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panadapter RTL-SDR IC-756pro2


iz1fks
 
Edited

Hello,

I have set up here a panadapter with ic-756pro2, with the RTL-SDR on the 1st IF freq.

I have a few issues: when I'm changing frequency with the radio vfo the spectrum and waterfall are freezed and start again only after vfo is stopped. In other word no spectrum and waterfall update during vfo knob rotation.
This behaviour appers only with bit SDR=>radio and RADIO=>SDR frequency tracking. If I disable SDR=>radio tracking spectrum is always updated during vfo rotation seeing signals moving left and right according to vfo. In this way I miss the function point and click to tune the radio. I have also noticed that without SDR=>radio tracking active at the software start sometimes trcking with the IF frequency is not corrected and RTL-SDR is not tuned at the right frequency.
If anybody is using a pandapter in this way can tell me if this behaiour is noticed.
I think that with CAT connection in panadapter mode the frequency bar under the spectrum/waterfall should be always updated tracking the radio VFO without interfering with spectrum/waterfall that now is freezing, while an option button shuold be available to disable the point and click function that change the frequency on the rig.

73 de Phil,iz1fks


iz1fks
 

nobody use the panadapter function?


iz1fks
 
Edited

unfortunately I cannot solve the issue even with the new release.

with following settings no frequency bar update in spectrum / waterfall:


with these settings (click on waterfall to change rtx vfo frequency) freeze of the spectrum / waterall during rtx VFO manual rotation:


73 de Phil, iz1fks


iz1fks
 

tested with latest release 3.0.21, unfortunately the annoying behaviour during radio vfo rotation is still there on the spectrum. the update looks slow and not fluid at all. I don't understand the reason since using for example qo-100 upconverter feature moving the radio vfo the receive frequency on the sdr is really very good.

anyone using sdr console as panadapter on extarnal radio IF can check this behaviour?

thanks

73 de Phil, iz1fks


jdow
 

I don't remember you ever citing what aspect of the radio looks or sounds slow to you. I do not even know if you are tuning an RX or the front end. There are many things that may make the receiver be perceived as tuning slowly, particularly in the spectrum/waterfall display.

Be specific about what irritates you. Then maybe we can help or tell you it is a feature of your front end or something like that.

{^_^}

On 20200323 06:01:28, iz1fks wrote:
tested with latest release 3.0.21, unfortunately the annoying behaviour during radio vfo rotation is still there on the spectrum. the update looks slow and not fluid at all. I don't understand the reason since using for example qo-100 upconverter feature moving the radio vfo the receive frequency on the sdr is really very good.
anyone using sdr console as panadapter on extarnal radio IF can check this behaviour?
thanks
73 de Phil, iz1fks


iz1fks
 

thank you for your reply, I try to describe the behaviour in more detail.

my setup:
SDR console 3.0.21
RTL-SDR
ICOM IC-756pro2 with cat control rs232, serial speed 19200bd

RTL-SDR is connected to the first IF tap of the rig (64.455 MHz).

external radio setting:





Using these setting frequency display in sdr console shows the frequency of the rtx vfo in the right way changing smoothly while rotating the vfo on the rig. the frequency display below the spectrum view is correct.
Unfortunately the spectrum is not updating smoothly as the frequency display while vfo is being rotated, but with a serius lag.

If I disable the SDR=>Radio tracking in the external radio configuration tab, the frequency indication in the main receive window of sdr console is lost as well as the frequency scale below the spectrum, but the spectrum is refreshed very quickly.

I have tried to perform a test simulating QO-100 satellite operation using the external rig set with upconverter function for tx uplink in external radio tab, and the RTL-SDR set as direct antenna insted of IF output. Here every thing is working fine the spectrum i smoothly updated accoring to rtx tx vfo changing, so I think the issue should be about IF output setting with SDR=>Radio tracking.

I hope the behaviour could be a little better detailed now, I don't know if a video could be uploaded here, it will be very easy to understand.

73 de Phil, iz1fks


jdow
 

(facepalm)
I've written a long reply to you about how delays come about in the software. The longest delays appear in the spectrum generation process. The more detail in the spectrum the more samples go into creating it. If you want say 1Hz resolution it will take as much as two seconds to generate that spectrum. That cannot be shortened except by reducing resolution. (The ProII resolution is VERY low (very few and wide bins). SDRC does not go down there.

So you are going to have to live with it.
{^_^}

On 20200325 06:16:57, iz1fks wrote:
[Edited Message Follows]
thank for your reply, I try to describe the behaviour in more detail.
my setup:
SDR console 3.0.21
RTL-SDR
ICOM IC-756pro2 with cat control rs232, serial speed 19200bd
RTL-SDR is connected to the first IF tap of the rig (64.455 MHz).
external radio setting:
Using these setting frequency display in sdr console shows the frequency of the rtx vfo in the right way changing smoothly while rotating the vfo on the rig. the frequency display below the spectrum view is correct.
Unfortunately the spectrum is not updating smoothly as the frequency display while vfo is being rotated, but with a serius lag.
If I disable the SDR=>Radio tracking in the external radio configuration tab, the frequency indication in the main receive window of sdr console is lost as well as the frequency scale below the spectrum, but the spectrum is refreshed very quickly.
I have tried to perform a test simulating QO-100 satellite operation using the external rig set with upconverter function for tx uplink in external radio tab, and the RTL-SDR set as direct antenna insted of IF output. Here every thing is working fine the spectrum i smoothly updated accoring to rtx tx vfo changing, so I think the issue should be about IF output setting with SDR=>Radio tracking.
I hope the behaviour colud be a little better detailed now, I don't know if a video could be uploaded here, it will be very easy to understand.
73 de Phil, iz1fks


iz1fks
 

sorry I haven't read anything from you about delays, where is it? I think there is a misunderstanding here.
I don't understand in which way proII resolution is related, I'm receiving at the IF port, sampling rf with RTL-SDR.
I attach a video here where it can be seen that the issue is about the panadapter function with SDR=>Radio tracking activated.
With tracking function disactivated the spectrum is very good.

73 de Phil, iz1fks


jdow
 

You are used to the speed of the very coarse ProII built in panadaptor. It is very coarse so it takes very little time to accumulate enough data to show a completely fresh spectrum as the incoming signals change. SDRC generally runs with a longer term FFT, which requires a longer time to get the new data to show a new FFT. The dongle interface itself is also causing your problems. The rtlsdr interfaces generally run with large chunks of data for data transfer efficiency.

I bet you are mistakenly running the rtlsdr dongle at 250 kHz sample rate. The rtlsdr dongle requires a minimum buffer size of 16k samples. One buffer is a minimum of 64 ms of delay, long enough to notice and be annoyed with it. I don't remember how many buffers are cascaded into one transfer with the SDRC tool. I tried to refresh my couple years old memory on this - it looks like Simon's calls to "ReadSamples()" typically ask for 65536 samples. This would be about 4 times 64 ms or a whole quarter second.

Could this plus the FFT time contribute to your feeling that it's slow and lagging?

{^_^}

On 20200326 06:06:37, iz1fks wrote:
sorry I haven't read anything from you about delays, where is it? I think there is a misunderstanding here.
I don't understand in which way proII resolution is related, I'm receiving at the IF port, sampling rf with RTL-SDR.
I attach a video here where it can be seen that the issue is about the panadapter function with SDR=>Radio tracking activated.
With tracking function disactivated the spectrum is very good.
73 de Phil, iz1fks
Attachments:
* panadapter_video.mp4 <https://SDR-Radio.groups.io/g/main/attachment/54708/0>


iz1fks
 
Edited

I'm not doing any comparison with the 756pro2 built in panadaptor, it does not make sense.

I'm doing comparison inside sdr console using the same RTL-SDR (tried also at 2.4M) in panadapter mode with or without the SDR=> RADIO tracking function activated as visible in the attached video.

The spectrum from the RTL-SDR is okay, the issue appears ONLY when activating the SDR=>RADIO tracking that is fundamental for panadapter function.

using the setup for qo-100 with SDR=>RADIO and RADIO=>SDR tracking rtl-sdr from external radio vfo used in tx with upconverter function (and not using IF) behaviour looks very fine.


jdow
 

I give up. I tried.
{+_+}

On 20200326 08:32:23, iz1fks wrote:
I'm not doing any comparison with the 756pro2 built in panadaptor, it does not make sense.
I'm doing comparison inside sdr console using the same RTL-SDR (tried also at 2.4M) in panadapter mode with or without the SDR=> RADIO tracking function activated as visible in the attached video.
The spectrum from the RTL-SDR is okay, the issue is ONLY activating the SDR=>RADIO tracking that is fundamental for panadapter function.
using the setup for qo-100 with tracking rtl-sdr from external radio used in tx with upconverter function (and not using IF) anything is very fine


jdow
 

(Apparently this was stuck on your machine for several days....)

So you are changing the tuned frequency for the radio and there is a pause while you are tuning the radio. This is mildly ambiguous to me. Is the display still running but not showing updated data? (That was my interpretation.) Or are you saying that drawing the display pauses until tuning stops?

And very roughly how long is "objectionable."

If the display keeps running but the data is stale this may be unavoidable. The display can lag due to the time the FFT takes to calculate and how long it takes for new data to even reach the FFT calculation. If objectionable is in the 10 ms to 100 ms range for new data to reach the screen as you tune but the display is still updating normally, I am afraid you're stuck with it if reducing "Resolution" on the View menu to "Standard" is not sufficient. Also set the dongle to 2.4 MHz sample rate. If it is longer than that then there is a problem.

If the display completely update stops while you are tuning then Simon has a problem to fix.

{^_^}

On 20200326 08:32:23, iz1fks wrote:
[Edited Message Follows]
I'm not doing any comparison with the 756pro2 built in panadaptor, it does not make sense.
I'm doing comparison inside sdr console using the same RTL-SDR (tried also at 2.4M) in panadapter mode with or without the SDR=> RADIO tracking function activated as visible in the attached video.
The spectrum from the RTL-SDR is okay, the issue appears ONLY when activating the SDR=>RADIO tracking that is fundamental for panadapter function.
using the setup for qo-100 with SDR=>RADIO and RADIO=>SDR tracking rtl-sdr from external radio vfo used in tx with upconverter function (and not using IF) behaviour looks very fine.


iz1fks
 

>So you are changing the tuned frequency for the radio and there is a pause while you are tuning the radio.

yes, there is a pause on the spectrum/waterfall display only, as visible in the video recording that I posted.

>Is the display still running but not showing updated data?

Yes, of course. The software is running and video display updated. Only the spectrum/waterfall is paused, as visible in the video recording that I posted.

IMHO FFT is not relevant at all about this issue. The issue apperas ONLY when CAT SDR=>RADIO tracking is activated. Without SDR=>radio tracking the spectrum-waterfall is perfect (on the waterfall/spectrum frequency axis update is not available of course)

As previously explained, in order to check there is not a problem about CAT communication and update with radio I have simulated a QO-100 setup, with ic-756P2 as IF for a 13cm upconverter. In this configuration everything is ok, moving the radio vfo the RTL-SDR receving at 739MHz is tuned accordingly with the frequency offset set in the relevant configuration box.

73


iz1fks
 

no news in 3.0.22, same behaviour and issue like in previous release


M0ZEH <m0zeh@...>
 

Is your sound card set to 48khz,16 bit?
Thanks Steve m0zeh 


iz1fks
 

sorry, I haven't understood the question. i'm not using soundcard but RTL-SDR dongle as receiver. I cannot see any link between soundcard setting and CAT tracking.

73 de Phil,iz1fks


iz1fks
 

I cannot understand where the issue is. Nobody is using panadapter with track CAT function?

73 de Phil,iz1fks


Nathan
 

I am running v3.0.22 with CAT tracking and the IF set for an External Radio (panadapter on 1st IF).

SDR is an SDRPlay RSP1A.

For me it slows down a bit when I tune with the radio dial but doesn't stall anything like yours. I suspect the issue is either the latency issue jdow described or a PC performance issue.

What is your CPU doing during this time? Is one of the SDR Console threads maxing out a core?


iz1fks
 

Thanks Nathan for your feedback.
rsp1a is sure far better than rtl-sdr and the issue is probably related with rtl-sdr use.

So do you not see difference monitoring IF with External Radio with or without CAT tracking? 
I'm asking since I have the issue only with cat tracking activated, and I cannot think that it could overload the pc.
Anyway I'm running a Xeon E5450 @3GHz quad core with 8 GB ram win7 x64.

73 de Phil


iz1fks
 

same problem still present in latest version.
tracking CAT SDR=> Radio look not to update the waterfall during vfo rotation.
73 de Phil,iz1fks