[DSP-10] Audio filters question

Sat, 15 Mar 2003 10:09:09 -0800

Hello Lyle and Bole,

Thanks Lyle, for the good comments. I will try to make sure this is all
reflected in the User's Manual.

I think the point about message indicatiing "the missing table pointer and
no new filter coefficients" is good. Almost always, this occurs because the
DSP program is not running at all, and this should be reflected in the error
message. I will make a note about this! However, this can also occur because
of running an old version of the DSP program (before 1.9, I think) that did
not have a pointer table. At this point, everyone should be using DSP
UHF3.EXE v 2.0 or later.

The names of the DSP and PC programs are unfortunately similar. Be careful
to keep them separate.

Let us all know aboout your experience with the audio prcessor. I do not use
it a lot, as I have the hardware going. In theory, any change to the RF
should be OK for the audio processor, since the audio processor is just
another "transverter" running with no LO and at about 0 Hz last I-F
frequency. The exceptions that I can think of are the EME Doppler correction
that uses a special UHFA.CFG variable to set the RF frequency, since the
dial frequency no longer applies, and the sidebands get reversed.

The "about 0 Hz" can be used to add RIT, after the audio output of the radio.

Another thought. The audio processor covers about a 4 kHz band. But, this
band can be tuned up to about 20 kHz. For instance, if the offset is set to
16000 Hz, USB would be displaying 16 to 20 kHz. This makes a handy spectrum
analyzer. The high linearity of the A/D put two-tone intermod more than 70
dB down, on the tests I did.

To go with this is a two-signal plus noise generator, up to 20 kHz, using a
separate EZ-Kit. This is described in Experimental Methods in RF Design,
page 11.11. In this case, the same high linearity of the D/A puts the
intermodulation below the screen.

One last thought. If you use the audio processor, and want to use it to
transmit (such as EME-2, PUA43 or even CW), the T/R control can be directed
to the PC's parallel port by setting the configuration file variable
lpt_port to either 888 or 956 depending on the PC and port selection. A
value of 0 disables this function. This makes 5 V available on pin 3 of the
25-pin connector. You will need to create an interface between this 0,5 Volt
logic and your transceiver's T/R control. If anyone does this, they might
share the circuit that works with some particular rig.

Good luck with all this!

73,
Bob  W7PUA

At 05:52 AM 3/15/03 -0800, Lyle wrote:
>Hello Bole!
>
>You need to edit the UHFA.CFG file.  The line that says "hardware 1" must be
>changed to "hardware 0".
>
>And the audio input to the EZ-Kit is on the middle contact of the connector
>rather than the tip, so you *must* use a stereo plug.
>
>Finally, you must select "tranverter 15" which is selection "o" (letter O,
>not the numeral 0).
>
>I went through these steps last night, and used it with my Elecraft K2 :-)
>
>Also note that if when you run UHFA on the PC it says it can't download some
>filter coefficients, that really means it isn't talking to the EZ-Kit and
>you need to restart the whole procedure.  At least this is what it appeared
>to mean in my case.
>
>Good Luck!
>
>73,
>
>Lyle KK7P
>
>> -----Original Message-----
>> From: [email protected]
>> [mailto:[email protected]]On Behalf Of Bozidar Benc
>> Sent: Saturday, March 15, 2003 3:51 AM
>> To: [email protected]
>> Subject: [DSP-10] Audio filters question
>>
>>
>> Hi,
>>
>> While waiting for DSP-10 kit to arrive, I wanted to experiment a
>> little with
>> Ezkit lite and UHFA.EXE v. 3.0 and UHF3.EXE v. 2.2.
>>
>> I thought that it is possible to use Ezkit/UHFA.EXE/UHF3.EXE
>> combination as
>> audio DSP filter with another rig. So, I connected audio output from my HF
>> rig (Elecraft K1) to Ezkit input and stereo headphones to Ezkit
>> output. I'm
>> booting my PC with DOS 6.22 diskette where I copied all necessary files.
>>
>> UHFA/UHF3 is processing my rig's audio as IF. Is it possible to
>> switch it to
>> process it as normal audio?
>> I'm mainly interested to try binaural mode (how to turn it on?).
>>
>> I've read documentation but it seems that I misunderstood something (my
>> English is really not very good).
>>
>> 73, Bole, 9A3RR
>>
>> _______________________________________________
>> DSP-10 mailing list
>> [email protected]
>> http://mailman.qth.net/mailman/listinfo/dsp-10
>>