Fwd: LF: 136KHz

Andre' Kesteloot akestelo@bellatlantic.net
Tue, 10 Nov 1998 21:25:52 -0500

Another member of AMRAD (Sandy WB5MMB) had kept the message we were discussing.
I agree with you that this places uncommon demands on vfo stability   :-)
Alberto wrote:
  This seems a rather tough requirement to meet on the transmitter side.
   For those of us without cesium or rubidium standards, any idea on how to
   achieve such precision and stability ?

   73, Alberto di Bene, I2PHD
>Steve Olney wrote:
>> G'day All,
>> I have read with interest the comments about stations on 136KHz.  My
>> particular interest is using FFT software I have written to detect tones
>> buried in noise.  Using SSB receive mode, measurements indicate that I can
>> detect a carrier heterodyne down to about -57dB S/N ratio. This is using a
>> maximum of 8,388,608 points (about 761 seconds @ 11025Hz sampling rate).
>> This gives a bin BW of 0.00134Hz.  The 136Khz stations sound like ideal
>> real signals to test my system on down under.  To do this I would need:
>> 1.  The Mark and Space frequencies.
>> 2. The assigned carrier frequencies.
>> It would be helpful to have these to an accuracy of better than +/- 10ppm.
>> Are the Mark and Space frequencies AM modulated (ie, carrier plus two sets
>> of two sidebands) or SSB-like (no carrier plus one set of sidebands -
>> either upper or lower)?
>> If I had the above information I could set my receiver to the carrier
>> frequency and search for the Mark and Space frequencies.
>> Regards,
>> Steve VK2ZTO
>> -------------------------------------------------------------------------
>> -       "Your point of view always depends on
>> -               where you are standing"
>> -
>> -                    Steve Olney
>> -                  North Richmond
>> -                     Australia
>> -
>> -      email:  ollaneg@zeta.org.au
>> -      Web Page:  http://www.zeta.org.au/~ollaneg
>> -------------------------------------------------------------------------