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Filter width issue with self made filter #sdrconsolev3

Ben Z en de rest
 

Hi,
Today a new type of radiosonde was launched. Not much specifications available, GFSK modulation, and approx 80 kHz bandwidth.

The maximum filterwidth for WFM (not BFM) in SDR console V3 is 40 kHz and I did not want to use the BFM mode.

So, I added a WFM filter with a bandwidth of 120 kHz, which appeared nicely in the filters. When receiving, I can choose this filter and the software switches to the choosen bandwidth. However, trying to narrow the filter down to a bit narrower it jumps directly to 48 kHz and can not be adjusted between 120 kHz and 48 kHz. Is this something I need to change in my selfmade filter definition ?

I added 2 screenshots, one is after selecting the self defined filter and the other one is what happens if I try to drag the filter bandwidth to anything narrower.

Thanks,

Ben - PE2BZ

Simon Brown
 

The maximum width in WFM is 48kHz.

 

BFM will be useless here.

 

Do you really need 120kHz? Can you get me a link with info about this Radiosonde?

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Ben Z en de rest
Sent: 09 September 2019 19:10
To: main@SDR-Radio.groups.io
Subject: [SDR-Radio] Filter width issue with self made filter #sdrconsolev3

 

Hi,
Today a new type of radiosonde was launched. Not much specifications available, GFSK modulation, and approx 80 kHz bandwidth.

The maximum filterwidth for WFM (not BFM) in SDR console V3 is 40 kHz and I did not want to use the BFM mode.

So, I added a WFM filter with a bandwidth of 120 kHz, which appeared nicely in the filters. When receiving, I can choose this filter and the software switches to the choosen bandwidth. However, trying to narrow the filter down to a bit narrower it jumps directly to 48 kHz and can not be adjusted between 120 kHz and 48 kHz. Is this something I need to change in my selfmade filter definition ?

I added 2 screenshots, one is after selecting the self defined filter and the other one is what happens if I try to drag the filter bandwidth to anything narrower.

Thanks,

Ben - PE2BZ

Ben Z en de rest
 

Hi Simon,
the link: http://windsond.com/ 
I made a decimator file of my recording, centered at 402.800 MHz, from which I attacht a screenshot playing back with console V2 with 96 kHz bandwidth. That fits, but I have seen sondes with over 100 kHz also.

I can share a link to 15 minutes of IQ recording, from my local cloud. 
http://gofile.me/35mDS/AE3aSEC8e which is at a reasonable fiber speed . 540 MB 

No decoder available yet ;-) GFSK is all that I know till now.

Ben, PE2BZ

Simon Brown
 

Ben,

 

Are you sure it’s FM modulation? Thinking about this, I’ll have all sorts of problems – my internal audio processing is at 48kHz so this would be a problem.

 

The links you have me didn’t tell me much about the modulation.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Ben Z en de rest
Sent: 09 September 2019 20:08
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Filter width issue with self made filter #sdrconsolev3

 

Hi Simon,
the link: http://windsond.com/ 
I made a decimator file of my recording, centered at 402.800 MHz, from which I attacht a screenshot playing back with console V2 with 96 kHz bandwidth. That fits, but I have seen sondes with over 100 kHz also.

I can share a link to 15 minutes of IQ recording, from my local cloud. 
http://gofile.me/35mDS/AE3aSEC8e which is at a reasonable fiber speed . 540 MB 

No decoder available yet ;-) GFSK is all that I know till now.

Ben, PE2BZ

Ben Z en de rest
 

Hi Simon,
No, I have no clue about the transmitted modulation. The spec sheet shows GFSK and till now, yesterday the first sonde of that type flew in the Netherlands, I did not hear of it.before. They appear to have been flying from Amsterdam to measure the air and compare 0 - 500 m altitude in main town and on rural area but those transmitted in the ISM 434 MHz band and where impossible to detect.

But for the moment it does play back in V2 so do not bother to much. 

Ben, PE2BZ