[1000mp] DSP in the Mark V

[Mike Schatzberg]

Hello Yaesu Fans:

The DSP filtering in the 4th IF of the Mark V does indeed function.  A
simple way to see the narrowing of the bandpass, is to set your second IF
for THRU, and switch the 3rd IF to the 6 KHz ceramic filter.   I'm sure that
you are all aware of the menu manipulations needed to accomplish this.

Then, activate the IDBT button, which engages the filters.  You will
instantly see the effect they have in providing a narrower bandpass, as you
depress the button repeatedly.

The issue for me on SSB, is whether when you have selected a narrower
cascaded pair of  2nd and 3rd IF filters, the fourth IF filters add any
significant additional selectivity or interference rejection.

Likewise on SSB, the audio DSP filtering seems to do little to assist with
noise reduction.  I sometimes use the lowest level, to quiet white noise.
But higher levels of NR seem to degrade the audio quality, so I avoid their
use.  Atmospheric noises are hardly removed at all by the circuitry.

I always limit the RF gain, and I have installed the Inrad roofing filter
which really does permit a quieter receiver with lower noise floor, with
lower IF gain in menu 9-1.  This seems the best way to listen to lower level
signals, those with S 1 signal strengths or even less.

Outboard DSP units seem to be quite expensive, and I really wonder if the
current Timewave model would be a significant improvement over the onboard
audio DSP.  I have tested my old JPS NIR 10, and it is somewhat better than
the onboard DSP, but it lacks AGC, and overloads easily.  The NIR 10 uses
Texas Instrument technology with ancient algorithms.

For those folks interested in a more economical approach than Timewave, I am
now investigating BHI, a British design and manufacturing company
specializing in Digital Signal Processing (DSP) noise cancellation products
that they claim greatly improve the intelligibility and clarity of speech.

They produce various modules which can be installed into your speaker
console easily, and are far more economic.  I have ordered their new ANEM
product which can be used more easily with several speaker consoles and is
microprocessor controlled.

I have been asked to write a review of the module, and I will so do after a
few weeks of operation.   In speaking with friends in the UK, who operate
with the Mark V and have the modules, they claim they never use their radios
without the module in line, it makes a significant improvement for them.

For those interested, here is the link to the BHI website:
http://www.bhi-ltd.co.uk  .

If anyone has previous experience with their various products and the Mark
V, I would be interested in learning about it.

73 and Happy DXing,

Mike
W2AJI