

There is a choice of many AC input 5V output supplies, but for the Pi 4B a 3A supply with USB-C plug to the pi will work. 
A GPIO header can also be used: J8-2 & J8-4=+5V. J8-6=Ground. ( Pi4 datasheet).
It would be good if there was no possible way the power supply can be unplugged.  Better to have a hard wired supply than something that can open up.
Also it should be on the back up mains supply so will keep working during AC mains failures.

Sensor Hat

The key sensor chip is the ST LSM9DS1. Accessory Hardware Docs: Schematic.

4 GB MicroSD card (Wiki)

SD cards come in three sizes: Standard, Mini and Micro.  the Pi uses micro cards which is also the size used in mobile phones (LG G6 SIM and microSD cards).
H2testw is WIN software that can test an SD card.  Note that there are counterfeit and mislabeled SD cards that do not perform as labeled.

RPi SD cards - large table of cards & if they work on a Pi.

Amazon: Kingston 32GB microSDHC Canvas Select Plus 100MB/s Read A1 Class10 UHS-I Memory Card w/o Adapter SDCS2/32GBSP

Amazon: SAMSUNG 32GB Evo Plus Class 10 Micro SDHC with Adapter 80MB/S (MB-MC32GA) Pack of 5

Ethernet cable

I think this is to connect the ADS-B receiver to the Ethernet. 
Another option is to use the Pi4 built-In WiFi to connect to your local network.

Pi Keyboard & Mouse

Johnwell 15.6" Monitor

Bundle ADS-B USB Dongle + "SCO-1090-MCX" Antenna (1090 MHz) Fig 4

Nooelec NESDR SMArTee v2 Bundle - Premium RTL-SDR w/ Aluminum Enclosure, Bias Tee, 0.5PPM TCXO, SMA Input & 3 Antennas. RTL2832U & R820T2-Based

ADS-B USB dongle
RTL2832U (USB Interface) & R820 T2 (Tuner IC - Optimum for ADS-B) - Based
eBay search term: "rtl2832u r820t2"
the better units are rated for 1 ppm or 0.5 ppm frequency stability.
Rx: 25 - 1750 MHz
Nooelec Downloads -
Drivers for:
WIN - Apps: CubicSDR,(feeds: Soundflower-MacOS , Jack Audio or VBCable)  & supports other SDR receivers (Manual): SDRPlay*, HackRF*, BladeRF, AirSpy*, NetSDR+, Red Pitaya, Audio Devices (some platform specific at the moment) or any other device with an available SoapySDR support module.
Background on SDR Dongles: About RTL-SDR - developed the SDR concept based on the I/Q output from the RTL2832U Digital TV chip.
The SDR receivers above marked * are mentioned as higher performance than that available from the RTL2832 family of receivers, but at higher cost ($100 to $300).
RTL-SDR Tutorial: Cheap ADS-B Aircraft RadarVirtual Radar Server - RTL1090 - dump1090: Pi, - Modesdeco - Cocoa1090-MacOS - gr-air-modes - Virtual Radar Server - PlanePlotter - adsbSCOPE - Globe-S -

HDSDR: (Alberto di Bene (I2PHD)

MathWorks: RTL-SDR Support from Communications Toolbox - (<$200)

1090MHz ADS-B Antenna (Fig 5)

A 1090 MHz vertical antenna, mounting bracket, SMA(f) to MCX(m) pigtail cable & 10 meter antenna cable SMA(m) to N(m)
eBay search term: "ads-b antenna 26 in" there are mounts that work on both flat wood surfaces and on metal masts (just remove the U-bolts).

5.5dBi 1090/978 N-type Female Antenna - 26-inch

Antenna Coax

This should be LRM-400 for low loss, similar to the cables used for the Agilent E4404B Spectrum Analyzer.  These can be ordered in pretty much any length and with most connectors.  But a short pigtail cable needs to be used between the LMR400 coax and the receiver since the LMR400 is rather stiff.

MicroSD Card Reader

Casing for Raspberry Pi

eBay search term: "raspberry pi4 case"
The Argon One seems like a nice plastic case about $20.  But there are also machined Aluminum cases. And both plastic and aluminum cases that include a small fan.
eBay title for one that looks good: "Case For Raspberry Pi 4 W LARGE Fan & � Aluminum Heat Sinks Model B Board Not In" seller: tlacres. notch for easy access to SD card.

The common cases all have an outline that's close to that of the Pi 4 unit.  I.e. the USB SDR dongle will be sticking out of the case.  Much better to have a case that contains all of the components it can.  Maybe even including a nominal 12 V DC input to 5 VDC buck converter.  That way I could use my existing 12 V backup power supply and not put this system on the AC mains backup.  That has an advantage in allowing this system to be located upstairs making for a shorter antenna cable.

RF Amplifier (Fig 6)

At VHF and above frequencies the cable loss adds directly to the receive noise figure (Wiki).  By adding an amplifier at the antenna the system noise figure is improved making for a very noticeable improvement in weak signal reception.  This simple improvement in receive NF can only be done on receive only systems.  For systems that both transmit and receive it's more complicated.

GPIO Labs: ADS-B Filtered Low Noise Amplifier LNA with 15 dB Gain - the noise figure of 1 dB should make a huge improvement in the s/n if the amp is mounted at the antenna (before the cable).  But waterproofing and DC power wwill need to be added.

ADS-B LNA High Performance Triple Filter Low NF Amplifier by RTL-SDR

Insights from the Manual

Operating Systems Supported

Linux (ARM=Raspberry Pi, BeagleBoard, x86, x64)
MacOS X (10.9 Mavericks or later)
Windows no longer supported, switch to Pi.

Receivers supported

Kinetics SBS1, SBS1er, SBS3 - USB and Network
Mode-S Beast - USB and Network
Most DVBT sticks - USB and Network
Most “AVR” compatible receivers - USB/Serial and Network
MicroADSB – USB and Network


Fig 1 ADS-B CanaKit Respberry Pi 4 Starter Kit (32GB, Black Case, 4GB Ram) & extra 32GB card
ADS-B CanaKit Respberry Pi 4 Starter Kit
                      (32GB, Black Case, 4 GB Ram) & extra 32GB

Fig 2 Pi Kit Contents

ADS-B CanaKit Respberry Pi 4 Starter Kit
                      (32GB, Black Case, 4 GB Ram) & extra 32GB
Fig 3 Pi 4 B
ADS-B CanaKit Respberry Pi 4 Starter Kit
                      (32GB, Black Case, 4 GB Ram) & extra 32GB
Fig 4 ADS-B USB Dongle SDR Receiver & Antenna Kit: NESDR SMArTee v2 Bundle (0.5 ppm)
ADS-B CanaKit Respberry Pi 4 Starter Kit
                      (32GB, Black Case, 4 GB Ram) & extra 32GB
Fig 5 ADS-B 1090 MHz Antenna
adsbexchange 1090-978 MHz antenna

Fig 6 ADS-B Filter Amplifier
ADS-B Filter Amplifier by RTL-SDR


E4404B ESA-E 9kHz - 6.7 GHz Spectrum Analyzer & Diamond D-130 Discone 25 - 1300 MHz

The Center Frequency is 1090 MHz, RBW: 100 kHz, Span: 200 kHz, Max Hold.
Start 2 PM 21 Oct 2021.




SigIDwiki: Automatic Dependent Surveillance-Broadcast (ADS-B) -


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