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PA2AGA > HDDIG 23.09.99 04:52l 217 Lines 7935 Bytes #-9769 (0) @ EU
BID : HD_99_237I
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Subj: HamDigitalDigest 99/237I
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Date: Wed, 22 Sep 99 21:15:29 MET
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From: pa2aga
To: hd_broadcast@pa2aga
Subject: HamDigitalDigest 99/237I
X-BBS-Msg-Type: B
>
> Netting the various transverters together on a common frequency
> is the only adjustment absolutely needed. That can't realistically be
> done by ear. You can do it by monitoring the eye pattern (with a scope)
> of another station known to be on frequency. If one of the group has an
> IFR or the like, you can use that without needing a priori to have one
> transverter spot on frequency.
Ok, I need a scope.
> Typically, we find that the transverters are a few kHz off frequency
> when first crystalled up, so they have to be netted. You don't have to
> get absolutely spot on, the modems use a tracking data detector
> that can handle up to about 5 kHz frequency error without impairing
> BER. But we'd like to reserve that as margin for thermal drift and
> component aging.
>
> It is also nice if you can monitor the eye pattern with a scope so you can
> adjust the transverter PA drive of other systems for best linearity (and
> monitor their received eye pattern to do the same for your PA). That'll
> make you a better spectral neighbor, and lower BER a bit too. But we've
> found that with the MMT transverters, turning the drive down to get about
> 4 watts out always gives us a clean spectrum, so you can do it with just
> a Bird. (You can't get away with that with the Hamtronics units, however,
> for them you *really* need access to a spectrum analyzer. Nasty things
> unless they're tuned *just* right.)
Ok, so I need to buy a scope.
> No external test equipment at all is needed for the RF modems. There are
> some switch settings to configure (if the defaults don't suit you). You
can
> select one of 10 frequencies (100 kHz spacing), select whether you want
> to operate duplex or half duplex, select TTL or RS422 on the computer
side,
> select whether you want FEC or not, etc. But the modems come configured
> to work right out of the box and shouldn't need any adjustments unless you
> want something other than the default settings.
>
> The stuff that had to be tweaked in the first generation modems has all
> been put into ASIC for the current modem, so there is no tune up involved.
> You can peak the IF filter if you like, but the modem has an internal
method
> of doing that which doesn't require any external test equipment. You just
> set a jumper, then tweak for max on the signal bargraph display. It should
> be fine right out of the box, however.
>
> >Where does one get these various modules?
> >What is their cost?
>
> Paccomm (and GRAPES) sell the W&T RF modems. The cost is $349.
> Transverters are available from their manufacturers, or at hamfests. I
> usually find MMT transverters for around $150 at most of the hamfests
> I attend. They're usually crystalled for the wrong segment of the band
> (the satellite or weak signal segment), so you need to spend $15 for a
> new set of crystals to move them into the data bandplan. New transverters
> range in price from under $200 to over $600 depending on make, model,
> and band. Virtually any linear transverter will work with the modems.
> You need a HDLC card in the computer too. I've personally used both
> the PI-2 card ($98) and the Gracilis PacketTwin (don't know the current
> cost on that one, but it is more expensive since it is full duplex DMA).
DMA probably overkill (or underkill, see some of the assembler
newsgroups for interesting measurements of DMA I/O vs. programmed
I/O, I was surprised at the results). Modern machine ("Pentium anything")
can easily handle many channels of 56k data. I personally do not like
the SCC chip, but that is "hacker bigotry" and nothing else.
> There are others. A Mac can work directly from its serial port since it
> comes stock with chips that can be programmed to handle RS422 and
> HDLC directly (about the only case I can think of where having a Mac is
> an advantage).
Hmmm ... my Imsai I/O chips can do HDLC ... back to CP/M ?
> Basically, you're looking at $600 to set up for 56 kb. That's more than
> it costs to dedicate a TNC and radio to 1.2 kb, but not much different
> from what it costs to set up to do 9.6 kb correctly (that's because you
> generally have to use an IF modulated multimode to get an acceptable
> BER with G3RUH style 9.6 kb).
Things are a bit cheaper for 9600. Any old serial card will work.
Radios are available cheap (TEKK e.g).
So we have:
$349 for a modem.
$200 for a transverter for each modem.
$100 for an HDLC card.
$x for coax. ($200 for 150' hard line e.g.)
$y for antenna. ($75 - $300 depending on gain required).
$z for misc. parts, box to put stuff in, connectors, etc.
Minimum of two each of the above.
Looks like I could set up one point to point link for about $1600.
Sounds reasonable. Now all I need is someplace to put the other end.
(I'll figure the cost of scope, dvm, freq counter, Bird, etc. as what
is needed to replace my old dead test gear). This sounds like an
interesting project. Doubtful I'll find anyone within line of sight
willing to play though ... hazard of living out in the boonies.
Thank you for all the info. Is filed in my "stuff to do now that I'm
retired" folder.
--
... Hank
http://horedson.home.att.net
>.
------------------------------
Date: 20 Sep 1999 22:49:26 GMT
From: Brian Pemberton <brpemb00@ariel.cslab.uky.edu>
Subject: Lexington, Kentucky
So, is there anything (Long haul or Landlid) in the way of
amatuer packet radio in Kentucky? No sense in learning the
widgets, hoisting the antenna, plugging in the computer, and
listening to static.
--
--
Brian Pemberton brpemb00@cslab.uky.edu
Today is Pungenday,the 44th day of Bureaucracy in the YOLD 3165
Bavarian Erisianism and states that the best method of reaching
enlightenment is through a Bavarian beer. It is possible to
achieve Enlightenment without beer, but on the same note it is
possible to climb a 10 meter wall without a ladder.
- Marc (paraphrase)
>.
------------------------------
Date: Tue, 21 Sep 1999 06:06:08 +0200
From: "A.H. FRANSMAN" <trd@netactive.co.za>
Subject: Pactor software for soundcard ?
Hello All
Where can I download Pactor software that uses the Soundcard ?
Tnx vy much.
73 Andre ZR1TRD
>.
------------------------------
Date: 20 Sep 1999 13:10:41 GMT
From: Hamish Moffatt <hamish@rising.com.au>
Subject: PSK31 and IC-706
Roger Basford <Roger@g3vkm.demon.co.uk> wrote:
> Make sure your microphone is unplugged if using the accessory socket and
Why's that? I use the accessory socket on my IC-726 with the sound
card (for G3PLX PSK31 and IZ8BLY Hellschreiber) with the microphone
still connected. I suppose you would upset it if you made noise
near the microphone though ..
Hamish
--
Hamish Moffatt Mobile: +61 412 011 176 hamish@rising.com.au
Rising Software Australia Pty. Ltd. http://www.risingsoftware.com/
Phone: +61 3 9894 4788 Fax: +61 3 9894 3362 USA: 1 888 667 7839
>.
------------------------------
Date: Mon, 20 Sep 1999 16:44:07 GMT
From: nomail@pe1chl.demon.nl (Rob Janssen)
Subject: PSK31 and IC-706
Hamish Moffatt <hamish@rising.com.au> wrote:
>Roger Basford <Roger@g3vkm.demon.co.uk> wrote:
>> Make sure your microphone is unplugged if using the accessory socket and
>Why's that? I use the accessory socket on my IC-726 with the sound
>card (for G3PLX PSK31 and IZ8BLY Hellschreiber) with the microphone
>still connected. I suppose you would upset it if you made noise
>near the microphone though ..
When I adapted my Yaesu FT212 and FT712 for HAPN 4k8 (they aren't suitable
To be continued in digest: hd_99_237J
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