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PA2AGA > HDDIG 08.10.99 03:04l 147 Lines 5841 Bytes #-9726 (0) @ EU
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From: pa2aga
To: hd_broadcast@pa2aga
Subject: HamDigitalDigest 99/252B
X-BBS-Msg-Type: B
received system gain, receiver noise figure. I would think that
the term "link margin" should be the amount of spare dB you have in the
received signal in the budget, for the link to work. If it's 0, you're right
on critical. If it's negative, the link isn't meeting your specs.
(Unfortunately, I sold all my university comms text books so I
can't check this terminology.)
> "Power Spread" - The difference between the ERP and noise floor at a
> Station.
Isn't this just the signal to noise ratio?!
> 3. Determine the Link Margin required to obtain the desired availability.
> 4. Determine the Power Spread required at each Station.
I don't really understand this.
> 6. We run some tests. First on 2M to verify signal levels because this
> is simple to do: turn a knob on an existing radio at each Station. There
> is plenty of signal. There is no Link Margin. This is not good. Since the
OK, so we do agree on the terminology.
> What about this "Power Spread" thing? Let's say we discover that Station A
> has a good deal more noise than Station B due to external noise sources near
> it's site. The simple way to compensate for this is to increase the ERP of
> Station B.
> What does this mean? It means that Station A has a smaller Power Spread than
> Station B, but the Link Margin can be made the same in both directions. It
> might
It means you need to add the amount of noise into your link budget
calculations -- so then you need to increase the EIRP to maintain
the link margin, or at least a non-negative link margin.
cheers
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: Tue, 5 Oct 1999 09:53:39 -0700
From: "Cathryn Mataga" <cathryn@junglevision.com>
Subject: Let's look at real numbers for TNC software sales
Eric S. Johansson wrote in message <7tbl0d$aib$1@harvee.billerica.ma.us>...
>> Really, it doesn't take that many bodies who say stuff to keep up a
>> conversation. I'd guess that less than about 10 people
>> account for most of the slightly heated discussion here on dig.misc.
>> So, for all the talk of the masses of bodies moving to the internet,
>> I really think we could do much of what we do here on PBBS.
>
>you're probably right. Only difference would be that I wouldn't be a
>part of the conversation because I can't stomach current packet
>technology. I admit it, I'm a speed snob. ;-)
For me, like the messages just show up like any othermessages.
So, from the user interface side, if you have it put
together right, it's not any slower than reading my email. Though
part of it is because I have a PBBS feed here. Mail/news isn't
really a huge bandwidth hog. Though obviously, 1200 baud isn't
quite good enough.
And me, I'll probably be on packet, whatever it is. That is PBBS or
ip or whatever. Mostly this is determined by who else is on
the air near me. I've done enough hassling with the internet,
where I don't want to do networking on it, unless I'm being paid money.
It just feels too much like work.
>
>> One other thing. I'm still trying to figure out if there's a way in Windows
to gateway
>> all the 44.xx.xx.xx addresses through the RF link, and all the rest of the
>> ip addresses through my regular gateway. I can do this in linux, but
>> I'm not enough of a registry guru to know how to make that happen. It
>> only lets me specify a gateway in Windows, but it doesn't allow me to
specify
>> a netmask or ip adress range in Win98 like I can with route statements
>> in Linux. Errr.
>
>there are some ways of making Windows route all that traffic but you
>are better off using your Linux box as your gateway to both the
>Internet and the 44... network. Much cleaner solution and more
>supportable.
Yeah, I guess that's the way to go. Right now I have one Linux box
for 44.xx.xx.xx and another with the ip connection for everything else.
Maybe I need to gateway to one Linux box, and then send the stuff for
the other ips it can't handle to the other -- which is a bit retarded from the
perspective of my local lan, but maybe that's the only way to do it. This
will also be an issue also with ham tcp/ip, that is if you had access
to multiple gateways that linked to different subnets. I'm not sure how this
could work on Windows.
>.
------------------------------
Date: 5 Oct 1999 16:46:43 -0700
From: brian@karoshi.ucsd.edu (Brian Kantor)
Subject: Let's look at real numbers for TNC software sales
Cathryn Mataga <cathryn@junglevision.com> wrote:
>
>And in nntp, how does it handle it when people come up with new fields, like
>Pactor@ww or pact@ww -- do you create a new newsgroup for
>each type?
That's a good way to handle it. The left-hand-side of the @ in the old
PBBS addressing format can be thought of as a newsgroup, and the RHS as
a distribution. Or you can swap the two, replace the @ with a dot, and
see it as a hierarchical newsgroup name. Of these two schemes, I prefer
the second one. e.g., you might have a pbbs.ww.pactor newsgroup where
you stuff incoming pact@ww traffic.
There are several Windows NNTP clients out there, but few servers.
Linux, of course, and the various BSD OSs come with INN, which is a
superb NNTP server. Perhaps having one of those accessable by the
To be continued in digest: hd_99_252C
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