PSN-L Email List Message

Subject: Re: Help with telemetry equipment
From: Ian Smith ian@...........
Date: Tue, 11 Jul 2006 13:44:17 +0100


Hi,

labview has some great demodulation software built into it as well as 
software to interface with sound cards.  That's what I was thinking of 
when I wondered how the signal was encoded.  Still wondering...

Cheers

Ian

James Hannon wrote:

>I would expect that a sound card would be stable enough to decode the telemetry signals. All the cards I have seen use a crystal for the reference frequency. As long as the temperature of the card doesn't vary over a wide range you will be ok. The real question is: Is there software avaliable to do the demodulation?
>
>As far as the radio stability is concerned: The signals are transmitted as FM so a slight mistuning of the radio will not affect the frequency of the tones. 
>
>Jim Hannon
>
>---------- Original Message ----------------------------------
>From: ian 
>Reply-To: psn-l@..............
>Date:  Tue, 11 Jul 2006 06:02:30 +0100
>
>  
>
>>Hi,
>>
>>thanks for the link.  I wasn't able to deduce from that page how the 
>>encoding/decoding works (call me dumb!).  Is there any other web page  
>>that would explain it?
>>
>>I note your comment about stability.  Will your average radio have 
>>similar stability or does the encoding method mean that that isn't an issue?
>>
>>Thanks
>>
>>Ian
>>
>>ChrisAtUpw@....... wrote:
>>
>>    
>>
>>>In a message dated 10/07/06, ian@........... writes:
>>>
>>>      
>>>
>>>>out of interest, what's the spec of how the data is encoded?  I'm 
>>>>wondering if a sound card can decode it.
>>>>        
>>>>
>>>
>>>Hi Ian,
>>>
>>>       It is sent as a narrow band sine wave tone. The channel 
>>>separation is only 340 Hz. For the center frequencies see 
>>>http://psn.quake.net/onlinedocs/demoddoc.html
>>>Hence the need for a precision encoder like the XR2206.
>>>       Does a sound card to have a stability in the low ppm range? 
>>>
>>>       Regards,
>>>
>>>       Chris Chapman
>>>      
>>>
>>
>>
>>    
>>
>
>--
>Jim Hannon
>http://www.fmtcs.com/web/jmhannon/
>42,11.90N,91,39.26W
>WB0TXL
>--
>__________________________________________________________
>
>Public Seismic Network Mailing List (PSN-L)
>
>To leave this list email PSN-L-REQUEST@.............. with 
>the body of the message (first line only): unsubscribe
>See http://www.seismicnet.com/maillist.html for more information.
>
>
>  
>

-- 





  
  


Hi,

labview has some great demodulation software built into it as well as software to interface with sound cards.  That's what I was thinking of when I wondered how the signal was encoded.  Still wondering...

Cheers

Ian

James Hannon wrote:
I would expect that a sound card would be stable enough to decode the telemetry signals. All the cards I have seen use a crystal for the reference frequency. As long as the temperature of the card doesn't vary over a wide range you will be ok. The real question is: Is there software avaliable to do the demodulation?

As far as the radio stability is concerned: The signals are transmitted as FM so a slight mistuning of the radio will not affect the frequency of the tones. 

Jim Hannon

---------- Original Message ----------------------------------
From: ian <ian@...........>
Reply-To: psn-l@..............
Date:  Tue, 11 Jul 2006 06:02:30 +0100

  
Hi,

thanks for the link.  I wasn't able to deduce from that page how the 
encoding/decoding works (call me dumb!).  Is there any other web page  
that would explain it?

I note your comment about stability.  Will your average radio have 
similar stability or does the encoding method mean that that isn't an issue?

Thanks

Ian

ChrisAtUpw@....... wrote:

    
In a message dated 10/07/06, ian@........... writes:

      
out of interest, what's the spec of how the data is encoded?  I'm 
wondering if a sound card can decode it.
        

Hi Ian,

       It is sent as a narrow band sine wave tone. The channel 
separation is only 340 Hz. For the center frequencies see 
http://psn.quake.net/onlinedocs/demoddoc.html
Hence the need for a precision encoder like the XR2206.
       Does a sound card to have a stability in the low ppm range? 

       Regards,

       Chris Chapman
      


    

--
Jim Hannon
http://www.fmtcs.com/web/jmhannon/
42,11.90N,91,39.26W
WB0TXL
--
__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@.............. with 
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.


  

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