Date: Sun, 30 Jan 94 04:30:23 PST
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Subject: Ham-Equip Digest V94 #17
To: Ham-Equip
Ham-Equip Digest Sun, 30 Jan 94 Volume 94 : Issue 17
Today's Topics:
DSP-9 Filters (and others) -- New Thread
Using ICOM filters in SONY ICF-2010/2001D?
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Date: 28 Jan 1994 15:31:21 GMT
From: news.cstar.andersen.com!news.acns.nwu.edu!casbah.acns.nwu.edu!rdewan@uunet.uu.net
Subject: DSP-9 Filters (and others) -- New Thread
To: ham-equip@ucsd.edu
In article <24cTgc1w165w@jackatak.raider.net>,
Jack GF Hill <root@jackatak.raider.net> wrote:
>
>The thread of DSP-9 (etc) Digital Filters and bandwidth/ringing has pretty
>well wound down, and while I do not mean to fire that discussion up, I am
>seeking information on a different aspect of these lovely little devices:
>
>Several hams using these filters have reported problems, both on the Nets
>and to the manufacturers, when engaging both the Heterodyne (tone)
>processing filter *AND* the random noise filter. The audio becomes
>distorted.
I have noticed this, both, in listening to broadcast stations and in
listening to demos done using recorded ssb qsos.
>
>A Ham from Louisiana offered the suggestion, that had been offered him and
>seemed to work well, that the unit would work OK if the operator would
>simply turn off their tranceiver's speech processor.
>
>There followed a VERY heated argument about how the speech processing
>circuit processes OUTBOUND audio only and has NOTHING to do with the
>INBOUND audio going to the processor. However, when the (RF) Speech
>Processors were turned off, the DSP-9 (and DSP-59 and a few other brands as
>well) *ALL* responded as they were supposed to...
I checked the schematic of my Kenwood TS850s. The compressor is not in
circuit during receive.
>
>The question was immediately raised: "What could the (RF) speech processor
>have to do with the incoming audio?"
>
>I speculated, and am seeking confirmation here, that the *RF* speech
>processor circuitry is engaged all the time the "compression" button is
>engaged, that unlike the final amp which is biased to cut-off, the speech
>processor runs, with no input, all the time. This would explain why the
>simple turning-off of the processor eliminates the problem, as does moving
>the DSP unit OFF the top of the radio and placing it a few feet away.
>
>A glance at the block diagram of my rig and a quick look at the schematic
>seems to bear this hypothesis out, but I am still unsure and seek
>additional input and thought...
>
>The real motive is: I have a DSP-9 that I intend to install in my mobile,
>but I have NO CHOICE about where to position the unit -- it MUST go right
>on top of the transceiver or not at all. I do NOT use a speech processor
>for a variety of reasons, but some of my co-pilots do...
I thought that it has more to do with the way in which the de-noiser and
the auto-notcher work. Crudely spreaking, the auto-notcher removes the
parts that are highly serially correlated and the denoiser removes the
parts that are least serially correlated. Both of these depend on the
time serial correlation characteristics of human voice. But this can
change with fast fades. Hence the problem.
Rajiv
aa9ch
r-dewan@nwu.edu
------------------------------
Date: Thu, 27 Jan 1994 17:43:20 GMT
From: nntp.ucsb.edu!library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!newsserver.jvnc.net!raffles.technet.sg!ntuix!ntuvax.ntu.ac.sg!asirene@network.ucsd.edu
Subject: Using ICOM filters in SONY ICF-2010/2001D?
To: ham-equip@ucsd.edu
Hi,
Does anyone know if I can use the SSB filters for ICOM or for
Kenwood in other radios or in my own IF strip? I am thinking of use
for SSB/RTTY/CW. The reason I ask is because the Kiwa filters I want
are not available locally but the ICOM filters are. Does anyone who
have access to both know?
I am looking to put the ICOM narrow filters (2.4 kHz) into my
SONY ICF-2010/2001D. Does anyone have any comments about doing this?
73 de 9V Daniel
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End of Ham-Equip Digest V94 #17
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