Chuck, W8MQW has sent in the following review by
VE7BQH on his TI DSP Board Matched Filter
I talked with you along with Dave, W5UN after your presentation at
the last CSVHF meeting in Colorado Springs. You ended up loaning the Texas
Instrument DSP board to Dave along with the books and your custom
After Dave had the filter for a short while, he sug- gested I use it as he was going to be away on an extended vaca- tion. So on Dave's last visit with me in Sept, the filter arrived at VE7BQH. I have been using the filter with a 450 cycle tuned frequency since Oct.
Like all new filters I have had, it takes some time to get fully accustomed and confident with them (months!). To get the very most out of the filter, I found I needed to add a small external audio amp to allow the input and output levels to be set to the optimum points. This is, of course, typical of any digital filter.
With the operating conditions set as above, I have been getting
some very good results. Clearly this filter produces a better signal
to noise ratio and copy ability than any other filter I have or tried.
This statement includes a Time Wave 59+. I have built too many filters
to describe; suffice to say the last three have been relatively simple
digital switched cap types.
My prime filter was the last of these. This is not to say the improvement with the TI DSP board was large. It was not. However, any noticeable difference is significant when listening to signals in the area of 0 dB S/N!
The "bonus", particularly at this QTH (in the city), is the noise reduction provided by the DSP technology. I have made several contacts in high noise conditions which would have been difficult, if not impossible otherwise.
The weakest link, I still have to deal with is the tuning rate of
the RIT on the digital VFO used with my TS830. I need to slow
down the rate either electrically or mechanically. It is a bit to
touchy for a filter of this bandwidth and signals as weak as I get!
From 432 And Above Newsletter by K2UYH
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For your comments or corrections: Rein, W6/PA0ZN