[OZAPRS] Doppler graph

[Glen English VK1XX]

Andrew

hint

whether it is of use depends on if the FM demodulator is receiving
distorted data.

This might happen if the signal was not centred in the filter passband.
Filters are never flat and if you are 'off one side' then the upper and
lower sidebands of the FM signal will be different and the demodulated
result will be distorted..

Also, some FM demods are only linear when the signal is centred

anyway, see what you come up with.


On 20/11/2017 6:28 PM, vk4tec at tech-software.net wrote:
>
> Thanks for your help
>
>  
>
> I am trying to show the pass band of my radio with the doppler
>
>  
>
> To show wether or not a system benefits from doppler shift
>
>  
>
> I need to do falconsat-3 as well
>
>  
>
> A
>
>  
>
> *From:*OZAPRS [mailto:ozaprs-bounces at aprs.net.au] *On Behalf Of *Mark
> Jessop
> *Sent:* Monday, 20 November 2017 5:24 PM
> *To:* Australian APRS Users <ozaprs at aprs.net.au>
> *Subject:* Re: [OZAPRS] Doppler graph
>
>  
>
> I didn't know what to send back either.
>
>  
>
> So I just read the man page for rigctld, which told me all I needed to
> know: http://manpages.ubuntu.com/manpages/zesty/man8/rigctld.8.html
>
>  
>
> 73
>
> Mark VK5QI
>
>  
>
> On Mon, Nov 20, 2017 at 5:46 PM, <vk4tec at tech-software.net
> <mailto:vk4tec at tech-software.net>> wrote:
>
>     Legend
>
>      
>
>     I did not know what to send back
>
>      
>
>     Cheers
>
>      
>
>     A
>
>      
>
>      
>
>     *From:*OZAPRS [mailto:ozaprs-bounces at aprs.net.au
>     <mailto:ozaprs-bounces at aprs.net.au>] *On Behalf Of *Mark Jessop
>     *Sent:* Monday, 20 November 2017 5:07 PM
>
>
>     *To:* Australian APRS Users <ozaprs at aprs.net.au
>     <mailto:ozaprs at aprs.net.au>>
>     *Subject:* Re: [OZAPRS] Doppler graph
>
>      
>
>     Gpredict is expecting to talk to a Hamib rigctld daemon, and will
>     likely be unhappy if it does not get back the responses it expects.
>
>     So, to get frequency data from gpredict, you would need to write
>     something which emulates enough of rigctld to satisfy gpredict.
>
>      
>
>     Here's a python script I just hacked up:
>
>     https://gist.github.com/darksidelemm/2a1fb385f6fc18566f3bcf29b4929053
>
>      
>
>     Gpredict seems happy enough with it. It listens on port 4532
>     outputs data as follows:
>
>     Marks-MacBook-Pro:Dev darkside$ python fake_rigctld.py
>
>     Connected by ('127.0.0.1', 49304)
>
>     2017-11-20T07:05:10.209830,145888809
>
>     2017-11-20T07:05:10.630798,145888810
>
>     2017-11-20T07:05:11.634510,145888812
>
>     2017-11-20T07:05:12.635496,145888813
>
>     ... etc
>
>      
>
>     73
>
>     Mark VK5QI
>
>      
>
>     On Mon, Nov 20, 2017 at 5:06 PM, <vk4tec at tech-software.net
>     <mailto:vk4tec at tech-software.net>> wrote:
>
>         Downloading gpredict source code to debug
>
>          
>
>         A
>
>          
>
>         *From:*OZAPRS [mailto:ozaprs-bounces at aprs.net.au
>         <mailto:ozaprs-bounces at aprs.net.au>] *On Behalf Of *Scott Evans
>         *Sent:* Monday, 20 November 2017 4:34 PM
>
>
>         *To:* Australian APRS Users <ozaprs at aprs.net.au
>         <mailto:ozaprs at aprs.net.au>>
>         *Subject:* Re: [OZAPRS] Doppler graph
>
>          
>
>         Oops didn't clearly READ! 😖
>
>          
>
>         On Mon., 20 Nov. 2017, 17:29 , <vk4tec at tech-software.net
>         <mailto:vk4tec at tech-software.net>> wrote:
>
>             Only getting a few and then it bombs out
>
>              
>
>             A
>
>              
>
>              
>
>             Back to gpredict
>
>             F  145893173
>
>             Back to gpredict
>
>             F  145893173
>
>             Back to gpredict
>
>             F  145893174
>
>             Back to gpredict
>
>             F  145893175
>
>             Back to gpredict
>
>             q
>
>             Back to gpredict
>
>              
>
>              
>
>             *From:*OZAPRS [mailto:ozaprs-bounces at aprs.net.au
>             <mailto:ozaprs-bounces at aprs.net.au>] *On Behalf Of *Scott
>             Evans
>             *Sent:* Monday, 20 November 2017 4:22 PM
>             *To:* Australian APRS Users <ozaprs at aprs.net.au
>             <mailto:ozaprs at aprs.net.au>>
>             *Subject:* Re: [OZAPRS] Doppler graph
>
>              
>
>             Gptedict already has Doppler correction support inbuilt? 🤔
>
>              
>
>             On Mon., 20 Nov. 2017, 17:04 , <vk4tec at tech-software.net
>             <mailto:vk4tec at tech-software.net>> wrote:
>
>                 Hi Guys
>
>                  
>
>                 I am trying to graph doppler shift for some satellites
>
>                  
>
>                 Does anyone have perl or python code that would allow
>                 gpredict to connect and then I can log the freq and
>                 graph it
>
>                  
>
>                 Cheers
>
>                  
>
>                 Andrew VK4TEC
>
>                  
>
>                 http://www.tech-software.net/blog
>
>                  
>
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