[FoxHunt] Re:HF SSB ADF question

[wolfbob]

As far as I understand only the Adcock type DF systems work well with SSB. 
They measure the phase angles in quadrature all the same instant so there is 
no phase or amplitude shifts due to modulation. You can also use doppler as 
that measures the psuedo frequency shift, but it requires a FM receiver to 
work well. Spinning things do not work well as they depend upon either 
finding the maximum amplitude which is a time variable with SSB or the zero 
phase which is a function of signal frequency which is ever changing with 
SSB voice.

Bob, WB6JPI


----- Original Message ----- 
From: "John Munsey, KB3GK" <munseyjohn at earthlink.net>
To: "Radio Direction Finding" <foxhunt at mailman.qth.net>
Sent: Monday, November 22, 2004 10:31 AM
Subject: Re: [FoxHunt] Re:HF SSB ADF question


> If I understand the problem correctly...
>
> The SSB carrier is not there when there is no modulation and then it 
> varies with the modulation level. Since this system looks for signal level 
> it can't read "nothing" zero signal level and varies with the signal level 
> when it is modulated.
>
> I suspect this is the cause of your problem.  I don't know of any "fix" if 
> that is indeed the problem.
>
> I have used the Doppler with reasonable success on SSB signals but even 
> there they can come and go with modulation.
>
> It will be interesting to hear from others on this.
>
>
> At 12:29 PM 11/22/2004 -0500, you wrote:
>>In using a Taiyo CH 338 HF ADF (crossed loop goniometer type with polar 
>>CRT
>>readout) I have noticed the following: SSB sigs give no clear "propellor"
>>pattern on the CRT, the sig strength varies with voice and no clear 
>>azimuth null or
>>peak can be seen. The exception is when there is a constant audio, like
>>engine acoustic noise on a boat, then it gives the signal a constant 
>>strength
>>background level (analogous to an AM carrier when no speech is present) 
>>which
>>allows a good CRT bearing in between spoken syllables. What is the basic 
>>problem?
>>Is the goniometer effective rotational speed too slow for SSB? Has anyone 
>>else
>>used these Taiyo ADFs for HF SSB?
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>
> Sincerely,
>
> John Munsey, KB3GK
>
>
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