Re: [amsat-bb] KO-23 Status ??? UO-36 Info ???

[John Melton - Sun UK - ENS <John.Melton@xxxxxxxxxx>]

Hi Jeff,

can't answer the first question about KO-23,  although I suspect it will not be 
returning.

For the 38k4 downlink on UO-36,  I can help.

There are 3 problems to resolve:

	1.  Receiver.
	2.  Modem.
	3.  TNC.
	
	
1 Receiver.
 
    There are a couple of options available -
    
    I have successfully used an Icom PCR-1000 for receiving the 38k4 downlink
    using the 50KHz filter in the Narrow FM mode,  and tuning the radio for
    doppler shift.
    
    A much better answer is to buy an IFD (Wide Band IF Strip) module from 
    Symek (http://www.symek.com).  This will tap into the first IF of your
    receiver and privide a digital output to the Modem.  It will support up
    to 153k6 data rates.  The price looks like it will be about $110.
    
    Symek also make a 435 MHz data radio that runs at speed up to 153k6.

2 Modem.

    Again there are a couple of options -
    
    The standard G3RUH modem can be modified (just a couple of resistors and
    capacitors) for 38k4.  Note that it cannot be modified to provide different
    transmit and receive data rates,  so 2 will be required to provide the
    9k6 uplink and the 38k4 downlink.
    
    GMSK Data Products (http://www.gmskdata.co.uk) make a modem based on the
    FX589 chip and a PIC microprocessor that can run at data rates up to 38k4.
    It interfaces with a TNC using the standard modem disconnect header.  
    Again,  you will need this for receive and another modem runnning at 9k6
    for the uplink.
    
3. TNC

    Again a couple of options -
    
    The PacComm Spirit 2 will run at a split speed of 9k6 and 38k4.
    
    There is some experimental software for the Motorolla 56002 EVM board that
    will run at speeds up to 38k4 and will allow configuring (at compile time)
    for different up/down speeds.  The software provides a KISS interface.
    The software is still in test form and does require some more work.
    
    Symek also  make a TNC (TNC3S) that take 2 modems,  so it is possible to
    install a 9k6 and 38k4 G3RUH modem and use one on the uplink and the other
    on the downlink.
    
    An existing TNC can be used with a modified G3RUH modem configured for
    38k4,  but beware of the maximum data rate that the TNC handle between
    it and the computer as some of the older ones do not go faster than 19k2.
    
    
Hope that gives you some answers.  I have used the PCR-1000 together with the 
GMSK modem,  and have been experimenting with the 56002 EVM board.  Symek have 
promised me one of the first IFD baords configured for the Icom 821H when they 
are available - any day now!

Regards,


-- John Melton  n6lyt/g0orx

        ((
      (|~~|
       `--'
       JAVA


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