Date   
Re: Spectrum Frequency Axis display issue in R1732 - with low sample rate

prog
 

DO NOT calibrate using ambient RF signals. Use hfplus_ppb.exe and a real calibrated signal generator. We have been discussing this for years. 

Re: Spectrum Frequency Axis display issue in R1732 - with low sample rate

Patrick
 

Hi Ian,

My HF+ Discovery also reads +1.1 Hz on the MW band (though perfectly calibrated on HF against various Time Stations).
Another MW Offset DX chaser ;-)

Patrick


Le dim. 15 mars 2020 à 04:20, Ian DXer <baxterinoz@...> a écrit :
On Sun, Mar 15, 2020 at 12:40 PM, prog wrote:
One of the reasons the IF plugin now displays the relative distance to the VFO and not the absolute frequency is exactly this problem.
Thanks for the prompt reply & info. Yes I'd been finding the IF plugin a more useful reference during the calibration procedure.

For the benefit of others when using the Airspy HF+ DP & preforming a frequency calibration from a cold start I found I needed to give the
HF+ DP a good 2 hours warm up from an ambient air temperature of around 22-23C. The frequency drift down from 258MHz was about 6Hz before stabilizing.
Interestingly whenever I switch off SDR# & exit SDR# & start it up again immediately, there's a typical 3Hz drift down over a 3-5minute period before settling on the correctly calibrated frequency display. 

Another observation when performing a frequency calibration with SDR# is that I only get a movement of carrier frequency on display every 3-4 ppb change in the CLK (PPB) figure.
I'm guessing that's also as per design & probably really pushing beyond design capabilities of hardware/software trying to improve.

>PS: I see your unit is well calibrated!
Seams to be or should be with the effort I've put in @ least at that frequency.
That said there is a 2Hz difference between what SDR# says compared to SDR Console, can always easily compensate for that with Simon's easy 'software' calibration tool in SDR Console.
Not sure however why my Airspy seams to still be on the higher end of 0.7Hz to 1.8Hz above local remote Kiwi SDR(GPS) units for Aussie x-band stations. 
I use the carrier offsets for keeping a tab(eye/ear) on Aussie xbanders for WRTH updates/editing.
I'll be comparing frequency accuracy on other frequencies later as I'm noting some variations & not sure why yet.

Cheers.

Ian

Re: Spectrum Frequency Axis display issue in R1732 - with low sample rate

Ian DXer
 

On Sun, Mar 15, 2020 at 12:40 PM, prog wrote:
One of the reasons the IF plugin now displays the relative distance to the VFO and not the absolute frequency is exactly this problem.
Thanks for the prompt reply & info. Yes I'd been finding the IF plugin a more useful reference during the calibration procedure.

For the benefit of others when using the Airspy HF+ DP & preforming a frequency calibration from a cold start I found I needed to give the
HF+ DP a good 2 hours warm up from an ambient air temperature of around 22-23C. The frequency drift down from 258MHz was about 6Hz before stabilizing.
Interestingly whenever I switch off SDR# & exit SDR# & start it up again immediately, there's a typical 3Hz drift down over a 3-5minute period before settling on the correctly calibrated frequency display. 

Another observation when performing a frequency calibration with SDR# is that I only get a movement of carrier frequency on display every 3-4 ppb change in the CLK (PPB) figure.
I'm guessing that's also as per design & probably really pushing beyond design capabilities of hardware/software trying to improve.

>PS: I see your unit is well calibrated!
Seams to be or should be with the effort I've put in @ least at that frequency.
That said there is a 2Hz difference between what SDR# says compared to SDR Console, can always easily compensate for that with Simon's easy 'software' calibration tool in SDR Console.
Not sure however why my Airspy seams to still be on the higher end of 0.7Hz to 1.8Hz above local remote Kiwi SDR(GPS) units for Aussie x-band stations. 
I use the carrier offsets for keeping a tab(eye/ear) on Aussie xbanders for WRTH updates/editing.
I'll be comparing frequency accuracy on other frequencies later as I'm noting some variations & not sure why yet.

Cheers.

Ian

Unhandled Exception Error - When zoom level increased beyond 50% - low sample rate

Ian DXer
 

Getting an error when when zoom level (top right slider) increased beyond ~50% with low sample rate. Then need to shut down SDR# to continue. 

Error Description:
See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.OverflowException: Overflow error.
   at System.Drawing.Graphics.CheckErrorStatus(Int32 status)
   at System.Drawing.Graphics.FillRectangle(Brush brush, Int32 x, Int32 y, Int32 width, Int32 height)
   at System.Drawing.Graphics.FillRectangle(Brush brush, Rectangle rect)
   at SDRSharp.BandPlan.BandPlanPanel.PaintBand(RangeEntry band, SpectrumAnalyzer spectrum, Graphics g)
   at SDRSharp.BandPlan.BandPlanPanel.controlInterface_CustomPaintHandler(Object sender, CustomPaintEventArgs e)
   at SDRSharp.PanView.CustomPaintEventHandler.Invoke(Object sender, CustomPaintEventArgs e)
   at SDRSharp.SharpControlProxy.spectrumAnalyzer_CustomPaint(Object sender, CustomPaintEventArgs e)
   at SDRSharp.MainForm.spectrumAnalyzer_CustomPaint(Object sender, CustomPaintEventArgs e)
   at SDRSharp.PanView.SpectrumAnalyzer.OnCustomPaint(CustomPaintEventArgs e)
   at SDRSharp.PanView.SpectrumAnalyzer.DrawSpectrum()
   at SDRSharp.PanView.SpectrumAnalyzer.DrawLayers()
   at SDRSharp.PanView.SpectrumAnalyzer.performTimer_Tick(Object sender, EventArgs e)
   at System.Windows.Forms.Timer.OnTick(EventArgs e)
   at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)


************** Loaded Assemblies **************

I deleted these unless you want them Youssef?

SETUP:
Windows 10 64bit
SDR# R1732
Frequency: 248MHz
Sample Rate: 16kbps
RX: Airspy HF+ DP
Rx mode: CW or NFM (probably not relevant)

Not sure if the error is unique to my setup or if other Win 10 users experience the same?
Only discovered this issue during frequency calibration procedure/setup.
Please let me know if more information required.

73s

Ian

Re: Spectrum Frequency Axis display issue in R1732 - with low sample rate

prog
 

On Sun, Mar 15, 2020 at 02:28 AM, Ian DXer wrote:
Can you comment &/or investigate this Youssef?  
No, this is not an issue. This is just a plain UX and taste question.
Here's the problem: The space reserved for the marked is finite, and the number of digits can only get bigger and bigger.
Someone will want another digit when zooming to the max. Then someone else will increase the decimation and a lower sample rate then asks for another couple of digits, and so on. At some point you will be rounding the displayed labels.
One of the reasons the IF plugin now displays the relative distance to the VFO and not the absolute frequency is exactly this problem.

PS: I see your unit is well calibrated!

Spectrum Frequency Axis display issue in R1732 - with low sample rate

Ian DXer
 

Hi Youssef & all,

Recently I purchased a Leo Bodnar Mini GPS clock. One of the reasons for the purchase was for accurate (or improved) frequency calibration on my Airspy HF+ DP & measurements of Aussie x-band stations (more on that later). A number of issues have surfaced. I'll just deal with one in this message for the moment.

Problem: Seemingly (?) incorrect x-axis (spectrum frequency) display when sampled frequency carrier wave zoomed-in with low sample rate, pertains to display of frequency in SDR# left of the LeoBodnar GPS clock frequency generated carrier. (eg 248MHz in this case)

In regard to SDR# eg R1732 using the setup below

1. Windows 10 64bit
2. SDR# R1732
3. Sample rate 16kbps
4. Frequency: 248,000,000Hz (label H & G)
5. SDR# Display Resolution 32768 / Blackman Harris 4
6. LeoBodnar Mini GPS Clock set to output: 248,000,000Hz GPS & PLL locked
7. CW demodulation
8. Although Free Tuning mode shown in image. Carrier is centred on screen & issue occurs with Centre Tuning.

Refer to attached diagram to "see" the issue.

Basically, referring to diagram & the labels I've drawn. It seams to me that frequency labels on the spectrum display; labels B to F should be displaying 247.9999 rather than 248.000
, Label A is correct. This display anomaly only occurs when using the zoom display slider control at a significant zoom level, a low sample rate makes this all the more obvious.

Comparing this with SDR Console 3.0.20, SDR Console whilst it does have a x-axis display with an extra significant digit bit eg 247.999.98 vs 247.9999(SDR#), SDR Console is displaying carrier position correctly along the frequency x-axis correctly at high zoom levels.

Can you comment &/or investigate this Youssef?  

Thanks very much.

Ian

Aircraft scatter at VHF frequencies using the AirSpy Discovery

Paul Cianciolo
 

A quick video showing another use for the AIrSpy Discovery.
Examining doppler shift caused by Aircraft flying between you and the airport. 

https://youtu.be/S3Gcgtq4rno


PaulC
W1VLF

Re: Building a WWVB Ferrite loop antenna Part 2

prog
 

Thank you for this excellent video, Paul.
I also have been playing with ferrite antennas last year and found these ones to be particularly good. All these variantes use the same Russian ferrites with permeability 400. The copper shield is open on one side to prevent shorting the whole rod, and is connected to the ground of the coax.
Many rods can be connected in series and work well if you space them by about 12 cm. Just make sure they are wound correctly, like in the photo:







Re: HF+ Discovery "No Device Selected" #airspydiscovery

Ron Johnson
 

Thank you! Thank you!  This worked perfectly.  I was selecting Airspy, but now with the other selection it works wonderfully.

 

Cheers,

Ron

 

Sent from Mail for Windows 10

 

From: prog
Sent: Thursday, March 12, 2020 1:00 AM
To: airspy@groups.io
Subject: Re: [airspy] HF+ Discovery "No Device Selected" #airspydiscovery

 

On Thu, Mar 12, 2020 at 08:56 AM, Ron Johnson wrote:

"No Device Selected"

Did you select the correct source?

 

Building a WWVB Ferrite loop antenna Part 2

Paul Cianciolo
 

For those interested I have loaded WWVB Antenna Build part 2 
Here https://youtu.be/2zrV60J52dc

PaulC
W1VLF

ADSB-Spy on the RPi4 - working good!

Ben Hall
 

Good afternoon all,

I now have ADSB-Spy working on the RPi4 after following the quick-start instructions. :)

Some stats: At the moment, PlanePlotter is reporting over 800 mode-S messages per second, the htop 15 minute load average is 0.37, memory usage is 110M, and vcgencmd reports temperature is 37 deg C using a Vilros case with little tiny heatsinks and a little tiny fan. :)

After many stupid mistakes with scripts and various methods of automatically running scripts when RPi starts...even got it so that it automatically starts ADSB-Spy when the RPi starts.

PlanePlotter seems very happy - all of the networking tests pass without issues. :)

Now for a dumb question! I can't seem to find a manual file for the RPi ADSB-Spy program. I'm curious to know more about the command line switches, such as if I don't manually set a gain command, what gain value does it use?

Thanks much and 73,
ben, kd5byb

Re: Does the RPi4 need performance tuning?

Ben Hall
 

On 3/13/2020 4:10 PM, prog wrote:
There is a very extensive thread on FlightAware discussion forums about our decoder and how it's setup.
https://discussions.flightaware.com/t/airspy-ads-b-decoder/55825
Excellent, thanks! While the Pi I'm asking about is destined to feed a PlanePlotter installation...I also have a FlightAware ADBS feeder setup that's currently running on an older RTL dongle.

The question I've got to decide is if I want to tie up my second AirSpy on that setup or keep it available for general HF/VHF use (I've got a Spyverter with it).

Perhaps I should buy an R2 for general use? ;) I just may do that once we get our house roof replaced. All spare $'s is currently going towards that work. :(

thanks much and 73,
ben, kd5byb

Re: Does the RPi4 need performance tuning?

prog
 

There is a very extensive thread on FlightAware discussion forums about our decoder and how it's setup.
https://discussions.flightaware.com/t/airspy-ads-b-decoder/55825

Re: Does the RPi4 need performance tuning?

Ben Hall
 

On 3/13/2020 1:20 PM, prog wrote:
No. The defaults for the RPi4 just work.
Excellent, thanks much! I'll go with the usual defaults. :)

Thanks much and 73,
ben, kd5byb

Re: Does the RPi4 need performance tuning?

prog
 

On Fri, Mar 13, 2020 at 06:31 PM, Brian Gregory wrote:
They look to me as if they will slow down a Pi3 quite a bit from the default.
Yes. That's intended to maintain a stable IRQ and processing response time while not causing the poor CPU to throttle.
Keep in mind that the RPi3, 2 and 1 have the ethernet and USB controllet sharing the same bus and this create a number of performance problems. The suggested setting seem to help somehow. That's not needed fot the RPi4, which is a completely different beast. 

Re: Does the RPi4 need performance tuning?

prog
 

On Fri, Mar 13, 2020 at 04:45 PM, Ben Hall wrote:
Does the RPi4 need the same /boot/config.txt steps as the RPi3:

force_turbo=1
arm_freq=800
No. The defaults for the RPi4 just work. 

Re: Does the RPi4 need performance tuning?

prog
 

On Fri, Mar 13, 2020 at 07:17 PM, Laurie wrote:
On 13/03/2020 17:30, Brian Gregory wrote:
Where did those values come from?
They come from the Quick Start page on airspy.com's website:
https://airspy.com/quickstart/

--
Laurie
These settings are specific to the adsb decoder. Don't cherry-pick the recommendations. 

Re: Does the RPi4 need performance tuning?

Jakob DD5JFK Ketterl
 

Hello,

I think I remember those settings, they were used to overclock the first generation Raspberry Pis.

Documentation: https://www.raspberrypi.org/documentation/configuration/config-txt/overclocking.md

Basically, setting arm_freq to 800 means you're going to run your CPU slower than default for any Pi 2 or later.

73s
Jakob DD5JFK

Re: Does the RPi4 need performance tuning?

Laurie
 

On 13/03/2020 17:30, Brian Gregory wrote:
Where did those values come from?
They come from the Quick Start page on airspy.com's website:
https://airspy.com/quickstart/

--
Laurie

Re: Does the RPi4 need performance tuning?

Brian Gregory
 

Where did those values come from?
They look to me as if they will slow down a Pi3 quite a bit from the default.
Maybe that's what you're after?

On Fri, 13 Mar 2020 at 15:45, Ben Hall <kd5byb@...> wrote:
Good morning all,

Because my Win10 PC has developed unreliable USB ports which causes
ADSB-Spy to randomly stop executing...I'm in the process of setting up
ADSB-Spy on a new RPi4.  :)

I notice that in the quick-start, it notes that:

"Raspberry Pi 3 Performance Tuning

The latest Raspbian distros come with a new default CPU governor that is
not suitable for sustained high performance operation."

Does the RPi4 need the same /boot/config.txt steps as the RPi3:

force_turbo=1
arm_freq=800

Or does it work okay as-is without the steps?

Thanks much and 73,
ben, kd5byb