Date   

Re: More Spyservers to play with. #spyserver

Martin - G8JNJ
 

Hi All,

I notice that (not surprisingly) my HF spyserver is suffering a this evening from the very strong shortwave broadcast stations we  experience in Europe. An SDR Play RSP1 I once had didn't like the strong signals either, so the dongle is holding up quite well in comparison.

Tomorrow as a further experiment I'll split the signal into two separate bands (at around 14.4MHz) and run it across two Spyservers.

Regards,

Martin - G8JNJ


Re: Direct Sampling frequency limit in r 1628 onwards #sdrsharp #spyserver

Kenneth Sejkora
 

Based on the revision log, it looks as though build 1627 was the last version of SDRSharp available before the 14.4 MHz ceiling was implemented in direct sampling mode.  As Martin points out, there are situations where it might be advantageous to at least have the option to run a dongle in direct sampling mode in the 14.4 to 28.8 MHz range as opposed to being forced to use quadrature sampling in this frequency range.  I totally respect Youssef's desire to implement the 14.4 MHz ceiling for the technical reasons he stated, but for an end user the option to exceed the ceiling should also be respected and left up to the user.  The user can 'assume' the negative consequences of operating direct sampling in the 14.4 to 28.8 MHz frequency range. However, at least for now, SDRSharp is freeware and Youssef has every right to call the shots.

Although it circumvents any improvements that might be afforded by new revisions to SDRSharp, it might behoove anyone that wants the option of using direct sampling in the 14.4 to 28.8 MHz range to obtain a copy of build 1627 to at least have the option of using that range of frequencies in either direct sampling or quadrature mode.  Not the best "fix", but a workable one.  Fortunately, I still have the Zip file for build 1627, and can maintain that version as a separate installation for whenever I need to use direct sampling above 14.4 MHz.

Ken, WBØOCV Norton, MA USA
41.959546N, 71.163996W  FN41kx



From: Martin via Groups.Io <martin_ehrenfried@...>
To: main@airspy.groups.io
Sent: Friday, November 24, 2017 9:36 AM
Subject: Re: [airspy] Direct Sampling frequency limit in r 1628 onwards #sdrsharp #spyserver

Hi Joanne,

Yesterday I tried to setup three concurrent FT8 decode sessions on 24MHz in order to test the receive performance of an Airspy R1, generic 820T2 dongle and RTL SDR V3 in direct sampling mode.

Unfortunately the propagation gods were not favourable and I discovered a few other issues, so today I connected them up to my tes tkit to try and figure out what was going on.

First the maximum sensitivity I could obtain for each type. These were measured using plain carrier and USB in a 2400KHz BW. The generator output was adjusted to obtain 10dB SINAD at 27MHz. Note my generator and attenuators may not be fully in calibration, but I used the same setup for each test, so I'm comparing like with like.

Airspy R1 = -122dBm (Gain setting in free mode 10/10/15)

Airspy Mini = -117dBm (Gain setting in free mode 10/10/15)

Generic 820T2 = -119dBm (Gain setting 49.6)

RTL SDR V3 Quadrature = -118dBm (Gain setting 49.6)

RTL SDR V3 Direct Sampling = -107 (No gain adjustment)

So in theory the Quadrature mode seems to offer about 10dB better sensitivity than when used in Direct Sampling mode.

However when I connected an antenna to the various SDR's using the maximum gain settings they all showed signs of overload and IMD products, apart from the V3 in Direct Sampling mode.

In each case I adjusted the gain settings until the overload and IMD products just disappeared and then remeasured the sensitivity with the new gain settings.

Airspy R1 = -116dBm (Gain setting in free mode 10/10/6)

Airspy Mini = -115dBm (Gain setting in free mode 10/10/9)

Generic 820T2 = -112dBm (Gain setting 29.7)

RTL SDR V3 Quadrature = -111dBm (Gain setting 29.7)

RTL SDR V3 Direct Sampling = -107 (No gain adjustment)

So now the difference is only 8dB best case (Airspy Mini) and is typically only 4dB (Generic 820T2 and RTL SDR V3)

In practice these figures could be improved by placing bandpass filters ahead of the SDR's but I just wanted to test their basic out of the box performance.

Other observations:-

All the dongle sensitivities remained fairly consistent across their frequency ranges.

When using Quadrature mode non of the dongles locked consistently below 24MHz. The 820T2  would not go below 24MHz, the Airspy R1 occasionally manged it down to 19MHz and the Airspy Mini would normally only lock down to about 25MHz. I could sometimes see a signal but it was not on the correct frequency (usually 1-1.5MHz low) So if you have it connected to an antenna you may think you are seeing signals below 24MHz, but they may not be on the correct frequency.

There is no mechanism to receive signals between 14.4MHz and 24MHz using Quadrature mode. Direct Sampling does work up to about 27MHz but above this frequency the 28.8MHz clock oscillator causes very high level unwanted noise spikes.

When using the RTL SDR V3 in Direct Sampling mode the sensitivity is typically -107dBm from 2MHz to 25MHz. It falls outside these limits as the Bias tee inductor and input diplexer add additional losses. This permits good reception on most bands up to about 20MHz (with a suitable antenna) and is only limited by the natural atmospheric noise floor. Reception is still adequate on higher frequencies up to about 27MHz, especially in urban areas where the noise floor is likely to be higher.

The RTL SDR V3 in Direct Sampling mode does have Nyquist Alias signals wrapped around 14.4MHz (1/2 of 28.8MHz sample rate). This results in signals appearing twice (one the correct frequency and one unwanted on the Nyquist image). Most of these can be removed by adding a simple high / low / Diplexing filter or if only certain frequency ranges are of interest a band pass filter.

This is why like to have the option of being able to use the Direct Sampling mode between 14.4MHz and 27MHz.

Regards,

Martin - G8JNJ



More Spyservers to play with. #spyserver

Martin - G8JNJ
 
Edited

Hi All,

A couple from me for you to play with until I re-purpose the hardware.

sdr://g8jnj.zapto.org:5557 - RTL SDR V3 in direct sampling mode 0-28MHz (Spyserver 1624) using whatever antenna is currently selected on my KiWi WEB SDR http://southwest.ddns.net:8073/

sdr://g8jnj.zapto.org:5558 - Airspy R1 100-500MHz using VHF /UHF white stick colinear

Located up a hill in the West Country of the UK - 50km South of Bristol



Regards,

Martin - G8JNJ


Re: Direct Sampling frequency limit in r 1628 onwards #sdrsharp #spyserver

Martin - G8JNJ
 

On Fri, Nov 24, 2017 at 08:31 am, David J Taylor wrote:
Thanks for your report, Martin. For the reasons you state, I guess you will already have an Airspy HF+ on order!
Ha maybe :-)

Although I'm quite happy with my KiWi SDR's, so perhaps not just yet, I like to let designs settle down a bit first and the early adopters to be the Beta testers for me....

The particular application I had in mind for the cheap dongles requires something to be as low cost as possible, almost a throw away item. It only needs to be good enough for the purpose.

Judging from the woeful performance of many existing WEB SDR's etc. I suspect that only a few folks will have a good enough antenna system and low enough noise floor to be able to take full advantage of the sensitivity and dynamic range of the HF+. 

In many cases these days an 'average' performance receiver is probably good enough. Although that still shouldn't stop us striving for the best performance possible to deal with 'edge cases'

Regards,

Martin - G8JNJ


Re: Direct Sampling frequency limit in r 1628 onwards #sdrsharp #spyserver

David J Taylor
 

Hi Joanne,
[]
This is why like to have the option of being able to use the Direct Sampling mode between 14.4MHz and 27MHz.

Regards,
Martin - G8JNJ
=====================================

Thanks for your report, Martin. For the reasons you state, I guess you will already have an Airspy HF+ on order!

73,
David GM8ARV
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv


Re: Direct Sampling frequency limit in r 1628 onwards #sdrsharp #spyserver

Martin - G8JNJ
 
Edited

Hi Joanne,

Yesterday I tried to setup three concurrent FT8 decode sessions on 24MHz in order to test the receive performance of an Airspy R1, generic 820T2 dongle and RTL SDR V3 in direct sampling mode.

Unfortunately the propagation gods were not favourable and I discovered a few other issues, so today I connected them up to my test kit to try and figure out what was going on.

First the maximum sensitivity I could obtain for each type. These were measured using plain carrier and USB in a 2400KHz BW. The generator output was adjusted to obtain 10dB SINAD at 27MHz. Note my generator and attenuators may not be fully in calibration, but I used the same setup for each test, so I'm comparing like with like.

Airspy R1 = -122dBm (Gain setting in free mode 10/10/15)

Airspy Mini = -117dBm (Gain setting in free mode 10/10/15)

Generic 820T2 = -119dBm (Gain setting 49.6)

RTL SDR V3 Quadrature = -118dBm (Gain setting 49.6)

RTL SDR V3 Direct Sampling = -107 (No gain adjustment)

So in theory the Quadrature mode seems to offer about 10dB better sensitivity than when used in Direct Sampling mode.

However when I connected an antenna to the various SDR's using the maximum gain settings they all showed signs of overload and IMD products, apart from the V3 in Direct Sampling mode.

In each case I adjusted the gain settings until the overload and IMD products just disappeared and then remeasured the sensitivity with the new gain settings.

Airspy R1 = -116dBm (Gain setting in free mode 10/10/6)

Airspy Mini = -115dBm (Gain setting in free mode 10/10/9)

Generic 820T2 = -112dBm (Gain setting 29.7)

RTL SDR V3 Quadrature = -111dBm (Gain setting 29.7)

RTL SDR V3 Direct Sampling = -107 (No gain adjustment)

So now the difference is only 8dB best case (Airspy Mini) and is typically only 4dB (Generic 820T2 and RTL SDR V3)

In practice these figures could be improved by placing bandpass filters ahead of the SDR's but I just wanted to test their basic out of the box performance.

Other observations:-

All the dongle sensitivities remained fairly consistent across their frequency ranges.

When using Quadrature mode none of the dongles locked consistently below 24MHz. The 820T2  would not go below 24MHz, the Airspy R1 occasionally manged it down to 19MHz and the Airspy Mini would normally only lock down to about 25MHz. I could sometimes see a signal but it was not on the correct frequency (usually 1-1.5MHz low) So if you have it connected to an antenna you may think you are seeing signals below 24MHz, but they may not be on the correct frequency.

There is no mechanism to receive signals between 14.4MHz and 24MHz using Quadrature mode. Direct Sampling does work up to about 27MHz but above this frequency the 28.8MHz clock oscillator causes very high level unwanted noise spikes.

When using the RTL SDR V3 in Direct Sampling mode the sensitivity is typically -107dBm from 2MHz to 25MHz. It falls outside these limits as the Bias tee inductor and input diplexer add additional losses. This permits good reception on most bands up to about 20MHz (with a suitable antenna) and is only limited by the natural atmospheric noise floor. Reception is still adequate on higher frequencies up to about 27MHz, especially in urban areas where the noise floor is likely to be higher.

The RTL SDR V3 in Direct Sampling mode does have Nyquist Alias signals wrapped around 14.4MHz (1/2 of 28.8MHz sample rate). This results in signals appearing twice (one the correct frequency and one unwanted on the Nyquist image). Most of these can be removed by adding a simple high / low / Diplexing filter or if only certain frequency ranges are of interest a band pass filter.

This is why like to have the option of being able to use the Direct Sampling mode between 14.4MHz and 27MHz.

Regards,

Martin - G8JNJ


Re: Airspy HF+

prog
 

On Thu, Nov 23, 2017 at 03:53 pm, jdow wrote:
They are indeed good to work with.

And it's time for some Thanksgiving so, thanks to Youssef and crew for their excellent work.

And a Happy Thanksgiving to all. Even if you don't celebrate it the way we do here in the colonies it is nice to sit back and reflect one a year on all the things for which we should be thankful in our lives.

{^_^} Joanne Dow
I like the concept. So, thank you all for supporting and encouraging us to do what we do. Really appreciated.


Re: Airspy HF+

jdow
 

They are indeed good to work with.

And it's time for some Thanksgiving so, thanks to Youssef and crew for their excellent work.

And a Happy Thanksgiving to all. Even if you don't celebrate it the way we do here in the colonies it is nice to sit back and reflect one a year on all the things for which we should be thankful in our lives.

{^_^} Joanne Dow

On 2017-11-23 14:35, John K0CQW wrote:
https://airspy.com/purchase/
https://v3.airspy.us/
Airspy.us ships from the US to the *Americas* and offers other high quality services and products.
Airspy. us are very good to work with. Excellent communications.
Thanks de John KØCQW
On Thu, Nov 23, 2017 at 3:41 PM, va3aqb via Groups.Io <va3aqb=yahoo.ca@groups.io <mailto:va3aqb=yahoo.ca@groups.io>> wrote:
Where is the best place to by Airspy HF+ in Canada so somewhere
in USA  I’m guessing. I did see someone in HongKong selling. Anyone any links.
my wife and kids are buying me one for Chrismas. I have the SDRPLAY 1 I use
with my TS590SG and LP Panadapter with my FTDX3000. I really like the sound
of The Airspy HF+


Re: Airspy Mini calibrate #hardware

jdow
 

The ATSC.org data for testing ATSC signals for compliance mention 1kHz frequency accuracy of the pilot carrier and data rate stability that is even worse. Now, I am aware that some stations take pride in a precise channel frequency. This has long been the case for some channels. Way back in the early NTSC days you could use the color subcarrier as a frequency reference at precisely 63/88ths of 5 MHz. Then the stations were allowed to get sloppy and many did - just about the time it would have been easy to build such a reference for myself. Ah well.

{^_^}

On 2017-11-23 07:36, Greg Ella wrote:
Here in the United States the new Digital TV (ATSC) pilot tones are extremely accurate and stable.  They have to be, for the receiving television to demultiplex the signal.  I think they are locked to either GPS or a Rubidium standard.  The standard frequency of the pilot tone is 309.440559 KHz above the bottom of the channel.  However, if two stations are close enough to cause interference with each other on the same channel, one station may use a different pilot tone.  I think Wikipedia had some good information on this.
Greg Ella
AD0JP


Re: Airspy HF+

Alan Brown
 

Thanks I ordered 

VA3AQB 🇨🇦 
Alan

On Nov 23, 2017, at 6:00 PM, VE4NSA@... wrote:

Used registered mail.

As far as I know, units are not shipping yet. End of November, beginning December I guess.


Re: Airspy HF+

Joe M.
 

I did that (registered mail) and shipping took over 3 weeks from ITEAD.

If you want to compare the shipping rates, compare the expedited shipping which is what you get as standard from airspy.us

Not sure about Canada, but US expedited shipping costs about US$10 more from ITEAD. Maybe Canada has a deal with China for lower costs.

Not sure where "End of November" came from. All posts
are saying a target of the first week of December.

Joe M.

On 11/23/2017 6:00 PM, VE4NSA@Gmail.com wrote:
Used registered mail.

As far as I know, units are not shipping yet. End of November, beginning
December I guess.


Re: Airspy HF+

VE4NSA@...
 

Used registered mail.

As far as I know, units are not shipping yet. End of November, beginning December I guess.


Re: Airspy HF+

Alan Brown
 

Shipping looks like a good price, what method did you use? Any surprise charges?

VA3AQB 🇨🇦 
Alan

On Nov 23, 2017, at 5:41 PM, VE4NSA@... wrote:

By from Itead!

https://www.itead.cc/airspy-hf-plus.html

You save big time on shipping cost


Re: Airspy HF+

VE4NSA@...
 

By from Itead!

https://www.itead.cc/airspy-hf-plus.html

You save big time on shipping cost


Re: CPU load on single board Linux computers with 12 bit SDR? #hardware #spyserver

dl8ebm
 

Dear Jeff,

many thanks for the feedback and the real life access to your Tinker based receivers.

8 MHz is quite a stretch and it may run well for while and then stutters and loops, for this much bandwidth the Ordoid may be the right choice, though it is not yet proven if the application uses its full resources.
The direct sampling RTL-SDR on 5557 is behaving very well for the fact that the dynamic range is so limited.
I tried to decode the VDL2 on 136.975 (SatRX on 5556) but was unable to get the IF wide enough to pass along the audio to be decoded.
Then I switched to full IQ which would have worked if the server didn't start stuttering.
How do you decode your satellite data, which is also wider than traditional signals?
Maybe it started stuttering because your satellite decoders in real I/Q mode kept the machine busy already?
Impressive S/N on the satellites by the way!

Happy Thanksgiving
Joe


Re: Airspy HF+

John K0CQW
 

Airspy.us ships from the US to the Americas and offers other high quality services and products.

Airspy. us are very good to work with. Excellent communications.

Thanks de John KØCQW

On Thu, Nov 23, 2017 at 3:41 PM, va3aqb via Groups.Io <va3aqb@...> wrote:
Where is the best place to by Airspy HF+ in Canada so somewhere
in USA  I’m guessing. I did see someone in HongKong selling. Anyone any links.
my wife and kids are buying me one for Chrismas. I have the SDRPLAY 1 I use with my TS590SG and LP Panadapter with my FTDX3000. I really like the sound of The Airspy HF+



Re: CPU load on single board Linux computers with 12 bit SDR? #hardware #spyserver

prog
 

On Thu, Nov 23, 2017 at 02:17 pm, <weird_joe@...> wrote:
Thanks so much for this comprehensive feedback, it really gives me a very good idea for what I can do and what to not invest in / try.

The Tinker is much cheaper than the octa core Odoids, where I may also have to build my own metal case ... so I will decide for the slightly less powerful Tinker with a standard Pi metal case with fan and heat sinks and I should be good to go.
I will let you know if I find a powerful low noise supply - will probably build a powerful one with a toroidal transformer and traditional regulation, swapping noise for heat, and run all my USB devices across one single clean unit.
The hint with the command line server call with its specific config is making life very convenient, especially when updating.

Happy Thanksgiving everyone
Joe
Happy Thanksgiving, Joe.


Airspy HF+

Alan Brown
 

Where is the best place to by Airspy HF+ in Canada so somewhere
in USA  I’m guessing. I did see someone in HongKong selling. Anyone any links.
my wife and kids are buying me one for Chrismas. I have the SDRPLAY 1 I use with my TS590SG and LP Panadapter with my FTDX3000. I really like the sound of The Airspy HF+


Re: CPU load on single board Linux computers with 12 bit SDR? #hardware #spyserver

dl8ebm
 

Thanks so much for this comprehensive feedback, it really gives me a very good idea for what I can do and what to not invest in / try.

The Tinker is much cheaper than the octa core Odoids, where I may also have to build my own metal case ... so I will decide for the slightly less powerful Tinker with a standard Pi metal case with fan and heat sinks and I should be good to go.
I will let you know if I find a powerful low noise supply - will probably build a powerful one with a toroidal transformer and traditional regulation, swapping noise for heat, and run all my USB devices across one single clean unit.
The hint with the command line server call with its specific config is making life very convenient, especially when updating.

Happy Thanksgiving everyone
Joe


locked Black Friday Offer #airspy

prog
 

Black Friday Discount on a selection of Airspy products at ITead studio: #AirspyR2, #AirspyMini and #SpyVerter

https://www.itead.cc/search/result/?cat=&q=airspy

Use this coupon on your cart: AIRSPYBLACK

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