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Re: Re: [amsat-bb] D700 TNC Calibrate mode etc (II)



Danny,
Deveation on 70 cm is typically +/- 5 KHz. A modulation index of 1 is usally 
used to conserve bandwidth. 9600 Baud/2 = 4800 Hz as the highest modulation 
frequency. 5000/4800 = 1.04 for the modulation index.
FSK requires no modem as the data is used to directly modulate the 
transmitter. Only a filter to prevent excess sidebands in the transmission 
of data is required. Receiving is more difficult as the timming may vary, 
and timing tolarant UART is required for decoding in noisy conditions are 
typical of RF communications.
AMSAT Journal archives is most likely the best resource for satellite 
standards. The Digital modes were devloped in the early 90's, and Manchester 
encoding was used on tape transports for the IBM 360 devloped in the mid 
60's of the last century. Any technology with BAUD rates under 1MBPS was 
most likely developed in the last Century and will require some digging in 
the archives of that period for the how and why.

Art,
KC6UQH
----- Original Message ----- 
From: "Danny Jacobs" <jacobs@physics.montana.edu>
To: <amsat-bb@amsat.org>
Sent: Sunday, June 04, 2006 12:30 PM
Subject: [amsat-bb] Re: [amsat-bb] D700 TNC Calibrate mode etc (II)


>   I have now read the TAPR modem documentation
>   (ftp://ftp.tapr.org/info/kits/manuals/9600_modem_man.pdf) but I still
>   have many questions.
>   1) Where are the standards that allow the TAPR modem to talk to any
>   other 9600 FSK modem?  How did the designers know what to do?
>   2) Like what frequency deviation? I can pick anywhere from 1 to 64kHz.
>   3) If the transitions are filtered, will different modems with
>   different filters still talk to each other?
>   4) What scrambling polynomial is being used?  TAPR manual tells me a
>   17bit one, but which tap bit?  Is it 12 like in the g3ruh modem
>   (http://www.amsat.org/amsat/articles/g3ruh/109/fig03.gif) or 5 like in
>   the KD2BD modem
>   (http://www.amsat.org/amsat/articles/kd2bd/9k6modem/fig1.gif)?
>   5) Can an FSK modem interface to a GMSK modem?  How can one tell what
>   kind of modulation a modem is doing?
>   My interest here is more broad than just the D700, I just happen to
>   have that one and know its been used to work satellites in the past.
>   What I really want is to standardize my link so that it works with the
>   largest number of ham hardware as possible.  What is the most common,
>   high quality, FSK modem used for satellites by hams?
>   Thanks everyone,
>   ~Danny KE7DHQ
>      ~~~~~~~~~~~~~~~~~~~~~~~~
>      Space Science and Engineering Laboratory
>      Montana State University
>     Bozeman, MT
>   -----Original Message-----
>   From: "Sanford, Fred" <fred.sanford@ips.invensys.com>
>   Sent 6/3/2006 6:49:43 PM
>   To: "'Danny Jacobs'" <jacobs@physics.montana.edu>
>   Subject: RE: [amsat-bb] D700 TNC Calibrate mode etc (II)
>
>   The D700 9600 is compatiable (not sure if generated using the same
>   method as) with the 9600 bps modem kits that TAPR used to offer. You
>   should be able to find information on the TAPR web page, try starting
>   at http://www.tapr.org/pub_9600.html .  If this does not help, let me
>   know and I will try help you.
>
>   73 - ka1cqd
>
>   -----Original Message-----
>   From: owner-AMSAT-BB@amsat.org [mailto:owner-AMSAT-BB@amsat.org] On
>   Behalf Of Danny Jacobs
>   Sent: Saturday, June 03, 2006 1:08 PM
>   To: amsat-bb@amsat.org
>   Subject: [amsat-bb] D700 TNC Calibrate mode etc (II)
>
>      Is anyone on this list familiar enough with the Kenwood D700 to
>      describe exactly what the Calibrate function of the TNC does and/or
>      describe exactly how the modulation is done at 9600.
>      I am attempting to close a 9600 digital link between the D700 on Tx
>   and
>      a CC1000 FSK chip radio on Rx.   I have control over many
>   demodulation
>      settings such as FSK seperation frequency and peak detect in the
>   CC1000
>      but I dont have much information on the standard Ham FSK modulation
>      that I think the D700 is doing in 9600 mode. I can easily close the
>      link between two of the chip radios.
>      So here are my questions:
>      1) Is the D700 doing true FSK in 9600 bps mode?
>      2) If it is, what is the seperation between mark and space?
>      3) Is a scrambling polynomial being used, (i am trying 17 bit
>   register
>      with bit 5 as tap)
>      4) Is the Calibrat mode in the TNC a scrambled square wave?  Has
>   anyone
>      gotten this to work?
>      5) I have read in several articles oblique references to standards
>   for
>      FSK links but havent been able to find any.  Where are they?  How do
>      different Ham radio manufacturers build radios that can talk to each
>      other?
>      This is part of a University satellite project. We could use
>   matching
>      chip radios to talk to our satellite but we want very much to
>   provide a
>      friendly packet-style ham interface to our operation, however we are
>      finding that interfacing to the ham equipment quite difficult.
>   Please
>      Help!
>      ~Danny KE7DHQ
>      ~~~~~~~~~~~~~~~~~~~~~~~~
>      Space Science and Engineering Laboratory
>      Montana State University
>   ----
>   Sent via amsat-bb@amsat.org. Opinions expressed are those of the
>   author.
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> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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----
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