Date   
Re: Building a WWVB Ferrite loop antenna Part 2

Mitch
 

Quite interesting, thanks for the details. Have you by chance tried that antenna with one of the Universal Solder WWVB receiver boards?  They package the traditional short ferrite rod antenna in their kits.  This "WWVB Curtain" approach lends itself well to being hung in a Westward facing window.  The tiny receiver board would not tie up the SDR device when a time standard is the goal.

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

Ian DXer
 

On Sun, Mar 15, 2020 at 09:05 PM, prog wrote:
Use hfplus_ppb.exe and a real calibrated signal generator. We have been discussing this for years.
I couldn't recall mention & usage of hfplus_ppb.exe & only really find it's usage mentioned once in msg#30767 when searching the messages.
I see the file in firmware package. Any videos showing usage for interest sake?
I used debug mode 1 to change clk as per earlier advisement if needed. Some of the early units weren't calibrated as well
as they should have been I thought I recall some saying in past & offsets lost during firmware upgrades etc.
A real calibrated signal generator would be nice to have, but all precision test equipment needs regular & probable expensive calibration too...
Anyway...I understand you don't want others getting themselves in trouble, especially when not needed with recent units etc..

>Another MW Offset DX chaser ;-)
Hi Patrick,
Not really. I find studying these local MW xband offsets exhausting :-)
Just a useful tool with Spectrum Lab etc for keeping a tab on the local band re changes here for others to benefit from.
Thanks for your interesting comments.
Cheers

Ian




Re: Experimenting with Frequency Alignment with HF+ DP/SDR# & Leo Bodnar Mini GPS Clk

prog
 

On Sun, Mar 15, 2020 at 11:53 AM, Ian DXer wrote:
Setup was using the above with sample rate of SDR# initially set to 16kbps
Everything past this step is wrong. Do not use low-IF for calibration. Either you know the IF offset and compensate for it or leave the factory calibration as is. 

Experimenting with Frequency Alignment with HF+ DP/SDR# & Leo Bodnar Mini GPS Clk

Ian DXer
 

The purpose of this exercise was to determine what if any variation in frequency alignment occurs with the Airspy HF+ DP when used with SDR# R1732 & a Leo Bodnar Mini Precision GPS Reference Clock as a reference signal over a wide range of frequencies.

Setup was using the above with sample rate of SDR# initially set to 16kbps
Various frequencies were samples from 258MHz down to 63MHz, mostly in 10MHz steps & then from 30MHz down to 1MHz mostly in 5MHz steps to 5MHz, then 1MHz steps from 5-1MHz, further 100kHz steps from 1.9 to 1.1MHz & so on. The 9kHz step MW xband frequencies were also used. More later.

Nominal earlier calibrated frequency was 248MHz, but returning home later this drifted up to +0.2Hz.

Results:
1st column is the signal reference frequency. 2nd column is the SDR# offset freq. as displayed & measured in IF spectrum (ref. Zoom FFT)
258MHz +1.9Hz
250      +1.8
248      +0.2
240      +0.7
230      -1.2
220      -4.0
210      -1.1
200      +3.0
190      +0.2
180      -1.1
170      -3.9
160      -0.8
150      -2.2
140      +1.9
130      -2.2
120      +0.9
110      +0.3
100      +0.6
  90      +0.6
  80      +0.6
  70      +0.7
  65      -1.1
  64      +0.6
  63      +0.1
  30      -0.4
  25      +0.6
  20      +0.5
  15      +0.4
  10      +0.3
    5      +0.2
    4      +0.3
    2      +0.6
 1.9      +0.3
 1.8      +0.1
 1.7      +0.8
 1.6      +0.6
 1.5      +0.2
 1.4      +0.9
 1.3      +0.6
 1.2      +0.3
 1.1      +0.1
 1.0      +0.8

The MW xband 9kHz channels were also checked with results again for 16kbps sample rate.

1.611  +0.6Hz
1.620  +0.6Hz
1.629  +0.6Hz
1.638  +0.6
1.647  +0.6
1.656  +0.6
1.665  +0.6
1.674  +0.7
1.683  +0.7
1.692  +0.7
1.701  +0.8

Interesting when I changed the sample rate to 384kbps I achieved more accurate frequency alignment for most of the xband channels. Results below.

1.611  +0.6Hz
1.620  -0.3Hz
1.629  -0.3Hz
1.638  -0.3Hz
1.647  -0.2Hz
1.656  -0.2Hz
1.665   -0.2Hz
1.674   -0.2Hz
1.683   -0.2Hz
1.692   -0.1Hz
1.701   -0.1Hz
with this sample rate the carrier traces of my rxer now closely match the better aligned remote KIWI SDRers. Either way now knowing the measured offsets of my rxer I can compensate for future carrier offset measurements with xband mw stations.

As an exercise I tried aligning the HF+ to an mw xband channel, but this was a waste of time as almost 200ppb CLK steps were required to gain the slightest movement in frequency alignment. Hence as previously advised in this forum calibrate your SDR to the highest known precision frequency possible is the best advice to maintain best frequency calibration accuracy across the widest frequency range. (NB altering the freq calibration CLK for MW would have greatly effected frequency alignment in the upper frequencies, - don't do it!)

As previously advised in this forum don't touch the frequency calibration unless you know what you're doing. And don't touch it unless it can be improved on or you need to.

In summary; the  Leo Bodnar Mini Precision GPS Reference Clock is a great tool in both precisely aligning your SDR (if it ever needed doing) & for also checking your frequency alignment for a given frequency or range of frequencies for a given sample rate with SDR#.
Very simple to use too.
Helped me gain a better picture of my own SDR's alignment on the xband & helped me determine which of the regional remote SDR's were frequency calibrated/aligned correctly. A worthwhile exercise & investment.

NB the above are my results & may not be typical, others might gain entirely different results.

73s

Ian

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

prog
 

On Sun, Mar 15, 2020 at 11:33 AM, Patrick wrote:
Then why does my unit always read +1Hz when comparing - in real time - the same MW carriers - with people who run properly calibrated SDR (Perseus, G31, G33, etc) using a signal generator ?  
Poor understanding of receiver architechtures.
Use Zero IF and tune near the center. 

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

Patrick
 

Then why does my unit always read +1Hz when comparing - in real time - the same MW carriers - with people who run properly calibrated SDR (Perseus, G31, G33, etc) using a signal generator ?  


Le dim. 15 mars 2020 à 11:05, prog <info@...> a écrit :
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

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