Carsten Groen's (OZ9AAR) personal place

SkyScanner

My current location is in a small village with houses having solar panels, inverters, bad switching mode power supplies, not to mention all the electronic equipment I have in my own house. I have some directions where there are more noise than other directions, and it would be good to somehow visualize that. 
The idea about the "SkyScanner" was born. This is a "project under development" and somewhat experimental. If it ever will be finished I don't know, at least I have/will learn something during the development, which is pretty much why I do stuff like this :) 

The need got bigger and triggered me to do something about it when I installed my 70cm EME system. On EME, every 0.1 dB counts, and as I always try to optimize whatever I'm doing, I started the SkyScanner project.

SkyScanner is basically a PC (Windows) application that will control a Az/El rotor for your antennas (supports PstRotator, Yaesu GS-232 (B version), OE5JFL controller and my own URC RotorController), sample the audio from a transceiver (via soundcard or built-in soundcard in the radio) and present the measured "noise" from the transceiver and map this on a "dome".

Once the "sky has been scanned", the idea is that you can leave the application running, it will then always show you the current antenna position (by coloring the zone green the antenna currently points to). SkyScanner also shows the current position of the sun (orange zone) and the moon (dark gray zone) position on the dome.

The audio from the transceiver is sampled via Windows sound system, so no special needs there.

In recent versions, SkyScanner can also scan the area around the sun. You specify the span in azimuth and elevation as well as the "step size", both in degrees. SkyScanner will then follow the sun as it moves and scan according to the parameters set. The output data will be saved in a text file and in a CSV file that is ready to be used in Excel. This will allow you to see the pointing accuracy of your antenna by examining the measured sun noise.

As mentioned, this is a project "under development", so expect some things to be changed along the way. Be sure to check this page for new versions once in a while.

Below you will find a couple of screenshots and a video showing the fundamental operation.

Recommendation of SkyScanner by 
Joe Taylor K1JT

December 2024 I got a note from K1JT Joe Taylor regarding SkyScanner! Joe had been using SkyScanner to survey the sky at the club station of the Delaware Valley Radio Association (W2ZQ).

He posted the message and screenshot below on the moon-net email reflector

(the message has been included here by permission of Joe!)

Hi all,

This message has two main purposes: to convey my hearty congratulations to Carsten, OZ9AAR, on his "SkyScanner" program, and to recommend its use by others who may not have tried it already.

I installed SkyScanner yesterday at W2ZQ, club station of the Delaware Valley Radio Association. Those active on 1296 MHz EME know that we have a well-equipped EME station on that band, using a 3m dish and septum feed.

I configured SkyScan to control the drives for our 3m dish through PstRotator. I then used it to produce a map of apparent sky background temperature, covering all Azimuths 40 to 300 deg and Elevations 3 to 45 deg with 3 degree steps in each coordinate. The full map took about 4.5 hours to make.

The attached screen shot shows the map for Azimuths from about 50 to 220 deg using Carsten's "sky dome" projection. The big red splotch slightly north of east (center at Az=74, El=16) is QRM from a cell tower (Ugh!) about 100 m away from the dish. It produces strong QRM from front-end overload when we point at it. The splotch on the left side (Az=210,

El=21) is another set of cell antennas on a water tower. You can also clearly see two isolated trees at Az=120 and 160 deg and a larger clump of trees extending from Az=175 to 205. There's another isolated tree in the map at 245 deg, but that's not visible in this particular view.

Pretty much everything above El=30 deg should be "cold sky" at 1296 MHz, and you can see that's the case for us.

In normal use, this map appears on the SkyScanner main screen in an interactive way. You can tilt or rotate the map as desired, and even look at it from "underneath" -- as though you were at the center of the sky dome. If you hover the mouse pointer over a square in the map, a ToolTip will display the time the measurement was made, the square's coordinates, the measured noise level in dB, and the Sun's position at the time of measurement.

For this run the cold sky reading was -39.7 dB. With the antenna pointed at low elevations in the dense clump of trees (Az=190, El=3), the reading was -34.2 dB. Thus, we're seeing about 5.5 dB of "ground noise"

when the beam is mostly filled with lossy stuff at approximate winter temperature T=270 K. These numbers translate to an effective system noise temperature of T_sys = 102 K. The total is made up of main-beam antenna noise, side and back lobes or "spillover" noise, and receiver noise.

I find SkyScanner to be a really well designed tool, and very convenient to use. It will be a big help to us in testing and commissioning our new

4.6 m dish.

Many thanks, Carsten, for your gift to the community!

                             -- 73, Joe, K1JT

Screenshots

Noise Measurement window

The application has a window that will allow you to monitor the noise level currently received. The application uses a soundcard interface to sample the audio, filters this and calculates the RMS value from this. It is VERY important that you DISABLE AGC completely when doing this, only by disabling the AGC the measurements will make any sense. It is also VERY important that the receive chain is linear in the range of the noise measured, clipping/limiting by the receiver will make the measurements invalid!

Using the controls to the left, you can select  the dB per division and the width of the graph in seconds.

Pressing the "Delta = 0" button will take a snapshot of the current measured noise level. The "Delta(dB)" number just below the button, will show the delta between the snapshot and current noise level (The "snapshot" used will also be save in settings, so the next time the application is started, this stored value will be used as the basis for the delta value). Pressing "Pause" will pause the update of the graf, the data collected will be inserted once the button is pressed again. Right click with the mouse inside the graph area to bring up a submenu.

Avoiding scanning specific areas

Some installations might have limitations on where the antenna(s) can be pointed. This can be due to cable restrictions, you might not be able to access the area around north from the ground to zenith because of cables or mechanical limitations. 

In SkyScanner, you can define a list of "keep out zones", SkyScanner will not show these zones that are included in the areas, and the antenna will not be able to be commanded into this area either.

The algorithm behind this is not super clever, so you might end up needing to move the antennas to the area being scanned yourself, its not so that SkyScanner does a lot of route planning etc to get to a certain point. It will just command the rotor(s) to move to a specific Az/El.

But, it will monitor the current rotor position, and if it enters one of the defined "not allowed" zones, it will stop the rotor, you then have to move the rotor out from the area again before continuing.

Sunsweep - Scanning around the sun

SkyScanner can also map an area around the sun. This can be used for checking pointing accuracy etc of your antenna. You specify the span and step-size for the scan in both azimuth and elevation.

When the Sunsweep function runs, it will follow the sun over the sky. So if a full scan takes a long time, each measurement is done with the correct offset to the sun as the position are calculated when a new measurement is to be taken.

Please note that the data from Sunsweep are not shown on the dome view or added to the database for this. Sunsweep data are only saved in a .TXT and a .CSV file as selected by the user.

Below is a screenshot of the setup of the Sunsweep function and the CSV data in Excel.

Moonsweep - Scanning around the moon

Just as SkyScanner can map an area around the sun it can also do the same with the moon as the target.

When the Moonsweep function runs, it will follow the moon over the sky. If a full scan takes a long time, each measurement is done with the correct offset to the moon as the position are calculated when a new measurement is to be taken.

Please note that the data from a Moonsweep are not shown on the dome view or added to the database for this. Moonsweep data are only saved in a .TXT and a .CSV file as selected by the user.

User defined targets

You can define up to four targets in SkyScanner. This can be used for "maintenance position", "cold sky" etc.

A label can be set for each target, azimuth and elevation. Each of the four targets can be selected by using the menuitem "Antenna" -> "User positions" and pressing the "GO" button next to the target you want the antenna to go to.

Scanning South to West

The screenshots below shows a complete scan from south to west, horizon to zenith. The zones not measured was too close to the sun and was automatically skipped by the program. I can the re-visit these once the sun is out of the way. The full scan too 1 hour on my 70cm EME array.

After the sun moved out of the way, the last zones were selected and scanned.

The single "gray" zone is the current moon position and the lonely orange is the current sun position.

The screenshots below is from a scan I did with my 70cm EME antenna. When you download the application, the database with these measurements is included in the ZIP file, you can then experiment with the controls of the program, zoom, pan etc.

Demo video

Please notice that some of the videos below is from the first beta version of the program, some of the features have been changed in the application since the video was recorded.

Interfacing to PSTRotator

Selection of zones

Although you can select which zones (and the order) to scan using the mouse while holding the ALT key down, it becomes a bit tiresome when you need to select many zones. You can use the "Select zones" window to help with the selection.

Below is a small youtube video of the function.

The data

The data that is being collected by SkyScanner is saved to a database, I'm using LiteDB, a small and relatively simple database. You can use the data in the database(s) for your own usage too if needed. Each record has information about the azimuth, elevation, timestamp, validity of measurement, the resolution of the zones measured (more on that later) and the measured noise level (in dB).

If you need to use the data from the database, the class in C# that holds each record looks like this:

Download

SkyScanner runs under Windows operating system. There are no installation to be done. The program consists of a single .exe file, simply download this, copy it to a folder and execute it from there.

SkyScanner will create a configuration file in the folder it is located in, this file contains all settings from the program.

REMEMBER! Please keep antennas under constant observation at ALL TIMES when SkyScanner commands them/scans zones!

I do NOT take any responsibility for the correctness of SkyScanner, it might work, it might not work !!

If you notice "funny things" with saving settings, storing data, please make sure that the program has write access to the folder where you try and write to (for settings problems, the folder where the application is located). Alternatively you might try and start the application in "Administrator mode".

If you use PstRotator to drive your antenna, please make sure you have the lastest PstRotator installed, version 17.67 or newer!

2024-11-28 SkyScanner - Version 1.0.0.4

2024-11-26 SkyScanner - Version 1.0.0.3

2024-11-14 SkyScanner - Version 1.0.0.2

2024-11-10 SkyScanner - Version 1.0.0.1

Release notes

2024-11-28 - Version 1.0.0.4

• BETA: Added support for OE5JFL controller (Thanks Walter ON4BCB)
  (If OE5JFL is selected, the observer and date/time can be set in the controller with "Antenna" -> "Set time/observer in controller")
• Added four user defined "goto" targets in "Antenna" -> "User positions" (Thanks Walter ON4BCB)
  
• BETA: Added "Moonsweep", basically the same as "Sunsweep", just for the moon as target
  

2024-11-26 - Version 1.0.0.3

• Added possibility to export the current open database as a CSV file (Thanks for the final "push" from Nico PA3ESH :)
  
• Added culmination time and max elevation for sun/moon in tooltip for az/el info for sun/moon
  
• Added tracking of user defined RA/DEC (new menu item under "Actions"). (Thanks John G4SWX)
  
• Fixed error in GS-232B rotor interface (Thanks Nico PA3ESH)
  
• Added new feature, "Sunsweep". Will measure noise in a defined grid around the sun and save data as a txt and csv file (Thanks Nico PA3ESH)
  

2024-11-14 - Version 1.0.0.2

• Tooltip for moon and sun position (when you hover the mouse over the info field) will show next set/rise time in UTC
  
• Minor fixes
  

2024-11-10 - Version 1.0.0.1

• Fixed error in Settings with Lon/Lat entry (uses fixed "." as decimal point) (Thanks Jayson VK1JA)
  
• Added possibility for 300 and 600 baud when driving Yaesu GS232B rotors (Thanks Stefan OE6ISP)
  

2024-11-09 - Version 1.0.0.0 

• This is the initial release