Hi, Mark,

It's all about bandwidth conservation and mapping.

The last 15/32 in/s tapes I did were FM seismic tapes and it was most 
convenient to run them at 60 in/s into 48 ks/s A-D converters. That gave 
us 375 s/s real time and that was still more than what was needed. 
Seismic recordings are generally made at 100 s/s or with the sensors on 
these, 50 s/s. So, I decimated the 375 s/s by a factor of 7.5 to get the 
50 s/s files for the client. Since I saw data above the 25 Hz cutoff of 
the 50 s/s files, I urged the client to also archive the 375 s/s 
files...and they are.

The 5 kHz low pass on the FM demod effectively limited the HF response 
to 78 Hz, but that was more than 25 or less.

As I said, you need to understand the recorded bandwidth and map that 
into a reproducing system.

I've found 96/24 at 7.5 in/s is adequate for 15/32 logging tapes. If you 
start with 40 kHz bandwidth and take that down 16 X you end up with 2500 
Hz bandwidth which is probably optimistic for most 15/32 logging tapes. 
Comms channels are brick walled at 3000 or 3200 Hz.



On 2012-04-13 4:27 PM, Mark Durenberger wrote:
> Next challenge Richard:  tackling the 15/32 in/s projects I'm working on!
> Regards,
> Mark Durenberger

Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada           (905) 713 6733     1-877-TAPE-FIX
Quality tape transfers -- even from hard-to-play tapes.