PSN-L Email List Message
Subject: Re: Help with telemetry equipment
From: "James Hannon" jmhannon@.........
Date: Tue, 11 Jul 2006 07:39:37 -0500
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.
---------- Original Message ----------------------------------
Date: Tue, 11 Jul 2006 06:02:30 +0100
>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?
>> 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
>> Hence the need for a precision encoder like the XR2206.
>> Does a sound card to have a stability in the low ppm range?
>> Chris Chapman
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